Holographic recording system having a relay system
View Patent ↗According to one aspect and example, a holographic recording system includes a light source, an object for modulating an object beam from the light source, and a relay system adapted to magnify (positive or negative) the modulated beam (e.g., an image of the object) to an output image. The object may include an SLM operable to modulate the object beam with an information layer comprising a plurality of data pages. The output image is directed to the holographic storage medium, where a reference beam is also directed, to record the resulting interference pattern. Additionally, the relay system converges the output image to an output Fourier plane, which may be disposed within the holographic storage medium. A filter may be placed at an intermediate Fourier plane located prior to the output Fourier plane, and a phase mask may be placed at the position of the output image.
1. A method for recording holographic storage media, comprising:
illuminating an object to produce a modulated object beam;
relaying the modulated object beam with a relay system to provide an output modulated object beam comprising an output image of the modulated object beam and an output Fourier transform pattern of the modulated object beam;
directing the output modulated object beam to a holographic storage medium;
propagating a reference beam to the holographic storage medium to record a resulting interference pattern between the output modulated object beam and the reference beam in the holographic storage medium, wherein the reference beam comprises a plane wave;
forming an intermediate Fourier plane prior to the output Fourier transform pattern of the modulated object beam;
disposing an aperture at the intermediate Fourier plane location; and
recording holograms via polytopic multiplexing by translating the holographic storage medium with respect to the reference beam and output modulated object beam between holograms, wherein a beam waist of the output modulated object beam is positioned outside of the holographic storage medium when recording each of the holograms, wherein at least two of the holograms substantially spatially overlap within the holographic storage medium and wherein there is substantially no overlap in respective output modulated object beam waists used to record the at least two holograms.
2. The method of claim 1 , wherein the output image is magnified relative to the object.
3. The method of claim 2 , wherein the output image is magnified between 0.1 and 10.0.
4. The method of claim 1 , wherein the object beam illuminates the object with a converging beam.
5. The system of claim 1 , wherein at least one dimension of the aperture is between 0.5 to 4.0 times the Nyquist aperture size for polytopic multiplexing.
6. The method of claim 1 , wherein the object includes an SLM or a data mask.
7. The method of claim 1 , wherein the output image is formed before the output Fourier transform pattern of the modulated object beam and includes a real or virtual image.
8. The method of claim 1 , wherein the output image is a real image formed after the output Fourier transform pattern of the modulated object beam.
9. The method of claim 1 , further including a phase mask disposed at the location of the object.
10. The method of claim 1 , further including a phase mask disposed at the location of the output image.