Abstract: There is provided an optical glass suitable for mold pressing having optical constants of a refractive index (nd) within a range from 1.60 to 1.69 and Abbe number (?d) within a range from 35 to 45, having a glass transition point (Tg) within a range from 300° C. to 500° C., being free from devitrification when the optical glass is held at a temperature which is higher by 100° C. than the glass transition point (Tg) for 30 minutes, comprising in mass % on oxide basis: SiO2 20–less than 40% B2O3 5–20% Al2O3 0–5% ZrO2 more than 3%–15% Nb2O5 10–30% MgO + CaO 0–less than 5% in which MgO 0–less than 5% CaO 0–less than 5% SrO 0–10% BaO 0–10% ZnO 0–18% Li2O more than 5%–15% Na2O 1–10% K2O 1–10% Sb2O3 0–1%, and being free from La2O3, TiO2, Ta2O5 and PbO.

Abstract: An optical glass having a small photoelastic constant (?) suitable for parts for polarizing optical system and light polarization control elements and having a refractive index (nd) within a range from 1.60 to 1.68 and an Abbe number (? d) within a range from 40 to less than 65 comprises, as atoms constituting the optical glass, P 5–10 mol % Al 1–3 mol % Ba 8–13 mol %, Gd 1–5 mol % Nb 0.1–3 mol % F 15–35 mol % and O 40–52 mol %.

Abstract: There are provided low expansion transparent glass-ceramics obtained by heat treating a base glass produced at a relatively low melting temperature of 1530° C. or below. The glass-ceramics have an average linear thermal expansion coefficient within a range from +6×10?7/° C. to +35×10?7/° C., 80% transmittance wavelength (T80) of 700 nm or below internal transmittance of 75% or over at light wavelength of 1550 nm, heat resisting temperature of 800° C. or over and Young's modulus of 90 GPa or over. The glass-ceramics comprise SiO2, Al2O3, MgO, CaO, BaO, ZnO, Li2O, TiO2 and ZrO2 and contain ?-quartz or ?-quartz solid solution as a predominant crystal phase.

Abstract: An optical glass comprises, in mass percent, 15–35% of P2O5, 40–60% of Nb2O5, 0.5% to less than 15% of Na2O and 3% to less than 25% of BaO, has a ratio in mass % of (BaO+Nb2O5)/{(TiO2+WO3)×3+Bi2O3+Nb2O5}>1.0; is free of Pb and As; and has a refractive index (nd) within a range from 1.78 to 1.90 and an Abbe number (?d) within a range from 18 to 27.

Abstract: A glass ceramics having a chemical composition of aRO.bNb2.O5.cSiO2.dB2O3.eTeO2.fX (where R represents Ba and/or Sr, X represents one or more oxide selected from the group consisting of TiO2, ZrO2, P2O5 and ZnO, a>b?0.05, 0.60?c?0, 0.70?d?0, 0.70?e?0, c+d+e?0.175, a+b+c+d+e=1.0 and 0.10?f?0). The ratio dielectric constant at 1 kHz ?1 to dielectric constant at 100 kHz ?100 (?1/?100) is 10 or more.

Abstract: Glass for a light filter capable of preventing variation of refractive index in a band-pass filter has a coefficient of thermal expansion within a range from 90×10?7/° C. within a temperature range from ?20° C. to +70° C. and, preferably, Young's modulus of 75 GPa or over and Vickers hardness of 550 or over, and light transmittance for plate thickness of 10 mm of 90% or over within a wavelength range from 950 nm to 1600 nm.

Abstract: An optical glass comprising in mass %: P2O5 25%-less than 45% B2O3 6-20% BaO 24%-less than 40% ZnO 3-14% MgO 0-15% CaO 0-15% SrO 0-15% Li2O 0-5% Na2O 0-5% K2O 0-5% WO3 0-5% and Al2O3 0-5%. The optical glass should preferably contain 0.1-5% WO3, 3.6-15% MgO, 0.1-5% Li2O+Na2O+K2O, 0—less than 0.5% and Sb2O3+As2O3 with the mass ratio of ZnO/BaO being 0.12—less than 0.50. The optical glass should preferably have refractive index (nd) within a range from 1.54 to 1.65 and Abbe number (?d) within a range exceeding 57 up to 69 and liquid phase temperature within a range from 870° C. to 930° C. There is provided an optical glass having high resistance to devitrification and medium refractive index and low dispersion characteristics which is free of ingredients such as Ta2O5 having a high cost of raw material and therefore can be manufactured at a relatively low cost of raw materials.

