NEAR-INFRARED ABSORBING GLASS AND NEAR-INFRARED CUT FILTER

Abstract

The near-infrared absorbing glass, which contains at least four kinds of main cations selected from the group consisting of P ions, Li ions, Cu ions, Al ions, Ba ions, Sr ions, Ca ions, Mg ions, Zn ions, K ions, Na ions, La ions, Gd ions, and Y ions, contains P ions, Li ions, and Cu ions as essential cations, and contains at least O ions as anions, wherein a ratio (O ion/P ion) of a content of O ions relative to a content of P ions is 3.15 or less; in a glass composition indicated by anion %, a content of O ions is 90.0 anion % or more; and in an oxide-based glass composition on a molar basis, a total content of oxides of the main cations is 90.0% or more, and a total content (MgO+Al2O3) of MgO and Al2O3 is 8.0% or less.

Description

TECHNICAL FIELD

The present invention relates to a near-infrared absorbing glass and a near-infrared cut filter

BACKGROUND ART

In recent years, image data obtained from compact cameras such as smartphones is not only digitized, but images are reconfigured by subjecting such image data to a variety of computational processes. For example, it is now common practice to extract a specific object and adjust the color and contrast of an image. During this process, if color data that was not originally present is inputted into an image element as a result of reflection of light in an optical element, this data must be removed, which is not desirable.

Near-infrared cut filters have the function of cutting out unnecessary near-infrared light (which has a wavelength of 700 to 1200 nm) in the sensitive wavelength region of an image element. A near-infrared cut filter is generally provided immediately in front of an image element.

Filters which comprise a near-infrared absorbing glass as a base material and which are polished on a flat plate are widely used as near-infrared cut filters.

Near-infrared absorbing glasses generally contain Cu ions. FIG. 1 shows an example of spectral transmission properties of a near-infrared absorbing glass. However, FIG. 1 in no way limits the present invention. Light absorption characteristics at wavelengths in the vicinity of 700 to 1200 nm are exhibited by Cu ions (Cu²⁺) in the glass. A glass that contains both Cu ions and P ions can exhibit near-infrared absorption characteristics, which are inherent in Cu ions (Cu²⁺), across a broad wavelength range, and is therefore useful as a glass for a near-infrared cut filter (for example, see PTL 1).

CITATION LIST

Patent Literature

[PTL 1] Japanese Patent Application Publication No. 2014-12630

Beyond a wavelength of 600 nm in the transmittance curve in FIG. 1, the wavelength at which the transmittance becomes 50% is known as the “half value”, and is a primary standard for the near-infrared cut filter. The half value varies according to filter specifications, but is often set to fall within the wavelength range of 600 nm to 650 nm. Ordinary methods for setting the half value to be a prescribed value include adjusting the thickness of a glass base material or the concentration of Cu ions (Cu²⁺) in a glass, in accordance with the Beer-Lambert law.

SUMMARY OF INVENTION

Technical Problem

It is required for near-infrared cut filters to exhibit excellent capacity for cutting near-infrared rays (that is, need to have low transmittance of near-infrared light while having a prescribed half value), and is also required to exhibit high transmittance of light in the visible region (the violet region to the red region).

In recent years, image element modules fitted to smartphones and the like have needed to be smaller in size and higher in performance, and the thickness of near-infrared cut filters has needed to be reduced. As a result, the thickness of near-infrared absorbing glasses has been reduced from 1 mm in the past to 0.45 mm, 0.3 mm or 0.2 mm in recent years, and there have been demands for further reductions in thickness to the 0.1 mm level.

Simply reducing the thickness of a near-infrared absorbing glass leads to a reduction in the optical density of CuO (number of moles×thickness), which is required for near-infrared absorption, and this causes a reduction in the efficiency of absorption of near-infrared rays. Increasing the amount of CuO has been considered as a means for solving the above situation. However, simply increasing the amount of CuO means that CuO absorbs visible light close to a wavelength of 600 nm (that is, the red region), and because transmittance on the short wavelength side also tends to decrease, it is difficult to maintain both transmittance of light in the visible region (the violet region to the red region) and absorption of near-infrared rays.

Furthermore, in order to provide a near-infrared cut filter suitable for use in high temperature high humidity environments, it is desirable to suppress a decrease in weathering resistance of a near-infrared absorbing glass in high temperature high humidity environments. According to investigations by the present inventors, however, it is not easy to suppress a decrease in weathering resistance while maintaining both transmittance of light in the visible region (the violet region to the red region) and absorption of near-infrared rays.

With these circumstances in mind, the object of one aspect of the present invention is to provide a near-infrared absorbing glass which exhibits excellent transmittance of light in the visible region (the violet region to the red region) and near-infrared cutting performance even if the thickness of the glass is reduced and which can suppress a decrease in weathering resistance, and also to provide a near-infrared cut filter comprised of this near-infrared absorbing glass.

Solution to Problem

One aspect of the present invention relates to:

• • a near-infrared absorbing glass (hereinafter also referred to as “Glass 1”) which contains at least four kinds of main cations selected from the group consisting of P ions, Li ions, Cu ions, Al ions, Ba ions, Sr ions, Ca ions, Mg ions, Zn ions, K ions, Na ions, La ions, Gd ions, and Y ions,
  • contains P ions, Li ions, and Cu ions as essential cations,
  • and contains at least O ions as anions, wherein:
  • the ratio of the content of O ions relative to the content of P ions (O ion/P ion) is 3.15 or less;
  • in a glass composition indicated by anion %, the content of O ions is 90.0 anion % or more; and
  • in an oxide-based glass composition on a molar basis,
  • the total content of oxides of the main cations is 90.0% or more,
  • the total content of MgO and Al₂O₃(MgO+Al₂O₃) is 8.0% or less,
  • the ratio of the total content of Na₂O, K₂O, and ZnO relative to the content of Li₂O ((Na₂O+K₂O+ZnO)/Li₂O) is 2.4 or less,
  • the total content of B₂O₃ and SiO₂ (B₂O₃+SiO₂) is 3.0% or less, and
  • the content of CuO is α₁% or more,
  • where α₁ is a value calculated by Equation 1 below,

α₁=70400×exp(−2.855×R)  (Equation 1)

• • and in Equation 1 above,
  • R is the ratio (O ion/P ion).

Another aspect of the present invention relates to:

• • a near-infrared absorbing glass (hereinafter also referred to as “Glass 2”) which contains at least four kinds of main cations selected from the group consisting of P ions, Li ions, Cu ions, Al ions, Ba ions, Sr ions, Ca ions, Mg ions, Zn ions, K ions, Na ions, La ions, Gd ions, and Y ions,
  • contains P ions, Li ions, and Cu ions as essential cations,
  • and contains at least O ions as anions, wherein:
  • the ratio of the content of O ions relative to the content of P ions (O ion/P ion) is 3.15 or less;
  • in a glass composition indicated by anion %, the content of O ions is 90.0 anion % or more; and
  • in an oxide-based glass composition on a molar basis,
  • the total content of oxides of the main cations is 90.0% or more,
  • the total content of MgO and Al₂O₃(MgO+Al₂O₃) is 8.0% or less,
  • the ratio of the total content of Na₂O, K₂O, and ZnO relative to the content of Li₂O ((Na₂O+K₂O+ZnO)/Li₂O) is 2.4 or less,
  • the total content of B₂O₃ and SiO₂ (B₂O₃+SiO₂) is 3.0% or less, and which satisfies Equation 2 below:

C−3200×exp(−2.278×R)≥0  (Equation 2)

• • and in Equation 2 above,
  • C is the content of CuO (units: mmol/cc) per molar volume of the glass, and
  • R is the ratio (O ion/P ion).

Another aspect of the present invention relates to:

• • a near-infrared absorbing glass (hereinafter also referred to as “Glass 3”) which contains at least four kinds of main cations selected from the group consisting of P ions, Li ions, Cu ions, Al ions, Ba ions, Sr ions, Ca ions, Mg ions, Zn ions, K ions, Na ions, La ions, Gd ions, Y ions, B ions and Si ions,
  • contains P ions, Li ions, and Cu ions as essential cations,
  • and contains at least O ions as anions, wherein:
  • the ratio of the content of O ions relative to the content of P ions (O ion/P ion) is 3.15 or less;
  • in a glass composition indicated by anion %, the content of O ions is 90.0 anion % or more; and
  • in an oxide-based glass composition on a molar basis,
  • the total content of oxides of the main cations is 90.0% or more,
  • the total content of MgO and Al₂O₃(MgO+Al₂O₃) is 8.0% or less,
  • the ratio of the total content of Na₂O, K₂O, and ZnO relative to the content of Li₂O ((Na₂O+K₂O+ZnO)/Li₂O) is 2.4 or less,
  • A, which is calculated by Equation 3 below, is 2500 or more,

A₁={O(P)−O(others)}×Cu  (Equation 3)

• • and in Equation 3 above,
  • O(P) denotes the amount of oxygen that constitutes the oxide of P ions in the oxide-based glass composition,
  • O(others) denotes the amount of oxygen determined by subtracting the value of O(P) from the amount of oxygen that constitutes the oxides of the main cations in the oxide-based glass composition, and
  • Cu denotes the content of CuO on a molar basis in the oxide-based glass composition.

Another aspect of the present invention relates to:

• • a near-infrared absorbing glass (hereinafter also referred to as “Glass 4”) which contains at least four kinds of main cations selected from the group consisting of P ions, Li ions, Cu ions, Al ions, Ba ions, Sr ions, Ca ions, Mg ions, Zn ions, K ions, Na ions, La ions, Gd ions, Y ions, B ions and Si ions,
  • contains P ions, Li ions, and Cu ions as essential cations,
  • and contains at least O ions as anions, wherein:
  • the ratio of the content of O ions relative to the content of P ions (O ion/P ion) is 3.15 or less;
  • in a glass composition indicated by anion %, the content of O ions is 90.0 anion % or more; and
  • in an oxide-based glass composition on a molar basis,
  • the total content of oxides of the main cations is 90.0% or more,
  • the total content of MgO and Al₂O₃(MgO+Al₂O₃) is 8.0% or less,
  • the ratio of the total content of Na₂O, K₂O, and ZnO relative to the content of Li₂O ((Na₂O+K₂O+ZnO)/Li₂O) is 2.4 or less, A₂, which is calculated by Equation 4 below, is 700 or more,

A₂={O(P)−O(others)}×C  (Equation 4)

• • and in Equation 4 above,
  • C is the content of CuO (units: mmol/cc) per molar volume of the glass,
  • O(P) denotes the amount of oxygen that constitutes the oxide of P ions in the oxide-based glass composition, and
  • O(others) denotes the amount of oxygen determined by subtracting the value of O(P) from the amount of oxygen that constitutes the oxides of the main cations in the oxide-based glass composition.

One aspect of the present invention relates to:

• • a near-infrared absorbing glass (hereinafter also referred to as “Glass 5”) which contains at least four kinds of main cations selected from the group consisting of P ions, Li ions, Cu ions, Al ions, Ba ions, Sr ions, Ca ions, Mg ions, Zn ions, K ions, Na ions, La ions, Gd ions, and Y ions,
  • contains P ions, Li ions, and Cu ions as essential cations,
  • and contains at least O ions as anions, wherein:
  • the ratio of the content of O ions relative to the content of P ions (O ion/P ion) is 3.15 or less;
  • in a glass composition indicated by anion %, the content of O ions is 90.0 anion % or more; and
  • in an oxide-based glass composition on a molar basis,
  • the total content of oxides of the main cations is 90.0% or more,
  • the total content of MgO and Al₂O₃(MgO+Al₂O₃) is 8.0% or less,
  • the ratio of the total content of Na₂O, K₂O, and ZnO relative to the content of Li₂O ((Na₂O+K₂O+ZnO)/Li₂O) is 2.4 or less,
  • the content of CuO is α₂% or more,
  • where α₂ is a value calculated by Equation 5 below

α₂=(76522)×exp(−2.855×R)  (Equation 5)

• • and in Equation 5 above,
  • R is the ratio (O ion/P ion).

Another aspect of the present invention relates to:

• • a near-infrared absorbing glass (hereinafter also referred to as “Glass 6”) which contains at least four kinds of main cations selected from the group consisting of P ions, Li ions, Cu ions, Al ions, Ba ions, Sr ions, Ca ions, Mg ions, Zn ions, K ions, Na ions, La ions, Gd ions, and Y ions,
  • contains P ions, Li ions, and Cu ions as essential cations,
  • and contains at least O ions as anions, wherein
  • the ratio of the content of O ions relative to the content of P ions (O ion/P ion) is 3.15 or less;
  • in a glass composition indicated by anion %, the content of O ions is 90.0 anion % or more; and
  • in an oxide-based glass composition on a molar basis,
  • the total content of oxides of the main cations is 90.0% or more,
  • the total content of MgO and Al₂O₃ (MgO+Al₂O₃) is 8.0% or less,
  • the ratio of the total content of Na₂O, K₂O, and ZnO relative to the content of Li₂O ((Na₂O+K₂O+ZnO)/Li₂O) is 2.4 or less, and
  • which satisfies Equation 6 below:

C−(3478)×exp(−2.278×R)≥0  (Equation 6)

• • and in Equation 6 above,
  • C is the content of CuO (units: mmol/cc) per molar volume of the glass, and
  • R is the ratio (O ion/P ion).

Effects of Invention

According to one aspect of the present invention, it is possible to provide a near-infrared absorbing glass which exhibits excellent transmittance of light in the visible region (the violet region to the red region) and near-infrared cutting performance even if the thickness of the glass is reduced and which can suppress a decrease in weathering resistance. According to a further aspect of the present invention, it is possible to provide a near-infrared cut filter comprised of the above near-infrared absorbing glass.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows an example of spectral transmission properties of a near-infrared absorbing glass.

DESCRIPTION OF EMBODIMENTS

[Near-Infrared Absorbing Glass]

Hereinafter, Glasses 1 to 6 are also collectively referred to simply as “glass” or “near-infrared absorbing glass”. Unless explicitly stated otherwise, statements relating to the composition and physical properties of glasses apply to all of Glasses 1 to 6.

In the present invention and the present description, the term “near-infrared absorbing glass” means a glass having the property of absorbing at least light in all or part of the near-infrared wavelength region (wavelengths of 700 to 1200 nm). In addition, the near-infrared absorbing glass according to one aspect of the present invention can be an oxide glass because the glass contains O ions as constituent ions. An oxide glass is a glass in which the main network-forming components of the glass are oxides. Furthermore, the near-infrared absorbing glass according to one aspect of the present invention can be a phosphate glass because the glass contains O ions (anions) and P ions (cations) as constituent ions. O ions are anions of oxygen atoms, and are commonly referred to as oxide ions.

Detailed explanations will now be given for Glasses 1 to 6.

<Glass Composition>

(Analysis Methods)

For components that constitute a glass, the content values of elements (mass percentages of elements) contained in the glass can be quantified using well-known methods, for example inductively coupled plasma-atomic emission spectrometry (ICP-AES) or inductively coupled plasma-mass spectrometry (ICP-MS).

Anion components contained in a glass can be identified and quantified using well-known analysis methods, for example ion chromatography methods or non-dispersive infrared absorption methods (ND-IR).

In the present invention and the present description, a case where a constituent component has a content of 0% or is not contained or introduced means that this constituent component is substantially not contained and that this constituent component may be contained at an unavoidable impurity level.

(Representation of Oxide-Based Glass Composition)

Based on results obtained using the analyses mentioned above, it is possible to calculate content values (units: mol %) of components in the oxide-based glass composition. Specific methods are as follows.

By dividing the content of an element i (the mass percentage P_i of the element), which is obtained using an analysis method mentioned above, by the atomic weight M_i of the element, the number of moles n_i (=P_i/M_i) of the element is determined.

In a case where the above element i is a cation component A_i, the thus obtained number of moles n_i of the element is replaced by the number of moles n′_i of the corresponding oxide. Specifically, if the compositional formula of the oxide of the cation component A_i corresponding to the element i is represented by A_ixOy, then n′_i=n_i/x.

In a case where the above element i is an anion component B_i other than an O ion, the number of moles n_i of the corresponding element is denoted by m_i hereinafter.

The content PA_i (mol %) of the oxide A_ixOy of the cation component A_i in the oxide-based glass composition is represented by:

PA_i=n′_i/(Σn′_i+Σm_i)×100

Content values in the oxide-based glass composition can also be referred to as oxide-based proportions.

In the oxide-based glass composition, the oxide-based proportion PBi (mol %) of an anion component B_i other than an O ion is represented by:

PB_i=m_i/(Σn′_i+Σm_i)×100

Here, Σn′_i is the total number of moles of oxides AixOy of cation components contained in the glass. However, depending on the number of significant figures in content values, ignoring trace components does not affect calculation results.

(Anion %)

“Anion %” is a value calculated as “(content, indicated by mol %, of anion i in question)/(total number, indicated by mol %, of anions contained in glass)×100”, and refers to the molar ratio of the amount of the anion in question relative to the total amount of anions.

Based on the explanation above of the representation of the oxide-based glass composition, the anion % of O ions can be calculated as

(ΣO_i−Σ(N_k/2)B_k)/(ΣO_i−Y(N_k/2)B_k+ΣB_k)×100

• • where the compositional formula of an oxide of component A_i that corresponds to the element i is represented by A_ixOy, the number of O contained in an oxide of a cation component A_i is denoted by O_i=PA_i×y using the oxide-based proportion PA_i (mol %) of the cation component A_i, and the valency of an anion component B_k is denoted by N_k,

Here, ΣO_i is the total number of moles of O ions in the oxide-based glass composition, and Σ(N_k/2)B_k denotes the number of moles of O ions replaced by the anion component B_k. The numerator of the formula, (ΣO_i−Σ(N_k/2)B_k), is the number of moles of O ions contained in the glass.

Meanwhile, with regard to the content of oxygen in the present invention and the present description, if anion components other than oxygen are not detected by analysis using well-known methods, all anion components (that is, 100 anion %) are taken to be O ions.

(Cation Component)

The nominal valency of each cation is used as the valency of the cation component. The nominal valency of the cation in question is the valency required in order for the oxide of the cation to be electrically neutral when the valency of the O ion that constitutes the oxide is taken to be −2, and the nominal valency can be definitively determined from the chemical formula of the oxide.

For example, in the case of a Cu ion, the valency of Cu is +2 in order for O²⁻ and Cu contained in the chemical formula of the oxide CuO to be electrically neutral. For example, in the case of a P ion, the valency of P is +2×5/2=+5 in order for O²⁻ and P contained in the chemical formula of the oxide P₂O₅ to be electrically neutral. If this is generalized, the nominal valency of the cation Ai contained in the oxide AixOy is “+2y/×”. Therefore, when the glass composition is analyzed, the valency of cations need not be analyzed.

In addition, the valency of an anion (for example, the valency of an O ion is −2) is the nominal valency based on the understanding that an O ion receives 2 electrons to attain a closed shell structure. Therefore, when the glass composition is analyzed, the valency of anions need not be analyzed. In addition, some Cu²⁺ may become Cu⁺ upon melting, but because the amount thereof is generally small, the valency of all the Cu can be taken to be +2.

(Anion Component)

The above glass contains at least O ions as anions, and the content thereof is 90.0 anion % or more in the glass composition indicated by anion %. The present inventors considered that if the O/P ratio is lowered in a glass containing mainly O ions as anions as described above, absorption by CuO in the red region can be shifted to the long wavelength side, and it is therefore possible to increase the content of CuO and improve near-infrared cutting performance without lowering the transmittance of light in the red region. The content of O ions in the glass composition, if expressed in terms of anion %, is 90.0% or more, preferably 95.0% or more, more preferably 98.0% or more, and further preferably 99.0% or more. A high proportion of O ions in the anion component is also preferable from the perspective of suppressing volatilization when the glass melts. Suppressing volatilization when the glass melts is preferable from the perspective of suppressing the occurrence of striation. It is particularly preferable for the content of O ions to be 100% from the perspectives of suppressing volatilization when the glass melts, increasing productivity and suppressing the generation of harmful gases during production. The nominal valency of an O ion is −2.

The above glass can contain only 0 ions as anions in one embodiment, and can contain O ions and one or more other types of anion in another embodiment. Examples of other anions include F ions, Cl ions, Br ions and I ions. The nominal valency of F ions, Cl ions, Br ions and I ions is −1.

From the perspectives of improving the uniformity and strength of the glass, the content of F ions in the glass composition, if expressed in terms of anion %, is preferably 15.0 anion % or less, more preferably 10.0 anion % or less, further preferably 5.0 anion % or less, yet more preferably 2.0 anion % or less, and further preferably 1.0 anion % or less. It is particularly preferable for the glass to contain no F ions from the perspectives of suppressing volatilization when the glass melts, increasing productivity and suppressing the generation of harmful gases during production.

(O/P Ratio)

The molar ratio of the content of cations and the content of anions is the ratio of the content (expressed in mol %) of components in question, where the total amount of all cation components and all anion components is taken to be 100 mol %. Therefore, the ratio of the content of O ions relative to the content of P ions (O ions/P ions) is the ratio of the content of O ions (expressed in mol %) relative to the content of P ions (expressed in mol %), where the total amount of all cation components and all anion components is taken to be 100 mol %.

O/P Ratio Calculation Method 1

With regard to the O/P ratio (also denoted by R), the O/P ratio based on the explanation above of the representation of oxide-based glass composition can be determined from:

R1=ΣO_i−Σ(N_k/2)B_k  Equation D1:

R2=proportion (mol %) based on oxide of P ions (that is, P₂O₅)×2  Equation D2:

• • where the compositional formula of an oxide of component A that corresponds to the element i is represented by AixOy, the number of O contained in an oxide of a cation component Ai is denoted by O_i=PA_ixy using the oxide-based proportion PAi (mol %) of the cation component Ai, and the valency of an anion component B_k is denoted by N_k,
  • and the O/P ratio (R) can be determined from:

R=R1/R2  Equation D3:

For example, in an explanation using Comparative Example A below as an example, content values, if expressed in mol %, in the oxide-based glass composition of Comparative Example A are P₂O₅=53.59, Li₂O=19.30 and CuO=27.11. The number of O in these molecular formulae are 5 in P₂O₅, 1 in Li₂O and 1 in CuO. The number of moles of O in these molecular formulae are 267.95 in P₂O₅, 19.30 in Li₂O and 27.11 in CuO.

The O/P ratio in the glass in this example can be determined in the following way.

The number N_S of O ions is determined in the molecular formula of the glass: 53.59P₂O₅-19.30Li₂O-27.11 CuO. The molecular formula of the glass is the compositional formula of the glass expressed in such a way that the total amount of molecules contained in the glass is 100.

That is, using the numbers of O ions contained in the molecular formula MxOy of the oxides (5 in P₂O₅, 1 in Li₂O, and 1 in CuO),

• • the value of N_S is calculated as:

N_S=53.59×5+19.30×1+27.11×2=314.36

In the glass in the example mentioned above, because the amount of O ions replaced by other anions in the molecular formula of the glass is O, by dividing this N_S value (314.36) by the number of moles of P contained in P₂O₅ (53.59)×2, the O/P ratio can be determined as 314.36/(53.59×2)=2.93.

O/P Ratio Calculation Method 2

In a case where one or more types of anion component other than oxygen are detected in analysis using a well-known method, the content of oxygen can be the content (units: anion %) calculated using a method shown in section (3) below from (1) the content of cations based on the valency of cation components contained in the glass and the molar percentages of elements, and (2) the content of anions based on the valency of anion components other than oxygen and the molar percentages of elements.

