Patent ID: 7368404

Claim:
An optical glass having a refractive index (nd) and Abbe number (νd) within a range enclosed with a border line consisting of straight lines connecting point A (nd being 1.75 and νd being 50.0), point B (nd being 1.80 and νd being 46.0), point C (nd being 1.80 and νd being 50.0) and point D (nd being 1.75 and νd being 56.0) in the order of the point A, the point B, the point C, the point D and the point A in x-y rectangular coordinates in which x coordinate represents Abbe number (νd) and y coordinate represents refractive index (nd), including refractive index (nd) and Abbe number (νd) on the border line except for the straight line connecting the point A with the point D and the straight line connecting the point B with the point C, comprising, as essential components, SiO 2 , B 2 O 3 , La 2 O 3 , Gd 2 O 3 , Li 2 O and F, and being substantially free of As 2 O 3 , the total amount of SiO 2 , B 2 O 3 , La 2 O 3 , Gd 2 O 3 , Li 2 O, ZrO 2 , Yb 2 O 3 , and ZnO is 94mass % or over and comprising not more than 2% of Y 2 O 3 .