IMPROVEMENTS RELATING TO DATA STORAGE AND RECORDING

摘要

An optical data storage medium for use in an optical read/write system using an optical read wavelength of W, the medium including a textured region having raised areas and depressed areas disposed in a regular array with a period (pitch) not greater than W. The medium comprises a substrate; a layer or a plurality of zones of magneto-optic material; and a layer or a plurality of zones of an optically reflective material (which may or may not be the same as and/or constituted by the magneto-optic material). The magneto-optic material is disposed so as to be accessible to incident optical radiation. In one embodiment, the texture is shallow, being generally in the range 10 to 50 nanometers. In a second embodiment, the depth of the texture is at least one tenth of the value of W. The texture can take the form of a grating, or of crossed gratings, or be defined between an array of protuberances; structures with sinusoidal, square-wave (top-hat) or saw-tooth profile are advantageous.