Claims
- 1. An electrically programmable hologram generator, comprising:
- a pixelated semiconductor device having a plurality of metallic pads physically arranged to define a pad pixel pattern, each of said metallic pads being electrically conductive;
- a liquid crystal having a first and a second surface, said first surface being in physical engagement with said metallic pads, and said metallic pads defining a corresponding liquid crystal pixel pattern for said liquid crystal;
- individual pixels within said liquid crystal pixel pattern being switchable to one of two states as a result of a control voltage applied thereto;
- an electrically conductive film in physical engagement with said second surface of said liquid crystal, wherein said electrically conductive film is beam transparent;
- electrical control means, coupled to said metallic pads, to apply said control voltage between selected ones of said plurality of metallic pads and said electrically conductive film, and operable to switch corresponding selected ones of said individual pixels of said liquid crystal in accordance with an electrical input data; and
- a photorefractive crystal, physically associated with said electrically conductive film, for receiving a reference beam of a first characteristic, an illumination beam of a second characteristic, and a reflected illumination beam of a third characteristic, wherein said reflected illumination beam interferes with said reference beam to write a hologram into said photorefractive crystal.
- 2. The hologram generator of claim 1, wherein said liquid crystal comprises a ferroelectric liquid crystal.
- 3. The hologram generator of claim 1, wherein said photorefractive crystal comprises a cobic NeLiO.sub.3 crystal.
- 4. The hologram generator of claim 1, wherein said electrically conductive film comprises indium oxide.
- 5. The hologram generator of claim 1, wherein said metallic pads selectively reflect said illuminating beam to produce said reflected illuminating beam.
- 6. The hologram generator of claim 1, wherein said photorefractive crystal physically engages said electrically conductive film.
- 7. The hologram generator of claim 1, wherein said pixelated semiconductor device is a chip.
- 8. The hologram generator of claim 1, wherein said pixelated semiconductor device is a hybrid.
- 9. The hologram generator of claim 1, wherein said first characteristic, said second characteristic, and said third characteristic are polarization.
- 10. The hologram generator of claim 1, wherein an angle between said reference beam and said reflected illumination beam varies in a range of from 0 and 50 degrees.
- 11. The hologram generator of claim 1, further including:
- a plurality of beam detectors physically arranged to define a detector pixel pattern corresponding to said pad pixel pattern, said beam detectors being physically arranged to intercept a reflected read beam produced by reflection of a read beam from said hologram within said photorefractive crystal; and
- signal responsive means, connected to said beam detectors, to provide a detector output corresponding to said hologram within said photorefractive crystal.
- 12. The hologram generator of claim 11, wherein said plurality of beam detectors are arranged to physically correspond to the positions of said plurality of metallic pads.
- 13. The hologram generator of claim 11, wherein said read beam and said illumination beam are of different frequencies.
- 14. The hologram generator of claim 11, wherein said metallic pads are square.
- 15. The hologram generator of claim 11, wherein said pad pixel pattern is square.
- 16. A method for generating holograms, comprising the steps of:
- arranging a physical structure comprising a pixelated semiconductor device, a liquid crystal, and a photorefractive crystal, wherein said pixelated semiconductor device includes a pad pixel pattern of metallic pads operatively associated with said liquid crystal and operating to define a liquid crystal pixel pattern for said liquid crystal;
- electrically writing an electrical input data into said pad pixel pattern so as to modulate said liquid crystal pixel pattern corresponding to said electrical input data;
- providing a reference beam to said photorefractive crystal;
- further providing an illumination beam to said liquid crystal; and
- reflecting said illumination beam to produce a reflected illumination beam which interferes with said reference beam and writes a hologram, corresponding to said electrical input data, in said photorefractive crystal.
- 17. The method for generating holograms of claim 16, wherein said step of reflecting includes said metallic pads selectively reflecting said illuminating beam to produce said reflected illuminating beam.
- 18. The method for generating holograms of claim 16, wherein said step of electrically writing includes receiving data from an electronic control means.
- 19. The method for generating holograms of claim 16, wherein said step of electrically writing includes the step of modulating pixels of said liquid crystal to on and off pixel states.
- 20. The method for generating holograms of claim 16, wherein said step of reflecting includes arranging said reference beam and said reflected illumination beam at an angle between 0 and 50 degrees.
- 21. The method for generating holograms of claim 16, further including the step of:
- further arranging a detector pixel pattern of photodetectors corresponding to said pad pixel pattern;
- reading said hologram by injecting a read beam into said photorefractive crystal and measuring a reflected read beam at said detector pixel pattern.
- 22. The method for generating holograms of claim 21, wherein said step of further arranging includes providing a further electronic control means, coupled to said detector pixel pattern, for monitoring a detector output from said detector pixel pattern.
- 23. The method for generating holograms of claim 21, wherein said detector pixel pattern is co-located with said pad pixel pattern.
- 24. A memory device, comprising:
- an electrically addressable pixel array comprising a plurality of pixels for receiving electrical data, each of said plurality of pixels comprising:
- a photodetector; and
- a reflective pad;
- a liquid crystal layer arranged on said electrically addressable pixel array;
- an electrically conductive film arranged on said liquid crystal layer, which together with each of said pads yields a corresponding plurality of pixel voltages across said liquid crystal layer; and
- a photorefractive crystal, wherein an illumination beam travels through said liquid crystal layer, said plurality of pixel voltages yield a corresponding polarization modified illumination beam at respective pixels, respective portions of which interfere with a reference beam within said photorefractive crystal.
- 25. A memory device, comprising:
- an electrically addressable pixel array comprising a plurality of pixels for receiving electrical data, each of said plurality of pixels including a reflective pad;
- a liquid crystal layer arranged on said electrically addressable pixel array;
- an electrically conductive film arranged on said liquid crystal layer, which together with each of said pads yields a corresponding plurality of pixel voltages across said liquid crystal layer; and
- a photorefractive crystal, wherein an illumination beam travels through said liquid crystal layer, said plurality of pixel voltages yield a corresponding polarization modified illumination beam at respective pixels, respective portions of which interfere with a reference beam within said photorefractive crystal.
RELATED APPLICATIONS
This is a regular application based on a provisional application under 37 C.F.R. .sctn.1.53(b)(2) having Ser. No. 60/009,652, filed Jan. 4, 1996, and this regular application claims priority thereof.
Government Interests
This invention was made with Government support under a contract by the national Science Foundation. The Government has certain rights in this invention.
US Referenced Citations (10)
Non-Patent Literature Citations (1)
Entry |
Yam, Philip, "Plastics, Benjamin . . . ", Scientific American (Jun., 1993), p. 140. |