Patent ID: 7515521
Filing Date: 2009-04-07
Classification: G11B

Abstract:
1. A hologram recording and reproducing apparatus in which coherent light emitted by a light source is split into a recording beam and a reference beam, both beams being superposed on each other for recording a hologram on a hologram recording medium, the hologram recording medium being irradiated with the reference beam for reproducing recorded information, the irradiation being corrected under a servo control, while a reflected beam from the hologram recording medium is detected with an optical detector for conversion of a reproduction signal, the apparatus comprising: an optical detector for servo control provided apart from the optical sensor for conversion of a reproduction signal; a pixel pattern generator that generates a recording pixel pattern and a servo pixel pattern on a wave surface of the recording beam when recording the hologram on the hologram recording medium, the recording pixel pattern being discretely distributed and corresponding to information to be recorded, the servo pixel pattern having a predetermined configuration and position for servo control; a reflected beam splitter that splits the reflected beam from the hologram recording medium into a reproduction beam and a servo beam, the reproduction beam directed to the optical detector for reproduction signal conversion to reproduce the recording pixel pattern, the servo beam being directed to the optical detector for servo control to reproduce the servo pixel pattern; and a servo controller that controls a tilting status of the reference beam with respect to the hologram recording medium, the control being based on an output signal from the optical detector for servo control.