HOLOGRAPHIC SYSTEM FOR SUBJECT RECOGNITION PERMITTING CONVERSION OF A PATTERN INTO A MACHINE-READABLE FORM

• US 3,764,979 A
• Filed: 08/03/1971
• Issued: 10/09/1973
• Est. Priority Date: 08/13/1965
• Status: Expired due to Term

• Current Assignee: Dennis Gabor
• Original Assignee: Dennis Gabor
• Inventors: Gabor, Dennis
• Primary Examiner(s): Schonberg, David
• Assistant Examiner(s): Stern, Ronald J.
• Application Number:
  US05/168,712
• Time in Patent Office: 798 Days
• Field of Search: 340/146.3P 250/219D 350/3.5
• US Class Current: 382/210
• CPC Class Codes: G03H 1/041 Optical element in the object space affecting the object beam, not otherwise provided for
• CPC Class Codes: G03H 1/12 Spatial modulation, e.g. ghost imaging
• CPC Class Codes: G03H 1/16 using Fourier transform G03H1/10, G03H1/12, G03H1/14 take precedence; analogue computers G06G, e.g. G06G7/19
• CPC Class Codes: G03H 2001/2675 Phase code multiplexing, wherein the sub-holograms are multiplexed according to spatial modulation of the reference beam
• 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
• CPC Class Codes: G11C 13/042 using information stored in the form of interference pattern
• CPC Class Codes: G11C 15/00 Digital stores in which information comprising one or more characteristic parts is written into the store and in which information is read-out by searching for one or more of these characteristic parts, i.e. associative or content-addressed stores

Abstract

A holographic device for producing output image patterns in response to different input pattern wavefronts is described. A novel hologram is formed by the interference of a first pattern of electromagnetic waves and a second pattern of electromagnetic waves. The resultant hologram may be irradiated with a pattern of electromagnetic waves corresponding to the first pattern to reconstruct the second pattern of electromagnetic waves, and vice versa. To form the hologram a coherent light beam, such as from a laser, is directed on an object such as a transparency having a pattern thereon. The light from the object is directed onto a photographic emulsion. A coherent light beam also illuminates a second pattern, such as a coded apertured plate, and the light passing through the apertures is directed onto the photographic emulsion where it forms an interference pattern with the light from the first pattern. A hologram is thereby formed which, when illuminated by a pattern similar to one of the original patterns will reconstruct an image of the other original pattern.

Claims

1. An optical character reader comprising:

a hologram having a plurality of interference patterns photographically recorded thereon, each interference pattern being formed by the interference of first and second associated electromagnetic wavefront patterns, said first wavefront patterns emanating from said characters and said second wavefront patterns emanating from groups comprised of a plurality of discrete and separate point sources of electromagnetic wavefronts where each said group forms a unique code representing a different one of said characters, a display means including a medium containing a plurality of said characters, said characters being related to said first electromagnetic wavefront patterns which formed said interference patterns of said hologram, a source of substantially coherent light, means for sequentially positioning said characters on said medium in the path of said coherent light, each of said characters scattering said coherent light into electromagnetic wavefronts, said electromagnetic wavefront patterns from each of said characters being related to said first electromagnetic wavefront patterns which formed said interference patterns of said hologram, an optical system for sequentially directing said electromagnetic wavefront patterns scattered by the characters on said medium onto said hologram, said electromagnetic wavefront patterns scattered by said characters and sequentially directed onto said hologram coacting with said interference patterns on said hologram to produce images of said second associated electromagnetic wavefront patterns emanating from said discrete point sources, said images being representative of said unique codes of the characters on said medium, and means responsive to each of said images of said second associated electromagnetic wavefront patterns to produce electrical signals representative of said codes of the characters on said medium.

2. An optical character reader according to claim 1 wherein produced images of said second electromagnetic wavefront patterns are manifested as coded discrete light arrays, and said means responsive to each of said images is a plurality of photoelectric devices for producing electrical signals in response to said coded discrete light arrays.

