Optical glass, preform for press-molding and optical element formed from preform

摘要

The present invention relates to an optical glass including, in terms of mass % on the basis of oxides, B2O3: 10% to 20%, SiO2: 0.5% to 12%, ZnO: 5% to 19%, Ta2O5: 3% to 17%, Li2O: 0.2% to 3%, ZrO2: 0.6% to 4.9%, WO3: 6.1% to 20%, La2O3: 32.5% to 50%, and Y2O3: 0.2% or more and less than 1.5%, in which a mass fraction (La2O3/Y2O3) of a content of La2O3 to a content of Y2O3 in terms of mass % is 40 or higher, and the optical glass has optical constants of a refractive index nd of 1.83 to 1.88 and an Abbe's number υd of 39 to 42.

主权项

1. An optical glass comprising, in terms of mass % on a basis of oxides:
B2O3: 10% to 20%, SiO2: 0.5% to 12%, ZnO: 5% to 19%, Ta2O5: 3% to 17%, Li2O: 0.2% to 3%, ZrO2: 0.6% to 4.9%, WO3: 6.1% to 20%, La2O3: 32.5% to 50%, and Y2O3: 0.2% or more, and wherein a mass fraction of a content of La2O3 to a content of Y2O3 in terms of mass % is 40 or higher, and wherein the optical glass has a refractive index nd of 1.83 to 1.88 and an Abbe's number υd of 39 to 42.