Patent ID: 7928027

Claim:
An optical glass for press molding, consisting essentially of: SiO 2 : 10 to 30% by weight, B 2 O 3 : 15 to 35% by weight, Li 2 O: 0 (inclusive) to 10% by weight, Na 2 O: 0 (inclusive) to 5% by weight, K 2 O: 0 (inclusive) to 5% by weight, Li 2 O+Na 2 O+K 2 O: 0 (inclusive) to 15% by weight, MgO: 0 (inclusive) to 25% by weight, CaO: 0 (inclusive) to 25% by weight, SrO: 0 (inclusive) to 25% by weight, ZnO: 35 to 55% by weight, MgO+CaO+SrO+ZnO: 35 to 55% by weight, La 2 O 3 : 5 to 20% by weight, Gd 2 O 3 : 0 to 10% by weight, ZrO 2 : 0 to 5% by weight, Nb 2 O 5 : 0 to 10% by weight, WO 3 : 0 to 10% by weight, Bi 2 O 3 : 0 to 5% by weight, and Sb 2 O 3 : 0 to 1% by weight, wherein the optical glass does not include Y 2 O 3 , TiO 2 , BaO, and Ta 2 O 3 .