| 摘要 |
PURPOSE:To attain extraction of a tracking and focusing control signal at recording and reading and also to eliminate the variance of a reflection characteristic by providing a film of a low reflection factor between a substrate and a film whose optical characteristics are changed by heat. CONSTITUTION:The semiconductor laser light is scanned relatively and at the same time irradiated from the side of a substrate 1 in a pattern accordant with the information signal. Then the laser light passes through the substrate 1 and films 2 and 3 and reaches a film 4. This film 4 has a high absorption factor and absorbs the light to convert it into the heat. This heat is transmitted to heat up the film 3. Thus the optical characteristics of the film 3 are varied and the reflection factor is increased when it is viewed from the side of the substrate 1. Then the information signal is recorded in the form of the variation of the reflection factor. When this information signal is read out, the laser light of a smaller output than that of a recording mode is irradiated in the same way as that of a recording mode. Then the variation of the reflected light is detected. |
