| 摘要 |
PROBLEM TO BE SOLVED: To produce lead-free optical glass having a refractive index nd 1.50-1.56 and an Abbe's numberνd of 50-64. SOLUTION: This optical glass has a compsn. consisting of, by weight on the oxide basis, 62-75%SiO2, 5-9.5% B2O3, 4.5-21% BaO, 0 to <14% ZnO, 0-0.5% CaO (ZnO+CaO>=0.05% and BaO+ZnO+CaO<=25%), 1-7% TiO2, 2-10% Na2O, 4.5-8% K2O, 0-1% Nb2O5, 0-1% Ta2O5 and 0-0.5% F, or further contains the usual amt. of a refining agent if necessary.
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