Patent ID: 8476177

Claim:
A lead-free and arsenic-free optical glass having a refractive index n d of 1.945≦n d ≦1.97, an Abbe number ν d of 33≦ν d ≦36, and an internal transmittance of >80% at 410 nm and at a thickness of 10 mm, wherein said optical glass has a composition comprising respective components in the following amounts expressed in % of corresponding cations of said respective components in said composition, with reference to a sum of all cations in the composition: B 3+ 35-46 La 3+ 25-35 Ta 5+ 6-14 W 6+ 6-13 Zr 4+ 1-7 Gd 3+ 0-5 Nb 5+ 0-4 Y 3+ 0-4 Ba 2+ 0-2 Σalkaline earth metal cations 0-2 ΣLa 3+ + Ta 5+ + W 6+ + Zr 4+ + Gd 3+ + Nb 5+ + Y 3+ ≧50 cations of at least one fining agent 0-0.3, wherein a ratio of B 3+ to La 3+ is 1.1 to 1.6, a ratio of B 3+ to Σ Si 4+ +B 3+ is greater than 0.5, and the glass is free of Ti 4+ , Th 4+ , Zn 2+ , F − and Hf 4+ , and wherein the glass contains less than 6 ppm of platinum.