Abstract: A P2O5—BaO—ZnO—Nb2O5 type optical glass contains 25-50 wt. % P2O5, 15-35 wt. % BaO, 1-25 wt. ZnO, and 3-10 wt. % Nb2O5. The optical glass has a high refractive index (particularly preferably the refractive index nd of 1.6 or more), low dispersion (an Abbe number ?d of 42 or more), a low deformation point, and improved resistance to devitrification upon molding, and is suitable for precision-mold press molding or other molding processes and also suitable for transfer of a fine structure.

Abstract: An optical glass having a high refractive index (particularly preferably a refractive index of 1.6 or more), low dispersion (an Abbe number of 45 or more), a low deformation point, and improved resistance to devitrification upon molding, and suitable for precision-mold press molding or other molding processes and also suitable for transfer of a fine structure is provided. The optical glass contains 1.0-4.5 wt. % SiO2, 30.5-50.0 wt. % B2O3, 1.1-8.0 wt. % Li2O, 10.1-19.5 wt. % BaO, 15.5-30.0 wt. % ZnO, 3.0-15.0 wt. % Y2O3, and 10.0-19.5 wt. % La2O3.

Abstract: An optical glass having a high refractive index (particularly preferably a refractive index of 1.6 or more), low dispersion (an Abbe number of 45 or more), a low deformation point, and improved resistance to devitrification upon molding, and suitable for precision-mold press molding or other molding processes and also suitable for transfer of a fine structure is provided. The optical glass contains 1.0-4.5 wt. % SiO2, 30.5-50.0 wt. % B2O3, 1.1-8.0 wt. % Li2O, 10.1-19.5 wt. % BaO, 15.5-30.0 wt. % ZnO, 3.0-15.0 wt. % Y2O3, and 10.0-19.5 wt. % La2O3.

Abstract: A P2O5—BaO—ZnO—Nb2O5 type optical glass contains 25-50 wt. % P2O5, 15-35 wt. % BaO, 1-25 wt. ZnO, and 3-10 wt. % Nb2O5. The optical glass has a high refractive index (particularly preferably the refractive index nd of 1.6 or more), low dispersion (an Abbe number ?d of 42 or more), a low deformation point, and improved resistance to devitrification upon molding, and is suitable for precision-mold press molding or other molding processes and also suitable for transfer of a fine structure.

Abstract: A method for producing a SiO.sub.2 glass material having regions changed in light refractive index is provided which comprises implanting at least 5.times.10.sup.19 Ge ions/cm.sup.3 into a SiO.sub.2 glass substrate, heat-treating the substrate at a temperature exceeding 300.degree. C., and exposing the substrate to an ultraviolet light. Also provided is a SiO.sub.2 glass material produced by the method.

Abstract: A process for producing a glass having a rod refractive index distribution, which includes pressing a glass at a temperature below the glass transition temperature to form a glass having a density increased towards the surface layer thereof, or alternatively includes heating a glass at a temperature around the transition temperature at the lowest to prepare glass having a uniformly enhanced density and heating the treated glass under a pressure lower than the applied pressure at a temperature below the glass transition temperature of the glass to prepare a rod glass having a density increased towards the central portion.

Abstract: A process for producing a rod glass having a refractive index distribution, which includes pressing a glass at a temperature below the glass transition temperature to form a glass having a density increased towards the surface layer thereof, or alternatively includes heating a glass at a temperature around the transition temperature at the lowest to prepare glass having a uniformly enhanced density and heating the treated glass under a pressure lower than the applied pressure at a temperature below the glass transition temperature of the glass to prepare a glass having a density increased towards the central portion.