| 摘要 |
PROBLEM TO BE SOLVED: To adjust the reproduction power for an optimum value to improve the reliability during reproduction of data. SOLUTION: The optical magnetic disc device 30 comprises edge detectors 32a, 32b for detecting edge parts of the record marks in reproduction signals obtained by reproduction in the domain wall displacement detection(DWDD) reproduction system and the usual reproduction system using beam spots different in reproduction power irradiated on an optical magnetic disc 40 having recorded record marks longer than a cutoff frequency determined by a natural wavelength and a numerical aperture of a reproduction laser beam in a reproduction optical system, a phase difference detector 34 for detecting the phase difference between two edge detection signals outputted from the edge detectors 32a, 32b, and a power controller 36 for controlling the reproduction power, based on a phase difference signal outputted from the phase difference detector 34.
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