Abstract: An optical glass having optical constants of a refractive index (nd) of 1.78 or over, an Abbe number (?d) of 30 or below, and a partial dispersion ratio (?g, F) of 0.620 or below comprises SiO2 and Nb2O5 as essential components, wherein an amount of Nb2O5 in mass % is more than 40%. The optical glass further comprising, in mass % on oxide basis, less than 2% of K2O and one or more oxides selected from the group consisting of B2O3, TiO2, ZrO2, WO3, ZnO, SrO, Li2O and Na2O wherein a total amount of SiO2, B2O3, TiO2, ZrO2, Nb2O5, WO3, ZnO, SrO, Li2O and Na2O is more than 90% and TiO2/(ZrO2+Nb2O5) is less than 0.32.

Abstract: Provided is an optical glass having optical constants, a refractive index (nd) of more than 1.9 and an Abbe number (?d) of not more than 38, having a small partial dispersion ratio and capable of being produced from inexpensive materials. The optical glass has a partial dispersion ratio (?g, F) of at most 0.615, and contains, as indispensable ingredients, B2O3, La2O3, TiO2, Nb2O5 and Ta2O5, wherein the ratio, as % by mass, of TiO2/Nb2O5 is at most 0.26 and GeO2/Nb2O5 is at most 0.38. The optical glass contains, in terms of % by mass, the following ingredients: B2O3 ??5 to 22%, La2O3 ??15 to 50%, TiO2 0.01 to 15%, Nb2O5 ??5 to 40%, and Ta2O5 ?0.1 to 25%, and SiO2 0 to 10% and/or GeO2 0 to 10% and/or Al2O3 0 to 10% and/or Gd2O3 0 to 16% and/or ZrO2 0 to 15% and/or WO3 0 to 22% and/or Sb2O3 0 to 1%.

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 having refractive index (nd) exceeding 1.85, Abbe number (?d) of 36 or over, comprising SiO2, B2O3, La2O3, Gd2O3, Ta2O5 and Li2O as essential components, being free of Pb and As components, and having glass transition temperature (Tg) of 630° C. or below.

Abstract: An optical glass of the present invention has optical constants of a refractive index (nd) within a range from 1.75 to 1.85 and an Abbe number (?d) within a range from 35 to 45, comprises SiO2 and B2O3 as essential components and one or more components selected from the group consisting of ZrO2, Nb2O5, Ta2O5 and WO3, has a glass transition temperature (Tg) of 580° C. or below and has weathering resistance (surface method) of Class 1 or Class 2.

Abstract: An optical glass having optical constants of a refractive index (nd) of 1.78 or over, an Abbe number (?d) of 30 or below, and a partial dispersion ratio (?g, F) of 0.620 or below comprises SiO2 and Nb2O5 as essential components, wherein an amount of Nb2O5 in mass % is more than 40%. The optical glass further comprising, in mass % on oxide basis, less than 2% of K2O and one or more oxides selected from the group consisting of B2O3, TiO2, ZrO2, WO3, ZnO, SrO, Li2O and Na2O wherein a total amount of SiO2, B2O3, TiO2, ZrO2, Nb2O5, WO3, ZnO, SrO, Li2O and Na2O is more than 90% and TiO2/(ZrO2+Nb2O5) is less than 0.32.

Abstract: An optical glass having optical constants of a refractive index (nd) of 1.78 or over, an Abbe number (?d) of 30 or below, and a partial dispersion ratio (?g, F) of 0.620 or below comprises SiO2 and Nb2O5 as essential components, wherein an amount of Nb2O5 in mass % is more than 40%. The optical glass further comprising, in mass % on oxide basis, less than 2% of K2O and one or more oxides selected from the group consisting of B2O3, TiO2, ZrO2, WO3, ZnO, SrO, Li2O and Na2O wherein a total amount of SiO2, B2O3, TiO2, ZrO2, Nb2O5, WO3, ZnO, SrO, Li2O and Na2O is more than 90% and TiO2/(ZrO2+Nb2O5) is less than 0.32.

