Optical glass

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PROBLEM TO BE SOLVED : To provide an optical glass suitable for molding such as precision mold press forming in which devitrification resistance in molding is improved, and rare earth content is suppressed by a medium refractive index (refractive index 1.58 or more), low dispersion (Abbe number 47 or more), and a low yield point. SOLUTION : There is provided an optical glass containing 20.0 to 40.0 wt.% B2O3, 1.0 to 10.0 wt.% SiO2, 0.1 to 8.0 wt.% Al2O3, 3.0 to 15.0 wt.% R12O, 10.0 to 40.0 wt.% R2O, 10.0 to 40.0 wt.% ZnO, 1.0 to 15.0 wt.% WO3, and 12.0 wt.% or less Ln2O3. In this case, R1 indicates one type or two or more types of elements selected from among Li, Na and K; and R2 indicates one type or two or more types of elements selected from among Mg, Ca, Sr and Ba; and Ln indicates one type or two or more types of elements selected from among Y, La and Gd. COPYRIGHT : (C)2013, JPO&INPIT