Patent ID: 8148280

Claim:
An optical glass comprising: SiO 2 , B 2 O 3 , La 2 O 3 , ZrO 2 , Nb 2 O 5 , Ta 2 O 5 , WO 3 , ZnO, and Li 2 O being substantially free of lead component, arsenic component and fluorine component, having a total amount of said oxides exceeding 96 mass %, wherein the optical glass contains SiO 2 from 6% to 10%, having a ratio of ZnO/SiO 2 of 3.303 or over, wherein the optical glass has a glass transition temperature (Tg) of 580° C. or below and having weathering resistance (surface method) of Class 1 or Class 2, and wherein the optical glass has optical constants of a refractive index (nd) within a range from 1.75 to 1.85 and an Abbe number (νd) within a range from 35 to 45.