Patent ID: 7760615
Filing Date: 2010-07-20
Classification: G11B

Abstract:
1. A rewritable phase-change optical recording medium, comprising: a substrate; a first information layer that is provided on a laser beam incident side of the substrate; and at least one semi-transparent information layer that is provided on the laser beam incident side of the substrate and is located farther away from the substrate than is the first information layer; wherein the semi-transparent information layer includes a recording film that exhibits a phase change between crystalline and amorphous states to provide rewritability, by using an optical system with λ/NA≦500 nm, where NA is a numerical aperture of an objective lens and λ is a wavelength of a laser beam, and wherein the recording film has an amorphous mark formed therein, the amorphous mark after repeated reproduction including a pair of narrow strip-shaped marks and a widthwise intermediate portion formed between the pair of narrow strip-shaped marks, the pair of narrow strip-shaped marks extending parallel to a scanning direction of the laser beam, the widthwise intermediate portion being crystallized and being located in a central portion in a width direction of the amorphous mark, the width direction being orthogonal to the scanning direction of the laser beam.