| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical pickup in which spherical aberration of an objective lens caused by thickness of a cover layer of an optical disk can be detected exactly though the pickup has simpler constitution. <P>SOLUTION: In an optical pickup 11, when a laser beam L1 emitted from a laser light source 12 is made incident on a polarization beam splitter 14, its one part is reflected by a polarization reflection plane 14a, after that, and transmitted through a 1/4 wavelength plate 15, an expander 16, and a first objective lens 17 in this order. And a laser beam L5 converged to an optical disk 18 is reflected by a reflection layer 18b of the optical disk 18, after that, the laser beam is converged on a light receiving element 21 constituting a photo-detector 20. In the optical pickup 11, the light receiving element 21 is divided into a plurality of light receiving regions of a concentric shape, while the pickup 11 is provided with a spherical aberration detecting circuit detecting spherical aberration based on output of these receiving regions. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
