| 摘要 |
PROBLEM TO BE SOLVED: To enable a high-density recording by forming recording marks, which are reduced in or removed of film thickness on a recording thin film which is changed in its film thickness by irradiation with a laser beam, specifying the difference in phases between the reflected light from an unrecorded region and the reflected light from a recording mark region to a specific range and specifying the reflectivity of the recording mark region and the reflectivity of the unrecorded region to specific values. SOLUTION: A protective layer 2 is formed on a substrate 1 and the recording this film 3 of, for example, Te or Te added with additives, such as C and Se, is formed thereon. A light interference layer 4 consisting of oxide of, for example, Al, Si, Ta, Zr, etc., is formed on the recording thin film 3. The range of the difference in the phases between the reflection from the unrecorded region and the reflected light from the recording mark region formed by the recording light with respect to the wavelength of the laser beam for reproducing the thickness of the light interference layer 4 is specified to (0.6 to 1.4)π+2nπ (n is an integer) and the reflectivity R1 of the recording mark region and the reflectivity R2 of the unrecorded region are specified to a relation R1>R2, by which the high-density recording and reproducing are made possible. |
