| 摘要 |
PCT No. PCT/JP92/01412 Sec. 371 Date Jun. 16, 1993 Sec. 102(e) Date Jun. 16, 1993 PCT Filed Oct. 30, 1992 PCT Pub. No. WO93/09536 PCT Pub. Date May 13, 1993A method for measuring a deviation between the centerline between grooves defined on both sides of a recording track of an optical disc of a sample servo tracking system and a control prepit pattern formed on the disc is disclosed. If the modulation indices of the wobbled pits are measured under continuous tracking control of the center region or land, a difference is produced in the modulation indices when there is a deviation between the center of the wobbled pits and the center of the grooves. If, under tracking control of the grooves, the tracking offset is adjusted so that the modulation indices of the wobbled pits are equal to each other, the tracking error signal has an offset quantity (DC component). A light beam is swept under tracking control of the land between the grooves and the deviation between the center of the grooves and the control prepit pattern is measured. The light beam is swept so that the playback outputs from the wobbles pits are equal to each other and the deviation between the control prepit pattern and the center of the grooves is measured by a tracking error signal of the land between the grooves.
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