Optical glass for mold press forming

摘要

The invention provides an optical glass for press molding which can satisfy all of the following requirements: (1) it contains no environmentally undesirable components; (2) it can easily achieve a low glass transition point; (3) it has a high refractive index and high dispersion; (4) it can easily provide a glass having an excellent visible light transmittance; and (5) it has excellent resistance to devitrification during preparation of a preform. The optical glass for press molding has a refractive index nd of 1.925 or more, an Abbe's number νd of 10 to 30, and a glass composition, in % by mass, of 20 to 80% Bi2O3, 10 to 30% B2O3, and 0 to 5.5% GeO2 and is substantially free of lead component, arsenic component, and F component.

主权项

1. An optical glass for press molding, having a refractive index nd of 1.925 or more, an Abbe's number νd of 10 to 30, and a glass composition, in % by mass, of 75 to 86% Bi2O3, 10 to 22.3% B2O3, 0 to 10% ZnO, 0 to 2.1% GeO2, 0 to 5% La2O3+Gd2O3+Ta2O5, and 99.99% or less Bi2O3+B2O3, and being substantially free of lead component, arsenic component, and F component, wherein the coloration λ70 is 475 nm or less.