| 摘要 |
<P>PROBLEM TO BE SOLVED: To effectively eliminate a stray light by a simple configuration, and also to suppress a DC component generated in a tracking error signal. <P>SOLUTION: Laser beams reflected by a disk are converged to first and second directions to introduce an astigmatism. Light advancing directions of four luminous flux areas A to D which are divided by two straight lines parallel to the first and second directions are converted respectively to directions Da to Dd. Thus, signal light areas containing only the signal light are formed on a photodetector. By preparing sensor patterns on these areas, influence of the stray light is suppressed. A correction magnification for suppressing the DC component of the tracking error signal is obtained by a light quantity balance of areas B and C when a test disk without track is irradiated with the laser beams and a light quantity balance of left/right of the respective areas A and D. By this correction magnification, the tracking error signal is corrected. <P>COPYRIGHT: (C)2011,JPO&INPIT |
