| 摘要 |
PURPOSE:To prevent disabled reproduction of all signals over one record length by recording and reproducing a time series signal as a position series signal while fixing the wavelength. CONSTITUTION:Suppose that a light spot radiated through an objective lens 14 is placed, e.g., at a point C of a header 19 of a radial position 22, since the medium 18 is turned in the direction of arrow R, the light spot is relatively scanned along the radial position 22 sequentially as point C point D point E point F. In this case, the wavelength of the light source is not scanned in the direction of the wavelength but fixed to the specific wavelength such as lambda1 or lambda2 to apply recording/reproduction. That is, even when a defect is caused to a storage element on a medium and reproduction is disabled, the defect is sufficiently recovered by the known error correction method.
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