Hologram recording and reproducing apparatus and hologram recording and reproducing method

A hologram recording and reproducing apparatus in which an interference fringe pattern is formed with irradiation of a signal light and a reference light and written on a hologram medium to record information, and the interference fringe pattern is irradiated with the reference pattern to reproduce the recorded information, the hologram recording and reproducing apparatus comprising:

• a pickup that includes a light source which emits a light beam, a branch unit that branches the light beam emitted from the light source into the signal light and the reference light, a spatial light modulator for adding two-dimensional data to the signal light, and a Galvano mirror for changing an incident angle of the reference light;
• an access control circuit that performs seeking operation for positioning the reference light and the signal light emitted from the pickup at a predetermined place of the hologram medium;
• and
• a servo control circuit that controls operation of the pickup,
• wherein in the case where angle multiplexing recording is performed on a hologram medium page by page with a change in an incident angle of the reference light, when an angle multiplexing recording unit at the same location on the hologram medium is defined as a stack and an aggregation of a plurality of the stacks whose recording positions are displaced from each other is defined as a book, a reference light angle of another stack is allocated into a reference light angle of one stack for recording in the stacks adjacent to each other, and the access control circuit performs the seeking operation for positioning the reference light and the signal light at a first stack place of the hologram medium,
• the servo control circuit swings the Galvano mirror with the reference light angle set allocated to the first stack to change the reference light angle, and records a plurality of pages allocated to the first stack, and
• when the page recording of the first stack is completed, the access control circuit performs the seeking operation for positioning at a recording place of a next second stack.