| 摘要 |
PROBLEM TO BE SOLVED: To realize an optical information recording and reproducing device capable of always satisfactorily maintaining a position relation between a detection beam and a photodetector parting line with high accuracy and improving a C/N. SOLUTION: In this optical information recording and reproducing device for converging light on a recording surface having an aperiodic groove shape with an optical pickup on a cross section advancing from an inner side to an outer side of a recording medium 106 and performing any of information recording, reproduction and erasure, the optical pickup is provided with a photodetector 108 having a light receiving surface for receiving reflected light from the recording surface while the light receiving surface is divided in a direction corresponding to the track direction of the recording medium, a parallel flat plate 109 disposed in an optical path between the recording medium and the photodetector in a freely turnable way, and a turn control mechanism 110 for adjusting the turn angle of the parallel flat plate according to a parallel flat plate turn control signal generated on the basis of a differential signal to each divided light receiving surface of the photodetector and an information signal obtained from the groove shape in the differential signal.
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