Patent ID: 6809996
Filing Date: 2004-10-26
Classification: G11B

Abstract:
An optical head for optical recording/reproducing apparatus comprising:two light sources for generating two laser beams having different wavelengths; a diffraction device for guiding a reflected light beam from an optical recording medium to one of two detectors individually arranged and having a corresponding wavelength, wherein said optical head uses an output obtained from said one of the two detectors to perform focus error detection and tracking error detection in the optical recording medium, reflected light beams of laser beams from said two light sources from the optical recording medium are simultaneously detected via split photo-detection devices, and when one of the two beams is focused on the optical recording medium for recording or reproducing, a spot diameter of the other non-focused beam on the optical recording medium is set larger than a spot diameter of said one of the two light beams, and the other non-focused beam is used for at least one of focus error detection and tracking error detection, wherein the spot diameter of the non-focused light beam on an optical recording medium is set to 2.5 to 15 times as large as the spot diameter of said focused light beam on the optical recording medium.