Importance

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Abstract

When a laser beam from an optical pickup is incident on an optical disc, the optical disc comprises a protective layer, a first recording layer having a desired pattern, a coating layer by which one part of the laser beam is reflected with a predetermined reflectance and through which the other part is transmitted, a dielectric layer, a second recording having a desired pattern and formed under the dielectric layer, and a reflective layer by which the laser beam is totally reflected, according to that order from a top of the disc. The disc has the coating layer having the predetermined reflectance between the first and second recording layers, thereby the light amount of the laser beam reflected from the coating layer for reading information of the upper first recording layer becomes larger than the light amount of the laser beam transmitted through the coating layer for reading information of the lower second recording layer. Since the difference between the light amounts of the two recording layers generates the change of amplitude of RF signals detected at photodetector of the optical pickup device, it is possible to separately record and/or reproduce the respective recording layers of the optical disc.

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First Claim