optical glass, press-molding glass gob and optical element and a manufacturing method of the production method as well as the optical element blank

摘要

PROBLEM TO BE SOLVED: To provide a high-refractive-index low-dispersion optical glass which can be stably supplied and has excellent glass stability and less coloration.;SOLUTION: An optical glass comprises, by mass, 5 to 12% of SiO₂, 9 to 15% of B₂O₃, 45 to 65% of total of La₂O₃, Gd₂O₃ and Y₂O₃, 0.5 to 10% of ZnO, 1 to 20% of total of TiO₂ and Nb₂O₅, 0 to 15% of ZrO₂, 0 to 12% of Ta₂O₅, and 0 to 5% of GeO₂, wherein: the mass ratio (SiO₂/B₂O₃) of the content of SiO₂ to the content of B₂O3 is 0.3-1.0; the mass ratio( (Gd₂O₃+Y₂O₃)/(La₂O₃+Gd₂O₃+Y₂O₃)) of the total content of Gd₂O₃ and Y₂O₃ to the total content of La₂O₃, Gd₂O₃ and Y₂O₃ is 0.05-0.6; and a refractive index nd is 1.90 to 2.0; an Abbe's number νd is 32-38; and a coloring degree λ70 is 430 nm or less.;COPYRIGHT: (C)2014,JPO&INPIT