US 2025/0154048 A1Published application

Optical glass, preform for precision press molding, and optical element

AssigneeSumita Optical Glass, Inc.

InventorMao ARAKI

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Abstract

Provided is an optical glass that in addition to having a high refractive index and low dispersion, also has a low glass-transition temperature and can suppress temperature dependence of image formation. The optical glass has a composition containing, by mass %, 1% to 15% of SiO2, 10% to 25% of B2O3, 1% to 5% of Li2O, 5% to 30% of CaO, 10% or less of BaO, 8% or less of Nb2O5, 0% to 8% of ZrO2, 8% or less of TiO2, 10% or less of Y2O3, 5% to 20% of La2O3, 15% or less of Gd2O3, 8% or less of Ta2O5, and 8% or less of WO3, and does not substantially contain ZnO. A molar ratio (R/F) of contents related to 10 specific components is 0.8 to 2.0, and a temperature coefficient (40° C. to 60° C.) of relative refractive index is −5.0×10−6° C.−1 to 3.0×10−6° C.−1.

Claims12

Dependent claims

An optical glass comprising a composition containing, by mass %:

not less than 1% and not more than 15% of SiO2;
not less than 10% and not more than 25% of B2O3;
not less than 1% and not more than 5% of Li2O;
not less than 5% and not more than 30% of CaO;
not less than 0% and not more than 10% of BaO;
not less than 0% and not more than 8% of Nb2O5;
not less than 0% and not more than 8% of ZrO2;
not less than 0% and not more than 8% of TiO2;
not less than 0% and not more than 10% of Y2O3;
not less than 5% and not more than 20% of La2O3;
not less than 0% and not more than 15% of Gd2O3;
not less than 0% and not more than 8% of Ta2O5;
and
not less than 0% and not more than 8% of WO3, wherein
the optical glass does not substantially contain ZnO,
R/F, where R is total content in mol % of Li2O, CaO, and BaO and F is total content in mol % of SiO2 and B2O3, is not less than 0.8 and not more than 2.0, and
a temperature coefficient of relative refractive index at a d-line of 587.562 nm for from 40° C. to 60° C. is not less than −5.0×10−6° C.−1 and not more than 3.0×10−6° C.−1.

14 more elements

Dependencies are inferred from the claim text.