| 摘要 |
PROBLEM TO BE SOLVED: To perform accurate tracking control by preventing the occurrence of offset caused by a variance in the optical efficiency of a light receiving elements for receiving reflected lights from two subspots. SOLUTION: Beams are divided into a main beam and two subbeams, and those among reflected lights received from a main spot formed on a target track by the irradiation of an optical disk with the main beam and two subspots formed to be in positions shifted from the main spot in a track direction and between target tracks are corrected so that signal values based on the reflected light amounts from the two subspots are at equal levels, and a tracking error signal is taken by taking a difference between the signal values. COPYRIGHT: (C)2005,JPO&NCIPI
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