Patent ID: 7518974

Claim:
A recording and reproducing apparatus comprising: a light source to emit a laser beam; an information light beam irradiation unit to irradiate a holographic recording medium with an information light beam modulated from the laser beam so as to be related to recording requested information; and a reference light beam irradiation unit to irradiate the same position as the position irradiated with the information light beam on the medium with a reference light beam generated from the laser beam so as to form a specific speckle pattern on the medium, wherein the reference light beam irradiation unit comprises a diffusion board provided in the way of a light path through which the laser beam is passed and generating the reference light beam, a rotation controller to rotate the diffusion board, and an identification information detector to detect identification information previously formed on a surface of the diffusion board, the diffusion board comprises a plurality of encode storage regions in which different identification information is formed and a plurality of diffusion pattern generation regions specified by the identification information, the laser beam is converted to the reference light beam to form a specific speckle pattern, in the diffusion pattern generation region, and the reference light beam irradiation unit controls the diffusion board, based on the identification information detected by the identification information detector such that the diffusion board is rotated by the rotation controller and a desired diffusion pattern generation region comes to a light path through which the laser beam is passed while the laser beam is outputted.