| 摘要 |
PROBLEM TO BE SOLVED: To provide high-dispersion optical glass having a small partial dispersion ratio and optical elements such as a lens, a prism and the like obtained by using the optical glass. SOLUTION: The optical glass having an optical constant whose relational formula between an Abbe's number (ν<SB>d</SB>) and the partial dispersion ratio (θg, F) is denoted asθg, F≤-0.0058×νd+0.7539 in a range ofνd≤25 andθg, F≤-0.0020×νd+0.6589 in a range ofνd>25, containing, in mol% on an oxide basis, 29-50% B<SB>2</SB>O<SB>3</SB>and 20-70% TeO<SB>2</SB>and having a B<SB>2</SB>O<SB>3</SB>/TeO<SB>2</SB>value of larger than 0.4 and less than 0.75 and a total content of Y<SB>2</SB>O<SB>3</SB>, La<SB>2</SB>O<SB>3</SB>and Gd<SB>2</SB>O<SB>3</SB>of 0 to less than 5% is provided. COPYRIGHT: (C)2011,JPO&INPIT
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