Patent ID: 6891875

Claim:
An optical device for processing optical signals coming to and from an optical disc, comprising: a laser beam source to output a laser beam, where the output level of the laser beam is controlled by a driving current; a beam splitter to divide the laser beam into first and second laser beams, where the first laser beam is directed to the optical disc; a reproducing signal beam receiver to receive an optical signal from the optical disc, said reproducing signal beam receiver operating to generate a reproducing signal; a beam-source monitoring beam receiver to receive the second laser beam, said beam-source monitoring beam receiver operating to monitor the characteristics of the second laser beam, where said beam-source monitoring beam receiver generates a monitoring signal; a noise cancellation apparatus configured to receive said monitoring signal and said reproducing signal, where said monitoring signal is used to substantially reduce noise contained in said reproducing signal; and a laser beam source current driver to provide said driving current for said laser beam source, where the amount of current generated in said monitoring signal is operatively adjusted so that laser beam source noise in said monitoring signal caused by said laser beam source is greater than circuit-related noise caused by circuits in the optical device.