| 摘要 |
PROBLEM TO BE SOLVED: To improve the light resistance of a recording layer and to enable preservation over a long period of time by incorporating an org. coloring material into a transparent substrate so that the quantity of transmitted light in a wavelength region below the wavelength of used laser light is regulated to a specified value or below. SOLUTION: An org. polymer or glass may be used as the material of a substrate and polycarbonate resin is preferably used. An org. coloring material incorporated into the substrate is required to have heat resistance by which it is proof against a high temp. at the time of molding the substrate, compatibility with the resin and high light resistance and to also have no absorption in the wavelength region of laser light for recording and reproduction and an absorption region below the wavelength of laser light having high light energy. The org. coloring material is preferably based on anthraquinone. It is used by mixing with the resin so that the quantity of transmitted light in a wavelength region below the wavelength of laser light for recording and reproduction is regulated to <=25%. The deterioration of a recording layer due to light is prevented and the objective medium withstanding preservation over a long period of use is obtd. |
