Patent ID: 6421315
Filing Date: 2002-07-16
Classification: G11B

Abstract:
A multi-layered optical disk to be used by a disk reproduction system which shines a reproduction light beam of a predetermined wavelength onto one side of the disk and reproduces information by interaction of the light beam with a plurality of recording layers on the disk, the disk comprising:a first and second disk substrate which have effectively the same thickness and which are arranged so as to face each other with a space between the substrates; a first recording layer provided on a side of the first disk substrate which faces the second disk substrate, through which the reproduction light passes and irradiates a second disk substrate; a first identification section storing an address of tracks, which are aligned on the first recording layer; a second recording layer, which responds to the same reproduction light wavelength as the first recording layer, provided on a side of the second disk substrate, which faces the first disk substrate; a second identification section storing an address of tracks, which are aligned on the second recording layer; and a spacer, filling the space between the substrates and formed of a material, which is transparent for the reproduction light wavelength, the spacer adheres to the first and second recording layer so as to maintain a fixed distance between the recording layers and the reproduction light passes through the first recording layer and then reaches the second recording layer wherein the spacer is an adhesive material between the first and second disk substrates having a thickness range of 10 to 100 &mgr;m.