| 摘要 |
PURPOSE:To obtain an optical glass having a good chemical resistance while maintaining prescribed optical constants and a yield point suitable for a mold press process, by using SiO2, B2O3, SrO and Li2O as essential components and specifying the other components to limit compositions of the components. CONSTITUTION:An optical glass contains components in ranges of composition in wt.% as SiO2: 25-50%, B2O3: 16-40%, Al2O3: 0-5%, TiO2: 0-1%, ZrO2: 0-5%, ZnO: 0-5%, MgO: 0-5%, CaO: 0-8%, SrO: 5-25%, BaO: 0-9%, Li2O: 1-10%, Na2O+ K2O: 0-5% and Sb2O3: 0-1%, and also has optical constants within certain ranges such as a refractive index (Nd) of 1.55-1.65, and an Abbe number (nud) of 55-63. Also to improve melting property and devitrification resistance of the glass, the other components than shown above, e.g. La2O3, Bi2O3, Cs2O, SnO, F, etc., may be added, as necessary.
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