Optical pick-up
AssigneeVictor Company of Japan, Ltd.
InventorsMakoto Itonaga, Yuichi Hasegawa
Life of this patent
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Abstract
An optical pick-up emits three laser beams onto an optical disk. The three laser beams are reflected on the optical disk and incident to a condenser lens. The three laser beams are further incident to a holographic device via the condenser lens. The surface of the holographic device is divided into a first and a second hologram region by a bisecting line oriented almost parallel to the track formed on the optical disk. The holographic device generates ±1th-order diffracted light beams on the hologram regions. The ±1th-order diffracted light beams are incident to a photodetector having a plurality of photo-detecting segments corresponding to the ±1th-order diffracted light beams. The photodetector detects signals recorded on the optical disk based on the ±1th-order diffracted light beams.
Claims9
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 ±1th-order diffracted light beam on the hologram regions;
- and
- a photodetector to accept the ±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 ±1th-order diffracted light beams;
- the holographic device generating at least twelve ±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 −1th-order diffracted light beams generated o the first or the second hologram region.
Dependencies are inferred from the claim text.