| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical glass with which it is possible to further inexpensively obtain a preform material having high devitrification resistance and which has a refractive index (n<SB POS="POST">d</SB>) and an Abbe number (ν<SB POS="POST">d</SB>) within a desired range; a preform material; and an optical element. <P>SOLUTION: The optical glass contains 10.0-50.0 mol% of a B<SB POS="POST">2</SB>O<SB POS="POST">3</SB>component and 5.0-30.0 mol% of an La<SB POS="POST">2</SB>O<SB POS="POST">3</SB>component relative to the total amount of the glass composition in terms of oxides, wherein the sum of (TiO<SB POS="POST">2</SB>+WO<SB POS="POST">3</SB>+Nb<SB POS="POST">2</SB>O<SB POS="POST">5</SB>) is 0.1-30.0 mol% relative to the total amount of the glass composition in terms of oxides. <P>COPYRIGHT: (C)2013,JPO&INPIT |
