| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical glass being optically homogeneous and high in quality, and not generating striae when used for manufacturing a preform for precise press molding. SOLUTION: This optical glass is a fluorine-containing glass, characterized in that, when the refractive index value of the glass is represented by nd(1) and a refractive index value, obtained by remelting the glass at 900°C for one hour in a nitrogen atmosphere, cooling down to the glass transition temperature, and then cooling to 25°C at the cooling rate of 30°C/h, is represented by nd(2), nd(1) and nd(2) are substantially the same. COPYRIGHT: (C)2007,JPO&INPIT
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