| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical element having a small dimensional change due to an environmental change. <P>SOLUTION: In the optical element, a thermal coefficient of expansion at -20°C to 80°C in three-dimensional directions (X-, Y-, and Z-axis directions) is not more than 2.2×10<SP>-5</SP>/°C. The optical element comprises: a thermoplastic resin of not less than 20 vol.% and less than 50 vol.%; an inorganic filler of more than 50 vol.% and not more than 80 vol.%; and a composition containing a fiber filler of 0-25 vol.%. The optical element can also comprises a stainless alloy, a metal composition, or the like for die casting. The optical element can be suitably used as an optical pickup substrate 6 of an optical pickup device 10. <P>COPYRIGHT: (C)2008,JPO&INPIT |
