Abstract: Provided is optical glass that does not contain lead, which is an environmental pollutant. The optical glass is ideal for the transmission of light even after being exposed to X-rays, and has a high refractive index. The optical glass comprises, by mass % in terms of oxide versus the glass total mass, 1.0% to 60.0% of an SiO2 component, and one or more selected from the group consisting of an La2O3 component, ZrO2 component, TiO2 component, Nb2O5 component, and Ta2O5 as essential components. The optical glass has a refractive index (nd) of 1.50 or greater, and has a light intensity recovery rate of 45% or greater when the glass having been irradiated with X-rays with a dose of 2.5 Gy is irradiated with light of a xenon lamp for 11 hours.

Abstract: There is provided an optical glass with a high refractive index and a low dispersion having a refractive index (nd) of not less than 1.75 and an Abbe's number (?d) of not less than 35 where the image formation characteristic is hardly affected by changes in temperature of the using environment. SiO2, B2O3 and La2O3 are contained as essential components and the ratio of the constituting components are adjusted whereby an optical glass in which a product of ? and ? where ? is an average linear expansion coefficient at ?30 to +70° C. and ? is an optical elasticity constant at the wavelength of 546.1 nm is not more than 130×10?12° C.?1×nm×cm?1×Pa?1 is able to be achieved.

Abstract: There is provided an optical glass with a high refractive index and a low dispersion having a refractive index (nd) of not less than 1.75 and an Abbe's number (?d) of not less than 35 where the image formation characteristic is hardly affected by changes in temperature of the using environment. SiO2, B2O3 and La2O3 are contained as essential components and the ratio of the constituting components are adjusted whereby an optical glass in which a product of ? and ? where ? is an average linear expansion coefficient at ?30 to +70° C. and ? is an optical elasticity constant at the wavelength of 546.1 nm is not more than 130×10?12° C.?1×nm×cm?1×Pa?1 is able to be achieved.

Abstract: Provided is optical glass that does not contain lead, which is an environmental pollutant. The optical glass is ideal for the transmission of light even after being exposed to X-rays, and has a high refractive index. The optical glass comprises, by mass% in terms of oxide versus the glass total mass, 1.0% to 60.0% of an SiO2 component, and one or more selected from the group consisting of an La2O3 component, ZrO2 component, TiO2 component, Nb2O5 component, and Ta2O5 as essential components. The optical glass has a refractive index (nd) of 1.50 or greater, and has a light intensity recovery rate of 45% or greater when the glass having been irradiated with X-rays with a dose of 2.5 Gy is irradiated with light of a xenon lamp for 11 hours.

Abstract: There is provided an optical glass with a high refractive index and a low dispersion having a refractive index (nd) of not less than 1.75 and an Abbe's number (?d) of not less than 35 where the image formation characteristic is hardly affected by changes in temperature of the using environment. SiO2, B2O3 and La2O3 are contained as essential components and the ratio of the constituting components are adjusted whereby an optical glass in which a product of ? and ? where ? is an average linear expansion coefficient at ?30 to +70° C. and ? is an optical elasticity constant at the wavelength of 546.1 nm is not more than 130×10?12° C.?1×nm×cm?1×Pa?1 is able to be achieved.

Abstract: There is provided an optical glass with a high refractive index and a low dispersion having a refractive index (nd) of not less than 1.75 and an Abbe's number (?d) of not less than 35 where the image formation characteristic is hardly affected by changes in temperature of the using environment. SiO2, B2O3 and La2O3 are contained as essential components and the ratio of the constituting components are adjusted whereby an optical glass in which a product of ? and ? where ? is an average linear expansion coefficient at ?30 to +70° C. and ? is an optical elasticity constant at the wavelength of 546.1 nm is not more than 130×10?12° C.?1×nm×cm?1×Pa?1 is able to be achieved.

Abstract: Optical glass has a refractive index of 1.83 or above and an Abbe number of 26 or less and contains SiO2, TiO2, Nb2O5 and Na2O as its essential constituents in such proportions on a final oxide basis that the amounts of its oxide constituents as expressed on a mass percentage basis may satisfy the relationship: (TiO2+Nb2O5)/(Na2O+K2O)=3.0 to 4.0.

Abstract: An optical glass having a refractive index (nd) within a range from 141 to 1.47 and an Abbe number (?d) within a range from 90 to 100 comprises in mass % on element basis: P ?0.1-5.0% Al ?1.0-20.0% F 30.0-60.0% and O ?1.0-20.0% and comprises, as an essential component, one or more elements selected from the group consisting of Ca, Sr and Ba. In this optical glass, the ratio (Si+B+P+Al)/F is within a range from 0.15 to 0.40.

