| 摘要 |
PROBLEM TO BE SOLVED: To detect a tilt of an image forming lens with respect to a recording medium and to adjust the tilt of the image forming lens in parallel to the recording medium without providing a special detection means in an optical information storage performing servo control according to a reflection beam from the recording medium. SOLUTION: A tracking error signal is detected according to the reflection beam from a magneto-optical disk 2, and fluctuation in the tracking error signal due to interference fringes caused by the interference between the 0-order beam and±1st-order beams in the reflection beam is detected, and a tilt angle of an objective lens 16 is controlled by controlling a drive signal to a focus coil moving the objective lens 16 according to the detection result and performing focus control, and the objective lens 16 is held parallel to the magneto-optical disk 2.
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