Hybrid optical and electronic associative memory

• US 4,837,843 A
• Filed: 06/19/1987
• Issued: 06/06/1989
• Est. Priority Date: 06/19/1987
• Status: Expired due to Fees

• Current Assignee: General Electric CGR SA (General Electric Company), Hughes Aircraft Company (Rtx Corporation)
• Original Assignee: Hughes Aircraft Company (Rtx Corporation)
• Inventors: Owechko, Yuri
• Primary Examiner(s): Boudreau, Leo H.
• Assistant Examiner(s): Mancuso, Joseph
• Application Number:
  US07/064,901
• Time in Patent Office: 718 Days
• Field of Search: 365/125, 382/31, 382/42, 350/162.11, 350/162.12, 350/162.13, 350/162.14, 350/162.15, 350/3.75, 350/3.67, 350/3.81, 350/3.82, 350/3.85
• US Class Current: 382/211
• CPC Class Codes: G11C 15/00 Digital stores in which information comprising one or more characteristic parts is written into the store and in which information is read-out by searching for one or more of these characteristic parts, i.e. associative or content-addressed stores

Abstract

An associative memory system is provided which is a hybrid of optical and electronic components. In the preferred embodiment, a Fourier transform hologram is used to convolve a reference beam with correlated input images and stored object images. An electronic iteration loop is provided which is used to derive an enhanced reference beam for use in matching and enhancing the associative memory of the hologram with the object input plane image. The iteration loop of electronic components comprises a vidicon which receives the correlation plane image and provides that image in the form of an electronic signal to an electronic thresholding device or image processor. The image processor is capable of viewing the data at the rate of 30 frames per second and is used in the preferred embodiment to threshold the data with reference to the greatest amplitude portion of the correlation spot provided to the vidicon. After the electronic threshold has processed the signal, an improved signal is provided to the cathode ray tube screen. This processed signal is used to phase-modulate a projection light readout beam through use of a liquid crystal light valve. A polarizing beam splitter converts the phase modulation of the readout beam to an amplitude modulation wherein an enhanced reference beam is derived which is processed back to the hologram for readout at the output plane of the system. In this manner a variable-gain fast response electronic and optical component hybrid is provided for use

This Invention was made with Government Support under Contract No. F49620-84-C-0096 awarded by Department of Air Force. The U.S. Government has certain rights in the Invention.

Claims

1. A hybrid optical and electronic associative memory system capable of recalling a stored image when the memory system is provided with a distorted input image which is a partial or distorted version of the stored image, comprising:

a hologram including at least one stored image, said stored image comprising a first stored image of a first object, said first stored image being recorded with a first reference beam, said first stored image being a transform of a first real image of said first object;

image transforming means for providing a transform of the distorted input image to said hologram, so as to generate a distorted reference beam;

means for transforming said distorted reference beam into a correlation image related to said first stored image and distorted input image; and

means for enhancing said correlation image, including;

an electro-optical thresholding means for thresholding said correlation image and eliminating low level spurious light therein while preserving shift-invariance, said electro-optical thresholding means including an electronic threshold processor for thresholding said correlation image, and

optical means for amplifying and conjugating the thresholded correlation image to generate an amplified correlation image signal, wherein said optical means includes a spatial light modulator.

2. The hybrid optical and electronic associative memory system of claim 1, wherein the image transforming means comprises a Fourier transform lens.

3. The hybrid optical and electronic associative memory system of claim 1, wherein the hologram is a Fourier transform hologram.

4. The hybrid optical electronic associative memory system of claim 1, wherein the hologram is a Fresnel hologram.

5. The Hybrid optical electronic associative memory system of claim 1, wherein the hologram is a volume hologram.

6. The hybrid optical and electronic associative memory system of claim 1, wherein said optical amplification means comprises a CCD-LCLV.

