Patent ID: 6438075
Filing Date: 2002-08-20
Classification: G11B

Abstract:
A light pick-up device comprising:a laser light source for emitting a laser light beam; an objected lens for converging the laser light beam on an optical recording medium; a first diffractor for separating the light beam emitted form the laser light source and a light beam reflected by the optical recording medium into different optical paths, the first diffractor having a diffraction grating pattern for dividing the reflected light beam in a direction perpendicular to a track direction of the optical recording medium such that an optical axis of the reflected light beam becomes the center of division in order to generate a first divided light beam and a second divided light beam; a photo detector for detecting illuminances of the first and the second divided light beams; a second diffractor for dividing the laser light emitted from the laser light source into a main beam, which is to be reflected by the optical recording medium as the reflected beam, and two subsidiary as tracking beams; and a signal processor for generating a reproduction signal and a deviation detecting signal which detects a deviation amount of the objective lens from the optical axis, in accordance with the detection of the photo detector.