OPTICAL GLASS, PREFORM, AND OPTICAL ELEMENT

摘要

Provided are an optical glass which has a refractive index (nd) and an Abbe number (?d) in respective desired ranges and, despite this, is suitable for use in correcting chromatic aberration and a lens preform obtained using the optical glass. The optical glass comprises, with respect to the total mass of the glass in terms of oxide composition in mass%, 1.0-31.0% B2O3 component, 40.0-65.0% Ln2O3 component, up to 30.0% TiO2 component, and up to 30.0% Nb2O5 component. The lens preform comprises this optical glass as the base material.