Use of an optical glass containing bismuth oxide for precision press molding

This invention claims a method for bismuth oxide optical glass, wherein the optical glass, a process for producing the heating in the step, glass not generate creamy white and devitrification medicine. durability of the glass, not generate of black. The optical glass has a r.i the first] is more than 1.75 and abbe amount of the pharmaceutical composition is more than 10 constants optical, the is characterised of: By mass of the VI-5, comprising than 10% and less than 90% Bi2O3, the following property the heating for detecting method, wherein the glass is substantially without opalization and a devitrification. Wherein the heating method: 15mm×15mm×30mm The film is the heating, wherein in the heat-preserving 30 minutes at a round glass-transition temperature (Tg) height 80℃ temperature of the optical glass, and cooling naturally arrives at room temperature, after detection on two opposite sides grinding to the mm thick, and visual).