Patent ID: 7911889
Filing Date: 2011-03-22
Classification: G11B

Abstract:
1. An optical disc apparatus comprising: a laser diode; a first optical component which branches beams from the laser diode into a first beam and a second beam; an objective lens which focuses the first beam on a recording film surface of an optical information recording medium, and which detects the reflected beam; an actuator which drives the objective lens in an optical axis direction; a reference mirror provided in an optical path of the second beam; an optical path length varying means which varies an optical path length of the second beam by moving a position of the reference mirror; a first photo detector; a second photo detector; a second optical component which branches beams obtained by combining the first beam reflected by the optical information recording medium and the second beam reflected by the reference mirror, and which makes the branched beams incident on the first and second photo detectors; and a signal processing part which generates a read-out radio frequency signal from an output signal of the first photo detector and an output signal of the second photo detector.