Abstract: A method of making a press-moldable glass, including melting starting materials, forming a melt, and annealing a formed glass, wherein the melt has a composition such that, (1) when rapidly cooled to room temperature, it becomes glass that has a scattering coefficient of less than 0.005 cm-1 at wavelengths of from 400 to 2,500 nm or comprises crystals with a volumetric ratio of less than 10-6, and (2) when maintained for three hours at a temperature 10° C. higher than the glass transition temperature, maintained for 10 min at a temperature yielding a viscosity of 104.5 to 103.5 dPa·s, and then rapidly cooled to room temperature, (3) the resulting glass has (a) a scattering coefficient of at least one wavelength from 400 to 2,500 nm of greater than 0.01 cm-1 or (b) crystals with a volumetric ratio of greater than 10-5. A temperature for annealing is lower than for glass transition.

Abstract: A method of making a press-moldable glass, including melting starting materials, forming a melt, and annealing a formed glass, wherein the melt has a composition such that, (1) when rapidly cooled to room temperature, it becomes glass that has a scattering coefficient of less than 0.005 cm?1 at wavelengths of from 400 to 2,500 nm or comprises crystals with a volumetric ratio of less than 10?6, and (2) when maintained for three hours at a temperature 10° C. higher than the glass transition temperature, maintained for 10 min at a temperature yielding a viscosity of 104.5 to 103.5 dPa·s, and then rapidly cooled to room temperature, (3) the resulting glass has (a) a scattering coefficient of at least one wavelength from 400 to 2,500 nm of greater than 0.01 cm?1 or (b) crystals with a volumetric ratio of greater than 10?5. A temperature for annealing is lower than for glass transition.

Abstract: Preforms for precision press molding made of optical glass, optical elements, and methods of manufacturing the same are provided. The preforms are suited to precision press molding having a broad range of dispersion characteristics, a low glass transition temperature, a low sag point, and good resistance to devitrification while containing no PbO. The optical element is obtained by precision press molding the preform. One example of the preform has a refractive index (nd) of greater than or equal to 1.7 and an Abbé number (?d) of less than or equal to 32. The other example of the preform has an Abbé number (?d) exceeding 32.

Abstract: Preforms for precision press molding made of optical glass, optical elements, and methods of manufacturing the same are provided. The preforms are suited to precision press molding having a broad range of dispersion characteristics, a low glass transition temperature, a low sag point, and good resistance to devitrification while containing no PbO. The optical element is obtained by precision press molding the preform. One example of the preform has a refractive index (nd) of greater than or equal to 1.7 and an Abbé number (vd) of less than or equal to 32. The other example of the preform has an Abbé number (vd) exceeding 32.

Abstract: An optical glass having high refractivity and a low sag temperature and having a low-temperature softening property that enables precision press-molding is provided, and the optical glass contains, by mol %, 5 to 50% of B2O3, 3 to 50% of SiO2, 5 to 40% of TiO2, 1 to 40% of ZnO, 5 to 20% of La2O3, 0 to 10% of Gd2O3, 0 to 15% of Nb2O5, 0 to 10% of ZrO2, 0 to 5% of Ta2O5, 0 to 10% of Bi2O3, 0 to 10% of MgO, 0 to 8% of CaO, 0 to 10% of SrO, 0 to 10% of BaO, provided that the total content of MgO, CaO, SrO and BaO is 15% or less, 0 to 20% of Li2O, and 0 to 5% of Na2O, optionally containing Sb2O3 as a refining agent, and having a refractive index (nd) of 1.8 or more and an Abbe's number (?d) of 35 or less.

Abstract: The present invention relates to an optical glass having a refractive index (nd) of greater than or equal to 1.65 and an Abbé number (? (nu)d) of greater than or equal to 50 for use in precision press molding. The glass exhibits that a ratio ? (alpha)1/? (alpha)2 is less than 17 when temperature denoting maximum value of differential in amount of elongation of glass relative to temperature differential DELTAT (where DELTAT denotes a constant value of 1° C. or less) over a temperature range from glass transition temperature (Tg) to sag temperature (Ts) is denoted as T1, average coefficient of linear expansion over a range from T1?5° C. to T1+5° C. is denoted as alpha1, and average coefficient of linear expansion over a range from the glass transition temperature (Tg)?160° C. to the glass transition temperature (Tg)?140° C. is denoted as alpha2.

