| 摘要 |
PROBLEM TO BE SOLVED: To provide a high refractive index-low to middle dispersion type optical glass composition that has a refractive index nd falling within a high refractive index range from 1.83 to 1.87 and an Abbe number νd falling within a range from 43 to 47. SOLUTION: The optical glass composition contains, by mole, 16.0-31.0% SiO<SB>2</SB>, 19.0-34.0% B<SB>2</SB>O<SB>3</SB>, 45.0-55.0% of SiO<SB>2</SB>+B<SB>2</SB>O<SB>3</SB>, 0-5.0% Li<SB>2</SB>O, 0-12.0% ZnO, 0-12.0% ZrO<SB>2</SB>, 15.0-26.0% La<SB>2</SB>O<SB>3</SB>, 2.0-5.0% Ta<SB>2</SB>O<SB>5</SB>, and 4.0-16.0% Gd<SB>2</SB>O<SB>3</SB>, and has nd of 1.83-1.87 and νd of 43-47. A preform and optical element are formed from the optical glass composition. COPYRIGHT: (C)2009,JPO&INPIT |
