| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical disk recording and reproducing device having a photo-detector which can detect highly accurately an LPP signal. <P>SOLUTION: A light shielding plate for shielding a reflected light from both ends of the vertical direction for a tangent of a groove of an optical disk is placed on a photo-detector of an optical disk recording and reproducing device. And by forming a light receiving spot shielding one part of the reflected light from both ends of the vertical direction for a tangent of the groove, difference of luminosity of left and right for a tangent of a groove in a light receiving spot in which a diffraction angle of the reflected light is varied by LPP is improved. <P>COPYRIGHT: (C)2004,JPO |
