OPTICAL INFORMATION RECORDING MEDIUM AND ITS INFORMATION READING OUT METHOD

摘要

PURPOSE:To provide the optical information recording medium provided with information in a change of depth of ruggedness and refractive index and the method for reading out the information therefrom. CONSTITUTION:This optical information recording medium has a structure formed by laminating at least three layers; a recording later 23 recorded with the information, a thin-film layer 22 and a surface layer 21 consisting of a light transmissive material and having a high refractive index. The information is recorded on this recording layer 23 by the change of depth of the ruggedness or refractive index. Reading out of the information of this recording medium is executed by making light incident on the thin-film layer 22 from the surface layer 21 at an angle larger than the critical angle of the total reflection determined by a relation of the refractive index between the surface layer 21 and the thin-film layer 22 or the recording layer 23. The reflected light or transmitted light depending on the information recorded on the recording layer 23 is detected by a photodetecting means.