Patent ID: 8921247

Claim:
An optical glass comprising, in terms of mass % on a basis of oxides: B 2 O 3 : 10% to 20%, SiO 2 : 0.5% to 12%, ZnO: 5% to 19%, Ta 2 O 5 : 3% to 17%, Li 2 O: 0.2% to 3%, ZrO 2 : 0.6% to 4.9%, WO 3 : 6.1% to 20%, La 2 O 3 : 32.5% to 50%, and Y 2 O 3 : 0.2% or more, and wherein a mass fraction of a content of La 2 O 3 to a content of Y 2 O 3 in terms of mass % is 40 or higher, and wherein the optical glass has a refractive index n d of 1.83 to 1.88 and an Abbe's number υ d of 39 to 42.