OPTICAL GLASS

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PURPOSE : Optical glass is provided to prevent the generation of an opacity phenomenon and a devitrifying phenomenon in the glass in case of the implementation of a re-heating test by adjusting the contents of boron oxide and bismuth oxide. CONSTITUTION : Optical glass includes 10 to 90 weight%% of bismuth oxide. The refractive index of the optical glass is 1.75 or more. The optical constant of the optical glass is more than or equal to 10 Abbe number. The generation of an opacity phenomenon and a devitrifying phenomenon is prevented in the glass in case of a re-heating test. The re-heating test includes the following : A test piece is re-heated. The temperature of the test piece is raised to 80 degrees Celsius higher the transition temperature of the test piece for 150 minutes. The test piece is maintained at 80 degrees higher temperature than the transition temperature of the glass for 30 minutes. The test piece is naturally cooled to the room temperature. Both opposing sides of the test piece are polished and observed. COPYRIGHT KIPO 2012