High output reflective optical correlator having a folded optical axis using ferro-electric liquid crystal spatial light modulators

• US 6,080,994 A
• Filed: 07/30/1998
• Issued: 06/27/2000
• Est. Priority Date: 07/30/1998
• Status: Expired due to Term

• Current Assignee: Northrop Grumman Systems Corporation (Northrop Grumman Corporation)
• Original Assignee: Litton Systems Incorporated (Northrop Grumman Corporation)
• Inventors: Lucas, John, Carrott, David T., Mills, Stuart, Karins, James P., Mitchell, Bob, Dydyk, Barry
• Primary Examiner(s): LE, QUE TAN
• Application Number:
  US09/126,450
• Time in Patent Office: 698 Days
• Field of Search: 250/550, 250/559.44, 359/561, 359/559-560, 382/130, 382/103, 382/278, 382/280, 356/345
• US Class Current: 250/550
• CPC Class Codes: G06E 3/005 using electro-optical or opto-electronic means

Abstract

An optical correlator system having a plurality of both active and passive reflective optical components between a source of electromagnetic radiation, such a visible coherent light, and an output detector array in a planar support body along a folded optical axis beam path within the body uses a ferro-electric liquid crystal spatial light modulator as the input sensor and the correlating filter to provide enhanced optical detection of an unknown object at a CCD detector array.

Claims

1. An improved optical correlator for detecting and identifying an unknown object, comprising:

a first spatial light modulator (SLM) for receiving image data of the unknown object and patterning an electromagnetic beam according to the image data of the unknown object;

a first toric mirror for producing a first Fourier transformation of the electromagnetic beam from the first SLM;

a second SLM for receiving a Fourier transformed pattern of a known object and patterning the electromagnetic beam from the first toric mirror according to the Fourier transformed pattern of the known object;

a second toric mirror for producing a second Fourier transformation of the electromagnetic beam from the second SLM;

a charge coupled device (CCD); and

a reflective surface for converging the electromagnetic beam from the second toric mirror onto the CCD.

2. The correlator of claim 1 wherein the CCD has a lower pixel count than each of the first and second SLM.

3. The correlator of claim 2 further comprising a third toric mirror positioned in the electromagnetic beam path between the reflective surface and the CCD for converging the electromagnetic beam onto the CCD.

4. The correlator of claim 3 wherein the second and third toric mirror and the reflective surface provide a 4:

1 convergence.

5. The correlator of claim 1 wherein each of the first and second SLM is a ferro-electric liquid crystal (FLC) SLM.

6. The correlator of claim 1 wherein the reflective surface is a flat mirror.