Patent ID: 7351675

Claim:
An optical glass having a refractive index (nd) of at least 1.57 but less than 1.67 and an Abbe's number (νd) of over 55 but not more than 65, the optical glass containing by mol %, 25 to 50% of B 2 O 3 , 15 to 40% of SiO 2 , over 0% but not more than 5% of La 2 O 3 , over 0% but not more than 5% of Gd 2 O 3 , 2 to 20% of Li 2 O, 0 to 10% of Na 2 O, 0 to 5% of K 2 O, over 0% but not more than 15% of BaO, and an alkaline earth metal oxide as essential components, and 1 to 12% by mol of SrO, having a B 2 O 3 and SiO 2 total content of 52% by weight or more, having an SiO 2 /B 2 O 3 content ratio of from 0.38 to 1.1 and a total content MgO, CaO, BaO and SrO as alkaline earth metal oxides is 12 to 25 mol %.