| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a high NA objective lens which is used for a high recording density optical disk such as a blue ray disk, and easy to be handled when machined, measured, and coated, reduced in the deterioration of transmissivity although it is a plastic lens. <P>SOLUTION: This objective lens 10 is a single lens formed of plastic and the first surface 11 of the light source side and the second surface 12 of the optical disk 20 side are convex. The lens has an NA of 0.75 or larger and includes an inflection point where the secondary differentiation of a sag within an effective light flux diameter becomes zero. <P>COPYRIGHT: (C)2009,JPO&INPIT |
