| 摘要 |
<P>PROBLEM TO BE SOLVED: To obtain a plastic objective lens having a good lens tilt characteristic even in both thickness of two layer disk within a use temperature range even in the plastic objective lens of NA 0.81 or more. <P>SOLUTION: In thickness of a transparent substrate having thickness being thicker than thickness of a transparent substrate of two layers at normal temperature (25±3°C), a point, where the third coma aberration quantity caused when lens tilt of the objective lens becomes equal to the third coma aberration quantity caused when the disk is tilted by the same angle quantity as the lens tilt angle, exists. <P>COPYRIGHT: (C)2009,JPO&INPIT |
