Real-time programmable optical correlator

• US 4,695,973 A
• Filed: 10/22/1985
• Issued: 09/22/1987
• Est. Priority Date: 10/22/1985
• Status: Expired due to Fees

• Current Assignee: United States Of America As Represented By The Secretary Of The Air Force
• Original Assignee: United States Of America As Represented By The Secretary Of The Air Force
• Inventors: Yu, Francis T. S.
• Primary Examiner(s): Harkcom, Gary V.
• Application Number:
  US06/790,292
• Time in Patent Office: 700 Days
• Field of Search: 364/807, 364/819, 364/822, 364/826-827, 364/861, 364/713, 364/728, 364/604, 350/162.11, 350/162.12, 350/162.13, 250/550
• US Class Current: 708/816
• CPC Class Codes: G06E 3/005 using electro-optical or opto-electronic means

Abstract

A real-time programmable joint transform optical correlator incorporating a magneto-optic spatial light modulator and a liquid crystal light valve therein. Object functions to be correlated are input into the magneto-optic spatial light modulator by a programmable microcomputer as input signals. Real time correlation takes place at the liquid crystal light valve with a coherent read out beam. Cross correlation between the input functions (signals) are obtained through the inverse Fourier transform of the read out coherent illumination and are subsequently output from the correlator.

Claims

1. A real-time programmable optical correlator, comprising:

means for providing a first beam of electromagnetic radiation and directing said beam of electromagnetic radiation along a preselected optical axis;

means located at a first preselected location along said optical axis for receiving said first beam of electromagnetic radiation, a first input signal and a second input signal and for generating images representative of said first and said second input signals;

means at a second preselected location along said optical axis for receiving said images and forming a joint Fourier transform of said images at a third preselected location along said optical axis;

means for providing a second beam of electromagnetic radiation and directing said second beam of electromagnetic radiation to said third preselected location along said optical axis;

means positioned at said third preselected location along said optical axis for receiving said joint Fourier transform of said images and said second beam of electromagnetic radiation and for generating a coherent power spectrum representative of said images;

means positioned at a fourth preselected location along said optical axis for forming an inverse Fourier transform of said coherent power spectrum of said images at a fifth preselected location along said optical axis, said inverse Fourier transform being representative of a correlation between said first and said second input signals.

2. A real-time programmable optical correlator as defined in claim 1 further comprising means located adjacent said fifth preselected location for detecting said inverse Fourier transform and emitting an output representative of said correlation between said first and said second input signals.

3. A real-time programmable optical correlator as defined in claim 2 further comprising means operably connected to said means located at said first preselected location for receiving an image of an object and for generating said first input signal representative thereof and for generating said second input signal.

4. A real-time programmable optical correlator as defined in claim 3 further comprising means for operably interconnecting said output with said means for generating said first and said second input signals.

5. A real-time programmable optical correlator as defined in claim 3 wherein said means for generating said first and said second input signals comprises a computer.

6. A real-time programmable optical correlator as defined in claim 2 wherein said means located adjacent said fifth preselected location comprises a charge coupled array detector and a television camera.

7. A real-time programmable optical correlator as defined in claim 1 wherein said means located at said first location comprises a magneto-optic spatial light modulator.

8. A real-time programmable optical correlator as defined in claim 7 wherein said means positioned at said third preselected location comprises a liquid crystal light valve.

9. A real-time programmable optical correlator as defined in claim 8 further comprising means located adjacent said fifth preselected location for detecting said inverse Fourier transform and emitting an output representative of said correlation between said first and said second input signals.

10. A real-time programmable optical correlator as defined in claim 9 further comprising means operably connected to said means located at said first preselected location for receiving an image of an object and for generating said first input signal representative thereof and for generating said second input signal.

11. A real-time programmable optical correlator as defined in claim 10 further comprising means for operably interconnecting said output with said means for generating said first and said second input signals.

12. A real-time programmable optical correlator as defined in claim 11 wherein said means for generating said first and said second input signals comprises a computer.

13. A real-time programmable optical correlator as defined in claim 12 wherein said means for providing said first beam of electromagnetic radiation comprises a laser.

14. A real-time programmable optical correlator as defined in claim 13 wherein said means for providing said second beam of electromagnetic radiation and for directing said second beam comprises a laser and a beamsplitter.

15. A real-time programmable optical correlator as defined in claim 14 wherein said means located adjacent said fifth preselected location comprises a charge coupled array detector and television camera.

16. A real-time programmable optical correlator as defined in claim 1 wherein said means positioned at said third preselected location comprises a liquid crystal light valve.

17. A real-time programmable optical correlator as defined in claim 1 wherein said means for providing said first beam of electromagnetic radiation comprises a laser.

18. A real-time programmable optical correlator as defined in claim 1 wherein said means for providing said second beam of electromagnetic radiation and for directing said second beam comprises a laser and a beamsplitter.