| 摘要 |
<P>PROBLEM TO BE SOLVED: To realize a transmittance required for a multilayer disc, without very much thinning the thickness of a recording material part and a metal part in a light-transmissive information recording layer. <P>SOLUTION: The light-transmissive information recording layer has a configuration which includes, sequentially from a laser light incident side, a first dielectric part with a refractive index of 2.4 or higher, with respect to the wavelength of the recording/reproducing laser light; a recording material part with a thickness of at least 5.2 nm; a second dielectric part; a metal part with a thickness of at least 7 nm; and a third dielectric part. A material with a refractive index of 2.4 or higher is also used for the third dielectric part. The third dielectric part is configured to have a refractive index in a refractive index range, where the transmittance of the light-transmissive information recording layer is decreased from the maximum transmittance by 1% or less, when the first dielectric part has a certain refractive index of 2.4 or higher. <P>COPYRIGHT: (C)2010,JPO&INPIT |
