| 摘要 |
PROBLEM TO BE SOLVED: To obtain optical glass having high negative anisotropic dispersibility, not contg. lead and arsenic compds. and excellent in homogeneity by specifying the compsn. of SiO2 -B2 O3 -ZrO2 -Nb2 O5 glass. SOLUTION: A mixture of, by weight, 10-40% SiO2 with 12.5-35% B2 O3 , 3-20% ZrO2 , 6-30% Nb2 O5 , 0-5% Li2 O, 0-25% Na2 O, 0-10% K2 O, 0-5% MgO, 0-5% MgO, 0-5% CaO (MgO+CaO<=5%), 0-15% SrO, 0-20% BaO, 0-15% ZnO, 0-3% Al2 O3 , 0-10% La2 O3 , 0-15% Ta2 O5 , 0-5% P2 O5 , 0-5% GeO2 , 0-2% SnO2 , 0-5% WO3 , 0-1% Sb2 O3 and 0-5% (expressed in terms of F) fluoride substd. for part of these metal oxides is vitrified to obtain the objective optical glass having a refractive index of 1.55-1.75 and an Abbe's number of 25-51.
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