Patent ID: 6434107
Filing Date: 2002-08-13
Classification: G11B,Y10T

Abstract:
Optical disc, comprising:first and second elementary discs adhesively bonded to each other, each of the elementary discs containing at least one transparent substrate and an information face provided with surface micro-alterations distributed over a spiral track or concentric tracks, wherein the information face of the first elementary disc is coated with a semi-reflecting layer adjacent to a transparent assembling adhesive layer, the information face of the second elementary disc is coated with a reflecting metallic layer and is situated opposite the transparent assembling adhesive layer, and the semi-reflecting layer has a coefficient of transmission greater than or equal to 95% for a wavelength of a laser greater than or equal to a first threshold and a coefficient of reflection greater than or equal to 25% for a wavelength of a second laser less than or equal to a second threshold, the first threshold being greater than the second threshold by at least 100 nm.