Patent ID: 8367575

Claim:
A high refraction and low dispersion optical glass comprising 6% -17% of B 2 O 3 , 2-10% of SiO 2 , more than 25% but less than 45% of La 2 O 3 , 5-25% of Gd 2 O 3 , 0-3% of Nb 2 O 5 , more than 19% but less than 27% of Ta 2 O 5 , 0-16% of ZnO, 0-5% of BaO, 0-5% of CaO, 0-5% of SrO, 0-9% of ZrO 2 , 0-8% of Y 2 O 3 , 0-8% of Yb 2 O 3 , 0-5% of WO 3 , 0-2% of Li 2 O, Na 2 O and K 2 O, from 0.01% to less than 0.1% of Sb 2 O 3 and 0-1% of SnO 2 by mass, wherein said high refraction and low dispersion optical glass is free of GeO 2 .