Optical glass - with high negative part dispersion in blue spectrum range as well as high refraction index and abbe number

摘要

Optical glass comprises in wt.%:- 0-12 SiO2; 0-2 GeO2; with 0-12 SiO2+GeO2; 9-26 B2O3; 0-2 Al2O3; 0-1 LiO2; 0-1 Na2O; 0-1 K2O; with 0-1 total alkali oxides; 0-4 MgO; 0-4 CaO; 0-4 SrO; 9-27 BaO; 0-4 ZnO; with less than 32 MgO+CaO+SrO+BaO+ZnO; 29-36 La2O3; 0-5 Y2O3; 3-9 ZrO2; 0-2 HfO2; 0-5 TiO2; 0-2 Ta2O5; 6-20 Nb2O5; 0-2 WO3; plus upto 1% purifying agents. ADVANTAGE - Has high negative part dispersion in blue range of the spectrum whilst having high refraction index of above 1.82 and Abbe number of 36-40. This helps to correct for secondary spectrum effect. Glass has high resistance to devitrification and has high transmission capability and is easy to produce.