That is, based on results of identification and quantification analysis using a well-known method,

• • (1) the total U of “the content of cations based on the number of oxygens per cation (y/x)×molar percentages of elements, where the number of oxygens is denoted by y and the number of cations is denoted by x in an oxide MxOy” is calculated for cation components contained in the glass,
  • (2) the total V of “content of anions based on molar percentages of elements×number of substituted oxygens (z/2) per anion” is calculated for anion components other than oxygen based on results of identification and quantification analysis using well-known methods and the valency z of anions, and
  • (3) the value of U-V can also be used as the content of O ions relative to the content of the P ions.

Calculation example 1 and calculation example 2 below are given as examples of calculation method 2.

Calculation example 1: when the molar percentages of elements of P ions, Li ions and Cu ions were quantitatively determined as 22.0, 8.0 and 5.5 (content values expressed as molar percentages of elements), the values of y/x in the corresponding oxides (P₂O₅, Li₂O and CuO) are 2.5, 0.5 and 1.0 respectively,

• • the value of U is 22×2.5+8×0.5+5.5×1.0=64.5, and
  • the value of V is 0.

Therefore, the molar percentage of O ions based on the molar percentages of these elements is 64.5 (content expressed as molar percentage of element).

From the ratio of the value for O ions determined in this way and the analyzed molar percentage of P ions, the O/P ratio can be determined as 64.5/22=2.93 . . . .

Calculation example 2: when the molar percentages of elements of P ions, Li ions and Cu ions were quantitatively determined as 22.0, 8.0 and 5.5 (content values expressed as molar percentages of elements) and the molar percentage of the element in F ions was quantitatively determined as 4.0 (a content value expressed as the molar percentage of the element), the values of y/x in the corresponding oxides (P₂O₅, Li₂O and CuO) are 2.5, 0.5 and 1.0 respectively, and because the valency of F is −1,

• • the value of U is 22×2.5+8×0.5+5.5×1.0=64.5, and
  • the value of V is 4×½=2.

Therefore, the molar percentage of O ions based on the molar percentages of these elements is 62.5 (content expressed as molar percentage of element).

From the ratio of the value for O ions determined in this way and the analyzed molar percentage of P ions, the O/P ratio can be determined as 62.5/22=2.84 . . . .

In Glasses 1 to 6, the ratio (O/P ratio) of the content of O ions relative to the content of P ions is 3.15 or less from the perspective of achieving both improved transmittance of light in the visible region and improved near-infrared cutting performance and also from the perspective of improving the thermal stability of the glass.

In Glasses 1 to 6, the O/P ratio is preferably 3.14 or less, and is more preferably 3.13 or less, 3.12 or less, 3.11 or less, 3.10 or less, 3.09 or less, 3.08 or less, 3.07 or less, 3.06 or less, 3.05 or less, 3.04 or less, 3.03 or less, 3.02 or less, 3.01 or less, or 3.00 or less in that order.

On the other hand, the O/P ratio in Glasses 1 to 6 is preferably high from the perspectives of improving weathering resistance and/or suppressing a decrease in meltability. From this perspective, the O/P ratio in Glasses 1 to 6 is preferably 2.50 or more, and is more preferably 2.60 or more, 2.65 or more, 2.70 or more, 2.73 or more, 2.75 or more, 2.77 or more, 2.80 or more, 2.81 or more, 2.82 or more, 2.83, 2.84 or more, or more, 2.85 or more, 2.86 or more, 2.87 or more, 2.88 or more, 2.89 or more, or 2.90 or more in that order.

(Cation Component)

Glasses 1 to 6 contain at least four kinds of main cations selected from the group consisting of P ions, Li ions, Cu ions, Al ions, Ba ions, Sr ions, Ca ions, Mg ions, Zn ions, K ions, Na ions, La ions, Gd ions, and Y ions, and contain P ions, Li ions and Cu ions as essential cations. In the oxide-based glass composition (on a molar basis) of Glasses 1 to 6, the total content of oxides of the main cations is 90.0 mol % or more.

In Glasses 1 to 6, the total content of oxides of the main cations being 90.0% or more can contribute to an improvement in thermal stability of the glasses and/or an improvement in the optical uniformity of the glass by suppressing striation, volatilization, and the like. From the above perspective, the total content of oxides of the main cations in Glasses 1 to 6 is preferably 92.0% or more, is more preferably 93.0% or more, 95.1% or more, 96.1% or more, 97.1% or more, 98.1 or more, 98.6% or more, 99.1% or more, or 99.6% or more in that order, and can be 100%. In one embodiment, the total content of oxides of the main cations in Glasses 1 to 6 can be 100% or less, 99.5% or less, 99% or less, 98.5% or less, 98.0% or less, or 97.5% or less.

An explanation will now be given of the content of a cation component as the content (on a molar basis) in the oxide-based glass composition.

Because CuO is an essential component for imparting near-infrared cutting performance to the glass, Glasses 1 to 6 contain Cu ions as essential cations.

In Glass 1, the content of CuO is a1% or more. α₁ can be calculated from Equation 1 below.

α₁=70400×exp(−2.855×R)  (Equation 1)

In Equation 1, R is the O/P ratio.

In Glass 2, the lower limit for the content of CuO is defined by Equation 2 below from the content of CuO per molar volume of the glass.

C−3200×exp(−2.278×R)≥0  (Equation 2)

In Equation 2, C is the content of CuO (units: mmol/cc) per molar volume of the glass, and R is the O/P ratio.

In Equation 2, the value of C is determined using the following method.

C can be calculated as:

C=mol % of CuO/(M/D)×1000 (units: mmol/cc)

• • by measuring the specific gravity D (g/cc) of the glass, determining the mass per mole of the glass composition, that is, the molar molecular weight M (g/mol), on the basis of the glass composition obtained through analysis in the manner described above, and determining the molar volume M/D (units: cc/mol) of the glass.

The molar molecular weight M mentioned above can be calculated as

M={Σ(PA_i×MA_i)+Σ(PB_k×MB_k)−Σ(N_k/2)Mo}/ΣPA_i

• • where the formula weight of an oxide corresponding to the cation component Ai mentioned above is denoted by MA_i, the atomic weight of the anion component B_k is denoted by MB_k, and the atomic weight of oxygen is denoted by Mo, based on the explanation above of the representation of the oxide-based glass composition

For example, if the glass composition is constituted from s mol % of a component A₂O on an oxide basis, t mol % of a component BO on an oxide basis and u mol % of a component F, the value of s+t+u is 100(%), the formula weight of the component A₂O is M_A (g/mol), the formula weight of the component BO is M_B (g/mol), the atomic weight of F is M_F (g/mol), and the atomic weight of oxygen is M_O (g/mol), then

M=(s×M_A+t×M_B+u×M_F−u/2×M_O)/(s+t)

For example, the molar molecular weight M of Comparative Example A below (in which content values expressed as molar percentages in the oxide-based glass composition are P₂O₅=53.59, Li₂O=19.30 and CuO=27.11) can be calculated as: M=(53.59×141.94+19.30×29.88+27·11×79.55)/(53.59+19.30+27.11)=103.40 (g/mol) using:

Formula weight of P₂O₅: 141.94 (g/mol)

Formula weight of Li₂O: 29.88 (g/mol)

Formula weight of CuO: 79.55 (g/mol)

As a result of extensive research by the present inventors, it was newly found that by lowering the O/P ratio in a glass containing mainly O ions as anions, absorption by CuO in the red region can be shifted to the long wavelength side, thereby suppressing a reduction in the transmittance of light in the red region and enabling the content of CuO to be increased. The present inventors also newly found that there is a strong correlation between the O/P ratio and the content of CuO, which is required in order to achieve a prescribed half value at a prescribed thickness, and the lower limit for the content of CuO (α₁, α₂) is specified by Equation 1 for Glass 1, in which the O/P ratio falls within the range mentioned above, and by Equation 5 for Glass 5. In addition, for a glass in which the O/P ratio falls within the range mentioned above, the content of CuO per molar volume of the glass is specified by Equation 2, and for Glass 6, the content of CuO per molar volume of the glass is specified by Equation 6.

In Glass 3, the content of CuO is defined on the basis of A₁, which is calculated from Equation 3 below, and the value of A₁ is 2500 or more.

A₁={O(P)−O(others)}×Cu  (Equation 3)

In equation 3, O(P) denotes the amount of oxygen that constitutes the oxide of P ions in the oxide-based glass composition, O(others) denotes the amount of oxygen determined by subtracting the value of O(P) from the amount of oxygen that constitutes the oxides of the main cations already mentioned in Glass 3 in the oxide-based glass composition, and Cu denotes the content of CuO on a molar basis in the oxide-based glass composition.

In Equation 3, “O(P)” is calculated in the following way.

If the content (on a molar basis) of P₂O₅ in the oxide-based glass composition is denoted by M mol %, the value of O(P) is calculated as “O(P)=M×5” using the number of oxygens (5) included in the chemical formula P₂O₅.

Similarly, for main cations other than P ions, the amount of oxygen that constitutes the oxides of these cations is calculated using the content values of the oxides (on a molar basis) in the oxide-based glass composition and the number of oxygens contained in the oxides formed in a state where the cations have nominal valencies.

The value of “O(others)” is calculated as a value obtained by subtracting the value of O(P) from the total amount of oxygen calculated for the oxides of the main cations.

If the content of CuO (on a molar basis) in the oxide-based glass composition is denoted by N mol %, the value of “A” is calculated as A₁={O(P)−O(others)}×N. As mentioned above, the present inventors newly found that by lowering the O/P ratio in a glass containing mainly O ions as anions, absorption by CuO in the red region can be shifted to the long wavelength side, thereby suppressing a reduction in the transmittance of light in the red region and enabling the content of CuO to be increased. It was also newly found that by using a chemical species which has a smaller ionic radius and a lower valency as a chemical species other than P—O that coordinates to CuO, it is possible to increase transmittance in the visible light region (the violet region to the red region) as a result of features 1) and 2) below. In view of these findings, the content of CuO in Glass 3 is defined on the basis of A, which is calculated from Equation 3.

1) By shifting absorption derived from Cu²⁺ to the long wavelength side, it is possible to increase the transmittance of light in the red region.

2) By enabling the glass to be in a liquid phase state at a low temperature, it is possible to suppress the generation of Cu₊, which exhibits absorption of light in the violet region close to a wavelength of 400 nm.

For Glass 3, the value of A₁ is 2500 or more, is preferably 2800 or more, and is more preferably 2900 or more, 3000 or more, 3100 or more, 3200 or more, 3300 or more, 3400 or more, 3500 or more, 3600 or more, 3700 or more, 3800 or more, 3900 or more, 4000 or more, 4100 or more, 4200 or more, 4300 or more, 4400 or more, 4500 or more, 4600 or more, 4700 or more, 4800 or more, 4900 or more, 5000 or more, 5100 or more, 5200 or more, 5300 or more, 5400 or more, 5500 or more, 5600 or more, 5700 or more, 5800 or more, 5900 or more, 6000 or more, 6100 or more, 6200 or more, 6300 or more, 6400 or more, or 6500 or more in that order from the perspective of achieving both improved transmittance of light in the visible region and improved near-infrared cutting performance. On the other hand, from the perspectives of suppressing a decrease in the thermal stability of the glass due to a high content of Cu and O, suppressing a decrease in transmittance at a desired half value wavelength and/or suppressing a decrease in thermal stability or weathering resistance of the glass due to an excessively low O(others) value, the value of A is preferably 20000 or less, and is more preferably 19000 or less, 18000 or less, 17000 or less, 16000 or less, 150000 or less, 14000 or less, 13000 or less, 12000 or less, 11000 or less, 10000 or less, 9000 or less, or 8000 or less. In order to achieve a desired half value at a lower thickness, it tends to be desirable for this numerical value to be high.

In Glass 4, the content of CuO is defined on the basis of A₂, which is calculated from Equation 4 below, and the value of A₂ is 700 or more.

A₂={O(P)−O(others)}×C  (Equation 4)

In Equation 4, C is the content of CuO (units: mmol/cc) per molar volume of the glass. O(P) denotes the amount of oxygen that constitutes the oxide of P ions in the oxide-based glass composition, and O(others) denotes the amount of oxygen determined by subtracting the value of O(P) from the amount of oxygen that constitutes the oxides of the above main cations in the oxide-based glass composition.

For Glass 4, the value of A₂ is 700 or more, is preferably 800 or more, and is more preferably 850 or more, 890 or more, 1000 or more, 1100 or more, 1200 or more, 1300 or more, 1400 or more, 1500 or more, 1600 or more, 1700 or more, or 1800 or more in that order from the perspective of achieving both improved transmittance of light in the visible region and improved near-infrared cutting performance. On the other hand, from the perspectives of suppressing a decrease in the thermal stability of the glass due to a high content of Cu and O, suppressing a decrease in transmittance at a desired half value wavelength and/or suppressing a decrease in thermal stability or weathering resistance of the glass due to an excessively low O(others) value, the value of A₂ is preferably 5000 or less, and is more preferably 4000 or less, 3500 or less, 3000 or less, 2500 or less, or 2000 or less. In order to achieve a desired transmittance half value at a lower thickness, it tends to be desirable for this numerical value to be high.

In addition, in Glass 5, the content of CuO is a2% or more. α₂ can be calculated from Equation 5 below.

α₂=76522×exp(−2.855×R)  (Equation 5)

In Equation 5, R is the O/P ratio.

In addition, in Glass 6, the lower limit for the content of CuO is defined by Equation 6 below from the content of CuO per molar volume of the glass.

C−3478×exp(−2.278×R)≥0  (Equation 6)

In Equation 6, C is the content of CuO (units: mmol/cc) per molar volume of the glass, and R is the O/P ratio.

The content of CuO in the oxide-based glass composition (on a molar basis) of Glasses 1 to 6 is preferably 4.0% or more, and is more preferably 5.0% or more, 6.0% or more, 7.0% or more, 7.5% or more, 8.0% or more, 8.5% or more, 9.0% or more, 9.5% or more, 10.0% or more, 10.5% or more, 11.0% or more, 11.5% or more, 12.0% or more, 12.5% or more, 13.0% or more, 13.5% or more, 14.0% or more, 14.5% or more, 15.0% or more, 15.5% or more, 16.0% or more, 16.5% or more, 17.0% or more, 17.5% or more, 18.0% or more, 18.5% or more, 19.0% or more, 19.5% or more, or 20.0% or more in that order. From the perspectives of leaving room for introduction of glass-forming components and maintaining the thermal stability of the glass, the content of CuO is preferably 48.0% or less, and is more preferably 47.0% or less, 46.0% or less, 45.0% or less, 44.0% or less, 43.5% or less, 43.0% or less, 42.5% or less, 42.0% or less, 41.5% or less, 41.0% or less, 40.5% or less, 40.0% or less, 39.5% or less, 39.0% or less, 38.5% or less, 38.0% or less, 37.5% or less, 37.0% or less, 36.5% or less, 36.0% or less, 35.5% or less, 35.0% or less, 34.5% or less, 34.0% or less, 33.5% or less, 33.0% or less, 32.5% or less, 32.0% or less, 31.5% or less, or 31.0% or less in that order.

As a transmittance characteristic calculated at a thickness of 0.11 mm, in order for the wavelength Δ_T50, at which the external transmittance including reflection losses becomes 50%, to fall within the range 600 nm to 650 nm, the content of CuO in the oxide-based glass composition (on a molar basis) is preferably 15.0% or more, and is more preferably 15.5% or more, 16.0% or more, 16.5% or more, 17.0% or more, 17.5% or more, 18.0% or more, 18.5% or more, 19.0% or more, 19.5% or more, or 20.0% or more in that order.

As a transmittance characteristic calculated at a thickness of 0.21 mm, in order for the wavelength Δ_T50, at which the external transmittance including reflection losses becomes 50%, to fall within the range 600 nm to 650 nm, the content of CuO in the oxide-based glass composition (on a molar basis) is preferably 10.0% or more, and is more preferably 10.5% or more, 11.0% or more, 11.5% or more, 12.0% or more, 12.5% or more, 13.0% or more, 13.5% or more, 14.0% or more, 14.5% or more, 15.0% or more, 15.5% or more, 16.0% or more, 16.5% or more, 17.0% or more, 17.5% or more, 18.0% or more, 18.5% or more, 19.0% or more, 19.5% or more, or 20.0% or more in that order.

As a transmittance characteristic calculated at a thickness of 0.25 mm, in order for the wavelength Δ_T50, at which the external transmittance including reflection losses becomes 50%, to fall within the range 600 nm to 650 nm, the content of CuO in the oxide-based glass composition (on a molar basis) is preferably 10.0% or more, and is more preferably 10.5% or more, 11.0% or more, 11.5% or more, 12.0% or more, 12.5% or more, 13.0% or more, 13.5% or more, 14.0% or more, 14.5% or more, 15.0% or more, 15.5% or more, 16.0% or more, 16.5% or more, 17.0% or more, 17.5% or more, 18.0% or more, 18.5% or more, 19.0% or more, 19.5% or more, or 20.0% or more in that order.

On the other hand, because the transmittance characteristic calculated at a thickness of 0.25 mm is such that the wavelength Δ_T50, at which the external transmittance including reflection losses becomes 50%, may be lower than 600 nm if the content of CuO is too high, the content of CuO is preferably 35.0% or less, and is more preferably 34.0% or less, 33.0% or less, 32.0% or less, 31.0% or less, 30.0% or less, 29.5% or less, 29.0% or less, 28.5% or less, 28.0% or less, 27.5% or less, 27.0% or less, 26.5% or less, 26.0% or less, 25.5% or less, 25.0% or less, 24.5% or less, 24.0% or less, 23.5% or less, 23.0% or less, 22.5% or less, 22.0% or less, 21.5% or less, 21.0% or less, 20.5% or less, or 20.0% or less in that order.

In order for the glass thickness at which the wavelength Δ_T50, at which the external transmittance including reflection losses becomes 50% at a wavelength of 550 nm or longer, is 645 nm to be 0.25 mm or less, the content of CuO in the oxide-based glass composition (on a molar basis) is preferably 10.0% or more, and is more preferably 10.5% or more, 11.0% or more, 11.5% or more, 12.0% or more, 12.5% or more, 13.0% or more, 13.5% or more, 14.0% or more, 14.5% or more, 15.0% or more, 15.5% or more, 16.0% or more, 16.5% or more, 17.0% or more, 17.5% or more, 18.0% or more, 18.5% or more, 19.0% or more, 19.5% or more, or 20.0% or more in that order.

In order for the glass thickness at which the wavelength Δ_T50, at which the external transmittance including reflection losses becomes 50% at a wavelength of 550 nm or longer, is 633 nm to be 0.25 mm or less, the content of CuO in the oxide-based glass composition (on a molar basis) is preferably 10.5% or more, and is more preferably 11.0% or more, 11.5% or more, 12.0% or more, 12.5% or more, 13.0% or more, 13.5% or more, 14.0% or more, 14.5% or more, 15.0% or more, 15.5% or more, 16.0% or more, 16.5% or more, 17.0% or more, 17.5% or more, 18.0% or more, 18.5% or more, 19.0% or more, 19.5% or more, or 20.0% or more in that order.

In Glass 2 and Glass 4, the value of C is preferably 3.0 or more, and is more preferably 3.1 or more, 3.3 or more, 3.5 or more, 3.7 or more, 3.9 or more, 4.0 or more, 4.1 or more, 4.2 or more, 4.3 or more, 4.4 or more, 4.5 or more, 4.6 or more, 4.7 or more, 4.8 or more, 4.9 or more, 5.0 or more, 5.1 or more, 5.2 or more, 5.3 or more, 5.4 or more, or 5.5 or more in that order. From the perspectives of leaving room for introduction of glass-forming components and maintaining the thermal stability of the glass, the value of C is preferably 16.0 or less, and is more preferably 15.0 or less, 14.0 or less, 13.5 or less, 13.0 or less, 12.5 or less, 12.0 or less, 11.9 or less, 11.8 or less, 11.7 or less, 11.6 or less, 11.5 or less, 11.4 or less, 11.3 or less, 11.2 or less, 11.1 or less, 11.0 or less, 10.9 or less, 10.8 or less, 10.7 or less, 10.6 or less, 10.5 or less, 10.4 or less, 10.3 or less, 10.2 or less, 10.1 or less, 10.0 or less, 9.9 or less, 9.8 or less, 9.7 or less, 9.6 or less, 9.5 or less, 9.4 or less, 9.3 or less, 9.2 or less, 9.1 or less, 9.0 or less, 8.9 or less, 8.8 or less, 8.7 or less, 8.6 or less, or 8.5 or less in that order.

In Glasses 1 to 6, the content of CuO can be a3% or more. α₃ can be calculated from Equation 7 below.

α₃=(70400×0.25/d)×exp(−2.855×R)  (Equation 7)

In Equation 7, R is the O/P ratio. The value of d can be more than 0 and not more than 0.25. For example, the value of d can be 0.25, 0.24, 0.23, 0.22, 0.21, 0.20, 0.19, 0.18, 0.17, 0.16, 0.15, 0.14, 0.13, 0.12, 0.11, 0.10, 0.09, 0.08, 0.07, 0.06, 0.05, 0.04, 0.03, 0.02, 0.01, and the like. However, the value of d is not limited to these values. In order to achieve a desired transmittance half value at a lower thickness, it tends to be desirable for the value of d to be low.

For example, if d=0.11, the content of CuO can be a3% or more, and the value of a3 is calculated from the equation below.

α₃=(70400×0.25/0.11)×exp(−2.855×R)

In one embodiment, if D (mm) denotes the sheet thickness of the glass at which the external transmittance of light having a wavelength of 633 nm becomes 50%, it is possible for d=D in Equation 7 above. In this case, the value of a3 is calculated from the equation below.

α₃=(70400×0.25/D)×exp(−2.855×R)

In Glasses 1 to 6, the lower limit for the content of CuO can be defined by Equation 8 below from the content of CuO per molar volume of the glass.

C−3200×0.25/d×exp(−2.855×R)≥0  (Equation 8)

In Equation 8, the value of d can be more than 0 and not more than 0.25. For example, the value of d can be 0.25, 0.24, 0.23, 0.22, 0.21, 0.20, 0.19, 0.18, 0.17, 0.16, 0.15, 0.14, 0.13, 0.12, 0.11, 0.10, 0.09, 0.08, 0.07, 0.06, 0.05, 0.04, 0.03, 0.02, 0.01, and the like. However, the value of d is not limited to these values. In order to achieve a desired transmittance half value at a lower thickness, it tends to be desirable for the value of d to be low.

For example, if d=0.11, Equation 8 is the following equation.

C−3300×0.25/0.11×exp(−2.855×R)≥0

In one embodiment, if D (mm) denotes the sheet thickness of the glass at which the external transmittance of light having a wavelength of 633 nm becomes 50%, it is possible for d=D in Equation 8 above. In this case, Equation 8 is the following equation.

With regard to the content of CuO, Glasses 1 to 6 can also satisfy one or more other glass-related equations.

Glasses 1 to 6 contain P ions as essential cations. As mentioned above, a low O/P ratio is preferred from the perspective of achieving both improved transmittance of light in the visible region and improved near-infrared cutting performance. It is preferable to increase the content of P₂O₅ in order to lower the O/P ratio. From this perspective, the content of P₂O₅ in the oxide-based glass composition (on a molar basis) is preferably 33.0% or more, and is more preferably 34.0% or more, 35.0% or more, 36.0% or more, 37.0% or more, 38.0% or more, 39.0% or more, 40.0% or more, 40.5% or more, 41.0% or more, 41.5% or more, 42.0% or more, 42.5% or more, 43.0% or more, 43.5% or more, 44.0% or more, 44.5% or more, 45.0% or more, 45.5% or more, 46.0% or more, 46.5% or more, 47.0% or more, 47.5% or more, 48.0% or more, 48.5% or more, 49.0% or more, 49.5% or more, or 50.0% or more in that order. Because P₂O₅ itself does not exhibit near-infrared absorption capacity, the content of P₂O₅ is preferably 72.0% or less, and is more preferably 71.0% or less, 70.0% or less, 69.5% or less, 69.0% or less, 68.5% or less, 68.0% or less, 67.5% or less, 67.0% or less, 66.5% or less, 66.0% or less, 65.5% or less, 65.0% or less, 64.5% or less, 64.0% or less, 63.5% or less, 63.0% or less, 62.5% or less, 62.0% or less, 61.5% or less, 61.0% or less, 60.5% or less, or 60.0% or less in that order from the perspective of increasing the content of CuO, which does exhibit near-infrared absorption capacity. In addition, it is preferable for the content of P₂O₅ to be not higher than the value mentioned above from the perspectives of further suppressing a decrease in weathering resistance and/or suppressing a decrease in meltability.

