Optical CdO and ThO.sub.2 -free glass with refractive indices of 1.73-1. 78 abbe numbers of 30-34, and high devitrification stability

摘要

A new, CdO-and ThO.sub.2 -free optical glass with refractive indices of 1.73-1.78 and Abbe numbers of 30-34 and with particularly good devitrification stability comprises (in weight %):PP ______________________________________ PPSiO.sub.2 PP 12-20, B.sub.2 O.sub.3 PP 10-18, PbO 50-60 PPAl.sub.2 O.sub.3 PP 2-7, ZnO 0-4, ZrO. sub.2 PP 0.5-3 PPLa.sub.2 O.sub.3 PP 2-10, Cs.sub.2 O PP 0-5, M.sub.2 O PP 0-1 PP(M.sub.2 O Na.sub.2 O, K.sub.2 O, Li.sub.2 O) TiO.sub.2 0-5 PPwith the SiO.sub.2 /B.sub. 2 O.sub.3 -ratio being about 1.0 to PP ______________________________________ PP1.5. P P