| 摘要 |
PROBLEM TO BE SOLVED: To provide optical glass having a refractive index (n<SB>d</SB>) of≥1.78, Abbe's number (v<SB>d</SB>) of≤30 and a small partial dispersion ratio. SOLUTION: The optical glass has an optical constant wherein the partial dispersion ratio (θg,F) is in a range of≤0.624 and contains SiO<SB>2</SB>and Nb<SB>2</SB>O<SB>5</SB>as essential ingredients wherein the content of Nb<SB>2</SB>O<SB>5</SB>is more than 40% by mass. The optical glass contains, by mass, <2% K<SB>2</SB>O wherein the ratio of TiO<SB>2</SB>/(ZrO<SB>2</SB>+Nb<SB>2</SB>O<SB>5</SB>) is <0.32, and the total amount of SiO<SB>2</SB>, B<SB>2</SB>O<SB>3</SB>, TiO<SB>2</SB>, ZrO<SB>2</SB>, Nb<SB>2</SB>O<SB>5</SB>, WO<SB>3</SB>, ZnO, SrO, L<SB>2</SB>O and Na<SB>2</SB>O is more than 90%. COPYRIGHT: (C)2009,JPO&INPIT |
