The present invention provides an optical disc provided with a watermark inside, which is visible with naked eyes from a reproduction side of the optical disc, and the producing method and the production apparatus thereof. The optical disc comprises a transparent substrate having an information...http://www.google.fr/patents/US6168207?utm_source=gb-gplus-shareBrevet US6168207 - Optical discs, producing methods and production apparatus of the optical discs
Optical discs, producing methods and production apparatus of the optical ...
