| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide optical glass useful for correcting chromatic aberration of an optical element, and hardly generating a flaw or a crack when being polished, conveyed or the like, and to provide a preform using the optical glass. <P>SOLUTION: This optical glass contains Bi<SB POS="POST">2</SB>O<SB POS="POST">3</SB>component, SiO<SB POS="POST">2</SB>component and/or B<SB POS="POST">2</SB>O<SB POS="POST">3</SB>component, and F component in terms of an oxide conversion composition, and has Knoop hardness (Hk) of ≥250 in a measuring method pursuant to 'JOGIS09-1975 Measuring method of Knoop hardness of optical glass', wherein the partial dispersion ratio [θg, F] is ≥0.63, and the Abbe number [νd] is ≤27, and an inequality: partial dispersion ratio [θg, F]>-0.0131×[νd]+0.9000 is satisfied. <P>COPYRIGHT: (C)2012,JPO&INPIT |