In the glasses mentioned above, it is preferable for the oxide-based glass composition to be constituted mainly from P₂O₅, Li₂O and CuO in order to achieve the desired transmission characteristics. From this perspective, the total content of P₂O₅, Li₂O and CuO (P₂O₅+Li₂O+CuO) is preferably 50.0% or more, and is more preferably 55.0% or more, 60.0% or more, 65.0% or more, 70.0% or more, 75.0% or more, 80.0% or more, 83.0% or more, 86.0% or more, 88.0% or more, or 90.0% or more in that order. The glasses mentioned above contain P ions, Li ions and Cu ions as essential cations, and also contain one or more types of cation selected from among the main cation group in order for the glasses to exhibit thermal stability and/or chemical durability. Therefore, the total content (P₂O₅+Li₂O+CuO) is less than 100%, is preferably 9.9% or less, and is more preferably 99.8% or less, 99.7% or less, 99.6% or less, 99.5% or less, 99.4% or less, 99.2% or less, 99.0% or less, 98.0% or less, 97.0% or less, 96.0% or less, 95.0% or less, 94.0% or less, 93.0% or less, 92.0% or less, 91.0% or less, 90.0% or less, 89.0% or less, 88.0% or less, 87.0% or less, 86.0% or less, or 85.0% or less in that order.

As a transmittance characteristic calculated at a thickness of 0.11 mm, in order for the wavelength Δ_T50, at which the external transmittance including reflection losses becomes 50%, to fall within the range 600 nm to 650 nm in one embodiment, the total content of P₂O₅, Li₂O and CuO (P₂O₅+Li₂O+CuO) in the oxide-based glass composition (on a molar basis) is preferably 84.0% or more, and is more preferably 85.0% or more, 86.0% or more, 87.0% or more, 88.0% or more, 89.0% or more, or 90.0% or more in that order.

As a transmittance characteristic calculated at a thickness of 0.21 mm, in order for the wavelength Δ_T50, at which the external transmittance including reflection losses becomes 50%, to fall within the range 600 nm to 650 nm, the total content of P₂O₅, Li₂O and CuO (P₂O₅+Li₂O+CuO) in the oxide-based glass composition (on a molar basis) is preferably 80.0% or more, and is more preferably 81.0% or more, 82.0% or more, 83.0% or more, 84.0% or more, 85.0% or more, 86.0% or more, 87.0% or more, 88.0% or more, 89.0% or more, or 90.0% or more in that order.

As a transmittance characteristic calculated at a thickness of 0.25 mm, in order for the wavelength Δ_T50, at which the external transmittance including reflection losses becomes 50%, to fall within the range 600 nm to 650 nm, the total content of P₂O₅, Li₂O and CuO (P₂O₅+Li₂O+CuO) in the oxide-based glass composition (on a molar basis) is preferably 75.0% or more, and is more preferably 76.0% or more, 77.0% or more, 78.0% or more, 79.0% or more, 80.0% or more, 81.0% or more, 82.0% or more, 83.0% or more, 84.0% or more, 85.0% or more, 86.0% or more, 87.0% or more, 88.0% or more, 89.0% or more, or 90.0% or more in that order.

In order for the glass thickness at which the wavelength Δ_T50, at which the external transmittance including reflection losses becomes 50% at a wavelength of 550 nm or longer, is 645 nm to be 0.25 mm or less, the total content of P₂O₅, Li₂O and CuO (P₂O₅+Li₂O+CuO) in the oxide-based glass composition (on a molar basis) is preferably 80.0% or more, and is more preferably 81.0% or more, 82.0% or more, 83.0% or more, 84.0% or more, 85.0% or more, 86.0% or more, 87.0% or more, 88.0% or more, 89.0% or more, or 90.0% or more in that order.

In order for the glass thickness at which the wavelength Δ_T50, at which the external transmittance including reflection losses becomes 50% at a wavelength of 550 nm or longer, is 633 nm to be 0.25 mm or less, the total content of P₂O₅, Li₂O and CuO (P₂O₅+Li₂O+CuO) in the oxide-based glass composition (on a molar basis) is preferably 81.0% or more, and is more preferably 82.0% or more, 83.0% or more, 84.0% or more, 85.0% or more, 86.0% or more, 87.0% or more, 88.0% or more, 89.0% or more, or 90.0% or more in that order.

Glasses of Examples 1 to 60 below can be given as examples of glasses corresponding to the above embodiment.

On the other hand, as another embodiment, for a glass in which the molar ratio ((MgO+CaO+SrO+BaO+ZnO)/(Li₂O+Na₂O+K₂O)) of the total content of MgO, CaO, SrO, BaO and ZnO (MgO+CaO+SrO+BaO+ZnO) relative to the total content of Li₂O, Na₂O and K₂O (Li₂O+Na₂O+K₂O) is 2.0 or more, in order for the wavelength Δ_T50, at which the external transmittance including reflection losses becomes 50%, to fall within the range 600 nm to 650 nm as a transmittance characteristic calculated at a thickness of 0.11 mm, the total content of P₂O₅, Li₂O and CuO (P₂O₅+Li₂O+CuO) in the oxide-based glass composition (on a molar basis) is preferably 65.0% or more, and is more preferably 66.0% or more, 67.0% or more, 68.0% or more, 69.0% or more, or 70.0% or more in that order.

As a transmittance characteristic calculated at a thickness of 0.21 mm, in order for the wavelength Δ_T50, at which the external transmittance including reflection losses becomes 50%, to fall within the range 600 nm to 650 nm in another embodiment mentioned above, the total content of P₂O₅, Li₂O and CuO (P₂O₅+Li₂O+CuO) in the oxide-based glass composition (on a molar basis) is preferably 60.0% or more, and is more preferably 61.0% or more, 62.0% or more, 63.0% or more, 64.0% or more, or 65.0% or more in that order.

As a transmittance characteristic calculated at a thickness of 0.25 mm, in order for the wavelength Δ_T50, at which the external transmittance including reflection losses becomes 50%, to fall within the range 600 nm to 650 nm in another embodiment mentioned above, the total content of P₂O₅, Li₂O and CuO (P₂O₅+Li₂O+CuO) in the oxide-based glass composition (on a molar basis) is preferably 55.0% or more, and is more preferably 56.0% or more, 57.0% or more, 58.0% or more, 59.0% or more, or 60.0% or more in that order.

In order for the glass thickness at which the wavelength Δ_T50, at which the external transmittance including reflection losses becomes 50% at a wavelength of 550 nm or longer, is 645 nm to be 0.25 mm or less in another embodiment mentioned above, the total content of P₂O₅, Li₂O and CuO (P₂O₅+Li₂O+CuO) in the oxide-based glass composition (on a molar basis) is preferably 60.0% or more, and is more preferably 61.0% or more, 62.0% or more, 63.0% or more, 64.0% or more, or 65.0% or more in that order.

In order for the glass thickness at which the wavelength Δ_T50, at which the external transmittance including reflection losses becomes 50% at a wavelength of 550 nm or longer, is 633 nm to be 0.25 mm or less in another embodiment mentioned above, the total content of P₂O₅, Li₂O and CuO (P₂O₅+Li₂O+CuO) in the oxide-based glass composition (on a molar basis) is preferably 61.0% or more, and is more preferably 62.0% or more, 63.0% or more, 64.0% or more, 65.0% or more, or 66.0% or more in that order.

Glasses of Examples 61 to 66 below can be given as examples of glasses corresponding to another embodiment mentioned above.

For Glasses 3 and 4, the main cation group mentioned above includes B ions and Si ions. For Glasses 1, 2, 5 and 6, on the other hand, the main cation group mentioned above does not include B ions or Si ions, which tend to increase the melting temperature. In one embodiment, Glasses 1 to 6 can be glasses which contain B ions and/or Si ions, which shift the half value to the short wavelength side, from the perspectives of increasing the near-infrared cutting performance of the glass and improving the transmittance of light in the visible region, and can be glasses that contain no B ions and no Si ions in another embodiment.

From the perspective of improving the transmittance of light in the visible region, the total content of B₂O₃ and SiO₂ (B₂O₃+SiO₂) in the oxide-based glass composition (on a molar basis) of Glass 1 and Glass 2 is 3.0% or less, is preferably 2.5% or less, and is more preferably 2.0% or less, 1.5% or less, 1.0% or less, or 0.5% or less in that order.

From the perspective of further improving the transmittance of light in the visible region, the total content of B₂O₃ and SiO₂ (B₂O₃+SiO₂) in the oxide-based glass composition (on a molar basis) of Glasses 3 to 6 is preferably 3.0% or less, and is more preferably 2.5% or less, 2.0% or less, 1.5% or less, 1.0% or less, or 0.5% or less in that order.

In Glasses 1 to 6, the total content of B₂O₃ and SiO₂ (B₂O₃+SiO₂) can be 0%, 0% or more, or more than 0%.

From the perspective of greatly improving the transmittance of light in the visible region, the content of B₂O₃ in Glasses 1 to 6 is preferably 3.0% or less, and is more preferably 2.5% or less, 2.0% or less, 1.5% or less, 1.0% or less, or 0.5% or less in that order. The content of B₂O₃ can be 0%.

For Glasses 1 to 6, on the other hand, in a case where a quartz crucible is used for crudely melting the glass in order to facilitate homogenization of the glass, the content of SiO₂ is preferably more than 0%, and is more preferably 0.01% or more, 0.02% or more, 0.03% or more, 0.04% or more, 0.05% or more, 0.1% or more, 0.2% or more or 0.3% or more in that order. However, excessive introduction of SiO₂ into the glass tends to lower the optical uniformity of the glass. From this perspective, the content of SiO₂ in Glasses 1 to 6 is preferably 2.0% or less, and is more preferably 1.4% or less, 0.9% or less, 0.8% or less, 0.6% or less, or 0.4% or less in that order.

Glasses 1 to 6 contain Li ions as essential cations. Compared to a variety of glass components, Li₂O has a high ability to maintain absorption by CuO in the long wavelength region, and has small adverse effect on weathering resistance. From this perspective, the content of Li₂O is preferably 0.1% or more, and is more preferably 0.5% or more, 1.0% or more, 1.5% or more, 2.0% or more, 2.5% or more, 3.0% or more, 3.5% or more, 4.0% or more, 4.5% or more, 5.0% or more, 5.5% or more, 6.0% or more, 6.5% or more, 7.0% or more, 7.5% or more, or 8.0% or more in that order. On the other hand, from the perspective of ensuring thermal stability of the glass and/or the perspective of further suppressing a decrease in weathering resistance, the content of Li₂O is preferably 35.0% or less, and is more preferably 34.0% or less, 33.0% or less, 32.0% or less, 31.0% or less, 30.0% or less, 29.5% or less, 29.0% or less, 28.5% or less, 28.0% or less, 27.5% or less, 27.0% or less, 26.5% or less, 26.0% or less, 25.5% or less, 25.0% or less, 24.5% or less, 24.0% or less, 23.5% or less, 23.0% or less, 22.5% or less, 22.0% or less, 21.5% or less, 21.0% or less, 20.5% or less, or 20.0% or less in that order.

From the perspectives of improving meltability and improving the transmittance of light in the visible region, the total content of MgO and Al₂O₃(MgO+Al₂O₃) in Glasses 1 to 6 is 8.0% or less, is preferably 7.5% or less, is more preferably 7.0% or less, 6.5% or less, 6.0% or less, 5.5% or less, 5.0% or less, 4.5% or less, 4.0% or less, 3.5% or less, 3.0% or less, 2.5% or less, 2.0% or less, 1.8% or less, 1.6% or less, 1.5% or less or 1.4% or less in that order, and can be 0%. On the other hand, from the perspectives of increasing the weathering resistance of the glass and improving the mechanical strength of the glass, the total content of MgO and Al₂O₃(MgO+Al₂O₃) can be more than 0%, is preferably 0.1% or more, and is more preferably 0.2% or more, 0.3% or more, 0.4% or more, 0.5% or more, 0.6% or more, 0.7% or more, 0.8% or more, 0.9% or more, 1.0% or more, 1.1% or more, or 1.3% or more in that order.

Al₂O₃ is a component that can contribute to an increase in weathering resistance in particular. The content of Al₂O₃ can be 0%, 0% or more, or more than 0%, and from the perspective of increasing the weathering resistance of the glass, is preferably 0.1% or more, and is more preferably 0.2% or more, 0.3% or more, 0.4% or more, 0.5% or more, 0.6% or more, 0.7% or more, 0.9% or more, 1.1% or more, 1.3% or more, or 1.5% or more in that order. On the other hand, from the perspective of further suppressing a decrease in the transmittance of light in the visible region, the content of Al₂O₃ is preferably 8.0% or less, and is more preferably 7.5% or less, 7.0% or less, 6.0% or less, 5.5% or less, 5.0% or less, 4.5% or less, 4.0% or less, 3.5% or less, 3.0% or less, or 2.5% or less in that order. In one embodiment, from the perspectives of prioritizing improving near-infrared absorption properties rather than maintaining the weather resistance of the glass, increasing the transmittance of light in the visible region by suppressing a short-wavelength shift of CuO absorption, and improving near-infrared absorption properties, the content of Al₂O₃ is preferably less than 2.0%, and is more preferably 1.9% or less, 1.8% or less, 1.7% or less, 1.6% or less, 1.5% or less, 1.4% or less, 1.3% or less, 1.2% or less, 1.1% or less, 1.0% or less, 0.9% or less, 0.8% or less, 0.7% or less, 0.6% or less, or 0.5% or less in that order.

MgO is a component that can be added, as appropriate, in order to adjust the thermal stability of the glass, but MgO shifts absorption by CuO to the short wavelength side, and it therefore tends to be difficult to increase the content of CuO. In addition, as the content of MgO increases, the meltability of the glass tends to decrease. From these perspectives, the content of MgO is preferably 9.0% or less, and is more preferably 8.0% or less, 7.0% or less, 6.0% or less, 5.0% or less, 4.0% or less, 3.0% or less, or 2.0% or less in that order. The content of MgO can be 0%. In one embodiment, the content of MgO can be more than 0%, is preferably 0.5% or more, and is more preferably 1.0% or more from the perspective of improving the mechanical strength of the glass.

La₂O₃ is a component that can contribute to an increase in weathering resistance without sacrificing the near-infrared absorption characteristics of the glass. The content of La₂O₃ is preferably 0.10% or more, and is more preferably 0.15% or more, 0.18% or more, or 0.21% or more in that order. On the other hand, from the perspective of further suppressing a decrease in the transmittance of light in the visible region, the content of La₂O₃ is preferably 8.0% or less, and is more preferably 7.0% or less, 6.5% or less, 6.0% or less, 5.5% or less, 5.0% or less, 4.5% or less, 4.0% or less, 3.5% or less, 3.0% or less, 2.5% or less, 2.0% or less, 1.5% or less, or 1.0% or less in that order.

Y₂O₃ is also a component that can contribute to an increase in weathering resistance without sacrificing the near-infrared absorption characteristics of the glass. The content of Y₂O₃ is preferably 0.10% or more, and is more preferably 0.15% or more, 0.20% or more, 0.25% or more, 0.30% or more, 0.35% or more, 0.40% or more, 0.45% or more, or 0.50% or more in that order. On the other hand, from the perspective of further suppressing a decrease in the transmittance of light in the visible region, the content of Y₂O₃ is preferably 8.0% or less, and is more preferably 7.0% or less, 6.5% or less, 6.0% or less, 5.5% or less, 5.0% or less, 4.5% or less, 4.0% or less, 3.5% or less, 3.0% or less, 2.5% or less, 2.0% or less, 1.5% or less, or 1.0% or less in that order. It is possible to introduce Y₂O₃ from the perspective of increasing the molar volume of the glass without increasing the specific gravity of the glass.

Gd₂O₃ is also a component that can contribute to an increase in weathering resistance. The content of Gd₂O₃ is preferably 0.10% or more, and is more preferably 0.15% or more, 0.18% or more, or 0.21% or more in that order. On the other hand, from the perspective of further suppressing a decrease in the transmittance of light in the visible region, the content of Gd₂O₃ is preferably 8.0% or less, and is more preferably 7.0% or less, 6.5% or less, 6.0% or less, 5.5% or less, 5.0% or less, 4.5% or less, 4.0% or less, 3.5% or less, 3.0% or less, 2.5% or less, 2.0% or less, 1.5% or less, or 1.0% or less in that order.

The oxide-based glass composition may, or may not, contain one or more rare earth oxides other than those mentioned above, such as Lu₂O₃ or Sc₂O₃. Because these components are generally expensive components, the content of a rare earth oxide other than La₂O₃, Y₂O₃ and Gd₂O₃ (the total content of these if two or more types thereof are contained) is preferably 2.5% or less, is more preferably 1.5% or less, 1.0% or less or 0.5% or less, and can be 0%.

From the perspective of improving weathering resistance, the total content of Al₂O₃, La₂O₃, Y₂O₃ and Gd₂O₃ (Al₂O₃+La₂O₃+Y₂O₃+Gd₂O₃) in Glasses 1 to 6 is preferably 0.1% or more, and is more preferably 0.15% or more, 0.20% or more, 0.25% or more, 0.30% or more, 0.35% or more, 0.40% or more, 0.45% or more, or 0.50% or more in that order. On the other hand, from the perspectives of ensuring the thermal stability of the glass and/or lowering the melting temperature of the glass, the total content (Al₂O₃+La₂O₃+Y₂O₃+Gd₂O₃) is preferably 8.0% or less, and is more preferably 7.0% or less, 6.5% or less, 6.0% or less, 5.5% or less, 5.0% or less, 4.5% or less, 4.0% or less, 3.5% or less, 3.0% or less, 2.5% or less, 2.0% or less, 1.5% or less or 1.0% or less in that order.

If cations having a nominal valency of +2 are seen in the overall glass composition, it tends to be difficult to achieve prominent effects in terms of weathering resistance and improving the transmittance of light in the visible region. Therefore, the total content of MgO, CaO, SrO and BaO, which are oxides of cations having a nominal valency of +2, is preferably such that the molar ratio relative to the content of Li₂O ((MgO+CaO+SrO+BaO)/Li₂O), which is an oxide of Li ions, which are essential cations, is 2.0 or less, and is more preferably 1.5 or less, 1.3 or less, 1.2 or less, 1.1 or less, 1.0 or less, 0.9 or less, 0.8 or less, 0.7 or less, 0.6 or less, 0.5 or less, 0.4 or less, 0.3 or less or 0.2 or less. As mentioned later, the components mentioned above are optional components that can be used together with some alkali components in order to adjust the half value.

In addition, the total content of MgO, CaO, SrO, BaO and ZnO, which are oxides of cations having a nominal valency of +2, is preferably such that the molar ratio relative to the content of Li₂O ((MgO+CaO+SrO+BaO+ZnO)/Li₂O), which is an oxide of Li ions, which are essential cations, is 2.0 or less, and is more preferably 1.5 or less, 1.3 or less, 1.2 or less, 1.1 or less, 1.0 or less, 0.9 or less, 0.8 or less, 0.7 or less, 0.6 or less, 0.5 or less, 0.4 or less, 0.3 or less or 0.2 or less from the perspective of improving the transmittance of light in the visible region. On the other hand, from the perspective of improving weathering resistance, the value of (MgO+CaO+SrO+BaO+ZnO)/Li₂O) is preferably 2.0 or more, and is more preferably 2.5 or more, 3.0 or more, 3.5 or more, or 4.0 or more in that order. As mentioned later, the components mentioned above are optional components that can be used together with some alkali components in order to adjust the half value.

The content of BaO can be 0%, 0% or more, or more than 0%. BaO is a component that can increase weathering resistance when introduced at a certain quantity, and causes little change in the value of T600 when introduced. T600 will be explained later. BaO can be added in order to increase the thermal stability of the glass and adjust the meltability of the glass. In addition, BaO can be used in order to adjust the concentration of CuO. The content of BaO is preferably 0.5% or more, and is more preferably 1.0% or more, 1.5% or more, 2.0% or more, 2.5% or more, 3.0% or more, 3.5% or more, 4.0% or more, 4.5% or more, 5.0% or more, 5.5% or more, 6.0% or more, 6.5% or more, or 7.0% or more in that order. However, excessive introduction tends to lead to a decrease in the value of T400. T400 will be explained later. From the perspectives mentioned above, the content of BaO is preferably 36.0% or less, and is more preferably 35.0% or less, 34.0% or less, 33.0% or less, 32.0% or less, 31.0% or less, 30.0% or less, 29.0% or less, 28.0% or less, 27.0% or less, 26.0% or less, 26.0% or less, 25.0% or less, 24.0% or less, 23.0% or less, 22.0% or less, 21.0% or less, 20.0% or less, 19.0% or less, 18.0% or less, 17.0% or less, 16.0% or less, 15.0% or less, 14.0% or less, 13.0% or less, 12.0% or less, 11.0% or less, 10.0% or less, or 9.0% or less in that order.

The content of SrO can be 0%, 0% or more, or more than 0%. Like BaO, SrO is a component that is unlikely to lower weathering resistance, and is a component that can be added, as appropriate, for reasons such as adjusting the thermal stability of the glass, and the like. SrO can also be used in order to adjust to the concentration of CuO. The content of SrO is preferably 0.5% or more, and is more preferably 1.0% or more, 1.5% or more, 2.0% or more, 2.5% or more, 3.0% or more, 3.5% or more, 4.0% or more, 4.5% or more, 5.0% or more, 5.5% or more, 6.0% or more, 6.5% or more, or 7.0% or more in that order. However, because excessive introduction tends to lead to a decrease in the value of T400, the content of SrO is preferably 30.0% or less, and is more preferably 29.0% or less, 28.0% or less, 27.0% or less, 26.0% or less, 26.0% or less, 25.0% or less, 24.0% or less, 23.0% or less, 22.0% or less, 21.0% or less, 20.0% or less, 19.0% or less, 18.0% or less, 17.0% or less, 16.0% or less, 15.0% or less, 14.0% or less, 13.0% or less, 12.0% or less, 11.0% or less, 10.0% or less, or 9.0% or less in that order.

The content of CaO can be 0%, 0% or more, or more than 0%. CaO is a component that is unlikely to lower weathering resistance, and is a component that can be added, as appropriate, for reasons such as adjusting the thermal stability of the glass, and the like. CaO can also be used in order to adjust to the concentration of CuO. The content of CaO is preferably 0.5% or more, and is more preferably 1.0% or more, 1.5% or more, 2.0% or more, 2.5% or more, 3.0% or more, 3.5% or more, 4.0% or more, 4.5% or more, 5.0% or more, 5.5% or more, 6.0% or more, 6.5% or more, or 7.0% or more in that order. However, because excessive introduction tends to lead to a decrease in the value of T400, the content of CaO is preferably 30.0% or less, and is more preferably 29.0% or less, 28.0% or less, 27.0% or less, 26.0% or less, 26.0% or less, 25.0% or less, 24.0% or less, 23.0% or less, 22.0% or less, 21.0% or less, 20.0% or less, 19.0% or less, 18.0% or less, 17.0% or less, 16.0% or less, 15.0% or less, 14.0% or less, 13.0% or less, 12.0% or less, 11.0% or less, 10.0% or less, or 9.0% or less in that order.