Abstract: An optical glass which has an Abbe's number (?d) of 50 to 59, has the property of not easily reacting with a press mold, a low-temperature softening property, excellent glass stability and high refractivity, and is suitable for precision press-molding. The optical glass comprising B2O3 and SiO2 as essential components and having a B2O3 and SiO2 total content (B2O3+SiO2) of 45 to 70 by mol % and an SiO2 content/B2O3 content molar ratio (SiO2/B2O3) of from 0.1 to 0.5, the optical glass further comprising, by mol %, 5 to 15% of La2O3, 0.1 to 8% of Gd2O3, provided that the total content of La2O3 and Gd2O3 is 8% or more, 0 to 10% of Y2O3, 3 to 18% of Li2O, provided that the molar ratio of the content of Li2O to the total content of B2O3 and SiO2 [Li2O/(B2O3+SiO2)] is over 0 but not more than 0.2, 0.

Abstract: The optical glass has a refractive index of equal to or greater than 1.65 and an Abbé number ranging from 50 to 60. In the optical glass, as molar basis, a ratio of SiO2 content to B2O3 content is greater than 0.5 and equal to or less than 0.90; a total content of SiO2 and B2O3 ranges from 50 to 70 percent; Li2O content ranges from 5 to 20 percent; La2O3 content ranges from 0.5 to 22 percent; a ratio of ZnO content to RO (MgO, CaO, SrO and BaO) is equal to or greater than 0.5; a total content of Gd2O3, Y2O3 and Yb2O3 ranges from 1 to 15 percent; Sb2O3 content ranges from 0 to 1 percent; and no BaO is comprised, or a ratio of the total content of La2O3, Gd2O3, Y2O3 and Yb2O3 to the content of BaO is equal to or greater than 10.

Abstract: An optical glass having high refractivity and a low sag temperature and having a low-temperature softening property that enables precision press-molding is provided, and the optical glass contains, by mol %, 5 to 50% of B2O3, 3 to 50% of SiO2, 5 to 40% of TiO2, 1 to 40% of ZnO, 5 to 20% of La2O3, 0 to 10% of Gd2O3, 0 to 15% of Nb2O5, 0 to 10% of ZrO2, 0 to 5% of Ta2O5, 0 to 10% of Bi2O3, 0 to 10% of MgO, 0 to 8% of CaO, 0 to 10% of SrO, 0 to 10% of BaO, provided that the total content of MgO, CaO, SrO and BaO is 15% or less, 0 to 20% of Li2O, and 0 to 5% of Na2O, optionally containing Sb2O3 as a refining agent, and having a refractive index (nd) of 1.8 or more and an Abbe's number (vd) of 35 or less.

Abstract: An optical glass taking account of meltability and the moldability of a preform, having optical constants including a refractive index (nd) of at least 1.57 but less than 1.67 and an Abbe's number (?d) of over 55 but not more than 65, having the property of softening at a low temperature and being suitable as a glass for precision press-molding, the optical glass including an optical glass containing B2O3, SiO2, La2O3, Gd2O3, an alkali metal oxide and an alkaline earth metal oxide as essential components, having a B2O3 and SiO2 total content of 52% by weight or more and having an SiO2/B2O3 content ratio of from 0.38 to 1.2, and an optical glass wherein the relationship of the refractive index (nd) and the Abbe's number (?d) satisfies the equation (1), ?d>260?126×nd.

