Patent ID: 7755819

Claim:
A hologram recorder comprising: a light source for emission of a coherent beam; a spatial light modulator including unit areas provided with beam reflection elements, respectively, each of the beam reflection elements configured to reflect the coherent beam from the light source in a main direction as a signal beam or in a cut-off direction; and a signal beam optical system for directing the signal beam to a hologram recording medium; the hologram recorder further comprising: a wavefront reshaper for concentration and wavefront reshaping of beams reflected in the cut-off direction by the beam reflection elements of the spatial light modulator; a reference beam optical system for directing a beam from the wavefront reshaper to the hologram recording medium as a reference beam to overlap with the signal beam on the hologram recoding medium; and a power-monitoring light sensor for monitoring an output state of the light source; wherein the wavefront reshaper includes a condenser lens for condensation of a beam, and an optical filter at a focal point of the condenser lens, and a collimator lens for collimating a beam from the optical filter, wherein the optical filter is provided with a central transmissive part and a peripheral reflective part around the central transmissive part, the central transmissive part allowing a beam of a low-frequency component to pass through to the collimator lens, the peripheral reflective part reflecting a beam of a high-frequency component to the power-monitoring light sensor.