Remotely controllable real-time optical processor

• US 4,772,101 A
• Filed: 11/07/1986
• Issued: 09/20/1988
• Est. Priority Date: 11/07/1986
• Status: Expired due to Fees

• Current Assignee: The United States of America As Represented By The Secretary of Agriculture
• Original Assignee: United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration
• Inventors: Liu, Hua-Kuang
• Primary Examiner(s): Miller, Stanley D.
• Assistant Examiner(s): DUONG, TAI V
• Application Number:
  US06/927,972
• Time in Patent Office: 683 Days
• Field of Search: 350/331 R, 350/336, 350/342, 350/162.13, 350/174, 350/333, 350/347 E, 350/345, 356/71, 358/236, 358/240, 358/250, 382/31, 382/42
• US Class Current: 349/17
• CPC Class Codes: G06E 3/005 using electro-optical or opto-electronic means

Abstract

An optical processor is provided which facilitates selection of any of a variety of patterns or images which are to be compared with a Fourier transform of a template image, wherein the processor can be constructed at low cost. One of the two images that are to be compared is formed by generating video signals representing the image and using those signals to drive a liquid crystal array through which light passes.

Claims

1. In an optical processor which includes means for directing coherent light through an imput pattern formed by an imput device that includes a liquid crystal array containing multiple pixels whose transparancies can be controlled and a means for controlling the pixels to form the input pattern, means for forming a substantially Fourier transform image of the input pattern onto a matched filter device, and means for sensing the degree of correlation of the input pattern with the template pattern on which the matched filter device is based, the improvement wherein:

said liquid crystal array includes a stack of original layers which has opposite stack ends and which can form an image, said array also including a layer of liquid crystal material and a pair of sheets of substantially transparent material on opposite sides of said layer of liquid crystal material at opposite ends of said stack; and

a pair of outer plates lying facewise adjacent to opposite ends of said stack, and a quantity of flowed material lying between each end of the stack and the corresponding outer plate, each outer plate having a precision flat face lying furthest from the stack, and said flowed material having about the same index of refraction as the material of said layers which lie at opposite ends of said stack.

2. An optical processor comprising:

an input device which produces a pattern comprising relatively transparent and opaque areas;

a filter device representing substantially the Fourier transform of an image; and

means for detecting the degree of correlation of the pattern of said input device and the image represented by said filter device, including means for directing coherent light at said imput device to engage said pattern, and for directing light which has engaged said pattern onto said filter device;

said input device including an addressable liquid crystal array comprising a multiplicity of pixels, and means for generating video signals connected to said array to address said pixels to control their transparency;

said liquid crystal array includes a stack of original layers which has opposite stack ends and which can form an observable image, said stack including a pair of sheets of substantially transparent material at opposite ends of said stack;

said array also including a pair of outer plates lying facewise adjacent to opposite ends of said stack, and a quantity of substantially liquid material lying between each end of the stack and the corresponding outer plate, each outer plate having a precision flat face lying furthest from the stack, and said flowed material having about the same index of refraction as the material of said layers which lie at opposite ends of said stack.

3. In a method for determining the correlation between first and second images by forming a first transparency having a pattern representing substantially the Fourier image transform of a first of the images, forming a second transparency having a pattern representing the second image, and passing coherent light through said transparencies and detecting the correlation of said beams, wherein one of said transparencies is formed by generating video signals representing one of said patterns and energizing a liquid crystal array with said video signals to control the transparency of the pixols of the array to produce the pattern of said one of said transparencies, the improvement wherein:

said step of forming one of said transparencies includes placing a stack of layers which includes a layer of liquid crystal material that is sandwiched between sheets of transparent material, between a pair of transparent plates that each has a precision flat surface on a face thereof furthest from the stack, and maintaining an intermediate flowed material of about the same index of refraction as said sheets between the ends of the stack and said plates.

4. In an optical processor which includes means for directing coherent light through an input pattern formed by an input device, means for forming a substantially Fourier transform image of the input pattern onto a matched filter device, and means for sensing the degree of correlation of the input pattern with the template pattern on which the matched filter device is based, the improvement wherein:

said input device comprises a liquid crystal array that includes a grid formed of a multiplicity of largely opaque row and column electrical conductors and means for generating video signals as input informations, coupled to said electrical conductors; and

said template pattern is the image of an object, and said matched filter device is the Fourier transform of the image of said object superimposed on the Fourier transform of said grid which are largely opaque regions.

5. In a method for determining the correlation between first and second images by forming a first transparency having a pattern representing substantially the Fourier image transform of a first of the images, forming a second transparency having a pattern representing the second image, passing coherent light through said transparencies and detecting the correlation of said beams, the improvement wherein:

said step of forming said second transparency includes generating video signals as input informations of one of said patterns, and energizing a liquid crystal array with said video signals to control the transparency of the pixels of the array to produce the pattern of said second transparency, wherein the array includes a grid of opaque conductor lines;

said step of forming said first transparency includes dividing coherent collimated light into reference and active beams, directing the active beam through said array while energizing said array to form said first image, and onto a photographic emulsion, and directing the reference beam at said emulsion, to produce a Fourier transform of said first image superimposed on the Fourier transform of said grid lines of said array