| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide optical glass in which chromatic aberration of a lens can be corrected in higher precision though its Abbe's number (ν<SB>d</SB>) lies in a desired range, and also which has high thermal stability, and a preform and an optical element using the same. <P>SOLUTION: The optical glass comprises, to the whole mass of the glass with a composition expressed in terms of oxide, by mass%, an Nb<SB>2</SB>O<SB>5</SB>component in <75.0% and a P<SB>2</SB>O<SB>5</SB>component in <40.0%, and has a partial dispersion ratio [θg, F] of 0.62 to 0.69 and has an Abbe's number (ν<SB>d</SB>) of 15 to 27, and in which a differenceΔT between a glass transition point (Tg) and a crystallization starting temperature (Tx) is≥90°C. The preform and the optical element are composed of the optical glass. <P>COPYRIGHT: (C)2011,JPO&INPIT</p> |
