HOLOGRAM REPRODUCTION SYSTEM USING AN OPTICAL GRATING

• US 3,641,264 A
• Filed: 12/31/1969
• Issued: 02/08/1972
• Est. Priority Date: 12/31/1969
• Status: Expired due to Term

• Current Assignee: Albert Macovski
• Original Assignee: Albert Macovski
• Inventors: Macovski, Albert
• Primary Examiner(s): Griffin, Robert L.
• Assistant Examiner(s): Eckert, Jr., Richard K.
• Application Number:
  US04/889,392
• Time in Patent Office: 769 Days
• Field of Search: 178/6.5,6.8,DIG.3 350/3.5 313/77
• US Class Current: 348/40
• CPC Class Codes: G03H 1/22 Processes or apparatus for obtaining an optical image from holograms G03H1/26 - G03H1/34 take precedence
• CPC Class Codes: G03H 2001/0088 for video-holography, i.e. integrating hologram acquisition, transmission and display

Abstract

A holographic image reconstruction system in which holographic light amplitude and phase information are resolved separately for reconstruction of the original hologram. The amplitude component is separately detected and reproduced on a cathode-ray tube or other electronically addressable optical display. The image of the amplitude component is projected through an external optical grating onto a film for recording or onto a real time imaging system. Phase information from the holographic data is separately detected and superimposed on the amplitude data by varying the phase of the shadow image of the optical grating on the amplitude image. Phase modulation of the image of the grating is accomplished by modulating the aperture or angle of the lens which images the amplitude pattern through the grating onto the film, or by modulating the grating itself.

Claims

1. In a hologram reproduction system wherein an electrical signal is generated having signal components corresponding to holographic light amplitude and phase information, the improvement comprising:

means for detecting and separating said amplitude signal and phase signal components;

means generating an amplitude pattern from said amplitude signal components;

means for superimposing said amplitude pattern on a spatial frequency carrier; and

means for modulating the phase of said spatial frequency carrier in response to said phase component signal.

2. A method for constructing a hologram from holographic light amplitude and phase information in electrical analog signal form comprising:

detecting and separating the amplitude and phase components from said signal;

generating an amplitude pattern from said amplitude component;

superimposing said amplitude pattern on a spatial frequency carrier; and

modulating the phase of said spatial frequency carrier in response to the phase component of said signal.

3. A method for reproducing a hologram from holographic light amplitude and phase information comprising:

generating an electrical analog signal containing said holographic light amplitude and phase information;

detecting the amplitude component of said electrical signal;

generating from said amplitude component an amplitude pattern comprising an image of the amplitude component of said function;

projecting said amplitude image through an optical grating thereby to superimpose a shadow image of the grating on said amplitude pattern; and

detecting the phase component of said electrical signal and modulating the phase of the superimposed shadow image of said grating on said amplitude pattern in accordance with said phase component signal.

4. A method for constructing a hologram from holographic light amplitude and phase information modulated on an electrical signal carrier comprising:

separating the amplitude and phase information components;

applying the amplitude component signal to an electronically addressable optical display to generate an amplitude image;

projecting the amplitude image formed by said optical display through an optical grating thereby to superimpose the shadow image of said optical grating on said amplitude pattern; and

modulating the phase of the shadow image of said optical grating superimposed on the amplitude pattern in accordance with said phase component signal.

5. A holographic image reproduction system for constructing a hologram for holographic light amplitude and phase information in electrical analog signal form comprising;

means for envelope detecting the electrical analog signal to provide a signal corresponding to the holographic light amplitude information;

electrically addressable optical display means for generating from the holographic light amplitude signal, an amplitude image;

an optical grating spaced from said optical display means;

a lens system for imaging the amplitude pattern generated by said optical display through the optical grating;

means for detecting the phase information from said holographic electrical signal to thereby generate a signal corresponding to said holographic phase information; and

means for modulating the phase of the shadow image formed by said optical grating in response to said electrical phase signal.

6. A holographic image reproduction system as set forth in claim 5 wherein said means for modulating the phase of the shadow image formed by said optical grating comprises:

means for modulating the effective position of the aperture of the amplitude pattern imaging lens system.

7. A holographic image reproduction system As set forth in claim 6 wherein said means for modulating the effective position of the aperture comprises:

a sonic delay line interposed between crossed polarizers;

means for generating acoustic pulses in the sonic delay line; and

means for modulating the acoustic pulse generator according to said electrical phase signal.

8. A holographic image reproduction system as set forth in claim 7 wherein said means for modulating the phase of the shadow image formed by the said optical grating comprises:

means for modulating the effective position of said grating.

9. A method of reproducing a hologram from a hologram intensity function comprising:

separating said hologram intensity function into real and imaginary parts;

generating a two-dimensional pattern in response to each component;

superimposing said patterns on a spatial frequency carrier in phases spaced approximately 90* apart; and

summing said superimposed patterns to form an image.

10. A hologram reproduction system for constructing a hologram from a hologram intensity function in electrical analog signal form comprising:

synchronous detector means for separating said hologram intensity function into its real and imaginary parts comprising waveforms with positive and negative values;

means for separating each said real and imaginary part into positive and negative components;

means for forming the absolute value of each said component;

electrically addressable optical display means and means for sequentially applying said components to the optical display thereby to generate in sequence patterns corresponding to each said component;

means for superimposing said patterns on a spatial frequency carrier in phases spaced approximately 90* apart; and

means for adding said superimposed patterns to form a composite image.

