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AssigneeHoya Corporation
InventorsYoshiko Kasuga, Xuelu Zou
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An optical glass taking account of meltability and the moldability of a preform, having optical constants including a refractive index (nd) of at least 1.57 but less than 1.67 and an Abbe's number (νd) of over 55 but not more than 65, having the property of softening at a low temperature and being suitable as a glass for precision press-molding, the optical glass including an optical glass containing B2O3, SiO2, La2O3, Gd2O3, an alkali metal oxide and an alkaline earth metal oxide as essential components, having a B2O3 and SiO2 total content of 52% by weight or more and having an SiO2/B2O3 content ratio of from 0.38 to 1.2, and an optical glass wherein the relationship of the refractive index (nd) and the Abbe's number (νd) satisfies the equation (1), νd>260−126×nd. (1)
An optical glass having a refractive index (nd) of at least 1.57 but less than 1.67 and an Abbe's number (νd) of over 55 but not more than 65,
An optical glass having a refractive index (nd) of at least 1.57 but less than 1.67 and an Abbe's number (νd) of over 55 but not more than 65,
An optical glass having a refractive index (nd) of at least 1.57 but less than 1.67, an Abbe's number (νd) of over 55 but not more than 65 and a glass transition temperature Tg of 590° C. or lower,
Dependencies are inferred from the claim text.