Patent ID: 6700855
Filing Date: 2004-03-02
Classification: G11B

Abstract:
An optical disc drive comprising:means for rotating an optical disc; a light source to emit a light used for write and/or read of signals to and/or the optical disc; a head having installed therein an objective lens which converges the light emitted from the light source and being scanned over the optical disc being rotated by the rotating means to radiate the light converged by the objective lens to the optical disc; means for receiving a return light being a part of the light radiated from the head to the optical disc and which is reflected from the optical disc and detecting signals from the return light; and means for transmitting the light emitted from the light source to the head and the return light from the optical disc to the signal detecting means; the light transmitting means including a polarization maintaining optical fiber and phase difference generating means to cancel out a phase difference between electric field vibration components generated when the light going towards the head or the return light going towards the signal detecting means is guided through the polarization maintaining optical fiber by the phase difference generated by the phase difference generating means or multiply the phase difference by an integer multiple of &pgr;.