| 摘要 |
PURPOSE:To develop a lightweight optical glass having a high refractive index and low dispersion by incorporating Nb2O5 and CaO having comparatively small sp.gr. and affording a high refractive index into an optical glass composition as essential components. CONSTITUTION:The optical glass has the following composition. A starting material is melted, homogenized, and annealed to obtain the glass contg. 5-32% SiO2 and 5-40% B2O3 where SiO2+B2O3=30-51%, 16-25% La2O3 and 0-5% Y2O3 where La2O3+Y2O3=16-25%, 1-15% Nb2O5, 1-8% ZrO2, 13-32% CaO and 0-15% MgO where CaO+MgO=13-32%, <10% ZnO, <5% BaO, <8% SnO, <5% PbO, <4% TiO2, <5% Ta2O5, <5% WO3, <8% Al2O3, and <8% P2O5. The high-refractive index and low dispersion optical glass having 1.67- 1.78 nd, 41-55 nud, and 3.0-3.9 sp.gr. can be obtained.
|
