| 摘要 |
PURPOSE:To obtain the recording medium having a large recording density by providing a thin-film material layer which is changed in optical constant by irradiation of laser light on a substrate and detecting the change in the quantity of reflected or transmitted light. CONSTITUTION:An optical layer 2 consisting of transparent dielectrics, etc. and a recording thin layer 3, is provided on a substrate 1 and further, a transparent dielectric layer 4 and a reflecting layer 5 are provided thereon. A material which is different in refractive index from the substrate 1 is used for the transparent layer 2. The medium having a large phase change is obtd. by adequately selecting the thickness t2 of the thin recording film layer 3, the thicknesses t1, t2 of the transparent optical layers 2, 4 and the thickness t4 of the reflecting layer 5. This medium is not changed in reflectivity and is changed only in the phase of the reflected light so that the recording optically equiv. to the phase change recording by ruggedness is executed. The recording of the large recording density is possible in this way in spite of the phase change recording and the erasing and rewriting are possible as well. |
