| 摘要 |
PURPOSE:To contrive higher recording and reproduction characteristics and higher productivity, by providing a thin film of or containing a specified cyanine coloring matter on a substrate, recording information directly by a laser beam, and reproducing the information through variations in reflected light. CONSTITUTION:A coloring matter used for a recording layer is desirably a coloring matter having high reflectance, a narrow temperature range for thermal change and a high solubility in solvents which does not attack a substrate. A thin film of a recording medium can be formed only of a cyanine coloring matter of formula I, but a stabilizer such as a UV absorber or a resin binder for preventing the formation of grain boundaries in the coloring matter thin film may be added, as required. In the formula, each of R1 and R2, which may be the same or different, is preferably a 1-10C alkyl or substd. alkyl, wherein the alkyl may be methyl, ethyl, propyl, isopropyl, butyl, pentyl or the like, and the substd. alkyl may be benzyl, phenetyl, methoxyethyl or the like. |