11. A hologram reproduction system for constructing an image from a holographic intensity function comprising:

synchronous detector means for separating said hologram intensity function into real and imaginary components, each said component comprising a waveform having positive and negative portions;

means for separating each said component into positive and negative subcomponents thereby to generate four subcomponents, namely, real positive, real negative, imaginary positive and imaginary negative components;

means for sequentially applying said four subcomponents to an electronically addressable optical display thereby sequentially to form four patterns corresponding to said four subcomponents;

an optical grating spaced from said optical display;

means for imaging the sequential patterns formed by said optical display through said optical grating to thereby superimpose the shadow image of said optical grating on each said pattern; and

means for spacing the phase of said shadow images superimposed on said patterns in approximately 90* increments of the spatial frequency of said optical grating.

12. A hologram reproduction system as set forth in claim 11 wherein said means for spacing the phase of said shadow images comprises means for changing the position of the effective aperture of said imaging means.

13. A hologram reproduction system as set forth in claim 11 wherein said means for spacing the phase of said shadow images comprises means for changing the position of the grating.

14. A hologram reproduction system as set forth in claim 12 wherein said means for moving the effective position of the aperture of the imaging means according to the pattern being formed by said cathode-ray tube comprises a plurality of light valves in the exit pupil of said imaging means.

15. A hologram reproduction system as set forth in claim 12 wherein said means for moving the effective position of the aperture comprises an electro-optic polarizing plate intermediate the electronically addressable optical display and said imaging means and a linear polarizer having bands of varying polarization on the other side of the imaging means.

16. A hologram image reproduction system wherein an electrical signal is generated having signal components corresponding to holographic light amplitude and phase information, the improvement comprising:

a cathode-ray tube having an electron beam generator, electron beam deflection plates, and a screen of phosphor or controllable transparency responsive to said electron beam, said cathode ray tube further provided with phase deflection electrodes and magnetic focusing means along the path of the electron beams generated by said cathode ray tube, and a grating means positioned inside cathode-ray tube spaced from but close to the screen of phosphor or controllable transparency whereby the amplitude component of said electrical signal can be applied to the electron beam generator and whereby the phase component of said electrical signal can be applied to the phase deflection electrodes to sum on the screen of phosphor or controllable transparency amplitude patterns on which are superimposed the shadow image of said grating means in variable phases according to the signal applied to said phase deflection electrodes.

17. A system for three-dimensional real time imaging from holographic light amplitude and phase information comprising:

means for generating an amplitude pattern from said amplitude information;

means for superimposing said amplitude pattern on a spatial frequency carrier;

means modulating the phase of said spatial frequency carrier in accordance with said phase information;

means for displaying said amplitude pattern and superimposed spatial frequency carrier of variable phase in real time; and

means for interrogating said display with coherent light.

18. A method for constructing a hologram from holographic light amplitude and phase information in electrical analog signal form comprising:

detecting and separating the amplitude and phase components from said signal;

generating an amplitude pattern from said amplitude component;

superimposing said amplitude pattern on a spatial frequency carrier;

modulating the phase of said spatial frequency carrier in response to the phase component of said signal;

displaying said amplitude pattern and superimposed spatial frequency carrier in real time; and

illuminating said display with coherent light.

19. A holographic image reproduction system for constructing a hologram from holographic light amplitude and phase information in electrical analog signal form comprising:

means for envelope detecting the electrical analog signal to provide a signal corresponding to the holographic light amplitude information;

electrically addressable optical display means for generating from the holographic light amplitude signal, an amplitude image;

an optical grating spaced from said optical display means;

a lens system for imaging the amplitude pattern generated by said optical display through the optical grating;

means for detecting the phase information from said holographic electrical signal to thereby generate a signal corresponding to said holographic phase information;

means for modulating the phase of the shadow image formed by said optical grating in response to said electrical phase signal;

a screen of controllable transparency for displaying in real time, said amplitude pattern and superimposed optical grating shadow image; and

a coherent light source for illuminating said screen with coherent light.

20. A method for constructing a hologram from holographic light amplitude and phase information modulated on an electrical signal carrier comprising:

separating the amplitude and phase information components;

applying the amplitude component signal to an electronically addressable optical display to generate an amplitude image;

projecting the amplitude image formed by said optical display through an optical grating on saId amplitude pattern;

modulating the phase of the shadow image of said optical grating superimposed on the amplitude pattern in accordance with said phase component signal;

displaying the amplitude pattern and superimposed optical grating shadow image on a screen of controllable transparency;

illuminating said screen with coherent light.

21. A system for producing three-dimensional real time imaging comprising:

a cathode-ray tube for reconstructing a hologram from holographic light amplitude and phase information components in electrical analog signal form comprising electron beam generator means for generating an electron beam having an intensity responsive to the amplitude component of said electrical signal, scanning deflection means for scanning said electron beam in a predetermined raster, a screen of controllable transparency responsive to said electron beam, phase deflection means for controlling the angle of said electron beam in accordance with the phase component of said electrical signal, and grating means positioned within said cathode-ray tube and spaced from but close to said screen of controllable transparency; and

a coherent light source for interrogating said screen of controllable transparency with coherent light.