Patent ID: 6140011
Filing Date: 2000-10-31
Classification: G11B,Y10S

Abstract:
A method of making an optical information recording medium, said method comprising the steps of:selecting a wavelength of light .lambda. for irradiation of said medium;providing a transparent substrate constituting an optical disk;forming a first dielectric layer on said transparent substrate;forming a recording layer on said first dielectric layer, said recording layer undergoing a reversible phase change between a crystalline state and an amorphous state when irradiated by a laser beam;forming a second dielectric layer of uniform thickness on said recording layer;forming a reflecting layer on said second dielectric layer, said reflecting layer comprising one of a transparent thin metal film and a transparent high-refractive-index material;selecting a dielectric material having a refractive index n for a third dielectric layer;selecting a thickness D for said third dielectric layer based on said wavelength of light .lambda. and said refractive index n of said dielectric material, wherein said thickness D is selected to satisfy .lambda./6n<D<.lambda./3n so as to control an absorbance Ac of said recording layer in said crystalline state to be always greater than an absorbance Aa of said recording layer in said amorphous state; andforming said third dielectric layer on said reflecting layer according to said selected thickness.