Holographic memory apparatus and method for adjusting incident angle of reference beam
AssigneesHitachi-LG Data Storage, Inc., Hitachi Consumer Electronics Co., Ltd.
InventorKenichi Shimada
Life of this patent
Estimating the term…
Abstract
A holographic memory apparatus includes an optical detector which receives reflected light of reference beam from the surface of a hologram recording medium. An incident angle of the reference beam is estimated on the basis of information on a focused position on the optical detector. When the incident angle is different from a target incident angle, the incident angle of the reference beam is adjusted according to a difference between the incident angle and the target incident angle.
Claims8
A holographic memory apparatus which causes interference between a reference beam and signal beam, records an obtained interference pattern in a hologram recording medium as page data by angularly multiplexed recording, and reproduces the recorded page data, the apparatus comprising:
- an optical detector which receives reflected light of the reference beam from the surface of the hologram recording medium;
- an angle changing unit which changes an incident angle of the reference beam with respect to the hologram recording medium;
- a detection circuit which detects a focused position of the reflected light on the optical detector;
- an incident angle calculation circuit which estimates an incident angle of the reference beam with respect to the hologram recording medium on the basis of information on the focused position;
- an angle shift generation circuit which generates a difference between the incident angle of the reference beam and a target value thereof;
- and
- a control circuit which controls the angle changing unit according to the angle shift.
A method of adjusting an incident angle of a reference beam with respect to a hologram recording medium in a holographic memory apparatus which causes interference between the reference beam and signal beam, records an obtained interference pattern in the hologram recording medium as page data by angularly multiplexed recording, and reproduces the recorded page data,
- wherein the holographic memory apparatus comprises:
- an optical detector which receives reflected light of the reference beam from the surface of the hologram recording medium;
- an angle changing unit which changes an incident angle of the reference beam with respect to the hologram recording medium;
- a detection circuit which detects a focused position of the reflected light on the optical detector;
- an incident angle calculation circuit which estimates an incident angle of the reference beam with respect to the hologram recording medium on the basis of information on the focused position;
- an angle shift generation circuit which generates a difference between an incident angle of the reference beam and a target value thereof;
- and
- a control circuit which controls the angle changing unit according to the angle shift,
- and wherein the incident angle of the reference beam is estimated on the basis of the information on the focused position of the reflected light, and then the incident angle of the reference beam is adjusted by the angle changing unit according to a difference between the incident angle and the target value thereof when the incident angle is different from the target value.
Dependencies are inferred from the claim text.