Abstract: A globular glass manufacturing apparatus includes: a flow nozzle to flow a molten glass in a form of continuous flow, a collection tank to collect droplet-like glass gobs deformed from the molten glass flowing in a form of continuous flow during fall. Further, the globular glass manufacturing apparatus comprises a gas nozzle to shift one or both of falling trajectories of the glass gobs neighboring above and below by blowing gas to the glass gobs or sucking the glass gobs, wherein the gas nozzle rotates in which the center is on falling trajectory of the glass gobs.

Abstract: A glass containing 5 to 25 mass % of P2O5, 0 to 15 mass % of B2O3, 0 to 5 mass % of SiO2+GeO2, 21 to 50 mass % of BaO+SrO, 0 to 3 mass % of Li2O+Na2O+K20, and 35 to 65 mass % of Nb2O5, not substantially containing PbO, satisfying Nb2O5/(BaO+SrO)=0.85 to 2.20, having a dielectric constant of 15 or greater, a dielectric loss of 10.0×10?4 or less, and a resistivity of 1.0×1016 ?·cm or more.

Abstract: An optical glass having a positive anomalous dispersion comprises, in mass %, SiO2 40-60% B2O3 3-9% TiO2 ?3-15% Nb2O5 0.1-5.0% Al2O3 ?3-15% WO3 0.5-5.0% MgO 0-3% CaO 0-3% SrO 0-3% BaO 0-3% K2O exceeding 10% and up to 21% Na2O ?0-10% Sb2O3 0-1% and a fluoride or fluorides of a metal element or elements ??3-10%, contained in the above metal oxides, a total amount of F contained in the fluoride or fluorides is free of PbO and As2O3 except for unavoidable mixing of these compounds as impurities, has optical constants of a refractive index (nd) within the range from 1.48 to less than 1.55 and an Abbe number (?d) within the range from 45 to 55, and has an anomalous dispersion (??g,F) of +0.0010 or over.

Abstract: A coefficient of linear expansion measuring apparatus includes: two reflection plates between which a sample is put, a container to house them, which is filled with a gas having known rate of a refractive index variation, a temperature regulating member to set a temperature in the container variably, a light source to irradiate an irradiating light to reflecting surfaces of the reflection plates, a light receiving element to receive reflected lights in which the lights interferes each other and detecting a light intensity thereof, and a calculating member to calculate a coefficient of linear expansion of the sample, wherein: the calculating member calculates an optical path length variation between the reflecting surfaces from an output variation of the light receiving element, and calculates a length variation of the sample by correcting a part of the optical path length variation derived from the refractive index variation of the gas caused by the temperature variation.

Abstract: An optical glass which is free of PbO which causes environmental pollution and also is free of expensive Ta2O5 and Nb2O5 comprises, in mass %, SiO2 40-60% B2O3 1 to less than 5% Al2O3 0-3% TiO2 15.5-19%?? ZrO2 0-1% WO3 0-5% ZnO 0-5% CaO 0-4% SrO 0-10% BaO 10.5-20%?? Na2O + K2O 11-20% in which Na2O 0-9% and K2O ?6-20% a refining agent 0-1% and has optical constants of a refractive index (nd) within a range from 1.55 to less than 1.67 and an Abbe number (?d) within a range from 30 to 45.

Abstract: An optical glass suitable for precision press molding has a refractive index (nd) of 1.88 or over and an Abbe number (&ngr;d) within a range from 22 to 28, comprises, in mass %, SiO2 15-25% B2O3 0-5% La2O3 0-5% TiO2  5-15% ZrO2  0-10% Nb2O5 30-50% WO3 0-5% CaO  0-10% BaO  0-10% Li2O  3-12% Na2O  0-10% K2O  0-10% Bi2O3  0-15% and has a glass transition point (Tg) within a range from 500° C. to 580° C. The optical glass preferably has a yield point (At) within a range from 550° C. to 640° C.

Abstract: An optical glass having a refractive index (nd) and an Abbe number (vd) which are within an area surrounded by the straight lines which are drawn by connecting point A (nd=1.835, vd=46.5), point B (nd=1.90, vd=40.0), point C, (nd=1.90, vd=35.0) and point D (nd=1.835, vd=38.0) in a sequence of A, B, C, D and A as border lines in x-y coordinates shown in FIG. 1, in which X-axis is the Abbe number (vd) and Y-axis is the refractive index (nd), the area including the border line. The optical glass has low glass transition temperature (Tg), and suitable for precision mold pressing. The optical glass which has the refractive index (nd) and Abbe number (vd) within the above-described area, where the area includes the border lines, has the composition of SiO2—B2O3—La2O3—Gd2O3—Li2O—F system, the transition temperature (Tg) of 550 to 650° C., and is free from lead, cadmium, thorium, Y2O3, P2O5 and TeO2.

