Patent ID: 6657946
Filing Date: 2003-12-02
Classification: G11B

Abstract:
A phase change optical disk with a multilayered structure obtained by sequentially forming at least a lower dielectric layer, recording layer, upper dielectric layer, and reflective layer on a substrate, whereina thickness of said lower dielectric layer is set to not less than &lgr;/(9n) and not more than &lgr;/(3n) and a thickness of said upper dielectric layer is set to not less than &lgr;/(5n) and not more than &lgr;/(2.5n) where n is a refractive index of said dielectric layer with respect to a wavelength &lgr; of not less and 380 nm to not more than 430 nm, and &Dgr;Rc/|Rcâˆ’Ra|<0.05 is satisfied where &Dgr;Rc is a change in reflectance Rc that takes place when a crystalline state of said recording layer changes depending on information recording/erasing condition,so that the reflectance Rc of said disk with respect to light with a wavelength of 380 nm to 430 nm, when said recording layer is in the crystalline state, is set lower than a reflectance Ra of said disk when said recording layer is in an amorphous state.