| 摘要 |
PURPOSE: Optical glass is provided to reduce striae or devitrification, to enable formation of a preform material with a large diameter and to ensure refractive index(nd) and Abbe's number(vd) suitable for high refractivity and low dispersion. CONSTITUTION: Optical glass includes, based on whole glass mass of an oxide reduction composition, 5.0-35.0% B2O3 component, 15.0-50.0% La2O3 component, 10.0% or less of Rn2O component, 1.0-25.0% WO3 component. In the equation Rn2O, Rn is at least one kind selected from the group consisting of Li, Na, and K. A mass ratio Rn2O/WO3 of the oxide reduction composition is 3.00 or less. |
