| 摘要 |
PURPOSE:To perform a high-density recording operation and a high-resolution reproduction by means of a laser beam utilizing the dependence on the wavelength of a supersaturated absorber. CONSTITUTION:In an optical head 1 for recording use, a beam of light from a laser light source 3W at a wavelength of lambda1 is narrowed to a recording layer 14 via a collimation lens 4W, a polarization beam splitter 5W, a prism 7W and a lens 8W. A beam of reflected light is guided to a detection optical system via the beam splitter 5W. A beam of light which has been polarized and separated into two light fluxes is detected by two photodetection faces at a detector 6W; track dislocations are obtained; an information signal is obtained from their sum. On the other hand, in a head 2 for replay use, a beam of light from a light source 3r at a wavelength of lambda2 is processed in the same detection optical system as in the head 1, and respective signals are obtained. A nickel phthalocyanine film is used for an supersaturated absorber layer 13, l1>=lambda2 is set and a high-density recording operation and a high-resolution replay operation which are two to three times those in conventional cases can be realized. |