Among the cations included in the main cation group mentioned above, Na ions, K ions and Zn ions tend to cause a deterioration in the weathering resistance of the glass, and it is therefore difficult to freely use these ions instead of Li ions, which are essential cations. From the additional perspective of improving the transmittance of light in the visible region or near-infrared region, the ratio of the total content of Na₂O, K₂O and ZnO relative to the content of Li₂O ((Na₂O+K₂O+ZnO)/Li₂O) in Glasses 1 to 6 is 2.4 or less, is preferably 2.3 or less, is more preferably 2.2 or less, 2.1 or less, 2.0 or less, 1.9 or less, 1.8 or less, 1.7 or less, 1.6 or less, 1.5 or less, 1.4 or less, 1.3 or less, 1.2 or less, 1.1 or less, 0.9 or less, 0.8 or less, 0.7 or less, 0.6 or less, 0.5 or less, 0.4 or less, 0.3 or less, 0.2 or less, 0.1 or less or 0.05 or less in that order, and can be 0.00. On the other hand, from the perspective of lowering raw material costs of the glass, the molar ratio ((Na₂O+K₂O+ZnO)/Li₂O) can be 0, 0 or more, or more than 0, and is preferably 0.05 or more, and can be 0.1 or more, 0.2 or more or 0.3 or more, from the perspective of facilitating a decrease in the value of Tg or Tm, which are explained later, by mixing a plurality of components.

In addition, it becomes difficult to introduce a large quantity of P₂O₅ in order to maintain weathering resistance as the content of Na ions, K ions and Zn ions increases, and it is therefore difficult to introduce a required amount of P₂O₅. From these perspectives and the perspective of suppressing a reduction in weathering resistance such as that mentioned above, the total content of Na₂O, K₂O and ZnO (Na₂O+K₂O+ZnO) is preferably 30.0% or less, and is more preferably 25.0% or less, 20.0% or less, 15.0% or less, 12.0% or less, 10.0% or less, 9.0% or less, 8.0% or less, 7.0% or less, 6.0% or less, 5.0% or less, 4.0% or less, 3.0% or less, 2.0% or less, or 1.0% or less in that order. The above total content can be 0%. On the other hand, from the perspective of lowering raw material costs of the glass, the total content (Na₂O+K₂O+ZnO) can be 1.0% or more, 2.0% or more, 3.0% or more or 5.0% or more.

The content of Na₂O can be 0%, 0% or more, or more than 0%. Na₂O, if introduced excessively, tends to cause a decrease in weathering resistance. Therefore, the content of Na₂O is preferably 20.0% or less, and is more preferably 19.0% or less, 18.0% or less, 17.0% or less, 16.0% or less, 15.0% or less, 14.0% or less, 13.0% or less, 12.0% or less, 11.0% or less, 10.0% or less, 9.0% or less, or 8.0% or less in that order. On the other hand, because Na₂O is a raw material that can be easily and inexpensively procured, and can be added, as appropriate, in order to improve meltability, the content of Na₂O can be, for example, 0.5% or more, and can be 1.0% or more, 1.5% or more, 2.0% or more, 2.5% or more, 3.0% or more, 3.5% or more, 4.0% or more, or 5.0% or more.

The content of K₂O can be 0%, 0% or more, or more than 0%. K₂O, if introduced excessively, also tends to cause a decrease in weathering resistance. Furthermore, it is preferable not to actively introduce K₂O, which tends to shift absorption by CuO to the short wavelength side. From these perspectives, the content of K₂O is preferably 20.0% or less, and is more preferably 19.0% or less, 18.0% or less, 17.0% or less, 16.0% or less, 15.0% or less, 14.0% or less, 13.0% or less, 12.0% or less, 11.0% or less, 10.0% or less, 9.0% or less, or 8.0% or less in that order. On the other hand, K₂O can be added, as appropriate, in order to improve the meltability of the glass. From this perspective, the content of K₂O is preferably 0.2% or more, and is more preferably 0.5% or more, 1.0% or more, 1.5% or more, 2.0% or more, 2.5% or more, 3.0% or more, 3.5% or more, 4.0% or more, or 5.0% or more in that order.

The content of Cs₂O can be 0%, 0% or more, or more than 0%. It is preferable not to actively introduce Cs₂O, which tends to cause a decrease in weathering resistance. The content of Cs₂O is more preferably 15.0% or less, 14.0% or less, 13.0% or less, 12.0% or less, 11.0% or less, 10.0% or less, 9.0% or less, 8.0% or less, 7.0% or less, or 6.0% or less in that order. On the other hand, in order to adjust thermal stability and meltability, the content of Cs₂O can be 0.5% or more, and can be 1.0% or more, 1.5% or more, 2.0% or more, 2.5% or more, 3.0% or more, 3.5% or more, or 4.0% or more.

From the perspective of increasing the meltability of the glass, the total content of Li₂O, Na₂O and K₂O (Li₂O+Na₂O+K₂O) is preferably 1.8% or more, and is more preferably 2.1% or more, 2.3% or more, 2.5% or more, 3.5% or more, 4.5% or more, 5.5% or more, 6.5% or more, 7.5% or more, 8.5% or more, 9.5% or more, 10.0% or more, or 10.5% or more in that order.

On the other hand, from the perspective of further suppressing a decrease in weathering resistance, the total content (Li₂O+Na₂O+K₂O) is preferably 35.0% or less, and is more preferably 33.5% or less, 32.5% or less, 31.5% or less, 30.5% or less, 29.5% or less, 28.5% or less, 27.5% or less, 26.5% or less, 25.5% or less, 24.5% or less, 23.5% or less, 21.5% or less, 20.5% or less, 19.5% or less, 18.5% or less, 17.5% or less, 16.6% or less, 15.5% or less, 14.5% or less, or 13.5% or less in that order. It is preferable for the total content (Li₂O+Na₂O+K₂O) to be not higher than the values mentioned above from the perspectives of preventing the occurrence of chipping and cracking in the glass as a result of stress exerted on the glass when the amount of expansion and shrinkage of the glass, which is caused by an increase in the coefficient of thermal expansion, increases and a change in volume of the glass is suppressed by another member.

From the perspective of suppressing deliquescence of the glass, the total content of Na₂O and K₂O (Na₂O+K₂O) is preferably 30.0% or less, and is more preferably 29.0% or less, 28.0% or less, 27.0% or less, 26.0% or less, 25.0% or less, 24.0% or less, 23.0% or less, 22.0% or less, 21.0% or less, 20.0% or less, 19.0% or less, 18.0% or less, 17.0% or less, 16.0% or less, 15.0% or less, 14.0% or less, 13.0% or less, 12.0% or less, 11.0% or less, 10.0% or less, 9.0% or less, 8.0% or less, 7.0% or less, 6.0% or less, 5.0% or less, 4.0% or less, 3.0% or less, 2.0%% or less, 1.0% or less, or 0.5% or less in that order. By setting the total content of Na₂O and K₂O (Na₂O+K₂O) to be 0%, it is possible to obtain a glass having further reduced deliquescence. On the other hand, from the perspective of lowering raw material costs of the glass while suppressing meltability of the glass and suppressing a decrease in the value of T600, the total content (Na₂O+K₂O) can be 1.0% or more, and can be 2.0% or more, 3.0% or more, 4.0% or more, 5.0% or more, 6.0% or more, 7.0% or more, 8.0% or more, 9.0% or more, 10.0% or more, 11.0% or more, 12.0% or more, 13.0% or more, 14.0% or more, or 15.0% or more.

CuO can be replaced with other components in order to adjust the thickness of the glass, but on such occasion, by forming a glass in which the total content of Na₂O, K₂O, CaO, SrO and BaO (Na₂O+K₂O+CaO+SrO+BaO) is 0% or more, it is possible to adjust the concentration of CuO without greatly altering the position of near-infrared absorption. The total content (Na₂O+K₂O+CaO+SrO+BaO) is preferably 0.5% or more, and is more preferably 1.0% or more, 1.5% or more, 2.0% or more, 2.5% or more, 3.0% or more, 3.5% or more, 4.0% or more, 4.5% or more, 5.0% or more, 5.5% or more, 6.0% or more, 6.5% or more, or 7.0% or more in that order. However, because excessive introduction tends to lead to a decrease in the value of T400, the total content (Na₂O+K₂O+CaO+SrO+BaO) is preferably 36.0% or less, and is more preferably 35.0% or less, 34.0% or less, 33.0% or less, 32.0% or less, 31.0% or less, 30.0% or less, 29.0% or less, 28.0% or less, 27.0% or less, 26.0% or less, 26.0% or less, 25.0% or less, 24.0% or less, 23.0% or less, 22.0% or less, 21.0% or less, 20.0% or less, 19.0% or less, 18.0% or less, 17.0% or less, 16.0% or less, 15.0% or less, 14.0% or less, 13.0% or less, 12.0% or less, 11.0% or less, 10.0% or less, or 9.0% or less in that order. From the perspective of maximizing the near-infrared absorption characteristics of the glass, the total content (Na₂O+K₂O+CaO+SrO+BaO) can be 8.0% or less, 7.0% or less, 6.0% or less, 5.0% or less, or 4.0% or less.

With regard to weathering resistance, the matter that deliquescence in the glass is reduced and/or the matter that the occurrence of precipitates at the surface of the glass is suppressed in high temperature high humidity environments can be used as an indicator of weathering resistance. This is explained later. In order to further improve weathering resistance, it is more preferable to introduce Al₂O₃, and it is preferable to then introduce one or more of Y₂O₃, La₂O₃ and Gd₂O₃. In addition, BaO can improve the weathering resistance if introduced at a relatively large quantity, and SrO and CaO need to be introduced at an even larger quantity from the perspective of improving weathering resistance, and a value calculated as “(3×Al₂O₃+Y₂O₃+La₂O₃+Gd₂O₃+BaO/3+(CaO+SrO)/6)” (units: mol %) is preferably 0% or more, is more preferably more than 0%, and is preferably 0.5% or more, 1.0% or more, 2.0% or more, 3.0% or more, 4.0% or more, 5.0% or more, 6.0% or more, 7.0% or more, or 8.0% or more. If emphasis is to be placed on the weathering resistance and mechanical strength of the glass, this value is more preferably 9.0% or more, 10.0% or more, 11.0% or more, 12.0% or more, 13.0% or more, 14.0% or more, 15.0% or more, 16.0% or more, 17.0% or more, 18.0% or more, or 19.0% or more in that order. In the expression “(3×Al₂O₃+Y₂O₃+La₂O₃+Gd₂O₃+BaO/3+(CaO+SrO)/6)”, “Al₂O₃” denotes the content of Al₂O₃, “Y₂O₃” denotes the content of Y₂O₃, “La₂O₃” denotes the content of La₂O₃, “Gd₂O₃” denotes the content of Gd₂O₃, “BaO” denotes the content of BaO, “CaO” denotes the content of CaO, and “SrO” denotes the content of SrO. That is, the expression “(3×Al₂O₃+Y₂O₃+La₂O₃+Gd₂O₃+BaO/3+(CaO+SrO)/6)” is the sum of a value calculated by multiplying the content of Al₂O₃ by 3, the content of Y₂O₃, the content of La₂O₃, the content of Gd₂O₃, a value calculated by dividing the content of BaO by 3, and a value calculated by dividing the sum of the content of CaO and the content of SrO by 6, and units for the thus calculated value are % (mol %).

On the other hand, a glass in which the value of “(3×Al₂O₃+Y₂O₃+La₂O₃+Gd₂O₃+BaO/3+(CaO+SrO)/6)” is excessively high tends to be poor in terms of meltability and tends to be such that the position of near-infrared absorption shifts towards the visible light side, and the value calculated as “(3×Al₂O₃+Y₂O₃+La₂O₃+Gd₂O₃+BaO/3+(CaO+SrO)/6)” is therefore preferably 40.0% or less, and is more preferably 37.0% or less, 35.0% or less, 33.0% or less, 32.0% or less, 30.0% or less, 28.0% or less, 26.0% or less, 25.0% or less, 24.0% or less, 23.0% or less, 22.0% or less or 21.0% or less in that order.

The ratio of the value calculated as “(3×Al₂O₃+Y₂O₃+La₂O₃+Gd₂O₃+BaO/3+(CaO+SrO)/6)” relative to the total content of P₂O₅, Li₂O and CuO, that is, “(3×Al₂O₃+Y₂O₃+La₂O₃+Gd₂O₃+BaO/3+(CaO+SrO)/6)/(P₂O₅+Li₂O+CuO)” can be 0.0 or more. Components selected from the group consisting of Al₂O₃, Y₂O₃, La₂O₃, Gd₂O₃, BaO, CaO and SrO are preferably introduced at a certain quantity or more relative to the quantity of P₂O₅, Li₂O and CuO, which are essential components. Therefore, the above ratio is preferably 0.01 or more, and is more preferably 0.02 or more, 0.03 or more, 0.04 or more, 0.05 or more, 0.06 or more, 0.07 or more, 0.08 or more, or 0.09 or more in that order. If weathering resistance is to be further increased, the above ratio is more preferably 0.10 or more, and is further preferably 0.11 or more, 0.12 or more, 0.13 or more, 0.14 or more, 0.15 or more, 0.16 or more, 0.17 or more, 0.18 or more, 0.19 or more, 0.20 or more, 0.21 or more, 0.22 or more, 0.23 or more, 0.24 or more, or 0.25 or more in that order.

On the other hand, because the transmittance characteristics of the glass decrease and the tendency for the stability of the glass to decrease becomes stronger if the above ratio is excessively high, the above ratio is preferably 0.36 or less, and is more preferably 0.35 or less, 0.34 or less, 0.33 or less, 0.32 or less, 0.31 or less, 0.30 or less, 0.29 or less or 0.28 or less in that order.

The content of ZnO can be 0%, 0% or more, or more than 0%. ZnO is a component that can be added, as appropriate, for reasons such as adjusting the thermal stability of the glass, and the like, but from the perspective that ZnO tends to cause a decrease in the weathering resistance of the glass and the perspective of ensuring that the introduced amount of P₂O₅, which is an essential component, is sufficient, the upper limit for the content thereof is preferably 20.0% or less, and is more preferably 19.0% or less, 18.0% or less, 17.0% or less, 16.0% or less, 15.0% or less, 14.0% or less, 13.0% or less, 12.0% or less, 11.0% or less, 10.0% or less, 9.0% or less, 8.0% or less, 7.0% or less, 6.0% or less or 5.0% or less in that order. If the effect of introducing another component is a priority, the content of ZnO can be 4.0% or less, 3.0% or less, 2.0% or less, or 1.0% or less. On the other hand, if ZnO is introduced in order to adjust the thermal stability of the glass and lower the value of Tg and/or Tm, the content of ZnO is more preferably 0.4% or more, 0.6% or more, 0.8% or more, 1.0% or more, 1.2% or more, 1.4% or more, 1.6% or more, 1.8% or more or 2.0% or more in that order.

The above glass is preferably constituted essentially from the components mentioned above, but may contain other components as long as the operational effects achieved by the components mentioned above are not impaired. In addition, inclusion of unavoidable impurities in the glass is not excluded.

For example, Nb₂O₅ and ZrO₂ can be introduced, as appropriate, respectively, at quantities of more than 0%, 0.1% or more, or 0.2% or more, as components other than the components mentioned above in order to adjust the weathering resistance and mechanical strength and improve the thermal stability of the glass, but the content of each of these components is preferably 5.0% or less, and are more preferably 4.0% or less, 3.0% or less, 2.0% or less, 1.0% or less, 0.5% or less or 0.3% or less in that order. The content of each of these components can be 0%.

TiO₂, WO₃ and Bi₂O₃ can be introduced, as appropriate to the extent that the transmittance of glass is not affected, respectively, at quantities of more than 0%, 0.1% or more, or 0.2% or more, as components other than the components mentioned above in order to adjust the weathering resistance and mechanical strength and improve the thermal stability of the glass, but the content of each of these components is preferably 4.0% or less, and are more preferably 3.0% or less, 2.0% or less, 1.0% or less, 0.5% or less or 0.3% or less in that order. The content of each of these components can be 0%.

Pb, As, Cd, TI, Be and Se are all toxic. Therefore, it is preferable for the above glass not to contain these as glass components.

U, Th and Ra are all radioactive elements. Therefore, it is preferable for the above glass not to contain these as glass components.

V, Cr, Mn, Fe, Co, Ni, Pr, Nd, Pm, Sm, Eu, Tb, Dy, Ho, Er and Tm increase coloration of a glass and can be a source of fluorescence. Therefore, in the above glass, the total content on an oxide basis of these elements in the oxide-based glass is preferably 10 ppm by mass or less, and it is more preferable for these elements not to be contained as glass components.

Of these, V₂O₅ is preferably not used due to being toxic. In one embodiment, Glasses 1 to 6 are preferably glasses that do not contain V ions, and the content (on an oxide basis) of V₂O₅ in the oxide-based glass composition is preferably 1.0% or less, is more preferably 0.3% or less, 0.1% or less and 0.01% or less in that order, and it is more preferable for these glasses to contain no V₂O₅.

As one example, the ratio of V₂O₅ and Li₂O, which is an essential component, is such that the ratio of the content of V₂O₅ relative to the content of Li₂O (V₂O₅/Li₂O) is preferably 0.0080 or less, and is more preferably 0.0048 or less, 0.0028 or less, 0.0018 or less or 0.0014 or less in that order.

CoO causes a decrease in the transmittance of light in the visible region of the glass, and is toxic, and is therefore preferably not used. In one embodiment, Glasses 1 to 6 are preferably glasses that do not contain Co ions, and it is preferable for the oxide-based glass composition to contain no CoO.

Raw materials for introducing Ge and Ta into the glass are expensive. Therefore, it is preferable for the above glass not to contain these as glass components.

Sb (Sb₂O₃), Sn (SnO₂), Ce (CeO₂) and SO₃ are elements that can be optionally added as clarifying agents. Of these, Sb (Sb₂O₃) is a clarifying agent having a high clarifying effect.

Sn (SnO₂) and Ce (CeO₂) have a lower clarifying effect than Sb (Sb₂O₃). These clarifying agents, if added at large quantities, tend to enhance coloration of the glass. Therefore, in a case where a clarifying agent is added, it is preferable to add Sb (Sb₂O₃) in view of the effect on coloration caused by the addition.

The content values of the components listed below that are able to function as clarifying agents are expressed as oxide-based values in the glass composition.

The content of Sb₂O₃ is expressed as an outer percentage. That is, if the total content as oxides of all glass components other than Sb₂O₃, SnO₂, CeO₂ and SO₃ is taken to be 100.0 mass %, the content of Sb₂O₃ is preferably less than 2.0 mass %, and is more preferably 1.5 mass % or less, 1.2 mass % or less, 1.0 mass % or less, 0.9 mass % or less, 0.8 mass % or less, 0.7 mass % or less, 0.6 mass % or less, 0.5 mass % or less, 0.4 mass % or less, 0.3 mass % or less, 0.2 mass % or less or less than 0.1 mass % in that order. The content of Sb₂O₃ may be 0 mass %. However, from the perspectives of facilitating oxidation of the glass and increasing the transmittance of light in the visible region, the content of Sb₂O₃ can be 0.01 mass % or more, and can be 0.02 mass % or more, 0.03 mass % or more, 0.04 mass % or more, 0.05 mass % or more, 0.06 mass % or more, or 0.08 mass % or more.

The content of SnO₂ is also expressed as an outer percentage. That is, if the total content as oxides of all glass components other than SnO₂, Sb₂O₃, CeO₂ and SO₃ is taken to be 100.0 mass %, the content of SnO₂ is preferably less than 2.0 mass % or less than 1.0 mass %, and is more preferably 0.9 mass % or less, 0.8 mass % or less, 0.7 mass % or less, 0.6 mass % or less, 0.5 mass % or less, 0.4 mass % or less, 0.3 mass % or less, 0.2 mass % or less or 0.1 mass % in that order. The content of SnO₂ may be 0 mass %. If the content of SnO₂ falls within the range mentioned above, it is possible to improve the clarity of the glass.

The content of CeO₂ is also expressed as an outer percentage. That is, if the total content as oxides of all glass components other than CeO₂, Sb₂O₃, SnO₂ and SO₃ is taken to be 100.0 mass %, the content of CeO₂ is preferably less than 2.0 mass % or less than 1.0 mass %, and is more preferably 0.9 mass % or less, 0.8 mass % or less, 0.7 mass % or less, 0.6 mass % or less, 0.5 mass % or less, 0.4 mass % or less, 0.3 mass % or less, 0.2 mass % or less or less than 0.1 mass % in that order. The content of CeO₂ may be 0 mass %. If the content of CeO₂ falls within the range mentioned above, it is possible to improve the clarity of the glass.

The content of SO₃ is also expressed as an outer percentage. That is, if the total content as oxides of all glass components other than SO₃, Sb₂O₃, SnO₂ and CeO₂ is taken to be 100.0 mass %, the content of SO₃ is preferably less than 2.0 mass %, more preferably less than 1.0 mass %, further preferably less than 0.5 mass %, and yet more preferably less than 0.1 mass %. The content of SO₃ may be 0 mass %. If the content of SO₃ falls within the range mentioned above, it is possible to improve the clarity of the glass.

<Physical Properties of Glass>

(Transmittance Characteristics)

The above glass is suitable for use as a glass for a near-infrared cut filter. In the present invention and the present description, the term “transmittance” means external transmittance including reflection losses, unless explicitly indicated otherwise.

The half value Δ_T50, which is the wavelength at which the transmittance becomes 50% at a wavelength of 550 nm or longer, the transmittance T1200 at a wavelength of 1200 nm, the average transmittance value within the wavelength range from 1100 nm to 800 nm (referred to as “Ave.T1100-800”), and the transmittance T750 at a wavelength of 750 nm can be used as indicators of near-infrared cutting performance.

In addition, the above glass can exhibit high transmittance of light in the visible region. The transmittance T400 at a wavelength of 400 nm and the transmittance T600 at a wavelength of 600 nm can be used as indicators of transmittance of light in the visible region.

Transmittance characteristics of the glass are determined using the methods described below.

A glass sample is processed so as to have optically polished flat surfaces that are parallel to each other, and external transmittance is measured at wavelengths of 200 to 1200 nm. The external transmittance includes reflection losses of light rays at the sample surface.

The intensity of light rays incident perpendicularly to one of the optically polished flat surfaces is denoted by the intensity A, and the intensity of light rays emitted from the other flat surface is denoted by the intensity B, and the spectral transmittance including reflection losses is calculated as the value of B/A. The wavelength at which the spectral transmittance becomes 50% at a wavelength of 550 nm or longer is taken to be the half value Δ_T50. The spectral transmittance at a wavelength of 400 nm is denoted by T400, the spectral transmittance at a wavelength of 600 nm is denoted by T600, and the spectral transmittance at a wavelength of 1200 nm is denoted by T1200. The average value of the spectral transmittance within the wavelength range from 1100 nm to 800 nm is denoted by Ave.T1100-800, and the spectral transmittance at a wavelength of 750 nm is denoted by T750. In addition, in a case where a glass to be measured is not a glass having a thickness to be calculated, the thickness of the glass is denoted by d, the transmittance at each wavelength λ is calculated using Equation A below, and calculated values can be determined from spectral transmittance values obtained from the calculations.

T(λ)=(1−R(λ))²×exp(log_e((T₀(λ)/100)/(1−R(λ))²)×d/d₀)×100  Equation A:

In Equation A, T(λ) denotes the transmittance (%) calculated for a wavelength Δ, T₀(λ) denotes the measured transmittance (%) at the wavelength Δ, d denotes the thickness (mm) to be calculated, do denotes the thickness of the glass (mm), R(λ) denotes the reflectance at the wavelength Δ, which is represented by ((n(λ)−1)/(n(λ)+1))², and n(λ) denotes the refractive index at the wavelength Δ. Here, calculations are performed using the constants n(λ)=1.51680 and R(λ)=0.042165.

