| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical glass in which the devitrification resistance is high though a refractive index (n<SB POS="POST">d</SB>) and Abbe number (ν<SB POS="POST">d</SB>) are within a desired range and the use of a costly material is reduced, and to provide a preform material and an optical element that use the same. <P>SOLUTION: The optical glass includes: by mass%, 5.0-30.0% of a B<SB POS="POST">2</SB>O<SB POS="POST">3</SB>component; and 15.0-50.0% of an La<SB POS="POST">2</SB>O<SB POS="POST">3</SB>component based on the glass total mass of an oxide conversion composition, wherein the mass ratio of the oxide conversion composition La<SB POS="POST">2</SB>O<SB POS="POST">3</SB>/(La<SB POS="POST">2</SB>O<SB POS="POST">3</SB>+Gd<SB POS="POST">2</SB>O<SB POS="POST">3</SB>) is at most 0.690. In addition, the preform material and the optical element comprise the optical glass. <P>COPYRIGHT: (C)2012,JPO&INPIT |
