Patent ID: 7670978

Claim:
Optical glass having a refractive index (nd) of equal to or greater than 1.65 and an Abbé number (νd) ranging from 50 to 60, wherein, as molar basis, a ratio of SiO 2 content to B 2 O 3 content (SiO 2 /B 2 O 3 ) is greater than 0.5 and less than 0.8; a total content of SiO 2 and B 2 O 3 ranges from 50 to 70 percent; Li 2 O content ranges from 5 to 20 percent; La 2 O 3 content ranges from 0.5 to 22 percent; a ratio of ZnO content to RO that is the total content of MgO, CaO, SrO and BaO (ZnO/RO) is equal to or greater than 0.5; a total content of Gd 2 O 3 , Y 2 O 3 and Yb 2 O 3 ranges from 1 to 15 percent; Sb 2 O 3 content ranges from 0 to 1 percent; and no BaO is comprised, or a ratio of the total content of La 2 O 3 , Gd 2 O 3 , Y 2 O 3 and Yb 2 O 3 to the content of BaO ((La 2 O 3 +Gd 2 O 3 +Y 2 O 3 +Yb 2 O 3 )/BaO) is equal to or greater than 10.