Holographic memory apparatus and method for adjusting incident angle of reference beam

摘要

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.

主权项

1. 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.