| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical glass having high refractive index and low dispersion and high in stability, and a preform and an optical element using the same.SOLUTION: An optical glass contains, by mass% based on oxide, SiOcomponent of 1.0 to 20.0%, BOcomponent of 10.0 to 40.0%, and LnOcomponent of 15.0 to 60.0%, where Ln is one or more kinds selected from a group consisting of La, Gd, Y and Yb, and BaO component of 5.0 to 55.0% and, by mass% of outer split to mass based on oxide, F component of 5.0% to 40.0%, and has refractive index (n) of 1.50 to 1.74 and Abbe number (ν) of 45 to 65.SELECTED DRAWING: Figure 1 |
