| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical glass composition that has a refractive index nd falling within a high refractive index range from 1.88 to 1.92 and an Abbe number νd falling within a range from 33 to 37. SOLUTION: The optical glass composition contains, by weight, 1.0-12.0% SiO<SB>2</SB>, 8.5-18.0% B<SB>2</SB>O<SB>3</SB>, 0-6.0% ZnO, 1.0-10.0% of ZrO<SB>2</SB>, 25.0-47.0% La<SB>2</SB>O<SB>3</SB>, 0-5.0% R<SB>2</SB>O (where R is at least one of Li, Na and K), 0-16.0% Nb<SB>2</SB>O<SB>5</SB>, 0-7.0% TiO<SB>2</SB>, 0-15.0% Ta<SB>2</SB>O<SB>5</SB>, 1.0% or more of Nb<SB>2</SB>O<SB>5</SB>+TiO<SB>2</SB>+Ta<SB>2</SB>O<SB>5</SB>, 0-26.0% Gd<SB>2</SB>O<SB>3</SB>, and 0-13.0% WO<SB>3</SB>, and contains substantially no R'O (where R' is at least one of Ba, Sr, Ca and Mg) and has nd of 1.88-1.92 and νd of 33-37. A preform and an optical element are formed from the optical glass composition. COPYRIGHT: (C)2009,JPO&INPIT
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