7. A hybrid optical and electronic associative memory system capable of recalling a stored image when the memory system is provided with a distorted input image which is a partial or distorted version of the stored image, comprising:

a hologram including at least one stored image, said stored image including a first stored image of a first object, said first stored image being recorded with a first reference beam, said first stored image being a transform of a first real image of said first object;

image transforming means for providing a transform of the distorted input image to said hologram so as to generate a distorted reference beam;

means or transforming said distorted reference beam into a correlation image related to said first stored image and distorted input image; and

means for enhancing said correlation image, including an electro-optical thresholding means, for thresholding said correlation image and eliminating low level spurious light therein, wherein said electro-optical thresholding means includes;

(a) a first vidicon camera for receiving said correlation image and generating a vidicon signal;

(b) an electronic threshold processor for processing said vidicon signal to threshold and enhance the resolution of said vidicon signal and provide a thresholded output signal; and

(c) A CRT having a CRT output screen, the thresholded output signal being provided to said CRT so as to generate an electro-optical image signal at said CRT output screen;

optical amplification means for amplifying the threshold correlation image to generate an amplified correlation image signal, wherein said means for amplifying includes a spatial light modulator positioned in juxtaposed adjacent alignment with said CRT output screen, said spatial light modulator modulating a high intensity readout beam in response to the thresholded output signal, so as to generate the amplified correlation image signal.

8. The hybrid optical and electronic associative memory system of claim 7, wherein said spatial light modulator is a liquid crystal light valve (LCLV).

9. The hybrid optical and electronic associative memory system of claim 8, wherein said system acts as a resonator by further including:

(a) a second vidicon camera for receiving said output image from said hologram and generating a second vidicon signal;

(b) a second threshold pressure for processing said second vidicon signal and providing an object leg threshold signal;

(c) a second CRT, having an output screen, said second CRT for generating a CRT signal responsively to said object leg thresholded signal;

(d) a second LCLV, operatively linked to said second CRT, for modulating a second high intensity readout beam, and

(e) means for directing the modulated second high intensity readout beam to said hologram.

10. An associative memory system capable of associating a first body of data with a second incomplete body of data, comprising:

(a) data storage means for storing a first transformed set of data corresponding to said first body of data, and a reference set of data corresponding to a transform of a plurality of delta functions;

(b) data input means for providing said data storage means with a second transformed set of data corresponding to the second incomplete body of data so as to generate a composite product of the transform of said first body of data, the second transformed set of data and the reference set of data;

(c) means for enhancing the composite product including a first electronic data processing means for thresholding the composite product and generating a thresholded signal, and

a data amplifier operating in association with said electronic data processing means,

for receiving a readout beam and modulating said readout beam with the thresholded signal such that a modulated signal is generated;

(d) means for redirecting the modulated signal to said data storage means, and

(e) associative processing means, operatively linked to said data storage means, for retrieving said first body of data, by identifying an association between said first body of data and said second incomplete body of data, when said data storage means is provided with the modulated signal.

11. The system of claim 10 further comprising:

a data resonator which provides adjustable thresholding of said incomplete body of data, said resonator comprising;

a second electronic data processing means for thresholding, disposed on the side of said data storage means opposite from said first electronic data processing means, so that the modulated signal iteratively loops back and forth between the first and second electronic data processing means.

12. A hybrid optical and electronic associative memory system for recalling a first stored image when the memory system is provided with a distorted incomplete input image, comprising:

(a) a hologram having the first stored image of an object recorded therein as a scattered field pattern transform;

(b) means for providing the distorted incomplete input image to said hologram so as to generate a distorted reference beam;

(c) electro-optical means for resolving the reference beam so as to generate an enhanced reference beam, including;

a correlation lens;

image processor having an adjustable control for setting the threshold of the reference beam, and generating a thresholded reference beam;

means for modulating a readout beam responsively to the thresholded reference beam, so as to generate the enhanced reference beam, and

(d) an object leg of the system disposed on the side of said hologram opposite to said electro-optical means, to form a resonator with said electro-optical means, said object leg including;

a second means for modulating a second readout beam, and

a second thresholding means, the enhanced reference beam, from said electro-optical means iteratively looping through said hologram between said electro-optical means and said object leg, and reconstruction an output image corresponding to said first stored image.

13. The hybrid optical and electronic associative memory system of claim 12, wherein said first and second means for modulating are directly electronically controlled to modulate, respectively, said first and second readout beams.