Patent ID: 8134765

Claim:
A hologram recording and reconstruction apparatus for recording a hologram in a recording layer of a holographic recording medium by causing a signal light beam modulated in accordance with data to be recorded to interfere with a reference light beam, the signal light beam and the reference light beam being emitted from the same light source, the hologram recording and reconstruction apparatus reconstructing the recorded data from a diffracted light beam generated by emitting the reference light beam onto the recording layer, the hologram recording and reconstruction apparatus comprising: a spatial light modulator on which a reference light beam pattern for generating the reference light beam is displayed; an objective lens for allowing the signal light beam, the reference light beam, and the diffracted light beam to pass therethrough; focus controlling means for maintaining a predetermined distance between the objective lens and the recording layer; a temperature sensor for detecting the temperature of the holographic recording medium; and a control unit for controlling the distance between the objective lens and the recording layer in accordance with the temperature detected by the temperature sensor, wherein when reconstructing the recorded data, the control unit controls the distance between the objective lens and the recording apparatus based on a difference between the temperature detected by the temperature sensor and a temperature of the holographic recording medium at a recording time.