| 摘要 |
PROBLEM TO BE SOLVED: To obtain an optical glass having refractive index (n) and Abbe number (ν) in desired ranges, contributing light weight of optical equipment and high in devitrification resistance and a preform and an optical element using the same.SOLUTION: An optical glass contains, mol%, a BOcomponent of 10.0% to 50.0%, a LnOcomponent of 10.0% to 35.0%, where Ln is one or more kind selected from a group consisting of La, Gd, Y and Yb, and has molar sum (CaO+ZnO) of 1.0% to 35.0%, refractive index (nd) of 1.80 to 2.20, Abbe number (νd) of 25 to 38 and specific gravity of 5.50 or less.SELECTED DRAWING: Figure 1 |
