Patent ID: 7924680
Filing Date: 2011-04-12
Classification: G11B

Abstract:
1. An optical information recording and reproducing apparatus for recording information on a recording medium by forming interference fringes generated by interference between an information beam and a reference beam on the recording medium and for reproducing the information by irradiating, with the reference beam, the recording medium, in which the interference fringes are formed, said apparatus comprising: a spatial light modulator for spatially modulating at least a portion of a light beam emitted from a light source into the information beam, wherein said spatial light modulator comprises a plurality of modulators changing in the intensity of reflection light, according to a modulation signal; a light sensing device that reads the information beam extracted from the recording medium by the reference beam irradiated on the recording medium; a shift amount detector that detects a shift of the irradiating position of the light beam entering said spatial light modulator; and means that corrects a positional shift between a position of an area for modulating the information beam and a position of the light beam in said spatial light modulator, based on a positional shift amount detected by said shift amount detector.