COHERENT OPTICAL MULTICHANNEL CORRELATOR

• US 3,776,616 A
• Filed: 10/10/1972
• Issued: 12/04/1973
• Est. Priority Date: 11/22/1971
• Status: Expired due to Term

• Current Assignee: Nikolaos Douklias
• Original Assignee: Nikolaos Douklias
• Inventors: Douklias, Nikolaos
• Primary Examiner(s): Lindquist, William F.
• Application Number:
  US05/295,998
• Time in Patent Office: 420 Days
• Field of Search: 350/162SF 356/71
• US Class Current: 359/15
• CPC Class Codes: G06E 3/003 forming integrals of products, e.g. Fourier integrals, Laplace integrals, correlation integrals; for analysis or synthesis of functions using orthogonal functions
• CPC Class Codes: G06V 10/88 Image or video recognition using optical means, e.g. reference filters, holographic masks, frequency domain filters or spatial domain filters

Abstract

A coherent optical multichannel correlator having a plurality of channels of coherent light beams for permeating an object to be identified, a Fourier transmission lens receiving the light permeating the object, a number of filter holograms disposed on a focal plane of the transformation lens and one or more photo detectors for receiving the output of the filter holograms characterized by providing a matrix of controllable optical switches between the Fourier transformation lens and the photo detectors for sequentially blocking and passing selected channels to reduce background noise from cross correlation of adjacent channels. The matrix of optical switches can be an arrangement of mechanically actuated light shutters or a matrix of electrooptical polarization switches.

Claims

1. A coherent optical multichannel correlator for identifying objects comprising:

means for providing a plurality of beams of coherent light as channels for permeating an object to be identified;

a Fourier transformation lens for receiving the beams of light after permeating tHe object to be identified, a plurality of filter holograms located on the focal plane of the lens, optical sensing means arranged for receiving reconstructed reference waves from the filter holograms, and controllable means for sequentially blocking and passing the beams of coherent light, said controllable means being disposed between the lens and the optical sensing means so that the optical sensing means sequentially senses the reconstructed waves of selected hologram filters.

2. A coherent optical multichannel correlator according to claim 1, wherein the controllable means for sequentially blocking and passing comprises a matrix of optical switch elements with each switch element having a dimension for a channel of the coherent light, and said switch elements being arranged with a switch element associated with each of the channels.

3. A coherent optical multichannel correlator according to claim 1, wherein the controllable means for sequentially blocking and passing comprises a matrix of optical shutters which are mechanically operated with an optical shutter associated with each of the channels.

4. A coherent optical multichannel correlator according to claim 3, wherein the matrix of optical shutters is disposed between the hologram filters and the sensing means so that the reconstruction wave from each hologram filter is sequentially passed to the sensing means.

5. A coherent optical multichannel correlator according to claim 1, wherein the means for providing a plurality of light beams includes means for polarizing each of the beams and wherein the controllable means for sequentially blocking and passing the light includes a matrix of individually controllable electro-optical polarization switches with a switch associated with each of the channels.

6. A coherent optical multichannel correlator according to claim 5, wherein the matrix of electro-optical polarization switches is disposed between the hologram filters and the sensing means so that the reconstructed wave from each of the filter holograms is sequentially passed to the sensing means.

7. A coherent optical multichannel correlator according to claim 1, wherein the means for providing a plurality of beams with coherent light comprises a source producing a beam of coherent light and an optical diffraction grating receiving the beam of light and diffracting it into a plurality of coherent beams.