| 摘要 |
PURPOSE: An optical glass is provided to prevent the milkiness and the devitrifaction of the inside of the glass during a reheating process from the manufacturing process. CONSTITUTION: An optical glass has the refractive index over 1.75, and the Abbe's number over 10. The optical glass contains 10~90wt% of Bi_2O_3. The milkiness and the devitrifaction of optical glass are prevented during a reheating process. The reheating process comprises a step of re-heating sample pieces to the temperature 80 deg C higher than the transition temperature of each sample for 150 minutes, and a step of maintaining the temperature for 30 minutes.
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