| 摘要 |
PROBLEM TO BE SOLVED: To improve reliability of measuring results as to the property of a groove traverse signal. SOLUTION: By oscillating an optical pickup to a sine wave state in a radial direction to change tracking bias, control is made so that a relative locus such as shown with a dotted line T1 is plotted on an optical disk by the optical pickup. The coarse/fine distributions of the groove traverse under the relative locus T1 are shown in the figure. The distribution patterns of these coarse/fine distributions are almost reversed from the coarse/fine distributions of the groove traverse under the relative locus before the tracking bias is changed, which is shown by a dotted line T0. Then, a pseudo signal waveform having the almost uniform coarse/fine distribution of the groove traverse during one round is produced by combining the groove traverse signals obtained before and after changing the tracking bias. By carrying out calculation based on this pseudo signal waveform, measuring result as to the property of a groove traverse signal is obtained. The reproducibility or the like of the measurement are prevented from deteriorating due to the variance of the coarse/fine distributions of the groove traverse in the round.
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