| 摘要 |
PURPOSE:To obtain an optical which have small values of double refraction and has an extremely small dispersion within and between cards, by using a polycarbonate film obtd. by soln. cast molding to form a protective layer of an optical recording medium to the constitution in which information is recorded and reproduced optically from the protective layer side. CONSTITUTION:The optical card is formed on an optical recording layer 1, a base 2 such as PE film, a vinyl chloride substrate 3, and the protective layer 4 consisting of the polycarbonate film obtd. by soln. cast molding. Recording of information to such optical card is executed by projecting a laser beam from the protective layer 4 side and condensing the beam to the optical recording layer 1, thereby melting the layer 1 consisting of gelatin and silver particles and forming pits. Reading out of the information is also executed from the protective layer 4 side. |
