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US 7,622,409 B2Granted
Optical glass, precision press-molding preform, process for production thereof, optical element and process for the production thereof
AssigneeHoya Corporation
InventorKazutaka Hayashi
Life of this patent
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Abstract
Provided is an optical glass having high-refractivity low-dispersion properties, having a low glass transition temperature and having the property of being softened at a low temperature so that a preform therefrom is precision press-moldable, and the optical glass comprises, as essential components, B2O3, La2O3, Gd2O3 and ZnO and has a refractive index (nd) of over 1.86, an Abbe's number (vd) of less than 35 and a glass transition temperature (Tg) of 630° C. or lower.
Claims10
An optical glass comprising, by mol %,
- 15-45% B2O3,
- 5-20% La2O3,
- 1-20% Gd2O3,
- 10-45% ZnO,
- 0-15% WO3,
- 0-10% Ta2O5,
- 0-10% Nb2O5,
- 0-20% TiO2,
- 0-20% SiO2,
- 0-15% Li2O,
- 0-10% Na2O,
- 0-10% K2O,
- 0-10% MgO,
- 0-10% CaO,
- 0-10% SrO,
- 0-10% BaO
- 0-8% Y2O3,
- 0-8% Yb2O3,
- provided that the total content of La2O3, Gd2O3, Y2O3 and Yb2O3 is 10 to 30%,
- 0-less than 0.5% ZrO2,
- 0-10% Bi2O3, and
- 0-1% Sb2O3,
- and having a refractive index (nd) of over 1.86, an Abbe's number (vd) of 35 to less than 39.5 and a glass transition temperature (Tg) of 630° C. or lower.
20 more elements
Dependencies are inferred from the claim text.