Patent ID: 8361916

Claim:
An optical glass comprising, in terms of % by mass on the basis of oxides, respective components of B 2 O 3 : 10 to 20%, SiO 2 : more than 2 to 12%, La 2 O 3 : 25 to 50%, Gd 2 O 3 : 0 to 20%, Y 2 O 3 : 1 to 20%, provided that La 2 O 3 +Gd 2 O 3 +Y 2 O 3 : 35 to 60%, ZnO: 5 to 20%, Li 2 O: 0.2 to 3%, ZrO 2 : 0 to 0.5%, Ta 2 O 5 : 3 to 18% and WO 3 : 3 to 20%, and having optical constants of a refractive index n d of 1.84 to 1.86 and an Abbe number v d of 37 to 42, and a glass transition point (T g ) of 630° C. or lower.