If the value of T600, which is the transmittance of light in the red region, is high and the value of T1200, which is the transmittance of light in the near-infrared region, is low, this can mean that the transmittance of light in the visible region is improved and near-infrared cutting performance is also improved. In addition, if the value of T400, which is the transmittance of light in the violet region, is high, this can mean that the transmittance of light in the visible region is improved.

From the perspectives mentioned above, preferred ranges for the values of T400, T600 and T1200 are as indicated below.

The value of T400 is preferably 70% or more, and is more preferably 71% or more, 72% or more, 73% or more, 74% or more, 75% or more, 76% or more, 77% or more, 78% or more, 79% or more, or 80% or more in that order. The value of T400 can be, for example, 98% or less, 97% or less or 96% or less, but because a high T400 value can mean superior transmittance of light in the visible region, it is preferable for this value to be higher than the values shown above.

The value of T600 is preferably 50% or more, and is more preferably 55% or more, 56%, 57% or more, 58% or more, 59% or more, 60% or more, 61% or more, 62% or more, 63% or more, 64% or more, 65% or more, 66% or more, 67% or more, 68% or more, 69% or more, 70% or more, 71% or more, 72% or more, 73% or more, 74% or more, or 75% or more in that order. The value of T600 can be, for example, 90% or less, 85% or less or 80% or less, but because a high T600 value can mean superior transmittance of light in the visible region, it is preferable for this value to be higher than the values shown above.

The value of T1200 is preferably 30% or less, and is more preferably 29% or less, 28% or less, 27% or less, 26% or less, 25% or less, 24% or less, 23% or less, 22% or less, 21% or less, 20% or less, 19% or less, 18% or less, 17% or less, 16% or less, 15% or less, 14% or less, 13% or less, 12% or less, 11% or less, 10% or less, 9% or less, 8% or less, 7% or less, 6% or less, 5% or less, 4% or less, 3% or less, 2% or less, or 1% or less in that order. In order to also achieve the transmittance of light in the visible region, the value of T1200 can be, for example, 1% or more, 3% or more, 5% or more or 7% or more, but because a low T1200 value can mean superior near-infrared cutting performance, it is preferable for this value to be lower than the values shown above.

In one embodiment, the value of T1200 can be β1% or less.

β1 is calculated using Equation B1 below. In Equation B1, R is the O/P ratio.

β1=64×R−170  (Equation B1)

In one embodiment, T1200 can be not higher than a numerical value (units: %) represented by β2, β3, β4, β5 or β6, which are shown in Equations B2 to B6 below. In the equations below, R is the O/P ratio.

β2=64×R−175  Equation B2:

β3=64×R−180  Equation B3:

β4=80×R−220  Equation B4:

β5=80×R−224  Equation B5:

β6=80×R−228  Equation B6:

The half value Δ_T50, which is the wavelength at which the spectral transmittance becomes 50% at a wavelength of 550 nm or longer, is preferably 600 nm or more, and is more preferably 610 nm or more, 613 nm or more, 615 nm or more, 617 nm or more, 620 nm or more, 623 nm or more, 625 nm or more, or 628 nm or more in that order. The half value Δ_T50 is preferably 650 nm or less, and is more preferably 647 nm or less, 645 nm or less, 643 nm or less, 641 nm or less, 640 nm or less, 639 nm or less, or 638 nm or less in that order. Being able to achieve the half value Δ_T50, which is the wavelength at which the transmittance becomes 50% at a wavelength of 550 nm or longer, at a prescribed glass thickness or less is preferable from the perspective of achieving both reducing the thickness of the glass and improving near-infrared cutting performance. A prescribed glass thickness or less is preferably a thickness of 0.25 mm or less.

In addition, because the above glass exhibits excellent near-infrared absorption characteristics, the value of “Ave.T1100-800” can be suppressed to 15% or less. The value of “Ave.T1100-800” is preferably 14% or less, and is more preferably 13% or less, 12% or less, 11% or less, 10% or less, 9% or less, 8% or less, 7% or less, 6% or less, 5% or less, 4% or less, 3% or less, 2% or less, 1.3% or less, 1.0% or less, 0.3% or less, 0.1% or less, 0.03% or less, or 0.01% or less in that order.

In addition, because the above glass exhibits excellent near-infrared absorption characteristics, the value of T750 can be suppressed to 25% or less. The value of T750 is preferably 24% or less, and is more preferably 23% or less, 22% or less, 21% or less, 20% or less, 19% or less, 18% or less, 17% or less, 16% or less, 15% or less, 14% or less, 13% or less, 12% or less, 11% or less, 10% or less, 9% or less, 8% or less, 7% or less, 6% or less, 5% or less, 4% or less, 3% or less, 2% or less, 1.3% or less, 1.0% or less, 0.3% or less, 0.1% or less, 0.03% or less, or 0.01% or less in that order.

In one embodiment, the above glass can be used as a glass for a near-infrared cut filter having a thickness of 0.25 mm or less, as described in detail below.

For the above glass, characteristics (a) to (h) below can be given as transmittance characteristics that are preferred for a thin glass for a near-infrared cut filter having a thickness of 0.25 mm or less. The above glass preferably satisfies one or more of characteristics (a) to (h) below, and can satisfy two or more of these characteristics. By adjusting the glass composition in the manner explained above, it is possible to obtain a glass having preferred transmittance characteristics.

• • (a) A glass for which the wavelength Δ_T50, at which the external transmittance including reflection losses becomes 50% at a wavelength of 550 nm or longer, is 633 nm has a thickness of 0.25 mm or less, and
  • at this thickness, the external transmittance T600 including reflection losses at a wavelength of 600 nm is 50% or more, and the external transmittance T1200 including reflection losses at a wavelength of 1200 nm is 30% or less.

For characteristic (a), a glass for which the wavelength Δ_T50, at which the external transmittance including reflection losses becomes 50% at a wavelength of 550 nm or longer, is 633 nm has a thickness of 0.25 mm or less, and it is more preferable that the above thickness is within the thickness range described later for the thickness of a near-infrared cut filter. This is applied to characteristics (b), (e) and (f) below.

(b) A glass for which the wavelength at which the external transmittance including reflection losses becomes 50% at a wavelength of 550 nm or longer is 633 nm has a thickness of 0.25 mm or less, and at this thickness, the external transmittance T600 including reflection losses at a wavelength of 600 nm is 50% or more, and the external transmittance T1200 including reflection losses at a wavelength of 1200 nm is β1% or less. β is calculated from Equation B1 below. In Equation B1, R is the O/P ratio in the above glass.

β1=64×R−170  (Equation B1)

As mentioned above, the value of T1200 can be β2% or less, β3% or less, β4% or less, β5% or less, or β6% or less.

(c) As transmittance characteristics calculated at a thickness of 0.11 mm, the wavelength Δ_T50, at which the external transmittance including reflection losses becomes 50%, falls within the range 600 nm to 650 nm, the external transmittance T1200 including reflection losses at a wavelength of 1200 nm is 30% or less, and the external transmittance T400 including reflection losses at a wavelength of 400 nm is 70% or more.

(d) As transmittance characteristics calculated at a thickness of 0.21 mm, the wavelength Δ_T50, at which the external transmittance including reflection losses becomes 50%, falls within the range 600 nm to 650 nm, the external transmittance T1200 including reflection losses at a wavelength of 1200 nm is 25% or less, and the external transmittance T400 including reflection losses at a wavelength of 400 nm is 70% or more.

(e) A glass for which the wavelength at which the external transmittance including reflection losses becomes 50% at a wavelength of 550 nm or longer is 645 nm has a thickness of 0.25 mm or less, and

• • at this thickness, the external transmittance T600 including reflection losses at a wavelength of 600 nm is 50% or more, and the external transmittance T1200 including reflection losses at a wavelength of 1200 nm is 30% or less.

(f) A glass for which the wavelength Δ_T50, at which the external transmittance including reflection losses becomes 50% at a wavelength of 550 nm or longer, is 645 nm has a thickness of 0.25 mm or less, and

• • at this thickness, the external transmittance T600 including reflection losses at a wavelength of 600 nm is 50% or more, the external transmittance T1200 including reflection losses at a wavelength of 1200 nm is β1% or less, and β1 is a value calculated using Equation 4 above.

(g) As transmittance characteristics calculated at a thickness of 0.23 mm, the wavelength Δ_T50, at which the external transmittance including reflection losses becomes 50%, falls within the range 600 nm to 650 nm, the external transmittance T1200 including reflection losses at a wavelength of 1200 nm is 18% or less, and the external transmittance T400 including reflection losses at a wavelength of 400 nm is 70% or more.

(h) As transmittance characteristics calculated at a thickness of 0.25 mm, the wavelength Δ_T50, at which the external transmittance including reflection losses becomes 50%, falls within the range 600 nm to 650 nm, the external transmittance T1200 including reflection losses at a wavelength of 1200 nm is 16% or less, and the external transmittance T400 including reflection losses at a wavelength of 400 nm is 70% or more.

(Weathering Resistance)

The above glass can exhibit excellent weathering resistance by having the composition described above. Examples of indicators for weathering resistance can include weathering resistance evaluation results evaluated by eye using a method that is described in Examples section below, and any of evaluation results S to D are preferred, any of the evaluation results S to C are more preferred, any of evaluation results S to B are further preferred, evaluation results S and A are yet more preferred, and evaluation result S is further preferred.

Furthermore, haze value measured using a haze meter can also be used as an indicator of weathering resistance. A glass having a haze value of 15% or less can be given as an example of a glass having further superior weathering resistance.

For weathering resistance, a glass which has an evaluation result of S or A (and especially S) when evaluated by eye using the method mentioned above and which has a haze value, as measured using a haze meter, of 15% or less is yet more preferred.

(Glass Transition Temperature Tg and Temperature Tm at which an Endothermic Reaction Concludes Due to Melting)

The glass transition temperature of the above glass is not particularly limited. From the perspective of increasing the transmittance of light in the short wavelength region of the glass by improving the meltability of the glass and reducing the burden on an annealing furnace or molding device, the Tg value is preferably 450° C. or lower, and is more preferably 440° C. or lower, 430° C. or lower, 420° C. or lower, 410° C. or lower, or 400° C. or lower in that order. From the perspective of increasing the chemical durability and/or heat resistance of the glass, the Tg value is preferably 250° C. or higher, and is more preferably 260° C. or higher, 270° C. or higher, 280° C. or higher, 290° C. or higher, or 300° C. or higher in that order.

The Tg value of the glass can be controlled by adjusting the content of Li₂O, Na₂O or K₂O or the total content of these, or by adjusting the content of ZnO, the content of MgO, the content of Al₂O₃ or the total content of these.

The Tm value, which is the temperature at which an endothermic reaction concludes due to melting, is not particularly limited. As the Tm value decreases, meltability improves and devitrification is less likely to occur even if molding is carried out at a higher viscosity. In addition, as the meltability of the glass improves, it tends to be possible to increase transmittance by the glass of visible light in the short wavelength region. From these perspectives, the Tm value is preferably 890° C. or lower, and is more preferably 880° C. or lower, 870° C. or lower, 860° C. or lower, 850° C. or lower, 840° C. or lower, 830° C. or lower, 820° C. or lower, 810° C. or lower, 800° C. or lower, 790° C. or lower, 780° C. or lower, 770° C. or lower, 760° C. or lower, 750° C. or lower, 740° C. or lower, 730° C. or lower, 720° C. or lower, 710° C. or lower, 700° C. or lower, 690° C. or lower, 680° C. or lower, 670° C. or lower, 660° C. or lower, or 650° C. or lower in that order. The lower limit of the Tm value is not particularly limited, but because the weathering resistance of the glass tends to deteriorate if the Tm value is too low, the Tm value can be 500° C. or higher, 550° C. or higher, 580° C. or higher, 600° C. or higher, 620° C. or higher, or 640° C. or higher.

The Tm value of the glass can be controlled by adjusting the content of Li₂O, Na₂O or K₂O or the total content of these, or by adjusting the content of ZnO, the content of MgO, the content of Al₂O₃ or the total content of these.

(Specific Gravity)

The near-infrared cut filter is preferably lightweight in order to reduce the weight of an element or device in which the filter is incorporated. From this perspective, the specific gravity of the above glass is preferably 3.40 or less, and is more preferably 3.35 or less, 3.30 or less, 3.25 or less, 3.20 or less, 3.15 or less, 3.10 or less, 3.05 or less, 3.00 or less, 2.95 or less, 2.90 or less, 2.85 or less, 2.80 or less, 2.75 or less, 2.70 or less, 2.65 or less, or 2.60 or less in that order.

The specific gravity can be, for example, 2.0 or more or 2.4 or more, but because a low specific gravity is preferred from the perspective mentioned above, it is preferable for the specific gravity to be lower than the values listed above.

(Molar Volume)

The molar volume (M/D) of the glass is not particularly limited. From the perspective of increasing near-infrared absorption capacity by increasing the amount of CuO per unit volume, the molar volume of the glass is preferably lower. The molar volume can be lowered by replacing P₂O₅, La₂O₃, Y₂O₃, Gd₂O₃, BaO, K₂O, or the like, with Li₂O, and can be somewhat lowered by replacing Al₂O₃, CuO or Na₂O with Li₂O. On the other hand, the molar volume does not significantly change if CaO, ZnO or SrO is replaced with Li₂O, and the molar volume tends to increase if MgO is replaced with Li₂O. In view of these tendencies, the molar volume of the glass can be adjusted by adjusting the glass composition. The molar volume is preferably 45 cc/mol or less, and is more preferably 43 cc/mol or less, 42 cc/mol or less, 41 cc/mol or less, 40 cc/mol or less, 39.5 cc/mol or less, 39.0 cc/mol or less, 38.5 cc/mol or less, 38.0 cc/mol or less, or 37.5 cc/mol or less in that order.

On the other hand, the molar volume can be increased from the perspective of maintaining the weathering resistance of the glass, and from this perspective, the molar volume of the above glass can be 34.0 cc/mol or more, and can be 35.0 cc/mol or more, 36.0 cc/mol or more, 36.5 cc/mol or more, 37.0 cc/mol or more, 37.5 cc/mol or more, 38.0 mol or more, 38.5 cc/mol or more, 39.0 cc/mol or more, or 39.5 cc/mol or more.

<Method for Producing Glass>

The above glass can be obtained by mixing, melting and molding the glass raw materials. For the production method, the following descriptions can also be referred.

The above near-infrared absorbing glass is suitable for use as a glass for a near-infrared cut filter. In addition, the above near-infrared absorbing glass can be used in optical elements (lenses and the like) in addition to a near-infrared cut filter, can also be used in a variety of glass products, and can be modified in various ways.

[Near-Infrared Cut Filter]

One aspect of the present invention relates to a near-infrared cut filter (hereinafter also referred to simply as a “filter”) comprised of the above near-infrared absorbing glass.

The glass that constitutes the above filter is as described above.

A specific example of a method for producing the above filter will be explained below. However, the production method described below is merely an example, and does not limit the present invention.

A molten glass is obtained by using glass raw materials such as phosphates, oxides, carbonates, nitrates, sulfates and fluorides as appropriate, the raw materials are weighed out so as to attain a prescribed composition, mixed, and then melted at a temperature of, for example, 800° C. to 1100° C. in a melting vessel such as a platinum crucible. During this process, a lid of platinum or the like can be used in order to suppress volatilization of volatile components. In addition, the melting can be carried out in air, and can also be carried out in an oxygen atmosphere or while bubbling oxygen into the molten glass in order to suppress changes in valency of Cu. A homogenized molten glass in which the amount of bubbles is reduced (and which preferably contains no bubbles) is obtained by agitating and clarifying the molten glass. A glass can be obtained after clarifying the glass at 900° C. to 1100° C. and then lowering the temperature of the glass 800° C. to 1000° C. in order to facilitate oxidation of the glass. However, it is not desirable for the melting temperature or clarification temperature to be lower than the liquidus temperature of the glass for a long period of time.

After agitating and clarifying the molten glass, the glass is poured out, gradually cooled, and then molded into a prescribed shape. It is preferable to pour the glass out after cooling the glass to a temperature close to the liquidus temperature and increasing the viscosity of the glass because convection is less likely to occur in the poured out glass and striation is less likely to occur. The gradual cooling speed can be selected within the range −50° C./hr to −1° C./hr, and can be −30° C./hr or −10° C./hr.

Well-known methods such as casting, pipe outflow, rolling and pressing can be used as the method for molding the glass. The molded glass is transferred to an annealing furnace that has been heated in advance to a temperature close to the transition temperature of the glass, and allowed to cool gradually to room temperature. A near-infrared cut filter can be produced in this way.

An example of a molding method will be explained below. A mold is prepared so as to be configured from: a flat horizontal bottom surface; a pair of side walls which face each other in parallel across the bottom surface; and a barrier plate which is positioned between the pair of side walls and blocks one opening part. A homogenized molten glass is poured into this mold from a platinum alloy pipe at a fixed outflow speed. The poured molten glass spreads inside the mold, and a glass plate is formed so as to have a fixed width that is regulated by the pair of side walls. The formed glass plate is continuously drawn from the opening of the mold. By appropriately specifying molding conditions such as the shape and dimensions of the mold and the outflow speed of the molten glass, it is possible to form a large, thick glass block. The molded glass body is transferred to an annealing furnace that has been heated in advance to a temperature close to the glass transition temperature of the molded body, and allowed to cool gradually to room temperature. The molded glass body, in which strain has been eliminated through gradual cooling, is subjected to mechanical processing such as slicing, grinding and polishing. In this way, it is possible to obtain a near-infrared cut filter having a shape that is suitable for an application, such as plate-shaped or lens-shaped. Alternatively, it is also possible to use a method comprising molding a preform from the above glass, and then heating, softening and press molding the preform (in particular, a precision press molding method comprising press molding a finished product without subjecting an optically functional surface to mechanical processing such as grinding or polishing). An optical multilayer film may, if necessary, be formed on a surface of the filter.

The above near-infrared cut filter can exhibit both excellent near-infrared cutting performance and high transmittance of light in the visible region. According to this near-infrared cut filter, the color sensitivity of a semiconductor image element can be favorably corrected.

In addition, the above near-infrared cut filter can also be combined with a semiconductor image sensor and used in an imaging device. A semiconductor image sensor is a product obtained by attaching a semiconductor image element such as a CCD or a CMOS in a package and then covering a light-receiving part with a translucent member. The near-infrared cut filter can also serve as the translucent member, or the translucent member and the near-infrared cut filter can be separate components.

The imaging device described above can comprise a lens for forming an image of a subject on a light-receiving surface of a semiconductor image sensor, or an optical element such as a prism.

According to the above near-infrared cut filter, it is possible to provide an imaging device in which color sensitivity correction can be favorably achieved and which can yield an image having excellent image quality.

In one embodiment, the above near-infrared cut filter can be a near-infrared cut filter having a thickness of 0.25 mm or less. With the appearance of smartphones in recent years, the trend for the camera thickness of image elements to become smaller has been remarkable, and this has led to demands for near-infrared cut filters to exhibit performance at lower thicknesses. The above near-infrared cut filter is suitable for use as this type of near-infrared cut filter. The thickness of the above near-infrared cut filter can be 0.24 mm or less, 0.23 mm or less, 0.22 mm or less, 0.21 mm or less, 0.20 mm or less, 0.19 mm or less, 0.18 mm or less, 0.17 mm or less, 0.16 mm or less, 0.15 mm or less, 0.14 mm or less, 0.13 mm or less, or 0.12 mm or less. The thickness of the above near-infrared cut filter can be, for example, 0.21 mm or 0.11 mm. In addition, the thickness of the above near-infrared cut filter can be, for example, 0.50 mm or more, but the thickness is not limited to this. In the present invention and the present description, the term “thickness” means the thickness of a sample in a region where transmittance is measured, and can be measured using a thickness gauge, a micrometer, or the like. For example, the thickness may be measured at the approximate center of a position through which transmitted light passes, or the thickness of multiple points within a spot of transmitted light may be measured, with the average value of these measurements used.

For transmittance characteristics of the above near-infrared cut filter, earlier descriptions relating to Glasses 1 to 6 can be referred. For physical properties of the above near-infrared cut filter, earlier descriptions relating to Glasses 1 to 6 can be referred.

EXAMPLES

The present invention will be explained in further detail below through the use of Examples. However, the present invention is not limited to embodiments in Examples.

Examples 1 to 66 and Comparative Examples X and A to D

As glass raw materials, phosphates, fluorides, carbonates, nitrates, oxides, and the like, were weighed out and mixed so as to obtain 150 g to 300 g of a glass having a composition shown in Table 1, the obtained mixture was placed in a platinum crucible or a quartz crucible, melted for 80 minutes to 100 minutes at 800° C. to 1000° C., defoamed and homogenized by being agitated, and then flowed onto a preheated mold and molded into a prescribed shape. The obtained glass molded body was transferred to an annealing furnace that had been heated to a temperature close to the glass transition temperature and gradually cooled to room temperature. A test piece was cut from the obtained glass, both surfaces of the test piece were polished to a mirror finish to attain a thickness of approximately 0.2 mm, and evaluations were then carried out using the following methods.

[Evaluation Methods]

<Transmittance Characteristics>

Transmittance of test pieces were measured at wavelengths of 200 to 1200 nm using a spectrophotometer. From the measurement results, half values (units: nm), T400, T600, T1200 and Ave.T1100-800 (units:%) were determined as values calculated at half values of 645 nm and 633 nm and calculated at thicknesses of 0.11 mm, 0.21 mm, 0.23 mm and 0.25 mm.

<Glass Transition Temperature Tg and Temperature Tm at which an Endothermic Reaction Concludes Due to Melting>

Using a differential scanning calorimeter produced by Rigaku (DSC8270), the glass transition temperature Tg and the temperature Tm at which an endothermic reaction concludes due to melting were measured at a temperature increase rate of 10° C./min. The measurement temperature range was from room temperature to 1050° C.

<Specific Gravity>

Specific gravity was measured using the Archimedes method.

<Molar Volume>

Molar volume was calculated from the measured specific gravity using the method described above.

<Weathering Resistance Evaluation Classifications>

Each test piece was held for 3.5 hours in a constant-temperature constant-humidity chamber at a temperature of 85° C. and a relative humidity of 85%. The appearance of the test pieces was then evaluated by eye under a fluorescent lamp. Weathering resistance was evaluated from the evaluation results using the following criteria.

S: Clouding and/or precipitates seen at the surface were extremely slight.

A: Clouding and/or precipitates seen at the surface were slight.

B: Strong clouding was seen at the surface and/or precipitates were generated.

C: Surface wetting that indicated deliquescence was observed, albeit to a low degree, and/or thick precipitates were produced.

D: Deliquescence occurred to an extent whereby clear sheet thickness reduction was not observed, and/or precipitates that covered the base glass were produced.

E: Deliquescence occurred to an extent whereby a clear sheet thickness reduction was observed, and/or precipitates were produced to such an extent that the base glass could not be seen.

