Opthalmic and optical glass with high refractive index and low density - comprises compsns. of silica, germanium oxide, boron oxide and other oxide(s)

摘要

Ophthalmic and optical glass comprises in wt.% based on oxide:- 0-12 SiO2; 0-3 GeO2; 0-12 SiO2+GeO2; 14-30 B2O3; 0-2 P2O5; 0-2 Li2O; 0-2 Na2O; 0-2 K2O; 0-2 Cs2O; 0-2 M2O; 11-22 CaO; 0-2 MgO + SrO + BaO + ZnO + PbO; 0-2 Al2O3; 20-31 La2O3; 0-5 V2O3; 0-2 Bi2O3 + Gd2O3; below 3 La2O3 + Y2O3; 6-14 TiO2; 2 - less than 8 ZrO2; 0-5 Ta2O5; above 20-30 Nb2O5; 0-2 WO3; 0-2F, 0-2 SO3; and refining agents. USE/ADVANTAGE - Esp. for glasses having high refractive index which enables the wt. redn. of the glass. Glasses have high refractive index of at least 1.85 Abbe number of min. 30, with low density of max. 4.2g/cm3. Glass also has good crystallisation stability and good chemical resistance.