Ophthalmic and optical glasses
AssigneeKabushiki Kaisha Ohara
InventorMichiko Morishita
Life of this patent
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Abstract
Ophthalmic and optical glasses have a composition in weight percent of 4.5-9.5% SiO2, 10-19.5% B2O3, 0-3% Al2O3, 0-5% GeO2, 18—less than 23% La2O3, 0.3—less than 2% Gd2O3, 5.5-13.5% TiO2, 0-7.5% ZrO2, 15-21% Nb2O5, 0-1.5% Ta2O5, 0.3-5% WO3, with the proviso that (Ta2O5+WO3)/B2O3 is 0.5 or below in the ration terms of weight, 2.1-10% ZnO, 0-5% MgO, 7-12.5% CaO, 0-5% SrO, 0-4% BaO, ≧0.1% Li2O+Na2O+K2O in which 0-1% Li2O, 0-1% Na2O and 0-1% K2O, 0-0.5% As2O3 and 0-0.5% Sb2O3 and have a specific gravity of 4.1 or below, and optical constants of a refractive index (nd) exceeding 1.88 and up to 1.93 and an Abbe number j(ν d) within a range from 28 to 31. A preferable range of Nb2O5 is 15.5—less than 20.5% and a more preferable range of Nb2O5 is less 15.5-20%.
Claims9
Ophthalmic and optical glasses having the following composition in weight percent:
- SiO2 4.5-9.5% B2O3 10-19.5% Al2O3 0-3% GeO2 0-5% La2O3 18-less than 23% Gd2O3 0.3-less than 2% TiO2 5.5-13.5% ZrO2 0-7.5% Nb2O5 15-21% Ta2O5 0-1.5% WO3 0.3-5%
- with the proviso that (Ta2O5+WO3)/B2O3 is 0.5 or below in the ratio in terms of weight
- ZnO 2.1-10% MgO 0-5% CaO 7-12.5% SrO 0-5% BaO 0-4% Li2O + Na2O + K2O ≧0.1% in which Li2 O 0-1% Na2O 0-1% K2O 0-1% As2O3 0-0.5% Sb2O3 0-0.5%
- and having a specific gravity of 4.1 or below.
Ophthalmic and optical glasses having the following composition in weight percent:
- SiO2 4.5-9.5% B2O3 10-19.5% Al2O3 0-3% GeO2 0-5% La2O3 18-less than 23% Gd2O3 0.3-less than 2% TiO2 5.5-13.5% ZrO2 0-7.5% Nb2O5 15.5-less than 20.5% Ta2O5 0-1.5% WO3 0.3-5%
- with the proviso that (Ta2O5+WO3)/B2O3 is 0.5 or below in the ratio in terms of weight
- ZnO 2.1-10% MgO 0-5% CaO 7-12.5% SrO 0-5% BaO 0-4% Li2O + Na2O + K2O ≧0.1% in which Li2 O 0-1% Na2O 0-1% K2O 0-1% As2O3 0-0.5% Sb2O3 0-0.5%
- and having a specific gravity of 4.1 or below.
Ophthalmic and optical glasses having the following composition in weight percent:
- SiO2 4.5-9.5% B2O3 10-19.5% Al2O3 0-3% GeO2 0-5% La2O3 18-less than 23% Gd2O3 0.3-less than 2% TiO2 5.5-13.5% ZrO2 0-7.5% Nb2O5 15.5-20% Ta2O5 0-1.5% WO3 0.3-5%
- with the proviso that (Ta2O5+WO3)/B2O3 is 0.5 or below in the ratio in terms of weight
- ZnO 2.1-10% MgO 0-5% CaO 7-12.5% SrO 0-5% BaO 0-4% Li2O + Na2O + K2O ≧0.1% in which Li2 O 0-1% Na2O 0-1% K2O 0-1% As2O3 0-0.5% Sb2O3 0-0.5%
- and having a specific gravity of 4.1 or below.
Dependencies are inferred from the claim text.