Optical glass, precision press molding preform and manufacturing method of the same, optical element and manufacturing method of the same

摘要

The optical glass has a refractive index of equal to or greater than 1.65 and an Abbé number ranging from 50 to 60. In the optical glass, as molar basis, a ratio of SiO2 content to B2O3 content is greater than 0.5 and equal to or less than 0.90; a total content of SiO2 and B2O3 ranges from 50 to 70 percent; Li2O content ranges from 5 to 20 percent; La2O3 content ranges from 0.5 to 22 percent; a ratio of ZnO content to RO (MgO, CaO, SrO and BaO) is equal to or greater than 0.5; a total content of Gd2O3, Y2O3 and Yb2O3 ranges from 1 to 15 percent; Sb2O3 content ranges from 0 to 1 percent; and no BaO is comprised, or a ratio of the total content of La2O3, Gd2O3, Y2O3 and Yb2O3 to the content of BaO is equal to or greater than 10.