TABLE 1
Example
Comparative
Example	P2O5	Li2O	CuO	Al2O3	Y2O3	La2O3	Gd2O3	Na2O	K2O	MgO	CaO	SrO	BaO	ZnO
No	(mol %)	(mol %)	(mol %)	(mol %)	(mol %)	(mol %)	(mol %)	(mol %)	(mol %)	(mol %)	(mol %)	(mol %)	(mol %)	(mol %)
Example 1	61.36	10.15	26.31	1.45	0.50	0.22	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
Example 2	59.16	10.34	26.80	1.48	0.00	0.00	0.00	0.00	0.00	2.22	0.00	0.00	0.00	0.00
Example 3	60.04	10.50	27.21	1.50	0.52	0.23	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
Example 4	57.87	10.67	27.65	1.52	0.00	0.00	0.00	0.00	0.00	2.29	0.00	0.00	0.00	0.00
Example 5	58.76	10.83	28.08	1.55	0.54	0.23	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
Example 6	57.56	11.15	28.90	1.60	0.55	0.24	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
Example 7	56.61	10.99	28.48	1.57	0.00	0.00	0.00	0.00	0.00	2.35	0.00	0.00	0.00	0.00
Example 8	57.72	7.87	30.59	0.00	2.68	1.14	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
Example 9	56.73	10.31	30.06	0.00	2.03	0.87	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
Example 10	57.22	9.10	30.32	0.00	2.36	1.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
Example 11	58.23	6.62	30.86	0.00	3.01	1.29	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
Example 12	56.24	11.50	29.81	0.00	1.72	0.73	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
Example 13	56.24	11.50	29.81	0.00	1.47	0.98	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
Example 14	56.24	11.50	29.81	0.00	1.96	0.49	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
Example 15	56.24	11.50	29.81	0.00	2.20	0.25	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
Example 16	56.24	11.50	29.81	0.00	2.45	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
Example 17	56.24	11.50	29.80	0.83	1.14	0.49	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
Example 18	56.24	11.50	29.80	1.23	0.86	0.37	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
Example 19	56.24	11.50	29.80	0.42	1.43	0.61	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
Example 20	56.24	11.50	29.80	1.65	0.25	0.57	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
Example 21	56.24	11.50	29.80	1.65	0.57	0.25	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
Example 22	56.24	11.50	29.80	2.46	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
Example 23	55.33	16.23	24.40	1.62	0.00	0.00	0.00	0.00	0.00	2.42	0.00	0.00	0.00	0.00
Example 24	55.33	11.31	29.32	1.62	0.00	0.00	0.00	0.00	0.00	2.42	0.00	0.00	0.00	0.00
Example 25	56.24	11.50	21.44	1.65	0.57	0.25	0.00	0.00	0.00	0.00	0.00	0.00	8.37	0.00
Example 26	56.24	11.50	22.48	1.65	0.57	0.25	0.00	0.00	0.00	0.00	0.00	0.00	7.33	0.00
Example 27	56.24	20.55	20.76	1.65	0.57	0.25	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
Example 28	56.24	19.87	21.44	1.65	0.57	0.25	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
Example 29	53.59	15.72	23.64	0.00	0.00	0.00	0.00	0.00	0.00	2.35	0.00	0.00	4.71	0.00
Example 30	53.59	15.72	23.64	0.00	0.00	0.00	0.00	0.00	0.00	4.70	0.00	0.00	2.35	0.00
Example 31	53.59	9.23	23.64	0.00	0.00	0.00	0.00	0.00	0.00	0.00	13.55	0.00	0.00	0.00
Example 32	53.59	9.23	23.64	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	13.55	0.00	0.00
Example 33	53.59	9.23	23.64	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	13.55	0.00
Example 34	56.35	9.71	31.37	2.57	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
Example 35	54.44	15.97	24.01	0.80	0.00	0.00	0.00	0.00	0.00	4.78	0.00	0.00	0.00	0.00
Example 36	55.27	11.75	30.46	1.68	0.58	0.25	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
Example 37	54.34	11.56	29.97	1.65	0.00	0.00	0.00	0.00	0.00	2.48	0.00	0.00	0.00	0.00
Example 38	57.72	10.56	25.97	5.65	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
Example 39	54.63	10.09	32.61	2.67	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
Example 40	54.17	12.04	31.21	1.73	0.60	0.26	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
Example 41	53.19	12.30	31.88	1.76	0.61	0.26	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
Example 42	55.89	16.92	21.29	5.90	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
Example 43	55.89	22.72	15.49	5.90	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
Example 44	52.07	8.48	26.70	2.25	0.00	0.00	0.00	2.56	5.11	0.83	0.00	0.00	1.64	0.37
Example 45	55.42	22.23	15.48	5.90	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.96
Example 46	52.18	12.56	32.56	1.80	0.62	0.27	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
Example 47	52.89	23.50	16.37	6.24	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	1.02
Example 48	50.85	25.32	17.26	6.57	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
Example 49	50.32	24.78	17.26	6.58	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	1.07
Example 50	51.36	5.60	26.83	1.48	0.00	0.00	0.00	4.28	8.57	0.54	0.00	0.00	1.08	0.25
Example 51	52.52	21.41	14.07	5.68	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.33
Example 52	49.60	19.99	13.70	5.31	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	11.40
Example 53	56.24	8.50	32.80	1.65	0.57	0.25	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
Example 54	56.24	5.50	35.80	1.65	0.57	0.25	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
Example 55	56.24	2.50	38.80	1.65	0.57	0.25	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
Example 56	53.66	15.03	14.16	3.98	0.00	0.00	0.00	2.71	5.42	1.46	0.00	0.00	2.92	0.66
Example 57	52.92	12.01	14.23	3.18	0.00	0.00	0.00	4.54	9.09	1.17	0.00	0.00	2.33	0.52
Example 58	52.18	8.95	14.31	2.37	0.00	0.00	0.00	6.40	12.79	0.87	0.00	0.00	1.74	0.39
Example 59	53.59	15.72	23.64	0.00	0.00	0.00	0.00	0.00	0.00	7.05	0.00	0.00	0.00	0.00
Example 60	53.59	9.23	23.64	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	13.55
Comp. Ex. X	50.67	2.76	14.45	0.73	0.00	0.00	0.00	10.15	20.30	0.27	0.00	0.00	0.54	0.12
Comp. Ex. A	53.59	19.30	27.11	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
Comp. Ex. B	53.59	12.73	33.68	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
Comp. Ex. C	53.59	22.77	23.64	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
Comp. Ex. D	36.07	23.63	9.87	3.32	0.00	0.00	0.00	0.00	10.45	2.74	5.31	1.99	6.61	0.00
Example 61	51.65	1.09	16.9	1.66	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	28.63	0.00
Example 62	51.16	1.10	16.2	1.50	0.44	0.20	0.00	0.00	0.00	0.00	0.00	0.00	29.40	0.00
Example 63	53.00	1.28	17.7	2.97	0.00	0.00	0.00	0.00	2.63	0.00	0.00	0.00	22.34	0.00
Example 64	51.16	1.16	20.7	1.50	0.44	0.20	0.00	0.00	0.00	0.00	0.00	0.00	24.85	0.00
Example 65	50.60	0.40	17.8	2.80	0.46	0.21	0.00	0.00	0.80	0.00	0.00	0.00	26.89	0.00
Example 66	50.79	0.40	17.82	1.53	0.99	0.46	0.00	0.00	0.78	0.00	0.00	0.00	27.19	0.00

TABLE 2
Example												Molar			Number of		Total content
Comparative												molecular	Specific	Molar	cations selected		of oxides of	O ion
Example	B2O3	SiO2	Ta2O5	TiO2	ZrO2	Nb2O5	WO3	Bi2O3	Cs2O	V2O5	Total	weight	gravity	volume	from main cation	O/P	main cations	content
No	(mol %)	(mol %)	(mol %)	(mol %)	(mol %)	(mol %)	(mol %)	(mol %)	(mol %)	(mol %)	(mol %)	M(g/mol)	(g/cc)	(cc/mol)	group	ratio	(mo %)	(anionic %)
Example 1	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	114.39	2.78	41.103	6	2.850	100.00	100.00
Example 2	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	110.79	2.78	39.823	5	2.870	100.00	100.00
Example 3	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	113.45	2.80	40.517	6	2.870	100.00	100.00
Example 4	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	109.80	2.80	39.202	5	2.890	100.00	100.00
Example 5	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	112.54	2.82	39.908	6	2.890	100.00	100.00
Example 6	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	111.68	2.84	39.379	6	2.910	100.00	100.00
Example 7	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	108.84	2.82	38.583	5	2.911	100.00	100.00
Example 8	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	118.39	2.94	40.269	5	2.933	100.00	100.00
Example 9	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	114.93	2.91	39.537	5	2.933	100.00	100.00
Example 10	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	116.65	2.93	39.866	5	2.933	100.00	100.00
Example 11	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	120.17	2.95	40.679	5	2.933	100.00	100.00
Example 12	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	113.25	2.89	39.132	5	2.933	100.00	100.00
Example 13	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	113.49	2.90	39.149	5	2.933	100.00	100.00
Example 14	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	113.01	2.89	39.117	5	2.933	100.00	100.00
Example 15	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	112.76	2.88	39.140	5	2.933	100.00	100.00
Example 16	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	112.51	2.88	39.122	4	2.933	100.00	100.00
Example 17	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	112.00	2.88	38.914	6	2.933	100.00	100.00
Example 18	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	111.38	2.87	38.843	6	2.933	100.00	100.00
Example 19	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	112.62	2.89	39.023	6	2.933	100.00	100.00
Example 20	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	111.06	2.87	38.697	6	2.933	100.00	100.00
Example 21	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	110.74	2.86	38.719	6	2.933	100.00	100.00
Example 22	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	109.48	2.84	38.522	4	2.933	100.00	100.00
Example 23	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	105.42	2.77	38.113	5	2.933	100.00	100.00
Example 24	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	107.86	2.84	38.020	5	2.933	100.00	100.00
Example 25	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	116.92	2.95	39.606	7	2.933	100.01	100.00
Example 26	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	116.15	2.94	39.484	7	2.933	100.01	100.00
Example 27	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	106.25	2.73	38.962	6	2.933	100.01	100.00
Example 28	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	103.59	2.74	38.957	6	2.933	100.01	100.00
Example 29	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	107.73	2.87	37.602	5	2.933	100.00	100.00
Example 30	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	105.07	2.81	37.378	5	2.933	100.00	100.00
Example 31	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	105.22	2.80	37.606	4	2.933	100.00	100.00
Example 32	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	111.68	2.98	37.446	4	2.933	100.00	100.00
Example 33	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	118.40	3.09	38.316	4	2.933	100.00	100.00
Example 34	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	110.46	2.87	38.448	4	2.933	100.00	100.00
Example 35	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	103.89	2.76	37.601	5	2.933	100.00	100.00
Example 36	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	110.05	2.87	38.305	6	2.950	100.00	100.00
Example 37	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	107.11	2.85	37.530	5	2.951	100.00	100.00
Example 38	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	111.54	2.83	39.440	4	2.964	100.00	100.00
Example 39	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	109.22	2.90	37.677	4	2.964	100.00	100.00
Example 40	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	109.27	2.90	37.730	6	2.971	100.00	100.00
Example 41	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	108.56	2.91	37.256	6	2.990	100.00	100.00
Example 42	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	107.34	2.77	38.794	4	3.000	100.00	100.00
Example 43	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	104.48	2.68	38.935	4	3.000	100.00	100.00
Example 44	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	109.52	2.88	38.095	9	3.004	100.00	100.00
Example 45	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	104.43	2.70	38.676	5	3.009	100.00	100.00
Example 46	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	107.85	2.94	36.745	6	3.010	100.00	100.00
Example 47	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	102.29	2.73	37.484	5	3.063	100.00	100.00
Example 48	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	100.17	2.74	36.560	4	3.113	100.00	100.00
Example 49	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	100.13	2.76	36.253	5	3.124	100.00	100.00
Example 50	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	110.24	2.85	38.695	9	3.002	100	100.00
Example 51	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	103.07	2.76	37.414	5	3.060	100	100.00
Example 52	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	101.97	2.83	36.019	5	3.115	100	100.00
Example 53	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	112.23	2.93	38.290	6	2.933	100.00	100.00
Example 54	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	113.72	2.95	38.509	6	2.933	100.00	100.00
Example 55	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	115.21	2.97	38.751	6	2.933	100.00	100.00
Example 56	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	108.37	2.75	39.421	9	3.006	100.00	100.00
Example 57	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	109.12	2.73	40.046	9	3.005	100	100.00
Example 58	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	109.89	2.70	40.670	9	3.004	100	100.00
Example 59	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	102.41	2.76	37.091	4	2.933	100.00	100.00
Example 60	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	108.85	2.90	37.505	4	2.933	100.00	100.00
Comp. Ex. X	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	111.44	2.66	41.958	9	3.001	100	100.00
Comp. Ex. A	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	103.40	2.79	37.113	3	2.933	100	100.00
Comp. Ex. B	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	106.66	2.89	36.882	3	2.933	100	100.00
Comp. Ex. C	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	101.67	2.73	37.243	3	2.933	100	100.00
Comp. Ex. D	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100	95.62	2.95	32.413	9	3.478	99.99	100.00
Example 61	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100.0	132.70	3.40	39.03	5	3.00	100	100.00
Example 62	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100.0	134.08	3.42	39.24	7	3.02	100	100.00
Example 63	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100.0	129.49	3.25	39.84	6	3.00	100	100.00
Example 64	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100.0	130.67	3.39	38.55	7	3.02	100	100.00
Example 65	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100.0	132.70	3.30	39.14	8	3.06	100	100.00
Example 66	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	100.0	134.10	3.43	39.10	8	3.04	100	100.00

TABLE 3
Example
Comparative						A1 =	A2 =		α1 =	α2 =
Example	MgO + Al2O3	(Na2O + K2O +			O(P) −	(O(P) −	(O(P) −	C	70400 ×	76522 ×	C − 3200 ×	C − 3478 ×
No	(mol %)	ZnO)/Li2)	O(P)	O(others)	O(others)	O(others)) × Cu	O(others)) × C	(mmol/cc)	exp(−2.855 × R)	exp(−2.855 × R)	exp(−2.278 × R)	exp(−2.278 × R)
Example 1	1.45	0.00	306.788	42.994	263.794	6941.68	1688.85	6.40	20.58	22.37	1.5	1.14
Example 2	3.69	0.00	295.806	43.795	252.011	6754.81	1690.23	6.73	19.45	21.14	2.10	1.70
Example 3	1.50	0.00	300.182	44.464	255.718	6 9.24	1717.61	6.72	19.44	21.13	2.09	1.69
Example 4	3.81	0.00	289.362	45.177	244.185	6751.70	1722.29	7.05	18.3	19.9	2.53	2.25
Example 5	1.55	0.00	293.822	45.880	247.942	6962.41	1744.62	7.04	18.3	19.95	2.61	2.23
Example 6	1.60	0.00	287.781	47.224	240.557	69 2.94	1765.65	7.34	17.34	18.85	3.11	2.75
Example 7	3.92	0.00	283.059	46.529	238.530	6735.74	1745.78	7.38	17.31	18.81	3.1	2.79
Example 8	0.00	0.00	288.584	49.934	238.650	729 .89	1812.77	7.60	16.27	17.6	3.58	3.23
Example 9	0.00	0.00	283.629	49.077	234.552	7051.38	1783.51	7.80	16.27	17.69	3.59	3.24
Example 10	0.00	0.00	286.085	49.502	236.583	7174.03	1799.55	7.61	16.27	17.68	3.59	3.24
Example 11	0.00	0.00	291.127	50.274	240.752	742 .10	1826.28	2.59	16.27	17.69	3.57	3.22
Example 12	0.00	0.00	281.214	48.660	232.554	6931.77	1771.40	7.82	16.27	17.69	3.60	3.2
Example 13	0.00	0.00	281.214	48.660	232.554	8931.77	1770.60	7.61	16.27	17.69	3.60	3.2
Example 14	0.00	0.00	281.214	48.860	232.354	6931.77	1772.07	7.62	16.27	17.69	3.60	3.2
Example 15	0.00	0.00	281.214	48.660	232.354	6931.77	1771.03	7.62	16.27	17.69	3.60	3.25
Example 16	0.00	0.00	281.214	48.660	232.554	6931.77	1771.83	7.62	16.27	17.69	3.60	3.25
Example 17	0. 3	0.00	281.190	48.681	232.509	6929.83	1780.78	7.66	16.26	17.67	3. 4	3.30
Example 18	1.23	0.00	281.190	49.681	232.509	6928.83	1784.07	7.67	16.26	17.67	3.66	3.31
Example 19	0.42	0.00	281.190	48.681	232.509	6929.89	1775.82	7.64	16.26	17.67	3.62	3.27
Example 20	1.65	0.00	281.176	48.694	232.482	6928.69	1790.50	7.70	16.25	17.67	3.69	. 4
Example 21	1.65	0.00	281.176	48.694	232.482	6928.89	1789.47	7.70	16.25	17.67	3.68	3.3
Example 22	2.40	0.00	281.176	48.694	232.482	6928.69	1798.6	7.74	16.2	17.67	3.72	3.37
Example 23	4.04	0.00	276.631	47.908	298.724	5581.61	1464.50	6.40	16.25	17.67	2.39	2.04
Example 24	4.04	0.00	276.631	47.908	228.724	6706.50	1763.95	7.71	16.25	17.67	3.70	3.35
Example 25	1.65	0.00	281.176	48.700	232.475	4984.27	1258.45	5.41	16.25	17.67	1.40	1.05
Example 26	1.65	0.00	281.176	48.700	232.475	5226.04	1323.27	5.69	16.25	17.67	1.68	1.33
Example 27	1.65	0.00	281.176	48.703	232.473	4826.13	123 .69	5.03	16.25	17.66	1.32	0.97
Example 28	1.65	0.00	281.176	48.703	237.473	4984.21	1279.42	5.50	16.25	17.66	1.49	1.14
Example 29	2.3	0.00	267.043	46.411	221.532	5236.32	1392.58	6.29	16.25	17.66	2.27	1.92
Example 30	4.70	0.00	267.943	46.411	221.532	5236.32	1400.92	6.32	16.25	17.66	2.31	1.86
Example 31	0.00	0.00	267.941	48.412	221.529	5236.22	1392.38	6.29	16.25	17.	2.27	1.92
Example 32	0.00	0.00	267.941	48.412	221.529	5236.22	1398.36	6.31	16.25	17.6	2.30	1.95
Example 33	0.00	0.00	267.941	46.412	221.529	5236.22	1386.59	6.17	16.25	17.66	2.1	1.81
Example 34	2.57	0.00	281.732	48.803	232.929	7307.34	1800.57	.18	16.25	17.66	4.15	3.80
Example 35	5.58	0.00	272.206	47.158	225.048	5404.06	1437.23	6.39	16.25	17.66	2.37	2.03
Example 36	1.68	0.00	276.361	49.765	226.496	6901.85	1 01.82	7.95	15.47	16.82	4.09	3.76
Example 37	4.13	0.00	271.708	48.963	222.745	6675.06	1778.59	7.98	15.46	16.80	4.1	3.79
Example 38	5.65	0.00	788.611	53.583	235.027	6102.88	1547.37	.88	14.87	16.16	2.85	2.52
Example 39	2.67	0.00	273.160	50.715	222.445	7253.18	1925.11	.	14.87	16.16	4.92	4. 9
Example 40	1.73	0.00	270.861	50.989	219.872	6861.75	1818.05	8.27	14.60	15.87	4.59	4.27
Example 41	1.76	0.00	265.938	52.084	213.854.	6817.32	1829.86	8.56	13.83	15.03	5.03	4.72
Example 42	5.90	0.00	279.470	55.902	223.567	4759.86	1226.95	.49	13.42	14.59	2.04	1.74
Example 43	5.90	0.00	279.470	55.902	223.567	3482.51	8 9.32	3.98	13.42	14.59	0.53	0.23
Example 44	3.07	0.95	260.326	52.432	207.094	5550.91	1457.13	7.01	13.29	14.44	3.59	3.29
Example 45	5.90	0.04	277.099	56.381	220.717	3417.79	883.68	4.00	13.0	14.23	0.83	0.33
Example 46	1.80	0.00	260.911	53.203	207.708	6783.62	1840.69	8.88	13.0	14.19	5.49	5.20
Example 47	6.24	0.04	264.423	59.587	204.941	3352.26	94.33	4.37	11.20	12.18	1.38	1.12
Example 48	6.57	0.00	254.242	62.297	191.945	3312.83	906.14	4.72	9.73	10.58	2.06	1.82
Example 49	6.58	0.04	251.589	62.834	186.758	3257.30	898.50	4.76	9.41	10.73	2.17	1.94
Example 50	2.03	2.340	256.801	51.606	205.185	5505.96	1422.93	6.93	13.3	17.48	3. 1	3.21
Example 51	5.60	0.296	262.581	58.844	203.746	2065.91	766.00	3.76	11.30	12.2	0.76	0.50
Example 52	5.31	0.570	248.020	61.007	187.013	2 1.40	711.130	3.80	9.67	10.51	1.15	0.92
Example 53	1.85	0.00	281.176	48.694	232.482	7628.14	1991.7 2	8.57	1 .25	17.67	4.	4.20
Example 54	1.65	0.00	281.176	48.694	232.482	6323.59	2161.474	9.30	1 .25	17.67	5.28	4.9
Example 55	1.65	0.00	281.176	48.694	232.482	9021.03	2327.952	10.01	1 .25	17.67	6.00	5.65
Example 56	5.44	0.585	268.282	54.313	213.989	3029.4	28 .50	3.59	13.19	14.34	0.10	−0.10
Example 57	4.35	1.179	264.610	53.447	211.103	3005.00	750.39	3.55	13.23	14.39	0.15	−0.15
Example 58	3.24	2.1 7	260.892	52.570	208.322	2 0.18	732.77	.52	13.2	14.43	0.101	−0.20
Example 59	7.05	0.00	267.943	46.411	221.532	5236.32	1411.74	6.37	16.25	17.66	2.3	2.01
Example 60	0.00	1.47	267.941	46.412	221.529	5236.22	1398.15	6.30	18.25	17.	2.29	1. 4
Comp. Ex. X	1.00	11.073	253.360	50.793	202.567	2927.50	697.72	3.44	13.3	14.54	0.009	−0.29
Comp. Ex. A	0.00	0.000	267.943	46.411	221.532	6005.22		7.30	16.25	17.6	3.29	2.94
Comp. Ex. B	0.00	0.000	267.943	46.411	221.532	7461.38		9.13	16.25	17.6	5.12	4.77
Comp. Ex. C	0.00	0.000	267.943	46.411	221.532	6735.32		. 5	16.25	17.6	2.33	1.
Comp. Ex. D	6.06	0.44	180.350	70.560	109.790	1083.63		3.05	3.42	.73	1.89	1.78
Example 61	1.45	0.00	258.228	51.64	206.59	3498.49	896.34	4.34	13.42	14.59	0.834	0.595
Example 62	1.48	0.00	255.780	53.08	202.70	3275.81	8 4.73	4.12	12.68	13.78	0.827	0.541
Example 63	1.50	2.06	265.000	52.91	212.09	3162.01	944.35	4.45	13.42	14.59	1.008	0.708
Example 64	1.52	0.00	255.883	53.08	202.72	4188.47	10 6.61	5.3	12.68	13.78	2.061	1.774
Example 65	1. 5	1.98	252.999	56.34	196.6	3509.55	890.57	4.5	11.47	12.47	1.520	1.2
Example 66	1.	1.96	253.970	55.13	1 . 4	3542.58	906.1	4.5	11.87	12.90	1.433	1.162
indicates data missing or illegible when filed

