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.

Abstract: An optical glass having a refractive index (nd) and an Abbe number (?d) which are within an area surrounded by the straight lines which are drawn by connecting point A (nd=1.835, ?d=46.5), point B (nd=1.90, ?d=40.0), point C, (nd=1.90, ?d=35.0) and point D (nd=1.835, ?d=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 (?d) 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.

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 has a low glass transition temperature (Tg) and optical constants in which a refractive index (nd) is in the range of from 1.70 to less than 1.74 and an Abbe number (?d) is between 40 and 45 (excluding 40 and 45), has a content of SiO2 is 17% by mass or less, a glass transition temperature (Tg) is 540° C. or less, and a weathering resistance (surface-method) in Class 1 or 2, and has excellent chemical durability, particularly weathering resistance (surface-method) and is appropriate for precision mold press forming.

Abstract: An optical glass having a refractive index (nd) and Abbe number (?d) within a range enclosed with a border line consisting of straight lines connecting point A (nd being 1.75 and ?d being 50.0), point B (nd being 1.80 and ?d being 46.0), point C (nd being 1.80 and ?d being 50.0) and point D (nd being 1.75 and ?d being 56.0) in the order of the point A, the point B, the point C, the point D and the point A in x-y rectangular coordinates in which x coordinate represents Abbe number (?d) and y coordinate represents refractive index (nd), including refractive index (nd) and Abbe number (?d) on the border line except for the straight line connecting the point A with the point D and the straight line connecting the point B with the point C, containing, as essential components, SiO2, B2O3, La2O3, Gd2O3, Li2O and F, and being substantially free of As2O3.

Abstract: An optical glass having a refractive index (nd) within a range from 1.825 to 1.870, an Abbe number (? d) within a range from 22 to less than 27, a transformation temperature (Tg) within a range from 530° C. to 585° C. and an mean coefficient of linear thermal expansion (?) within a range from 80×10?7° C.?1 to 103×10?7° C.?1, comprising SiO2, TiO2, Nb2O5 and Li2O and being substantially free of a Pb compound.

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 optical glass suitable for precision mold pressing has a refractive index (nd) of 1.

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 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, said optical glass being free of Yb2O3, Y2O3 and TeO2, in mass % on the basis of the oxides: 1 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.

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 (&ngr;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.

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.

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 (&ngr;d) within a range from 35 to 45, having a glass transition point (Tg) within a range from 400° 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, and 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  1-15% Na2O  1-10% K2O  1-10% Sb2O3  0-1%.

Abstract: An optical glass suitable for precision press molding has a refractive index (nd) of 1.

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: 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: 1 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%.

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 (&ngr;d) within a range from 35 to 45, having a glass transition point (Tg) within a range from 400° 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, and comprising in mass % on oxide basis: 1 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  1-15% Na2O  1-10% K2O  1-10% Sb2O3  0-1%.

Abstract: Long-lasting phosphorescent glasses and glass-ceramics have a composition containing 30-65 mol % SiO2 and 20-50 mol % ZnO as basic ingredients and may also contain, as an activator or an auxiliary activator, 0-5 mol % LnxOy where L n is an element or elements selected from the group consisting of Y, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and Mn. In one aspect of the invention, long-lasting phosphorescent glass-ceramics have a composition containing 30-70 mol % SiO2, 5-40 mol % MgO and 10-55 mol % MO where M is an element or elements selected from the group consisting of Ca, Sr and Ba as basic ingredients. The composition further includes 0.0001-5 mol % Eu2O3 as an activator and 0.0001-6 mol % Ln2O3 as an auxiliary activator where Ln is an element or elements selected from the group consisting of Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu.