Optical glass null for press molding glass lens

摘要

PROBLEM TO BE SOLVED: To provide an optical glass which can be hot-pressed into a preform at rather low temp., which has the optical consts. of 1.56 to 1.62 refractive index (nd), 56.0 to 64.0 Abbe number (vd), and ≤440°C sag temp. (Ts) suitable for a press-formed lens, and ≤870°C liquid phase temp. (L.T.). ;SOLUTION: This glass contains, by wt.%, 48 to 58 P2O5, 1 to 3 Al2O3 1 to 4 Li2O, 0 to 4 La2O3, 0 to 5 MgO, 0 to 10 CaO, 0 to 10 SrO, 2 to 15 BaO (the total of MgO+CaO+SrO+BaO is 8 to 20), 18 to 32 ZnO, 1 to 5 Gd2O3, 0 to 1 ZrO2 and 0 to 2 Nb2O5.;COPYRIGHT: (C)2000,JPO