TABLE 4
								(3 × Al2O3 +
						Al2O2 +	(3 × Al2O3 +	Y2O3 + La2O3 +	O ion
Example		P2O5 +	Li2O +		Na2O +	Y2O3 +	Y2O3 + La2O3 +	Gd2O3 + BaO/3 +	(Coefficient of
Comparative	B2O3 +	Li2O +	Na2O +	Na2O +	K2O + CaO +	La2O3 +	Gd2O3 + BaO/3 +	(CaO + SrO)/6)/	oxide × molar
Example	SiO2	CuO	K2O	K2O	SrO + BaO	Gd2O3	(CaO + SrO)/6)	(P2O5 + Li2O +	percentage
No	(mol %)	(mol %)	(mol %)	(mol %)	(mol %)	(mol %)	(mol %)	CuO)	of cation)
Example 1	0.00	97.82	10.15	0.00	0.00	2.18	5.09	0.052	349.78
Example 2	0.00	96.31	10.34	0.00	0.00	1.48	4.43	0.046	339.60
Example 3	0.00	97.75	10.50	0.00	0.00	2.25	5.26	0.054	344.65
Example 4	0.00	96.19	10.67	0.00	0.00	1.52	4.57	0.048	334.54
Example 5	0.00	97.68	10.83	0.00	0.00	2.32	5.43	0.056	339.70
Example 6	0.00	97.61	11.15	0.00	0.00	2.39	5.59	0.057	335.00
Example 7	0.00	98.08	10.99	0.00	0.00	1.57	4.71	0.049	329.59
Example 8	0.00	96.17	7.87	0.00	0.00	3.83	3.83	0.040	338.52
Example 9	0.00	97.10	10.31	0.00	0.00	2.90	2.90	0.030	332.71
Example 10	0.00	96.64	9.10	0.00	0.00	3.36	3.36	0.035	335.59
Example 11	0.00	95.70	6.62	0.00	0.00	4.30	4.30	0.045	341.50
Example 12	0.00	97.55	11.50	0.00	0.00	2.45	2.45	0.025	329.87
Example 13	0.00	97.55	11.50	0.00	0.00	2.45	2.45	0.025	329.87
Example 14	0.00	97.55	11.50	0.00	0.00	2.45	2.45	0.025	329.87
Example 15	0.00	97.55	11.50	0.00	0.00	2.45	2.45	0.025	329.87
Example 16	0.00	97.55	11.50	0.00	0.00	2.45	2.45	0.025	329.87
Example 17	0.00	97.54	11.50	0.00	0.00	2.46	4.11	0.042	329.87
Example 18	0.00	97.54	11.50	0.00	0.00	2.46	4.93	0.051	329.87
Example 19	0.00	97.54	11.50	0.00	0.00	2.46	3.29	0.034	329.87
Example 20	0.00	97.54	11.50	0.00	0.00	2.46	5.76	0.059	329.87
Example 21	0.00	97.54	11.50	0.00	0.00	2.46	5.76	0.059	329.87
Example 22	0.00	97.54	11.50	0.00	0.00	2.46	7.39	0.076	329.87
Example 23	0.00	95.96	16.23	0.00	0.00	1.62	4.85	0.051	324.54
Example 24	0.00	95.96	11.31	0.00	0.00	1.62	4.85	0.051	324.54
Example 25	0.00	89.17	11.50	0.00	8.37	2.46	8.55	0.096	329.88
Example 26	0.00	90.21	11.50	0.00	7.33	2.46	8.20	0.091	329.88
Example 27	0.00	97.55	20.55	0.00	0.00	2.46	5.76	0.059	329.88
Example 28	0.00	97.55	19.87	0.00	0.00	2.46	5.76	0.059	329.88
Example 29	0.00	92.95	15.72	0.00	4.71	0.00	1.57	0.017	314.35
Example 30	0.00	92.95	15.72	0.00	2.35	0.00	0.78	0.008	314.35
Example 31	0.00	86.45	9.23	0.00	13.55	0.00	2.26	0.026	314.35
Example 32	0.00	86.45	9.23	0.00	13.55	0.00	2.26	0.026	314.35
Example 33	0.00	86.45	9.23	0.00	13.55	0.00	4.52	0.052	314.35
Example 34	0.00	97.43	9.71	0.00	0.00	2.57	7.72	0.079	330.53
Example 35	0.00	94.42	15.97	0.00	0.00	0.80	2.40	0.025	319.38
Example 36	0.00	97.48	11.75	0.00	0.00	2.52	5.89	0.060	326.13
Example 37	0.00	95.87	11.66	0.00	0.00	1.65	4.96	0.052	320.67
Example 38	0.00	94.35	10.68	0.00	0.00	5.65	16.96	0.180	342.19
Example 39	0.00	97.33	10.09	0.00	0.00	2.67	8.02	0.082	323.88
Example 40	0.00	97.42	12.04	0.00	0.00	2.58	6.03	0.062	321.85
Example 41	0.00	97.36	12.30	0.00	0.00	2.64	6.16	0.063	318.02
Example 42	0.00	94.10	16.92	0.00	0.00	5.90	17.69	0.188	335.37
Example 43	0.00	94.10	22.72	0.00	0.00	5.90	17.68	0.188	335.37
Example 44	0.00	87.24	16.15	7.67	9.32	2.25	7.29	0.084	312.78
Example 45	0.00	93.14	22.23	0.00	0.00	5.90	17.70	0.190	333.48
Example 46	0.00	97.31	12.56	0.00	0.00	2.69	6.29	0.065	314.11
Example 47	0.00	92.75	23.50	0.00	0.00	6.24	18.71	0.202	324.01
Example 48	0.00	93.43	25.32	0.00	0.00	6.57	19.72	0.211	316.54
Example 49	0.00	92.35	24.78	0.00	0.00	6.58	19.73	0.214	314.42
Example 50	0.00	83.79	18.45	12.85	13.94	1.48	4.81	0.057	308.41
Example 51	0.00	87.99	21.41	0.00	0.00	5.68	17.04	0.194	321.43
Example 52	0.00	83.29	19.99	0.00	0.00	5.31	15.92	0.191	309.03
Example 53	0.00	97.54	8.50	0.00	0.00	2.46	5.76	0.059	329.87
Example 54	0.00	97.54	5.50	0.00	0.00	2.46	5.76	0.059	329.87
Example 55	0.00	97.54	2.50	0.00	0.00	2.46	5.76	0.059	329.87
Example 56	0.00	82.84	23.16	8.14	11.06	3.98	12.93	0.156	322.60
Example 57	0.00	79.16	25.64	13.63	15.98	3.18	10.33	0.131	318.06
Example 58	0.00	75.44	28.14	19.19	20.93	2.37	7.70	0.102	313.46
Example 59	0.00	92.95	15.72	0.00	0.00	0.00	0.00	0.000	314.35
Example 60	0.00	86.45	9.23	0.00	0.00	0.00	0.00	0.000	314.35
Comp. Ex. X	0.00	87.89	33.22	30.45	30.99	0.73	2.38	0.035	304.15
Comp. Ex. A	0.00	100.00	19.30	0.00	0.00	0.00	0.00	0.000	314.35
Comp. Ex. B	0.00	100.00	12.73	0.00	0.00	0.00	0.00	0.000	314.35
Comp. Ex. C	0.00	100.00	22.77	0.00	0.00	0.00	0.00	0.000	314.35
Comp. Ex. D	0.00	69.57	34.08	10.45	24.36	3.32	13.38	0.192	250.91
Example 61	0.00	69.67	1.09	0.00	28.63	1.66	14.53	0.209	309.87
Example 62	0.00	68.42	1.10	0.00	29.40	2.14	14.93	0.218	308.86
Example 63	0.00	72.02	3.91	2.63	24.97	2.97	16.37	0.227	317.91
Example 64	0.00	72.98	1.16	0.00	24.85	2.14	13.42	0.184	308.88
Example 65	0.00	68.85	1.20	0.80	27.69	3.47	18.03	0.262	309.34
Example 66	0.00	69.01	1.18	0.78	27.97	2.98	15.11	0.219	309.10

TABLE 5
Example	Transmittance @ λ T50 = 645 nm	Transmittance @ λ T50 = 633 nm
Comparative	Sheet		Ave.				Sheet		Ave.
Example	thickness	T1200	T1100-800	T750	T600	T400	thickness	T1200	T1100-800	T750	T600	T400
No	(mm)	(%)	(%)	(%)	(%)	(%)	(mm)	(%)	(%)	(%)	(%)	(%)
Example 1	0.170	2.420	0.386	4.049	75.895	85.936	0.225	0.751	0.071	1.483	71.402	84.147
Example 2	0.153	3.585	1.204	4.379	76.550	87.133	0.203	1.241	0.297	1.619	72.148	85.676
Example 3	0.151	3.304	0.637	4.417	76.165	86.742	0.200	1.130	0.134	1.660	71.725	85.187
Example 4	0.136	4.965	1.520	4.856	76.366	86.849	0.180	1.935	0.410	1.379	71.971	85.323
Example 5	0.138	4.423	0.915	4.817	76.262	86.684	0.182	1.673	0.216	1.873	71.874	85.121
Example 6	0.117	6.096	1.176	5.454	75.642	85.667	0.153	2.810	0.316	2.255	71.209	83.849
Example 7	0.120	6.150	1.639	5.209	76.483	86.596	0.159	2.578	0.459	2.071	72.136	85.002
Example 8	0.099	10.009	3.639	6.913	75.589	86.127	0.129	5.181	1.391	3.167	71.295	84.500
Example 9	0.105	9.073	3.852	6.382	75.878	86.330	0.137	4.449	1.474	2.808	71.568	84.728
Example 10	0.103	9.130	3.065	6.520	75.821	86.198	0.134	4.514	1.098	2.909	71.534	84.572
Example 11	0.093	10.940	3.725	7.342	75.600	86.153	0.121	5.795	1.447	3.452	71.352	84.550
Example 12	0.110	7.889	2.030	5.618	76.300	86.133	0.145	3.614	0.614	2.310	71.954	84.421
Example 13	0.103	8.303	2.000	5.850	75.822	86.018	0.135	3.940	0.624	2.490	71.467	84.314
Example 14	0.105	7.935	1.805	5.707	75.906	85.851	0.137	3.713	0.551	2.411	71.572	84.101
Example 15	0.110	7.829	2.111	5.651	75.926	86.081	0.145	3.644	0.673	2.377	71.591	84.393
Example 16	0.110	7.829	1.868	5.713	75.952	85.683	0.144	3.630	0.569	2.401	71.601	83.873
Example 17	0.109	7.545	2.461	5.570	76.229	85.959	0.143	3.427	0.798	2.299	71.896	84.208
Example 18	0.107	8.279	3.704	5.792	75.944	85.808	0.141	3.909	1.379	2.446	71.595	84.036
Example 19	0.111	7.955	2.039	5.741	75.769	85.493	0.145	3.730	0.641	2.433	71.409	83.644
Example 20	0.109	7.575	1.719	5.696	75.771	85.549	0.143	3.492	0.517	2.404	71.402	83.712
Example 21	0.111	7.517	2.820	5.485	76.196	86.037	0.146	3.417	0.967	2.258	71.865	84.313
Example 22	0.113	6.912	2.245	5.466	26.144	85.839	0.149	3.065	0.720	2.252	71.810	84.061
Example 23	0.136	6.235	1.524	4.997	76.331	86.869	0.180	2.616	0.418	1.952	71.928	85.350
Example 24	0.109	7.924	2.518	5.792	76.198	86.051	0.143	3.648	0.821	2.414	71.847	84.335
Example 25	0.166	5.967	1.064	4.555	76.384	86.422	0.220	2.453	0.263	1.715	71.964	84.758
Example 26	0.164	6.131	1.032	4.644	76.229	86.462	0.216	2.571	0.259	1.782	71.826	84.831
Example 27	0.178	5.716	0.962	4.490	76.476	87.041	0.237	2.297	0.227	1.667	72.040	85.550
Example 28	0.166	5.871	0.952	4.567	76.344	86.795	0.220	2.383	0.226	1.707	71.878	85.230
Example 29	0.147	5.614	1.100	4.346	76.437	85.084	0.194	2.269	0.272	1.616	72.043	83.418
Example 30	0.141	6.138	1.191	4.708	76.434	86.083	0.187	2.562	0.306	1.804	72.057	84.330
Example 31	0.115	9.231	2.024	5.862	76.000	85.046	0.150	4.511	0.637	2.486	71.667	83.059
Example 32	0.118	8.642	1.911	5.389	75.947	83.451	0.155	4.099	0.584	2.202	71.548	80.992
Example 33	0.136	5.811	1.076	4.490	76.070	83.894	0.179	2.427	0.275	1.729	71.692	81.553
Example 34	0.095	8.422	3.869	6.327	75.500	78.928	0.123	4.090	1.514	2.818	71.178	75.416
Example 35	0.136	6.639	1.539	5.002	76.248	86.637	0.179	2.873	0.429	1.978	71.879	85.068
Example 36	0.098	9.186	2.418	6.354	75.858	85.818	0.127	4.546	0.813	2.810	71.575	84.084
Example 37	0.097	9.903	4.813	6.222	76.007	85.574	0.127	4.987	1.962	2.715	71.725	83.758
Example 38	0.089	13.671	4.955	8.284	74.773	79.147	0.115	7.946	2.187	4.174	70.538	75.884
Example 39	0.081	9.477	4.338	7.011	75.279	76.917	0.106	4.820	1.770	3.260	70.972	72.983
Example 40	0.093	10.613	2.829	6.630	75.612	84.696	0.121	5.535	1.008	2.987	71.303	82.686
Example 41	0.084	12.120	3.114	7.023	75.307	83.566	0.110	6.612	1.165	3.254	70.984	81.262
Example 42	0.123	12.199	2.875	7.632	75.001	81.159	0.159	6.780	1.088	3.700	70.728	78.313
Example 43	0.179	11.035	2.416	6.870	75.418	83.778	0.233	5.861	0.844	3.167	71.128	81.535
Example 44	0.121	5.836	1.463	4.971	75.636	83.755	0.158	2.483	0.418	2.013	71.239	81.421
Example 45	0.162	12.775	2.829	7.269	75.394	85.975	0.209	7.126	1.050	3.431	71.138	84.337
Example 46	0.077	13.453	3.829	7.299	75.463	82.431	0.100	7.596	1.520	3.435	71.199	79.845
Example 47	0.129	18.122	4.807	8.623	74.666	82.277	0.166	11.384	2.126	4.379	70.385	79.748
Example 48	0.108	21.057	6.228	9.481	74.244	76.092	0.138	14.069	3.048	5.091	70.061	72.289
Example 49	0.103	22.85	6.562	9.845	74.25	82.32	0.132	15.563	3.278	5.313	70.039	79.896
Example 50	0.142	3.235	1.070	3.535	76.009	82.607	0.188	1.088	0.280	1.224	71.490	79.832
Example 51	0.148	20.133	5.334	8.706	74.637	82.687	0.190	13.131	2.486	4.484	70.420	80.300
Example 52	0.130	24.979	6.961	9.278	74.584	80.034	0.167	17.341	3.486	4.979	70.375	77.026
Example 53	0.083	10.259		6.783	75.366	85.528	0.108	5.336	2.408	3.119	71.071	83.757
Example 54	0.077	10.318		7.232	75.154	85.485	0.100	5.410	2.270	3.414	70.853	83.719
Example 55	0.067	11.519		7.812	74.967	85.190	0.087	6.304	4.105	3.819	70.694	83.375
Example 56	0.232	6.624	1.108	4.899	75.666	82.733	0.304	2.925	0.295	1.969	71.265	80.314
Example 57	0.271	4.010	0.540	3.549	76.269	81.762	0.359	1.441	0.108	1.225	71.798	78.739
Example 58	0.315	2.547	0.268	2.575	76.479	79.774	0.421	0.766	0.041	0.777	71.951	76.121
Example 59	0.136	7.005	1.547	6.102	76.193	86.207	0.179	3.076	0.432	2.024	71.797	84.506
Example 60	0.123	9.383	2.532	5.946	76.147	86.607	0.162	4.617	0.847	2.539	71.859	85.069
Comp. Ex. X	0.352	1.846	0.156	2.059	73.631	69.056	0.463	0.538	0.023	0.621	68.694	63.135
Comp. Ex. A	0.125	5.963	2.057	4.579	76.344	81.915	0.166	2.459	0.610	1.733	71.929	76.960
Comp. Ex. B	0.091	7.734	4.856	5.651	75.965	83.367	0.119	3.561	1.965	2.368	71.619	80.912
Comp. Ex. C	0.147	5.181	0.938	4.201	76.536	85.249	0.196	2.010	0.217	1.521	72.100	83.212
Comp. Ex. D	0.089	36.027	13.809	13.887	72.114	87.082	0.111	28.827	8.950	8.852	68.090	86.005
Example 61	0.160	9.22	1.689	5.851	75.040	86.070	0.209	4.578	0.536	2.527	70.664	84.520
Example 62	0.165	11.38	2.359	6.472	74.730	86.550	0.214	6.136	0.837	2.950	70.410	85.180
Example 63	0.160	8.30	1.562	5.826	74.868	86.022	0.210	4.009	0.482	2.527	70.485	84.474
Example 64	0.120	11.00	2.498	6.542	74.889	86.311	0.156	5.850	0.879	2.977	70.580	84.867
Example 65	0.119	13.52	2.865	7.513	74.388	83.546	0.154	7.806	1.158	3.662	70.124	81.432
Example 66	0.127	12.87	2.981	7.126	74.576	85.270	0.164	7.230	1.159	3.363	70.256	83.564

TABLE 6
Example
Comparative	Transmittance@ Sheet thickness 0.11 mm	Transmittance@ Sheet thickness 0.21 mm
Example	λ T50	T1200	Ave. T1100-800	T750	T600	T400	λ T50	T1200	Ave. T1100-800	T750	T600	T400
No	(nm)	(%)	(%)	(%)	(%)	(%)	(nm)	(%)	(%)	(%)	(%)	(%)
Example 1	666	8.785	2.590	12.245	81.175	87.953	636	1.041	0.113	1.963	72.627	84.642
Example 2	660	8.882	4.008	10.259	80.528	88.400	632	1.063	0.243	1.400	71.526	85.465
Example 3	660	8.168	2.414	10.090	80.124	88.077	631	0.906	0.097	1.356	70.842	84.870
Example 4	655	8.624	3.285	8.471	79.065	87.755	627	1.005	0.165	0.973	69.066	84.279
Example 5	655	8.150	2.287	8.725	79.157	87.681	627	0.902	0.087	1.028	69.219	84.143
Example 6	648	7.112	1.496	6.403	76.476	86.001	620	0.696	0.042	0.569	64.812	81.093
Example 7	649	7.775	2.313	6.682	77.700	87.031	622	0.825	0.088	0.618	66.807	82.956
Example 8	640	7.953	2.581	5.232	74.028	85.543	614	0.861	0.107	0.387	60.908	80.269
Example 9	643	8.149	3.332	5.639	75.212	86.087	616	0.902	0.176	0.447	62.782	81.246
Example 10	642	7.788	2.429	5.434	74.831	85.828	615	0.827	0.094	0.416	62.176	80.780
Example 11	637	7.494	2.120	4.685	73.042	85.195	611	0.769	0.074	0.314	59.359	79.648
Example 12	645	7.939	2.049	5.659	76.336	86.147	619	0.858	0.059	0.450	64.586	81.356
Example 13	642	7.045	1.546	4.846	74.839	85.639	616	0.683	0.042	0.334	62.190	80.442
Example 14	643	7.046	1.498	4.987	75.210	85.575	616	0.683	0.041	0.353	62.780	30.326
Example 15	645	7.910	2.144	5.717	75.986	86.104	618	0.852	0.079	0.459	64.022	81.277
Example 16	645	7.830	1.868	5.715	75.953	85.683	618	0.836	0.061	0.458	63.969	80.521
Example 17	644	7.310	2.352	5.376	76.051	85.888	618	0.733	0.090	0.408	64.126	80.889
Example 18	644	7.823	3.437	5.427	75.607	85.673	617	0.834	0.184	0.415	63.413	80.503
Example 19	645	8.056	2.078	5.823	75.844	85.524	618	0.882	0.073	0.475	63.793	80.235
Example 20	645	7.466	1.681	5.605	75.687	85.514	618	0.763	0.051	0.442	63.541	80.218
Example 21	645	7.672	2.900	5.613	76.311	86.082	619	0.804	0.140	0.443	64.546	81.238
Example 22	646	7.439	2.490	5.922	76.549	86.001	619	0.758	0.105	0.490	64.930	81.093
Example 23	655	10.451	3.312	8.739	79.076	87.785	627	1.450	0.175	1.031	69.083	84.333
Example 24	644	7.661	2.397	5.575	76.004	85.985	618	0.802	0.094	0.437	64.050	81.063
Example 25	665	15.063	4.679	12.600	81.277	88.190	635	2.914	0.344	2.073	72.800	85.078
Example 26	664	14.883	4.347	12.347	81.002	88.159	634	2.848	0.304	1.994	72.331	85.021
Example 27	668	16.528	5.335	14.240	81.991	88.812	638	3.480	0.437	2.618	74.027	86.226
Example 28	664	14.767	4.268	12.497	81.200	88.425	635	2.806	0.293	2.040	72.668	85.512
Example 29	658	11.294	3.272	9.321	80.009	86.933	630	1.682	0.172	1.166	70.648	82.778
Example 30	657	11.167	3.056	9.084	79.586	87.305	628	1.646	0.155	1.110	69.936	83.455
Example 31	647	10.114	2.348	6.539	76.571	85.303	620	1.362	0.095	0.593	64.966	79.840
Example 32	648	10.083	2.447	6.485	76.890	83.969	621	1.355	0.103	0.583	65.483	77.474
Example 33	655	9.893	2.495	8.034	78.869	85.354	627	1.306	0.106	0.878	68.738	79.931
Example 34	638	5.725	2.341	4.106	73.159	77.032	612	0.460	0.093	0.244	59.551	65.714
Example 35	655	10.915	3.305	8.676	78.966	87.581	627	1.576	0.173	1.017	68.900	83.961
Example 36	639	6.865	1.538	4.532	74.054	85.095	614	0.650	0.042	0.294	60.950	79.469
Example 37	639	7.293	3.223	4.298	74.066	84.760	613	0.730	0.163	0.266	60.869	78.872
Example 38	635	8.768	2.535	4.727	71.289	76.466	608	1.037	0.107	0.319	56.679	64.796
Example 39	631	4.267	1.507	2.839	30.222	72.295	606	0.262	0.040	0.121	55.070	58.216
Example 40	637	7.065	7.488	4.039	72.903	83.428	611	0.687	0.040	0.236	59.155	76.524
Example 41	633	6.534	1.142	3.205	70.902	81.217	607	0.592	0.020	0.152	56.093	72.699
Example 42	650	15.078	4.098	9.910	76.805	82.211	621	2.920	0.277	1.310	65.021	74.406
Example 43	673	24.969	9.615	18.661	81.337	86.764	637	7.649	1.312	4.387	72.803	82.472
Example 44	649	7.453	2.101	6.439	76.943	84.435	621	0.761	0.074	0.575	65.570	78.296
Example 45	665	23.974	8.407	16.332	80.271	87.777	633	7.078	1.038	3.401	71.090	84.318
Example 46	629	5.874	1.006	2.448	69.361	78.709	604	0.483	0.020	0.091	53.789	68.472
Example 47	653	23.071	7.382	12.262	76.991	83.622	623	6.577	0.825	1.965	65.648	76.863
Example 48	644	20.512	5.944	9.106	73.965	75.838	615	5.255	0.555	1.115	60.810	63.784
Example 49	642	20.83	5.541	8.481	73.21	81.73	613	5.409	0.519	0.974	59.636	73.579
Example 50	657	6.896	2.888	7.386	79.315	84.591	629	0.656	0.135	0.748	69.482	78.574
Example 51	661	29.812	10.965	16.017	78.732	84.942	629	10.730	1.721	3.277	68.511	79.197
Example 52	654	30.593	10.283	13.259	77.030	81.755	623	11.272	1.568	2.285	65.712	73.621
Example 53	632	5.085	2.266	2.944	70.763	83.627	607	0.367	0.087	0.129	55.884	76.872
Example 54	629	4.013	1.552	2.412	68.947	82.914	604	0.233	0.043	0.088	53.177	75.626
Example 55	623	3.310	1.839	1.651	65.996	81.297	599	0.143	0.061	0.043	48.917	72.834
Example 56	684	26.390	10.936	22.873	83.730	87.356	650	8.502	1.664	6.470	77.063	83.549
Example 57	691	25.700	10.959	24.455	85.107	87.547	656	8.082	1.659	7.351	79.489	83.898
Example 58	697	26.282	11.455	26.383	86.102	87.378	663	8.435	1.801	8.497	81.274	83.589
Example 59	655	11.415	3.320	8.830	78.928	87.232	627	1.717	0.176	1.051	68.837	83.322
Example 60	650	11.996	3.707	7.984	77.691	87.147	623	1.887	0.215	0.867	66.792	83.167
Comp. Ex. X	702	27.042	11.822	27.977	85.646	83.945	668	8.907	1.910	9.504	80.453	77.430
Comp. Ex. A	651	8.277	3.230	6.560	78.045	83.036	624	0.929	0.162	0.596	67.374	75.838
Comp. Ex. B	638	4.609	2.656	3.165	73.041	81.723	611	0.304	0.114	0.148	59.369	73.566
Comp. Ex. C	658	10.745	2.941	9.189	80.140	86.853	630	1.529	0.143	1.134	70.868	82.633
Comp. Ex. D	633	28.002	9.056	8.961	68.186	86.034	603	10.180	1.289	1.081	52.078	81.152
Example 61	664.089	18.966	5.650	13.833	79.818	87.687	632.89	4.544	0.530	2.504	70.618	84.504
Example 62	666.119	22.795	7.758	15.647	79.897	88.114	633.85	6.455	0.911	3.147	70.753	85.292
Example 63	664.102	17.594	5.392	13.794	79.676	87.650	632.74	3.937	0.468	2.474	70.379	84.435
Example 64	649.438	13.229	3.396	8.227	76.193	86.736	620.60	2.284	0.191	0.922	64.622	82.762
Example 65	649.115	15.695	3.671	9.129	75.588	84.128	619.58	3.166	0.269	1.125	63.546	78.077
Example 66	652.109	16.642	4.559	9.955	76.583	86.040	622.36	3.540	0.366	1.327	85.255	81.500

