| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical glass having a refractive index (n<SB POS="POST">d</SB>) of ≥1.78, an Abbe number (ν<SB POS="POST">d</SB>) of ≤30, and a small partial dispersion ratio. <P>SOLUTION: This optical glass has such an optical constant that the partial dispersion ratio (θg, F) is in the range of ≤0.624, and contains SiO<SB POS="POST">2</SB>and Nb<SB POS="POST">2</SB>O<SB POS="POST">5</SB>as indispensable components, wherein the ratio of mass% of Nb<SB POS="POST">2</SB>O<SB POS="POST">5</SB>is >40%. The optical glass contains <2% K<SB POS="POST">2</SB>O in terms of the ratio of mass%. wherein TiO<SB POS="POST">2</SB>/(ZrO<SB POS="POST">2</SB>+Nb<SB POS="POST">2</SB>O<SB POS="POST">5</SB>) is below 0.32, and the total content of SiO<SB POS="POST">2</SB>, B<SB POS="POST">2</SB>O<SB POS="POST">3</SB>, TiO<SB POS="POST">2</SB>, ZrO<SB POS="POST">2</SB>, Nb<SB POS="POST">2</SB>O<SB POS="POST">5</SB>, WO<SB POS="POST">3</SB>, ZnO, SrO, Li<SB POS="POST">2</SB>O and Na<SB POS="POST">2</SB>O is larger than 90%. <P>COPYRIGHT: (C)2013,JPO&INPIT |