Abstract: The present invention relates to an optical glass having a refractive index (nd) of greater than or equal to 1.65 and an Abbé number (? (nu)d) of greater than or equal to 50 for use in precision press molding. The glass exhibits that a ratio ? (alpha)1/? (alpha)2 is less than 17 when temperature denoting maximum value of differential in amount of elongation of glass relative to temperature differential DELTAT (where DELTAT denotes a constant value of 1° C. or less) over a temperature range from glass transition temperature (Tg) to sag temperature (Ts) is denoted as T1, average coefficient of linear expansion over a range from T1-5° C. to T1+5° C. is denoted as alpha1, and average coefficient of linear expansion over a range from the glass transition temperature (Tg)?160° C. to the glass transition temperature (Tg)?140° C. is denoted as alpha2.

Abstract: Provided are optical glass exhibiting a refractive index (nd) in a range of 1.75 to 1.87, an Abbé number (?d) in a range of 80 to 45, and excellent low-temperature softening properties even when not incorporating Th2O5 as well as permitting a low production cost; a precision press molding preform and an optical element comprised of such glass; a method of manufacturing the preform; and a method of manufacturing the optical element. The optical glass comprises, in a molar percent, 30 to 45 percent of B2O3, 2 to 15 percent of SiO2, 10 to 20 percent of La2O3, 1 to 10 percent of TiO2, 10 to 30 percent of ZnO, 2 to 15 percent of Li2O, higher than 0 percent and 10 percent or less of WO3, 0 to 15 percent of Nb2O5, and 0 to 10 percent of ZrO2, wherein the total amount of the above-mentioned components is higher than 95 percent, the glass exhibits a refractive index (nd) in a range of 1.75 to 1.87, and an Abbé number (?d) in a range of 80 to 45.

Abstract: The optical glass has a refractive index of equal to or greater than 1.65 and an Abbé number ranging from 50 to 60. In the optical glass, as molar basis, a ratio of SiO2 content to B2O3 content is greater than 0.5 and equal to or less than 0.90; a total content of SiO2 and B2O3 ranges from 50 to 70 percent; Li2O content ranges from 5 to 20 percent; La2O3 content ranges from 0.5 to 22 percent; a ratio of ZnO content to RO (MgO, CaO, SrO and BaO) is equal to or greater than 0.5; a total content of Gd2O3, Y2O3 and Yb2O3 ranges from 1 to 15 percent; Sb2O3 content ranges from 0 to 1 percent; and no BaO is comprised, or a ratio of the total content of La2O3, Gd2O3, Y2O3 and Yb2O3 to the content of BaO is equal to or greater than 10.

Abstract: An optical glass being free of lead and fluorine, having a low glass transition temperature permitting press-molding with a mold formed of stainless steel and having high climate resistance includes an optical glass comprising, by mol %, 25 to 44% of P2O5, 10 to 40% of a total of Li2O, Na2O and K2O, 5 to 40% of ZnO, 1 to 35% of BaO and at least one components selected from Nb2O5, Bi2O3 and WO3, having a glass transition temperature (Tg) of 370° C. or lower and being free of lead and fluorine and an optical glass which is free of lead and fluorine, has a mass loss ratio of less than 0.25% when immersed in pure water, and has a glass transition temperature (Tg) of 370° C. or lower.

Abstract: An optical glass having a refractive index (nd) of 1.57 to 1.67, an Abbe's number (?d) of 55 to 65 and a glass transition temperature (Tg) of 560° C. or lower and having a low-temperature softening property and excellent climate resistance or a haze value of 3% or less, or an optical glass comprising, by mol %, 22 to 40% of B2O3, 12 to 40% of SiO2, 2 to 20% of Li2O, 5 to 15% of CaO, 2 to 14% of ZnO, 0.5 to 4% of La2O3, 0 to 3% of Gd2O3, 0 to 3% of Y2O3, the total content of La2O3, Gd2O3 and Y2O3 being at least 1%, 0 to 5% of Al2O3, 0 to 3% of ZrO2 and 0 to 5% of BaO, the total content of the above components being more than 96%, and having a refractive index (nd) of 1.57 to 1.67 and an Abbe's number (?d) of 55 to 65.