TABLE 7
Example
Comparative	Transmittance@Sheet thickness 0.23 mm	Transmittance@Sheet thickness 0.25 mm	DSC
Example	λ T50	T1200	T600	T400	λ T50	T1200	T600	T400	Tg	Tm	Weathering
No	(nm)	(%)	(%)	(%)	(nm)	(%)	(%)	(%)	(° C.)	(° C.)	resistance
Example 1	632	0.680	71.029	83.995	629	0.444	69.465	83.353	308	790	B
Example 2	628	0.695	69.850	84.889	625	0.455	68.214	84.318	314	812	B
Example 3	627	0.584	69.119	84.243	624	0.376	67.438	83.620	316	806	B
Example 4	623	0.654	67.223	83.600	620	0.425	65.429	82.927	318	817	B
Example 5	624	0.581	67.386	83.453	621	0.374	65.602	82.768	327	812	B
Example 6	617	0.437	62.702	80.145	614	0.274	60.661	79.208	327	816	A
Example 7	619	0.527	64.819	82.164	616	0.336	62.890	81.380	325	823	A
Example 8	610	0.552	58.578	79.254	608	0.354	56.337	78.252	357	828	B
Example 9	613	0.581	60.555	80.311	610	0.374	58.406	79.387	342	821	B
Example 10	612	0.528	59.915	79.807	609	0.337	57.736	78.846	352	825	B
Example 11	608	0.488	56.959	78.582	605	0.309	54.646	77.531	364	842	B
Example 12	615	0.550	62.463	80.430	612	0.352	60.409	79.515	341	809	B
Example 13	612	0.428	59.929	79.441	609	0.269	57.750	78.452	329	818	B
Example 14	613	0.429	60.552	79.316	610	0.269	58.403	78.318	334	816	B
Example 15	615	0.546	61.865	80.344	612	0.350	59.782	79.423	334	822	B
Example 16	615	0.534	61.809	79.526	612	0.342	59.722	78.544	328	817	B
Example 17	615	0.463	61.975	79.925	612	0.292	59.897	78.972	332	815	A
Example 18	614	0.533	61.221	79.507	611	0.341	59.105	78.524	333	817	A
Example 19	615	0.567	61.623	79.217	612	0.364	59.527	78.212	335	816	A
Example 20	614	0.484	61.356	79.199	611	0.306	59.247	78.193	334	823	A
Example 21	615	0.512	62.420	80.303	613	0.326	60.364	79.378	342	814	A
Example 22	616	0.480	62.827	80.145	613	0.304	60.792	79.209	333	822	A
Example 23	623	0.977	67.242	83.660	620	0.658	65.449	82.991			B
Example 24	615	0.510	61.895	80.113	612	0.325	59.812	79.174	342	817	A
Example 25	631	2.098	71.214	84.469	628	1.511	69.663	83.864	343	756	A
Example 26	632	2.067	71.655	84.908	628	1.487	70.131	84.338	341	768	A
Example 27	634	2.548	72.530	85.718	631	1.866	71.063	85.213	316	751	B
Example 28	631	2.013	71.073	84.941	628	1.444	69.512	84.374	316	757	B
Example 29	626	1.149	68.912	81.971	623	0.785	67.218	81.172			B
Example 30	625	1.122	68.151	82.706	622	0.765	66.412	81.963			B
Example 31	616	0.912	62.865	78.790	613	0.611	60.832	77.754	352	856	B
Example 32	617	0.907	63.414	76.237	614	0.607	61.409	75.019	361	794	B
Example 33	623	0.871	66.874	78.888	620	0.581	65.060	77.859	355	789	A
Example 34	609	0.278	57.150	63.659	606	0.168	54.845	61.667	373	840	B
Example 35	623	1.070	67.047	83.255	620	0.727	65.243	82.555			B
Example 36	610	0.406	58.622	78.390	607	0.253	56.383	77.325	344	823	B
Example 37	610	0.461	58.642	77.745	607	0.291	56.404	76.633	341	828	B
Example 38	605	0.677	54.138	62.685	602	0.442	51.711	60.643	408	820	S
Example 39	603	0.150	52.457	55.748	600	0.086	49.968	53.384	383	839	B
Example 40	608	0.431	56.733	75.213	605	0.270	54.411	73.925	356	819	B
Example 41	604	0.366	53.525	71.106	601	0.226	51.075	69.547	364	818	B
Example 42	617	2.103	62.924	72.936	614	1.514	60.894	71.498	401	798	S
Example 43	633	6.037	71.324	81.639	630	4.765	69.779	80.815	393	835	S
Example 44	618	0.482	63.505	77.123	615	0.305	61.506	75.967	348	752	A
Example 45	629	5.545	69.384	83.643	625	4.345	67.719	82.973	393	824	S
Example 46	601	0.293	51.122	66.591	598	0.178	48.587	64.761	367	807	B
Example 47	619	5.117	63.589	75.578	616	3.981	61.594	74.316			S
Example 48	611	4.002	58.474	81.614	608	3.048	56.228	59.517	392	794	S
Example 49	609	4.131	57.239	72.049	606	3.155	54.938	70.550	391	803	S
Example 50	625	0.410	67.667	77.422	622	0.256	65.899	76.288	332	704	B
Example 51	625	8.746	66.632	78.095	621	7.130	64.804	77.009			B
Example 52	619	9.232	63.656	72.094	616	7.561	61.665	70.599	370	785	B
Example 53	604	0.217	53.307	75.588	601	0.128	50.849	74.326	359	848	B
Example 54	601	0.132	50.486	74.247	598	0.075	47.930	72.894	360	860	B
Example 55	596	0.078	46.073	71.251	593	0.042	43.395	69.701	377	873	B
Example 56	645	6.778	75.794	82.808	641	5.404	74.545	82.073	348	752	S
Example 57	652	6.412	78.411	83.187	648	5.088	77.348	82.481	326	833	B
Example 58	659	6.720	80.341	82.851	655	5.354	79.419	82.120	307	656	B
Example 59	623	1.175	66.979	82.561	620	0.805	65.172	81.808			C
Example 60	619	1.304	64.803	82.393	616	0.901	62.873	81.626	324	796	D
Comp. Ex. X	664	7.133	79.453	76.190	660	5.712	78.466	74.969	273	690	E
Comp. Ex. A	620	0.600	65.422	74.475	617	0.387	63.526	73.137			E
Comp. Ex. B	608	0.176	56.958	72.035	605	0.102	54.645	70.536			E
Comp. Ex. C	627	1.036	69.147	83.813	624	0.701	67.467	81.002	319	751	E
Comp. Ex. D	599	8.257	49.343	80.209	596	6.697	46.753	79.278	374	733	S
Example 61	629	3.416	68.940	83.897	625	2.565	67.237	83.261	435		S
Example 62	630	5.013	69.031	84.727	628	3.892	67.333	84.156	440		S
Example 63	629	2.918	68.652	83.806	625	2.161	66.931	83.162	420		S
Example 64	617	1.608	62.531	81.992	614	1.131	60.471	81.208	440		S
Example 65	616	2.299	61.508	76.927	613	1.668	59.396	75.770	450		S
Example 66	619	2.600	63.233	80.640	615	1.906	61.209	79.753	456		S

From the results shown in the tables above, it can be confirmed that the glasses of Examples 1 to 66 exhibited high transmittance of light in the visible region (the violet region to the red region), achieved excellent near-infrared cutting performance, and suppressed a reduction in weathering resistance.

With regard to weathering resistance, it can be confirmed from a comparison between Examples 1 to 58 and Example 59 that, relative to Example 59, in which the value calculated as “(3×Al₂O₃+Y₂O₃+La₂O₃+Gd₂O₃+BaO/3+(CaO+SrO)/6)” was 0, Examples 1 to 58, in which this value was higher, exhibited better weathering resistance.

In a comparison between Example 59 and Example 60, Example 60, in which the value calculated as “(3×Al₂O₃+Y₂O₃+La₂O₃+Gd₂O₃+BaO/3+(CaO+SrO)/6)” was 0 and the value of “(Na₂O+K₂O+ZnO)/Li₂O” was more than 1.4, which was higher than in Example 59, had a higher degree of deliquescence than Example 59, and had relatively poor weathering resistance.

In Comparative Example X, the value calculated as “(3×Al₂O₃+Y₂O₃+La₂O₃+Gd₂O₃+BaO/3+(CaO+SrO)/6)” was more than 0, but the value of “(Na₂O+K₂O+ZnO)/Li₂O” was high, more than 11, and weathering resistance was low.

Comparative Example A, Comparative Example B and Comparative Example C are glasses comprising only three components, namely, P₂O₅, Li₂O and CuO, and exhibit extremely low weathering resistance.

In Comparative Example D, the O/P ratio was more than 3.2, and the prescribed transmittance characteristics could not be achieved.

Among Examples in which the evaluation classification was S or A for the evaluation of weathering resistance by eye described above, haze values were determined for Examples 25, 33, 56 and 61 to 66 using a haze meter. Determined haze values are shown in Table 8.

	TABLE 8
	Weathering
	resistance			(3 × Al2O3+ Y2O3 + La2O3 +
	(evaluated			Gd2O3 + BaO/3 + (CaO + SrO)/6)	(MgO + CaO + SrO + BaO + ZnO)/
	by eye)	Haze value	O/P ratio	(mol %)	(Li2O + Na2O + K2O)
Example25	A	43.2%	2.93	8.55	0.73
Example33	A	34.9%	2.93	4.52	1.47
Example56	S	0.0%	3.01	12.93	0.22
Example61	S	13.0%	3.00	14.53	26.38
Example62	S	8.0%	3.02	14.93	26.64
Example63	S	1.0%	3.00	16.37	5.72
Example64	S	10.0%	3.02	13.42	21.45
Example65	S	0.5%	3.06	18.03	22.36
Example66	S	0.4%	3.04	15.11	23.00

As shown in Table 8, Examples 56 and 61 to 66, for which the evaluation classification was S for the evaluation of weathering resistance by eye, had haze values of 15% or less, which were lower in than Examples 25 and 33, for which the evaluation classification was A for the evaluation of weathering resistance by eye.

From the results above, it can be confirmed that in order to achieve both improved transmittance of light in the visible region and improved near-infrared cutting performance as well as achieve a haze value of 15% or less, the O/P ratio preferably falls within the range 3.00 to 3.15 and the value calculated as “(3×Al₂O₃+Y₂O₃+La₂O₃+Gd₂O₃+BaO/3+(CaO+SrO)/6)” (units: mol %) preferably falls within the range 10.0% to 40.0%.

Finally, the aspects described above will be summarized.

Glasses 1 to 6, which are described in detail above, are provided by one aspect.

In one embodiment, Glasses 1 to 6 can have an Al₂O₃ content of less than 2.0 mol %.

In one embodiment, Glasses 1 to 6 can have a total content of Al₂O₃, La₂O₃, Y₂O₃ and Gd₂O₃ (Al₂O₃+La₂O₃+Y₂O₃+Gd₂O₃) of 0.1 mol % or more.

In one embodiment, Glasses 1 to 6 can have the following transmittance characteristics.

A glass for which the half value Δ_T50, which is the wavelength at which the external transmittance including reflection losses becomes 50% at a wavelength of 550 nm or longer, is 633 nm has a thickness of 0.25 mm or less, and

• • at this thickness, the external transmittance T600 including reflection losses at a wavelength of 600 nm is 50% or more, and the external transmittance T1200 including reflection losses at a wavelength of 1200 nm is 30% or less.

A glass for which the half value Δ_T50, which is the wavelength at which the external transmittance including reflection losses becomes 50% at a wavelength of 550 nm or longer, is 633 nm has a thickness of 0.25 mm or less, and

• • at this thickness, the external transmittance T600 including reflection losses at a wavelength of 600 nm is 50% or more, and the external transmittance T1200 including reflection losses at a wavelength of 1200 nm is β1% or less,
  • β1 is a value calculated from Equation B1 below:

β1=64×R−170  (Equation B1)

In equation B1 above,

• • R is the ratio (O ion/P ion).

As transmittance characteristics calculated at a thickness of 0.11 mm, the half value Δ_T50, which is the wavelength at which the external transmittance including reflection losses becomes 50%, falls within the range 600 nm to 650 nm, the external transmittance T1200 including reflection losses at a wavelength of 1200 nm is 30% or less, and the external transmittance T400 including reflection losses at a wavelength of 400 nm is 70% or more.

As transmittance characteristics calculated at a thickness of 0.21 mm, the half value Δ_T50, which is the wavelength at which the external transmittance including reflection losses becomes 50%, falls within the range 600 nm to 650 nm, the external transmittance T1200 including reflection losses at a wavelength of 1200 nm is 25% or less, and the external transmittance T400 including reflection losses at a wavelength of 400 nm is 70% or more.

A glass for which the half value Δ_T50, which is the wavelength at which the external transmittance including reflection losses becomes 50% at a wavelength of 550 nm or longer, is 645 nm has a thickness of 0.25 mm or less, and

• • at this thickness, the external transmittance T600 including reflection losses at a wavelength of 600 nm is 50% or more, and the external transmittance T1200 including reflection losses at a wavelength of 1200 nm is 30% or less.

A glass for which the half value Δ_T50, which is the wavelength at which the external transmittance including reflection losses becomes 50% at a wavelength of 550 nm or longer, is 645 nm has a thickness of 0.25 mm or less, and

• • at this thickness, the external transmittance T600 including reflection losses at a wavelength of 600 nm is 50% or more, and the external transmittance T1200 including reflection losses at a wavelength of 1200 nm is β1% or less, β1 is a value calculated from equation B1 below:

β1=64×R−170  (Equation B1)

In equation B1 above,

• • R is the ratio (O ion/P ion).

Provided by one aspect is a near-infrared cut filter comprised of the above near-infrared absorbing glass.

The embodiments disclosed here are exemplifications in every sense and should not be considered to be limiting examples. The scope of the present invention is indicated by the claims, not by the explanations given above, and it is intended to cover all alternative forms falling within the spirit and scope of the invention.

For example, by subjecting the glass compositions exemplified above to compositional adjustments explained in the description, it is possible to obtain a near-infrared absorbing glass according to one aspect of the present invention.

In addition, it is of course possible to arbitrarily combine two or more matters that are described in the description as examples or preferred ranges.

Claims

1. A near-infrared absorbing glass,

which comprises at least four kinds of main cations selected from the group consisting of P ions, Li ions, Cu ions, Al ions, Ba ions, Sr ions, Ca ions, Mg ions, Zn ions, K ions, Na ions, La ions, Gd ions, and Y ions,

comprises P ions, Li ions, and Cu ions as essential cations,

and comprises at least O ions as anions,

wherein

a ratio of a content of O ions relative to a content of P ions (O ion/P ion) is 3.15 or less;

in a glass composition indicated by anion %, a content of O ions is 90.0 anion % or more; and

in an oxide-based glass composition on a molar basis,

a total content of oxides of the main cations is 90.0% or more,

a total content of MgO and Al2O3(MgO+Al2O3) is 8.0% or less,

a ratio of a total content of Na2O, K2O, and ZnO relative to a content of Li2O ((Na2O+K2O+ZnO)/Li2O) is 2.4 or less,

a total content of B2O3 and SiO2 (B2O3+SiO2) is 3.0% or less, and

a content of CuO is α1% or more,

where α1 is a value calculated by Equation 1 below, α1=70400×exp(−2.855×R)  (Equation 1)

and in Equation 1 above,

R is the ratio (O ion/P ion).

2. A near-infrared absorbing glass,

which comprises at least four kinds of main cations selected from the group consisting of P ions, Li ions, Cu ions, Al ions, Ba ions, Sr ions, Ca ions, Mg ions, Zn ions, K ions, Na ions, La ions, Gd ions, and Y ions,

comprises P ions, Li ions, and Cu ions as essential cations,

and comprises at least O ions as anions,

wherein

a ratio of a content of O ions relative to a content of P (O ion/P ion) ions is 3.15 or less;

in a glass composition indicated by anion %, a content of O ions is 90.0 anion % or more; and

in an oxide-based glass composition on a molar basis,

a total content of oxides of the main cations is 90.0% or more,

a total content of MgO and Al2O3(MgO+Al2O3) is 8.0% or less,

a ratio of a total content of Na2O, K2O, and ZnO relative to a content of Li2O ((Na2O+K2O+ZnO)/Li2O) is 2.4 or less,

a total content of B2O3 and SiO2 (B2O3+SiO2) is 3.0% or less, and

which satisfies Equation 2 below: C−3200×exp(−2.278×R)≥0  (Equation 2)

and in Equation 2 above,

C is a content of CuO (units: mmol/cc) per molar volume of the glass, and

R is the ratio (O ion/P ion).

3. A near-infrared absorbing glass,

which comprises at least four kinds of main cations selected from the group consisting of P ions, Li ions, Cu ions, Al ions, Ba ions, Sr ions, Ca ions, Mg ions, Zn ions, K ions, Na ions, La ions, Gd ions, Y ions, B ions and Si ions,

comprises P ions, Li ions, and Cu ions as essential cations,

and comprises at least O ions as anions,

wherein

a ratio of a content of O ions relative to a content of P ions (O ion/P ion) is 3.15 or less;

in a glass composition indicated by anion %, a content of O ions is 90.0 anion % or more; and

in an oxide-based glass composition on a molar basis,

a total content of oxides of the main cations is 90.0% or more,

a total content of MgO and Al2O3(MgO+Al2O3) is 8.0% or less,

a ratio of a total content of Na2O, K2O, and ZnO relative to a content of Li2O ((Na2O+K2O+ZnO)/Li2O) is 2.4 or less,

A1, which is calculated by Equation 3 below, is 2500 or more, A1={O(P)−O(others)}×Cu  (Equation 3)

and in Equation 3 above,

O(P) denotes an amount of oxygen that constitutes an oxide of P ions in the oxide-based glass composition,

O(others) denotes an amount of oxygen determined by subtracting the value of

O(P) from an amount of oxygen that constitutes oxides of the main cations in the oxide-based glass composition, and

Cu denotes a content of CuO on a molar basis in the oxide-based glass composition.

4-6. (canceled)

7. The near-infrared absorbing glass according to claim 1,

wherein a total content of Na2O and K2O is less than 15.0 mol %.

8. The near-infrared absorbing glass according to claim 1,

wherein a content of Al2O3 is less than 2.0 mol %.

9. The near-infrared absorbing glass according to claim 1,

wherein a total content of Al2O3, La2O3, Y2O3 and Gd2O3 (Al2O3+La2O3+Y2O3+Gd2O3) is 0.1 mol % or more.

10. The near-infrared absorbing glass according to claim 1,

wherein a glass for which a half value λT50, which is a wavelength at which an external transmittance including reflection losses becomes 50% at a wavelength of 550 nm or longer, is 633 nm has a thickness of 0.25 mm or less, and

at the thickness, an external transmittance T600 including reflection losses at a wavelength of 600 nm is 50% or more, and an external transmittance T1200 including reflection losses at a wavelength of 1200 nm is 30% or less.

11. The near-infrared absorbing glass according to claim 1,

wherein a glass for which a half value λT50, which is a wavelength at which an external transmittance including reflection losses becomes 50% at a wavelength of 550 nm or longer, is 633 nm has a thickness of 0.25 mm or less, and

at the thickness, an external transmittance T600 including reflection losses at a wavelength of 600 nm is 50% or more, and an external transmittance T1200 including reflection losses at a wavelength of 1200 nm is β1% or less,

β1 is a value calculated from Equation B1 below: β1=64×R−170  (Equation B1)

and in equation B1 above,

R is the ratio (O ion/P ion).

12. The near-infrared absorbing glass according to claim 1,

wherein as transmittance characteristics calculated at a thickness of 0.11 mm, a half value λT50, which is a wavelength at which an external transmittance including reflection losses becomes 50%, falls within a range 600 nm to 650 nm, an external transmittance T1200 including reflection losses at a wavelength of 1200 nm is 30% or less, and an external transmittance T400 including reflection losses at a wavelength of 400 nm is 70% or more.

13. The near-infrared absorbing glass according to claim 1,

wherein as transmittance characteristics calculated at a thickness of 0.21 mm, a half value λT50, which is a wavelength at which an external transmittance including reflection losses becomes 50%, falls within a range 600 nm to 650 nm, an external transmittance T1200 including reflection losses at a wavelength of 1200 nm is 25% or less, and an external transmittance T400 including reflection losses at a wavelength of 400 nm is 70% or more.

14. The near-infrared absorbing glass according to claim 1,

wherein a glass for which a half value λT50, which is a wavelength at which an external transmittance including reflection losses becomes 50% at a wavelength of 550 nm or longer, is 645 nm has a thickness of 0.25 mm or less, and

at the thickness, an external transmittance T600 including reflection losses at a wavelength of 600 nm is 50% or more, and an external transmittance T1200 including reflection losses at a wavelength of 1200 nm is 30% or less.

15. The near-infrared absorbing glass according to claim 1,

wherein a glass for which a half value λT50, which is a wavelength at which an external transmittance including reflection losses becomes 50% at a wavelength of 550 nm or longer, is 645 nm has a thickness of 0.25 mm or less, and

at the thickness, an external transmittance T600 including reflection losses at a wavelength of 600 nm is 50% or more, and an external transmittance T1200 including reflection losses at a wavelength of 1200 nm is 01% or less,

β1 is a value calculated from equation B1 below: β1=64×R−170  (Equation B1)

and in equation B1 above,

R is the ratio (O ion/P ion).

16. A near-infrared cut filter, which is comprised of the near-infrared absorbing glass according to claim 1.

17. A near-infrared cut filter, which is comprised of the near-infrared absorbing glass according to claim 2.

18. A near-infrared cut filter, which is comprised of the near-infrared absorbing glass according to claim 3.