| 摘要 |
PURPOSE:To reproduce information recorded in a high density by maintaining a high S/N ratio by reproducing change of reflectivity due to an uneven surface formed on an optical disk medium board as an electric signal. CONSTITUTION:A reproduced layer 2 made of a shape memory resin containing a dye is formed on a board 1 in which an uneven surface is formed corresponding to information to be recorded, a reflecting film 3 is formed thereon, and a resin protective layer 4 is further formed thereon, thereby forming a reproducing-only optical disk. The depth of the unevenness on the board 1 is set to (nXlambda/4 (n:odd number)) to a wavelength lambda of a laser light to be used for reproduction. This optical disk has reflectivity of the layer 2 of a part becoming a high temperature when the light is casted, of which reflectivity is the same either of a recess part and a protruding part of the uneven surface formed corresponding to the information to be recorded. Since the reflectivitiees of the recess part and the protruding part of the uneven surface of a part not becoming a high tempeerature without irradiated with the light are different from each other, the difference is converted into an electric signal, thereby reproducing the information. |