Abstract: An optical glass has optical constants of a refractive index (nd) within a range from 1.73 to less than 1.80 and an Abbe number (?d) within a range from 43 to 55, comprises SiO2, B2O3, Y2O3, La2O3, ZnO and Li2O as essential components, is substantially free of lead component, arsenic component and fluorine component, has a ratio of SiO2/B2O3 of 0.30 to 1.55 and a ratio of Y2O3/La2O3 of 0.15 to 1.00, and has a glass transition temperature (Tg) of 620° C. or below.

Abstract: An optical glass having optical constants of a refractive index (nd) of 1.78 or over, an Abbe number (v d) of 30 or below, and a partial dispersion ratio (? g, F) of 0.620 or below comprises SiO2 and Nb2O5 as essential components, wherein an amount of Nb2O5 in mass % is more than 40%. The optical glass further comprising, in mass % on oxide basis, less than 2% of K2O and one or more oxides selected from the group consisting of B2O3, TiO2, ZrO2, WO3, ZnO, SrO, Li2O and Na2O wherein a total amount of SiO2, B2O3, TiO2, ZrO2, Nb2O5, WO3, ZnO, SrO, Li2O and Na2O is more than 90% and TiO2/(ZrO2+Nb2O5) is less than 0.32.

Abstract: Provided is an optical glass having optical constants, a refractive index (nd) of more than 1.9 and an Abbe number (?d) of not more than 38, having a small partial dispersion ratio and capable of being produced from inexpensive materials. The optical glass has a partial dispersion ratio (?g, F) of at most 0.615, and contains, as indispensable ingredients, B203, La2O3, TiO2, Nb2O5 and Ta2O5, wherein the ratio, as % by mass, of TiO2/Nb2O5 is at most 0.26 and GeO2/Nb2O5 is at most 0.38. The optical glass contains, in terms of % by mass, the following ingredients: B2O3 ??5 to 22%, La2O3 ??15 to 50%, TiO2 0.01 to 15%, Nb2O5 ??5 to 40%, and Ta2O5 ?0.1 to 25%, and SiO2 0 to 10% and/or GeO2 0 to 10% and/or Al2O3 0 to 10% and/or Gd2O3 0 to 16% and/or ZrO2 0 to 15% and/or WO3 0 to 22% and/or Sb2O3 0 to 1%.

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) 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 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 of the present invention has optical constants of a refractive index (nd) within a range from 1.75 to 1.85 and an Abbe number (? d) within a range from 35 to 45, comprises SiO2 and B2O3 as essential components and one or more components selected from the group consisting of ZrO2, Nb2O5, Ta2O5 and WO3, has a glass transition temperature (Tg) of 580° C. or below and has weathering resistance (surface method) of Class 1 or Class 2.

Abstract: An optical glass having refractive index (nd) exceeding 1.85, Abbe number (?d) of 36 or over, comprising SiO2, B2O3, La2O3, Gd2O3, Ta2O5 and Li2O as essential components, being free of Pb and As components, and having glass transition temperature (Tg) of 630° C. or below.

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) 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.

Abstract: An optical glass suitable for precision mold pressing has a refractive index (nd) of 1.88 or over and an Abbe number (? 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 more than 30% and less than 50% WO3 0-5%? CaO 0-10% BaO 0-10% Li2O 3-12% Na2O 0-10% K2O 0-10% Bi2O3 0-15% Ta2O5 0-7%? 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 has optical constants of a refractive index (nd) within a range from 1.73 to less than 1.80 and an Abbe number (?d) within a range from 43 to 55, comprises SiO2, B2O3, Y2O3, La2O3, ZnO and Li2O as essential components, is substantially free of lead component, arsenic component and fluorine component, has a ratio of SiO2/B2O3 of 0.30 to 1.55 and a ratio of Y2O3/La2O3 of 0.15 to 1.00, and has a glass transition temperature (Tg) of 620° C. or below.

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.