| 摘要 |
PURPOSE:To obtain optical glass having superior light transmittance, chemical durability, defoamability in a molten state and economical efficiency with respect to starting materials by using B2O3-SiO2-La2O3-(Y2O3+ZrO2+Nb2O5) as a basic composition. CONSTITUTION:This optical glass contains, by weight, 25-35% B2O3, 1-5% SiO2, 35-58% La2O3, 0-6% Y2O3, 0-10% ZrO2, 0-<3% Nb2O5 (Y2O3+ZrO2+ Nb2O5=5-17%), 0-5% GeO2, 0-<2% Al2O3, 0-9.5% Gd2O3, 0-<2% Ta2O5, 0-10% WO3, 0-<2% TiO2, O-<3% SnO2 and 0-<2% PbO+SrO+BaO. The glass has optical constants such as about 1.74-1.80 refractive index nd and about 42-51 Abbe's number vd, and it has superior light transmittance, chemical durability, defoamability in a molten state and economical efficiency with respect to starting materials.
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