OPTICAL GLASS AND PROCESS FOR PRODUCING THE SAME

摘要

An optical glass which has a refractive index (nd) of 1.7 or higher and an Abbe's number (?d) of 40 or larger and contains at least 30% Ln<SUB>2</SUB>O<SUB>3</SUB> ingredient (Ln is one or more elements selected among Y, La, and Gd) in terms of oxide amount in mass% and in which the content of As<SUB>2</SUB>O<SUB>3</SUB> and Sb<SUB>2</SUB>O<SUB>3</SUB> ingredients is less than 0.1%. The proportion of the Gd<SUB>2</SUB>O<SUB>3</SUB> content to the total content of the Ln<SUB>2</SUB>O<SUB>3</SUB> ingredient (Gd<SUB>2</SUB>O<SUB>3</SUB>/Ln<SUB>2</SUB>O<SUB>3</SUB>) is preferably 20% or lower. The glass preferably contains a B<SUB>2</SUB>O<SUB>3</SUB> ingredient as an essential component and has a liquidus temperature of 1,100°C or lower.