Patent ID: 7312907
Filing Date: 2007-12-25
Classification: G03H,G11B,Y10S

Abstract:
1. A hologram apparatus for causing a coherent data beam reflecting data to be recorded and a coherent recording reference beam after being reflected by a mirror adjustable in inclination angle to be applied to a hologram recording medium to record a hologram so as to form interference fringes and for playing back a hologram based on a diffracted light obtained as a result of applying a coherent playback reference beam after being reflected by the mirror to the hologram recording medium at the same incidence angle as the recording reference beam, a test region being established in advance in the hologram recording medium, the test region being adapted to record a piece of test data for each of the reference incidence angle and a plurality of stepped incidence angles of the recording reference beam, the hologram apparatus comprising: a mirror controller that adjusts the inclination angle of the mirror; a system controller that successively adjusts the inclination angle of the mirror so as to set the incidence angle of the recording reference beam equal to the reference incidence angle or one of the plurality of the stepped incidence angles, successively records in the test region the piece of the test data corresponding to the reference incidence angle or one of the plurality of the stepped incidence angles that is successively set, and applies the playback reference beam to the test region at the same incidence angle as the recording reference beam to globally play back all the pieces of the test data that have been successively recorded; and a mirror inclination angle corrector that selects, among the test data that has been globally played back, the data with the maximum diffraction efficiency, and corrects the inclination angle of the mirror based on the difference between the reference incidence angle or one of the plurality of the stepped incidence angles corresponding to the selected data and the reference incidence angle.