| 摘要 |
PROBLEM TO BE SOLVED: To provide optical glass which is excellent in chemical durability, and especially in surface-method weatherability, and suitable for precision molding press forming. SOLUTION: The optical glass has an index of refraction (n<SB>d</SB>) of 1.70 or more and under 1.74, and an optical constant having an Abbe's number (ν<SB>d</SB>) of over 40 and under 45, and contains SiO<SB>2</SB>of 17 mass% or less while the glass transition temperature (Tg) is 540°C or lower and the surface-method weatherability is Class 1 or 2. COPYRIGHT: (C)2006,JPO&NCIPI
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