OPTICAL PROCESSOR FOR CONVOLUTION FILTERING

• US 3,809,873 A
• Filed: 11/03/1972
• Issued: 05/07/1974
• Est. Priority Date: 06/28/1971
• Status: Expired due to Term

• Current Assignee: Carl N. Klahr
• Original Assignee: Carl N. Klahr
• Inventors: Klahr, Carl N.
• Primary Examiner(s): Gruber, Felix D.
• Application Number:
  US05/303,313
• Time in Patent Office: 550 Days
• Field of Search: 235/181 350/160,96B,161,162SF 324/77A,77B,77K 340/15.5 343/1CL
• US Class Current: 708/816
• CPC Class Codes: G01S 13/9005 with optical processing of the SAR signals
• CPC Class Codes: G06E 3/001 Analogue devices in which mathematical operations are carried out with the aid of optical or electro-optical elements optical elements per se G02B; devices consisting of a plurality of solid state components, including light sensitive semiconductor components, formed in or on a common substrate H01L27/14; electro-, magneto- or acousto-optics, non-linear optics G02F1/00; graph reading G06K11/00

Abstract

This invention comprises apparatus for optical processing of two dimensional convolution integrals of a signal function with a filter function. It makes use of specific adaptations of an optical processor not requiring input storage medium, denoted OPWISM. When the filter function is available as a two dimensional spatially varying optical filter, a specific category of OPWISM apparatus is utilized to produce the convolution integral. When the filter function is available as an electronic signal, the convolution integral can be produced from a specific combination of OPWISM apparatus.

Claims

1. An optical processing apparatus for producing a processed image signal proportional to the two dimensional convolution integral of a two dimensional signal function with a specified two dimensional filter function, wherein said two dimensional signal function is inputted as a time sequence of signal data elements extending over a predetermined data frame time period corresponding to a time sequential scan of said two dimensional signal function, and said specified filter function is inputted as an optical spatial filter, comprising in combination 1 means for time sequential modulation by said signal function of at least one phase coherent beam to produce at least one phase coherent modulated beam 2 means for producing at least one optical reference beam phase coherent with said modulated beam 3 at least one optical detector storage surface, comprising a two dimensional array of individual detector storage elements 4 means for superimposing said coherent reference beam upon said optical detector storage surface 5 at least one optical spatial filter with two dimensional spatial variation in optical transmittance and optical phase change, corresponding on a spatial point by point basis to said specified filter function, wherein said spatial variation may be indexed by a two dimensional grid of spatial elements, wherein each said spatial element of said optical filter can be put into a one-to-one correspondence with a signal data element of the time sequential signal scan of said two dimensional signal function 6 at least one optical beam conformer adapted to spatially conform said phase coherent modulated beam to at least one specified set of spatial elements of said filter, thus producing a modulated beam image emerging from said filter, whose time and spatial amplitude variation is proportional to the product of said modulated beam and the spatial variation of optical tranSmittance and phase of said specified set of spatial elements of said filter 7 means for optical imaging of said modulated beam image emerging from said optical filter onto said optical detector storage surface 8 means for spatial displacement of said modulated beam image 9. at least one electronic synchronizer whose output signals produce a time synchronization between said time sequential modulation and between spatial displacement of the optical image produced by said optical spatial filter wherein said synchronizer regulates said means for spatial displacement to shift said image on said two dimensional optical detector surface in each dimension by the image width of one filter spatial element for each signal data element change, corresponding to said time sequential scan of the signal function in that dimension, inputted to the modulator, and wherein said optical detector surface performs storage and time summation for at least one data frame time period, of said modulated beam images incident on it, wherein the stored time summation on said optical detector surface of said spatially displaced modulated beam images incident on said surface over one data frame time period, constitutes said processed image signal proportional to said two dimensional convolution integral.

2. An optical processing apparatus as defined in claim 1 wherein said optical detector storage surface is on an optical image tube with electronic signal readout of said processed image signal.

3. An optical processing apparatus as defined in claim 2 wherein said means of spatial displacement of said modulated beam image upon said optical detector surface, returns said modulated beam image to an initial position upon said surface corresponding to the initiation of the calculation, at the completion of each said data frame time period.

4. An optical processing apparatus as defined in claim 1 wherein said means for spatial displacement of said modulated beam image on said optical detector storage surface comprises means for optical beam deflection of said modulated beam image emerging from said optical spatial filter.

5. An optical processing apparatus as defined in claim 1 wherein said means for spatial displacement of said modulated beam image on said optical detector storage surface includes means for optical beam deflection of said modulated beam image inputted to at least one said optical spatial filter.

6. An optical processing apparatus as defined in claim 1 wherein said means for spatial displacement of said modulated beam image on said optical detector surface includes means for spatial displacement of said optical spatial filter relative to the center of said modulated beam conformed upon it.

7. An optical processing apparatus as defined in claim 1 including means for phase adjustment of the optical phase of at least one said reference beam.

8. An optical processing apparatus as defined in claim 1 including means for spatial displacement of said coherent modulated beam emerging from said optical beam conformer upon successive sets of spatial elements of said optical spatial filter.

9. at least one electronic synchronizer whose output signals produce a time synchronization between said time sequential modulation and between spatial displacement of the optical image produced by said optical spatial filter wherein said synchronizer regulates said means for spatial displacement to shift said image on said two dimensional optical detector surface in each dimension by the image width of one filter spatial element for each signal data element change, corresponding to said time sequential scan of the signal function in that dimension, inputted to the modulator, and wherein said optical detector surface performs storage and time summation for at least one data frame time period, of said modulated beam images incident on it, wherein the stored time summation on said optical detector surface of said spatially displaced modulated beam images incident on said surface over one data frame time period, constitutes said processed image signal proportional to said two dimensional convolution integral.

10. An optical processing apparatus as defined in claim 1 wherein said reference beam follows an optical path that includes at least one said means for spatial beam displacement and excludes said optical spatial filter.

11. An optical processing apparatus as defined in claim 1 wherein said signal function is a time sequence of data elements produced by time sequential scan of a two dimensional data field, and wherein said filter function is an optical spatial filter corresponding to a spatial pattern whose presence in said data field is sought, and wherein said convolution integral is thus the cross correLation function for recognition of said pattern in said two dimensional data field.