| 摘要 |
PURPOSE:To produce a recording medium conveniently and at a low cost and to realize high S/N by using a cholesteric liq. crystal as a recording medium by equalizing the rotating direction of the circularly polarized light beam for reading with the spirally rotating direction of the cholesteric high molecular liq. crystal. CONSTITUTION:A light absorbing layer 2 and a cholesteric high molecular liq. crystal thin film 3 are successively formed on a substrate 1. Light is selectively reflected by the high molecular liq. crystal with the wavelength shown by lambda=np of the counterclockwise circularly polarized light as the center. When the pitch p is previously controlled to conform almost to lambda-np against the wavelength of the reading light source, extremely high reflectance is exhibited at a region wherein information is not written, meanwhile, the reflectance is rapidly decreased at the region wherein information is written in the mode to form a pit, and consequently high S/N can be realized. Besides, when the pitch p is previously controlled to lambda>>np against the wavelength of the reading light source and information is written in the light quantity region to increase the pitch length, extremely low reflectance is obtained in the unwritten part of information, high reflectance is obtained in the written part, and high S/N is similarly realized. |