Abstract: An information storage disk holding member for holding an information storage disk in position in an information storage disk drive device, the holding member being made of glass-ceramics in which a crystal phase is dispersed in a glass matrix. The holding member has specific rigidity (Young's modulus/specific gravity) of not greater than 37 GPa, specific gravity of not greater than 3.0, coefficient of thermal expansion within a range from −50° C. to +70° C. which is within a range from +35×10−7/° C. to +130×10−7/° C., Young's modulus within a range from 95 GPa to 130 GPa, specific gravity within a range from 2.40 to 2.60 and bending strength within a range from 400 MPa to 800 MPa.

Abstract: There is provided an optical glass suitable for precision mold pressing having optical constants of a refractive index (nd) within a range from 1.75 to 1.85 and an Abbe number (&ngr;d) within a range from 35 to 45, comprising in mass % on oxide basis: SiO2 + B2O3 16.5-less than 30% in which SiO2   1-7.5% B2O3 15.5-25% La2O3   25-40% ZrO2  1.5-10% Nb2O5   1-15% Ta2O5   1-10% WO3   1-10% ZnO 15.5-30% Li2O  0.6-5%. having a transition point (Tg) within a range from 500° C. to 590° C. and a yield point (At) within a range from 530° C. to 630° C., and being free from devitrification in a devitrification test conducted under a condition of 950° C./2 hours.

Abstract: There is provided a glass-ceramic which is suitable for use as a light filter. The glass-ceramic has Young's modulus (GPa) within a range from 95 to 120 and includes 5.3-8 weight percent of Al2O3, 0.5-3.5 weight percent of ZrO2 and 71-81 weight percent of SiO2, based respectively on the total content of the oxides. The glass-ceramic preferably has, as its predominant crystal phases, (a) lithium disilicate (Li2O.2SiO2) and (b) at least one of &agr;-quartz (&agr;-SiO2) and &agr;-quartz solid solution (&agr;-SiO2 solid solution), has specific gravity within a range from 2.4 to 2.6 and has a coefficient of thermal expansion within a range from 65×10−7/° C. to 130×10−7/° C. within a temperature range from −50° C. to +70° C.

Abstract: An optical glass includes SiO2; PbO; B2O3; not less than 0.1 mass % of TeO2; and not less than 0.4 mass % of Li2O.

Abstract: An optical glass has optical constants which are an refractive index (nd) of 1.70-1.75 and an Abbe number (&ngr;d) of 45.0-54.0; a glass transformation temperature (Tg) of 500-580° C. The glass has the following composition in mass percent of: SiO2 more than 5 to 15%; B2O3 20 to less than 30%; a total amount of SiO2+B2O3 more than 25 to 40%; La2O3 more than 21 to less than 30%; Y2O3 more than 5 to 15%; Gd2O3 0 to less than 10%; ZrO2 1-8%; Nb2O5 0.1-5%; Ta2O5 more than 5 to 12%; a total amount of ZrO2+Nb2O5+Ta2O5 7-20%; ZnO 0-10%; CaO 0-10%; SrO 0-5%; BaO 0-10%; a total amount of ZnO+CaO+SrO+BaO 5-15%; Li2O 1-8%; Sb2O3 0-1%; and As2O3 0-1%. Devitrification is not generated when the optical glass is kept at a temperature of 920° C. for two hours.

Abstract: An optical glass has optical constants which are an refractive index (nd) of 1.70-1.75 and an Abbe number (vd) of 45.0-54.0; a glass transformation temperature (Tg) of 500-580° C. The glass has the following composition in mass percent of: SiO2 more than 5-15%; B2O3 20-less than 30%; a total amount of SiO2+B2O3 more than 25-40%; La2O3 more than 21-less than 30%; Y2O3 more than 5-15%; Gd2O3 0-less than 10%; ZrO2 1-8%; Nb2O5 0.1-5%; Ta2O5 more than 5-12%; a total amount of ZrO2+Nb2O5+Ta2O5 7-20%; ZnO 0-10%; CaO 0-10%; SrO 0-5%; BaO 0-10%; a total amount of ZnO+CaO+SrO+BaO 5-15%; Li2O 1-8%; Sb2O3 0-1%; and As2O3 0-1%. The glass is substantially free of Yb2O3 and Al2O3. Devitrification is not generated when the optical glass is kept at a temperature of 920° C. for two hours.