| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical glass having a refractive index (nd) of 1.57-1.67 and an Abbe's number (νd) of 55-65 and having a low-temperature softening property and excellent weather resistance. SOLUTION: The optical glass has a refractive index (nd) of 1.57-1.67, an Abbe's number (νd) of 55-65, and a glass transition temperature (Tg) of 560°C or lower and has weather resistance having a haze value of 3% or less, or the optical glass comprises, by mol%, 22-40% of B<SB>2</SB>O<SB>3</SB>, 12-40% of SiO<SB>2</SB>, 2-20% of Li<SB>2</SB>O, 5-15% of CaO, 2-14% of ZnO, 0.5-4% of La<SB>2</SB>O<SB>3</SB>, 0-3% of Gd<SB>2</SB>O<SB>3</SB>, 0-3% of Y<SB>2</SB>O<SB>3</SB>(the total content of La<SB>2</SB>O<SB>3</SB>, Gd<SB>2</SB>O<SB>3</SB>and Y<SB>2</SB>O<SB>3</SB>being at least 1%), 0-5% of Al<SB>2</SB>O<SB>3</SB>, 0-3% of ZrO<SB>2</SB>and 0-5% of BaO, the total content of the above components being more than 96%, and has a refractive index (nd) of 1.57-1.67 and an Abbe's number (νd) of 55-65. COPYRIGHT: (C)2007,JPO&INPIT
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