OPTICAL GLASS, PREFORM FOR PRESS MOLDING AND OPTICAL ELEMENT

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PROBLEM TO BE SOLVED : To provide optical glass that is high in refractive index and low in dispersion, the glass having a high partial dispersion ratio and thus suitably used as a lens for reducing the chromatic aberration of an optical system. SOLUTION : Optical glass comprises, expressed in mol% on an oxide basis, B2O3 : 43-79.5%, La2O3 : 3-35%, Gd2O3 : 0-30%, Y2O3 : 0-20%, TiO2 : 0-15%, and Bi2O3 : 0-10%, wherein, the total amount of the rare earth component, Ln2O3, is 20.3-40% (where, Ln2O3 represents the total amount of at least one component selected from La2O3, Gd2O3 and Y2O3), and when the content of the TiO2 component is A and the content of the Bi2O3 component is B, the relational expression of A+20×B≥3.4 is satisfied, and a refractive index nd is 1.75-1.8 and an Abbe number νd is 46.7-55. COPYRIGHT : (C)2016, JPO&INPIT