Abstract: Disclosed is an optical glass comprising, expressed as weight percentages, greater than or equal to 18 percent and less than 30 percent of SiO2, greater than or equal to 12 percent and less than 23 percent of BaO, 22 to 37 percent TiO2, greater than or equal to 7 percent and less than 16 percent Nb2O5, 5 to 20 percent of Na2O, 0 to 6 percent of K2O, 0 to 5 percent of CaO, 0 to 5 percent of SrO, 0 to 4 percent of ZrO2, 0 to 3 percent of Ta2O5, 0 to 1 percent of Sb2O5, and greater than or equal to 0 percent and less than 0.5 percent of P2O5, and by essentially not comprising PbO, As2O3, and F. The optical glass exhibits a refractive index (nd) greater than or equal to 1.80 and an Abbé number (vd) less than or equal to 30. A method of manufacturing a glass material for press molding is disclosed.

Abstract: An optical glass having high refractivity and a low sag temperature and having a low-temperature softening property that enables precision press-molding is provided, and the optical glass contains, by mol %, 5 to 50% of B2O3, 3 to 50% of SiO2, 5 to 40% of TiO2, 1 to 40% of ZnO, 5 to 20% of La2O3, 0 to 10% of Gd2O3, 0 to 15% of Nb2O5, 0 to 10% of ZrO2, 0 to 5% of Ta2O5, 0 to 10% of Bi2O3, 0 to 10% of MgO, 0 to 8% of CaO, 0 to 10% of SrO, 0 to 10% of BaO, provided that the total content of MgO, CaO, SrO and BaO is 15% or less, 0 to 20% of Li2O, and 0 to 5% of Na2O, optionally containing Sb2O3 as a refining agent, and having a refractive index (nd) of 1.8 or more and an Abbe's number (vd) of 35 or less.

Abstract: An optical glass which has an Abbe's number (?d) of 50 to 59, has the property of not easily reacting with a press mold, a low-temperature softening property, excellent glass stability and high refractivity, and is suitable for precision press-molding. The optical glass comprising B2O3 and SiO2 as essential components and having a B2O3 and SiO2 total content (B2O3+SiO2) of 45 to 70 by mol % and an SiO2 content/B2O3 content molar ratio (SiO2/B2O3) of from 0.1 to 0.5, the optical glass further comprising, by mol %, 5 to 15% of La2O3, 0.1 to 8% of Gd2O3, provided that the total content of La2O3 and Gd2O3 is 8% or more, 0 to 10% of Y2O3, 3 to 18% of Li2O, provided that the molar ratio of the content of Li2O to the total content of B2O3 and SiO2 [Li2O/(B2O3+SiO2)] is over 0 but not more than 0.2, 0.

Abstract: Disclosed is an optical glass comprising, expressed as weight percentages, greater than or equal to 18 percent and less than 30 percent of SiO2, greater than or equal to 12 percent and less than 23 percent of BaO, 22 to 37 percent TiO2, greater than or equal to 7 percent and less than 16 percent Nb2O5, 5 to 20 percent of Na2O, 0 to 6 percent of K2O, 0 to 5 percent of CaO, 0 to 5 percent of SrO, 0 to 4 percent of ZrO2, 0 to 3 percent of Ta2O5, 0 to 1 percent of Sb2O5, and greater than or equal to 0 percent and less than 0.5 percent of P2O5, and by essentially not comprising PbO, As2O3, and F. The optical glass exhibits a refractive index (nd) greater than or equal to 1.80 and an Abbé number (vd) less than or equal to 30. A method of manufacturing a glass material for press molding is disclosed.

Abstract: An optical glass taking account of meltability and the moldability of a preform, having optical constants including a refractive index (nd) of at least 1.57 but less than 1.67 and an Abbe's number (?d) of over 55 but not more than 65, having the property of softening at a low temperature and being suitable as a glass for precision press-molding, the optical glass including an optical glass containing B2O3, SiO2, La2O3, Gd2O3, an alkali metal oxide and an alkaline earth metal oxide as essential components, having a B2O3 and SiO2 total content of 52% by weight or more and having an SiO2/B2O3 content ratio of from 0.38 to 1.2, and an optical glass wherein the relationship of the refractive index (nd) and the Abbe's number (?d) satisfies the equation (1), ?d>260?126×nd??(1).