Patent ID: 6846762

Claim:
An optical glass comprising, in mass %, SiO 2 40-60% B 2 O 3 1 to less than 5% Al 2 O 3 0-3% TiO 2 15.5-19% ZrO 2 0-1% WO 3 0-5% ZnO 0-5% CaO 0-4% SrO 0-10% BaO 10.5-20% Na 2 O + K 2 O 11-20% in which Na 2 O 0-9% and K 2 O 6-20% a refining agent 0-1% and having optical constants of a refractive index (nd) within a range from 1.55 to less than 1.67 and an Abbe number (νd) within a range from 30 to 45.