ION-EXCHANGE TREATMENT OF OPTICAL GLASS

摘要

PURPOSE:To form practically linear refractive index distribution in the optical axis direction by bringing a glass body contg. a monovalent cation component into contact with a medium contg. a monovalent cation component under specified conditions to exchange the cations. CONSTITUTION:A vessel 3 contg. the medium contg. a monovalent cation component (e.g. TlNO3) is plated in an electric furnace 2 and heated to form the molten salt 4 of the monovalent cation, then the glass body 5 contg. a monovalent cation component is dipped and brought into contact with the molten salt 4 under the conditions shown by inequalities I-III (M2O is the sum total of the monovalent cation components contained in the glass body composition before ion exchange treatment, NTl is the Tl2O content of the M2O, and MTl is the Tl<+> content of MTOTAL as the sum total of the monovalent cations M<+> contained in the medium) to exchange the monovalent cations.