PROTECTION ANTI-COPIE D'UN DISQUE OPTIQUE NUMERIQUE PAR ADJONCTION D'UNE ZONE AYANT DES PROPRIETES OPTIQUES MODIFIABLES LORS DE LA LECTURE

摘要

The optical disc has a zone formed on part of its surface that is modified by the illumination from the laser beam during reading. To protect the disc the delivery of the disc material must be through a program that reads the modified zone at two instants in time. The first passage of the laser generates a change in the data which remains for a period of time extending to the second reading. The data will reset after some time. Single pass reading will see incorrect data.