| 摘要 |
PURPOSE:To obtain the recording medium which is high in both of a modulation degree and reflectivity and is excellent in tracking property as well by providing specific relations between the depth of prepits and the film thickness of a recording layer and between the depth of pregrooves and the film thickness of the recording layer. CONSTITUTION:The following relation is provided between the depth of the prepits 8 and the film thickness of the recording layer 2: 0.15lambda<=nsdp- nd tp<=0.24l. The following relation is provided between the depth of the pregrooves and the film thickness of the recording layer 2: 0.02lambda<=nsdg- nd tg<=0.08lambda, where, ns is the refractive index of the substrate 1; nd is the refractive index of the recording layer 2; dp is the depth of the prepits; tp is the difference between the film thickness of the recording layer in the bottom of the prepits and the film thickness in the inter-prepit part; dg is the depth of the pregrooves; tg is the difference between the film thickness of the recording layer in the bottom of the pregrooves and the film thickness in the inter- pregroove part; lambda is the wavelength of a reproducing laser. |
