| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical pickup device, capable of controlling astigmatism caused by not only a laser light toward an optical disk, but also a light reflected on the optical disk having a polarization direction different from the laser light toward the optical disk, without need of power and a special system to correct the astigmatism. <P>SOLUTION: A phase plate 19, having a central portion and a phase modulation portion formed of different materials, is disposed between a collimator lens 8 and an objective lens 13, perpendicularly to the laser light. Among the laser light passing through the phase plate 19, it is configured to have mutually different optical path lengths between the laser light passing through and not passing through the phase modulation portion. Thus, an optical path length difference in between the tangential direction and the radial direction, which is produced when the laser light causing the astigmatism passes through a rising mirror 9, is canceled by the optical path length difference produced by the phase plate 19, so that the astigmatism is corrected. <P>COPYRIGHT: (C)2010,JPO&INPIT |
