Patent ID: 6281993
Filing Date: 2001-08-28
Classification: G03H,G11C

Abstract:
A holographic data storage system comprising:a light source for generating a coherent light beam;beam-forming optics for forming the coherent beam into a collimated coherent beam along an optical axis;a spatial light modulator located in the path of the beam from the beam-forming optics and having an array of regularly spaced pixels for generating individual beams of light from the coherent beam;a holographic recording medium;a Fourier transform lens located between the modulator and the medium and centered on the optical axis for directing the individual beams to the medium, the medium being located substantially in the Fourier transform plane where relatively high intensity spikes from the individual beams generated by the regularly spaced modulator pixels are concentrated; anda plurality of optical elements located between the beam-forming optics and the modulator and spaced around the optical axis of the collimated coherent beam from the beam-forming optics, the surface of each of the plurality of optical elements having a shape such that a sectional plane of the optical element in which the optical axis also lies defines a straight line oriented at a nonperpendicular angle to the optical axis, the optical elements directing the beam to the modulator as portions of light nonparallel to one another and to the optical axis, thereby imparting to each light portion a phase shift linearly proportional to the distance of the light portion from the optical axis, whereby the portions of light from the modulator are also nonparallel to one another and the intensity of the spikes in the Fourier transform plane is thereby substantially reduced.