Patent ID: 7827823
Filing Date: 2010-11-09
Classification: C03B,C03C

Abstract:
1. A process for producing an optical element, which comprises heating a precision press-molding preform and precision press-molding the preform with a mold, said precision press-molding preform being formed of an optical glass comprising, by mol %, 5 to 25.37% of B 3 to 50% of SiO 10 to 40% of TiO 10.45 to 40% of ZnO, 5 to 20% of La 0 to 10% of Gd 0 to 15% of Nb 0 to 10% of ZrO 0 to 5% of Ta 0 to 10% of Bi 0 to 6% of MgO, 0 to 8% of CaO, 0 to 10% of SrO, 0 to 6% of BaO provided that the total content of MgO, CaO, SrO and BaO is 15% or less, 0 to 20% of Li 0 to 5% of Na containing no PbO or As 2 O 3 , optionally containing not more than 1% by weight of Sb 2 O 3 as a refining agent, having a refractive index (nd) of over 1.88 and an Abbe's number (νd) of 35 or less and having a glass transition temperature of 620° C. or lower.