| 摘要 |
PURPOSE:To eliminate the variation of an initial value by detecting the spatial nonuniformity of a phase with respect to a recording medium where information is recorded with the aid of utilizing an optical multiple interference effect and changing the refractive index of the medium based on the detected value so that initialization may be performed. CONSTITUTION:Multi-valued information is recorded by heating the medium 1 with the aid of light from a semiconductor laser for recording 2 and changing the refractive index (nM) thereof. The change of the refractive index is recorded by making it correspond to the change of the phase difference of etalon. On the other hand, the reproduction thereof is detected as the change of wavelength corresponding to the changing amount of the phase difference thereof. Then, the change of the refractive index (DELTAnM) which cancels the irregularity of thickness (DELTAd) is given by heating with the aid of a recording laser and the medium is initialized. Thus, the recording medium is initialized by detecting the spatial nonuniformity of the product of the refractive index and the thickness of the recording layer of the recording medium having the optical multiple interference effect and giving the change of the refractive index based on the detected result. Thus, the nonuniformity of the phase occurring caused by the various kinds of conditions when the recording medium is manufactured, secular change, erasing or the like is dissolved and the variation of the initial value is eliminated. |
