| 摘要 |
PROBLEM TO BE SOLVED: To provide a tracking error signal detector capable of suppressing the deterioration of precision in the detection of a tracking error signal caused by high density and high linear velocity. SOLUTION: The center of a reproduction information track is irradiated with a main beam 302, and a position deviated outward from the center of the reproduction information track by a fixed quantity is irradiated with two sub-beams 303 and 304. The reflected light of the two sub-beams are photodetected by a quadrant photodetector 305 to detect tracking error signals by a DPD signal respectively, and the sum signal of them is detected as the tracking error signal of the main beam.
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