Against devitrification and chemical widerstandsfaehige optical glass with a high refractive index and in the case of a large moegen the, as main constituent, tellurium deep 2 and where deep 3 contains and method for its preparation and its use

摘要

A TeO2-WO3 glass with a high refractive index eta d of not lower than 2.0 and a high dispersing ability represented by Abbe's number of 21 or less, and having a greatly improved stability with respect to both devitrification and chemical durability, can be obtained by the inclusion, in the composition of the glass, of Li2O and at least one other oxide selected from the group consisting of K2O, MgO, BaO, ZnO, CdO, TiO2, PbO, La2O3, B2O3, Nb2O5 and Bi2O3.