Abstract: Provided is an optical glass having high refractivity and high dispersibility, having good moldability in precision pressing, and having high transmittance and good internal quality, of which the transmittance reduction with time is prevented. The optical glass has a Pt content of at most 1.5 ppm, and is characterized in that, when a sample of the glass polished on both surfaces and having a thickness of 10 mm is irradiated with UV and/or visible light at a light-receiving energy of at most 0.4 mW·cm?2 for at least 200 hours, then the difference in the internal transmittance to light having a wavelength of 420 nm, before and after the irradiation (before irradiation—after irradiation) of the sample, as calculated in terms of the sample having a thickness of 10 mm, is at most 0.1.

Abstract: An optical glass having optical constants of refractive index (nd) within a range from 1.49 to 1.54 and Abbe number (? d) within a range from 55 to 65 comprises, in mass %, SiO2 >65-75% R2O (R is at least one selected from the group ?15-25% consisting of Li, Na, K and Cs) where Li2O ?0.1-5.0% Na2O ?1.0-10.0% K2O ?5.0-20.0% and Cs2O ?0-5.0% R?O (R? is at least one selected from the group ?0.5-10% consisting of Mg, Ca, Sr or Ba) where MgO ?0-10% and/or CaO ?0-10% and/or SrO ?0-10% and/or BaO ?0-10% ZnO ?0-<3.0% and/or B2O3 ?0-6.0% and/or Al2O3 ?0-<1.0% and/or TiO2 ?0-<2.0% and/or ZrO2 ?0-2% and/or WO3 ?0-3.0% and/or Sb2O3 ?0-2.0% and a fluoride or fluorides of a metal element or ?0-2%.

Abstract: Optical glass has a refractive index of 1.83 or above and an Abbe number of 26 or less and contains SiO2, TiO2, Nb2O5 and Na2O as its essential constituents in such proportions on a final oxide basis that the amounts of its oxide constituents as expressed on a mass percentage basis may satisfy the relationship: (TiO2+Nb2O5)/(Na2O+K2O)=3.0 to 4.

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: An optical glass having a refractive index (nd) within a range from 141 to 1.47 and an Abbe number (?d) within a range from 90 to 100 comprises in mass % on element basis: P ?0.1-5.0% Al ?1.0-20.0% F 30.0-60.0% and O ?1.0-20.0% and comprises, as an essential component, one or more elements selected from the group consisting of Ca, Sr and Ba. In this optical glass, the ratio (Si+B+P+Al)/F is within a range from 0.15 to 0.40.

Abstract: Provided is an optical glass having high refractivity and high dispersibility, having good moldability in precision pressing, and having high transmittance and good internal quality, of which the transmittance reduction with time is prevented. The optical glass has a Pt content of at most 1.5 ppm, and is characterized in that, when a sample of the glass polished on both surfaces and having a thickness of 10 mm is irradiated with UV and/or visible light at a light-receiving energy of at most 0.4 mW·cm?2 for at least 200 hours, then the difference in the internal transmittance to light having a wavelength of 420 nm, before and after the irradiation (before irradiation—after irradiation) of the sample, as calculated in terms of the sample having a thickness of 10 mm, is at most 0.1.

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: 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: 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: An optical glass having optical constants of refractive index (nd) within a range from 1.49 to 1.54 and Abbe number (? d) within a range from 55 to 65 comprises, in mass %, SiO2 >65-75% R2O (R is at least one selected from the group ?15-25% consisting of Li, Na, K and Cs) where Li2O ?0.1-5.0% Na2O ?1.0-10.0% K2O ?5.0-20.0% and Cs2O ?0-5.0% R?O (R? is at least one selected from the group ?0.5-10% consisting of Mg, Ca, Sr or Ba) where MgO ?0-10% and/or CaO ?0-10% and/or SrO ?0-10% and/or BaO ?0-10% ZnO ?0-<3.0% and/or B2O3 ?0-6.0% and/or Al2O3 ?0-<1.0% and/or TiO2 ?0-<2.0% and/or ZrO2 ?0-2% and/or WO3 ?0-3.0% and/or Sb2O3 ?0-2.0% and a fluoride or fluorides of a metal element or ?0-2%.

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 includes SiO2; PbO; B2O3; not less than 0.1 mass % of TeO2; and not less than 0.4 mass % of Li2O.