Patent ID: 7320949

Claim:
An optical glass having a refractive index of (nd) of 1.88 or over and an Abbe number (ν d ) within a range from 22 to 28, comprising, in mass %, SiO 2 15-20% B 2 O 3 0-5% La 2 O 3 0-5% TiO 2 5-15% ZrO 2 0-10% Nb 2 O 5 more than 30% and less than 50% WO 3 0-5% CaO 0-10% BaO 0-10% Li 2 O 3-12% Na 2 O 0-10% K 2 O 0-10% Bi 2 O 3 0-15% Ta 2 O 5 0-7% and having a glass transition point (Tg) within a range from 500° C. to 580° C.