Patent ID: 6636471
Filing Date: 2003-10-21
Classification: G11B

Abstract:
An optical pick-up comprising:a condenser lens to accept three laser beams reflected on an optical disk; a holographic device to accept the three laser beams via the condenser lens, a surface of the holographic device being divided into a first and a second hologram regions by a bisecting line oriented almost parallel to track formed on the optical disk, thus generating Â±1th-order diffracted light beam on the hologram regions; and a photodetector to accept the Â±1th-order diffracted light beams to detect signals recorded on the optical disk, the photodetector having a plurality of photo-detecting segments corresponding to the Â±1th-order diffracted light beams; the holographic device generating at least twelve Â±1th-order diffracted light beams on the first and the second hologram regions in response to the three laser beams the photodetector including twelve photo-detecting segments, each set of three photo-detecting segments aligned almost parallel to the track formed on the optical disk accepting the +1th-order or the âˆ’1th-order diffracted light beams generated o the first or the second hologram region.