| 摘要 |
<P>PROBLEM TO BE SOLVED: To solve the problem resulting from stray light occurring in an optical disk device for reading a signal recorded in an optical disk including a plurality of signal recording layers. <P>SOLUTION: The optical disk device includes an objective lens 9 for focusing laser beams on a signal recording layer, a diffraction grating 2 for allowing laser beams to be made incident on to generate a main beam being 0-order light and sub-beams being +1-order light and -1-order light, and a photodetector 11 comprising a light receiving part for first and second sub-beams which is irradiated with a sub-beam reflected from the signal recording layer to generate a tracking error signal and is composed of a four-division sensor, and a light receiving part for a main beam which is irradiated with main beams reflected from the signal recording layer to generate a playback signal and a focus error signal and is composed of a four-division sensor, and eliminates the outside of a circle, centered on the center of the light receiving part for a main beam, of the light receiving part for sub-beams. <P>COPYRIGHT: (C)2012,JPO&INPIT |