3. An optical device, comprising:

a hologram formed by the interference of first and second electromagnetic wavefront patterns on a recording medium, said first pattern being comprised of electromagnetic wavefronts emanating from a subject and said second pattern being comprised of electromagnetic wavefronts emanating from a plurality of discrete and separate point sources of electromagnetic wavefronts, said plurality of point sources forming a code associated with said subject, means for irradiating said hologram with a pattern of electromagnetic wavefronts corresponding to said first pattern to produce an image of said second pattern of electromagnetic wavefronts, means responsive to each electromagnetic wavefront in the image of said second pattern for producing electrical signals coded in accordance with said code associated with said subject.

4. The device of claim 3, where said means for irradiating said hologram includes a medium cOntaining said subject and a source of substantially coherent electromagnetic radiation, said subject being located in the path of said electromagnetic radiation from said source and scattering said electromagnetic radiation, said means for irradiating further including means for directing said scattered radiation to said hologram to coact with said interference pattern of said first and second electromagnetic wavefronts, producing said image of said second electromagnetic wavefront pattern.

5. An optical device, comprising:

a hologram having a plurality of interference patterns thereon, each said pattern being formed by the interference of first and second electromagnetic wavefront sets, where said first sets are comprised of electromagnetic wavefronts emanating from separate subjects and said second sets are comprised of electromagnetic wavefronts emanating from combinations of discrete and separate sources of electromagnetic wavefronts, each said combination being a unique coded representation of one of said subjects, and means for irradiating said hologram with electromagnetic radiation corresponding to a selected first set of electromagnetic wavefronts from a selected subject to produce an image of the particular second set of electro-magnetic wavefronts which is a coded representation of the subject used to produce said selected first set of electromagnetic wavefronts, means responsive to each electromagnetic wavefront in said image for producing electrical signals having the particular code corresponding to said selected subject.

6. A device of claim 5, where said interference patterns are spatially separate on said hologram, said means for irradiating including a source substantially coherent electromagnetic radiation and a medium containing said subjects, said subjects scattering said electromagnetic radiation from said source to said separate interference patterns on said hologram, the scattered radiation from each said subject being incident on the interference pattern formed by electromagnetic wavefronts emanating from said subject when said interference pattern is formed on said hologram, thereby producing said coded representations associated with said interference patterns.

7. The device of claim 6, where said means for irradiating includes means for directing said scattered electromagnetic radiation to selected portions of said hologram.

8. An optical device, comprising:

a source of substantially coherent laser light, a recording medium, first means for irradiating a reference subject with a first selected portion of said laser light which produces scattered electromagnetic wavefronts that expose said recording medium to the electromagnetic wavefronts scattered by said subject, second means for separating a second selected given portion of said laser light into a plurality of discrete and separate sources of light that are mutually coherent with said first selected portion of said laser light, means for irradiating said recording medium with light from a combinatorial code of such discrete and separate point sources simultaneously with said scattered electromagnetic wavefronts from said subject to record on said recording medium the interference between said scattered wavefronts from said subject and light from said combinatorial code of point sources, said combinatorial code of point sources being different and unique for each separate subject being recorded, means for irradiating said recording medium with light that has been scattered from said subjects to produce wavefront patterns corresponding to combinatorial codes of said discrete and separate point sources representative of each subject used for reconstructing said combinatorial code wavefronts, means responsive to each reconstructed wavefront pattern for producing electrical signals having the combinatorial code associated with each said subject.

9. The device of claim 3, wherein said means for producing electrical signals is comprised of a plurality of photosensitive elements each of which is responsive to a different electromagnetic wavefront in said image.

10. The device of claim 3, wherein said means for producing electrical signals is comprised of an electron camera having a screen onto which said image is transmitted.

11. The device of claim 3, further including utilization means responsive to said coded electrical signals.

12. The device of claim 5, wherein said means for producing electrical signals is comprised of a plurality of photosensitive elements each of which is responsive to a different electromagnetic wavefront in said image.

13. The device of claim 5, wherein said means for producing electrical signals is comprised of an electron camera having a screen onto which said image is transmitted.