Hologram recording and reproducing apparatus

A hologram recording and reproducing apparatus in which coherent light is split into a recording beam and a reference beam, the recording beam and the reference beam being superposed on a hologram recording medium for recording a hologram on the hologram recording medium, and in which the hologram recording medium is irradiated with the reference beam for reproducing recorded information based on the hologram, and a reflected beam from the hologram recording medium is detected with an optical detector, the apparatus comprising:

• a movable optical device that guides the reference beam toward the hologram recording medium, and that changes an incident angle of the reference beam with respect to the hologram recording medium;
• an optical device controller that causes the movable optical device to move so as to set the incident angle at a predetermined angle in recording the hologram on the hologram recording medium, the optical device controller also causing the movable optical device to move, in reproduce the recorded information based on the hologram, so that the incident angle continuously changes within a predetermined range including the predetermined angle;
• and
• a reproduction unit that receives a detection signal from the optical detector while the incident angle changes continuously, the detection signal corresponding to intensity of the reflected beam, the reproduction unit reproducing the recorded information based on the detection signal when the intensity of the reflected beam is no lower than a predetermined level or reaches a maximum level.