METHOD AND APPARATUS FOR UNAIDED STEREO VIEWING

• US 3,802,769 A
• Filed: 08/28/1972
• Issued: 04/09/1974
• Est. Priority Date: 08/28/1972
• Status: Expired due to Term

• Current Assignee: Albert A. Friesem, Frederick B. Rotz
• Original Assignee: Albert A. Friesem, Frederick B. Rotz
• Inventors: Friesem, Albert A., Rotz, Frederick B.
• Primary Examiner(s): Hayes, Monroe H.
• Application Number:
  US05/284,051
• Time in Patent Office: 589 Days
• Field of Search: 352/43,44 350/117
• US Class Current: 352/43
• CPC Class Codes: G02B 5/32 Holograms used as optical elements
• CPC Class Codes: G03B 35/00 Stereoscopic photography
• CPC Class Codes: Y10S 359/90 Methods

Abstract

An unaided stereo viewing system using a hologram as a rear projection screen. The hologram, by having two sets of interference patterns recorded thereon, has the property that, if a stereo pair of transparencies is projected thereon by the conjugates of the two reference beams used to record the interference patterns, light from one image is diffracted into the right eye of an observer and light from the other image is diffracted into the left eye. A plurality of alternating sets of interference patterns provide a plurality of stereo viewing zones.

Claims

1. A method of fabricating a holographic viewing screen for transmission diffracting use in an unaided stereo viewing system comprising the steps of:

exposing a photographic plate to light from a first reference source;

spatially modulating diffuse light a first time from a third source coherent with said first reference source and on the same side of the plate as said first reference source to provide a light image area and a dark image area;

exposing said plate to light from said third source simultaneously with said step of exposing said plate to light from said first reference source;

exposing said plate to light from a second reference source;

spatially modulating light from said third source a second time to establish diffuse light in an area that was dark in said first spatial modulation of said third source and to eliminate light from an area that was light in the first spatial modulation of said third source, said first source being coherent with said second reference source and on the same side of said plate as said second source; and

exposing said plate to the light of said third source, as secondly modulated, simultaneously with said exposure to said second reference source.

2. The method of claim 1 including the further steps of:

positioning said third source so that its optical axis is perpendicular to said plate, and positioning said first and second reference sources so that their optical axes form an angle which is bisected by said third source'"'"''"'"'s optical axis.

3. The method of claim 2 wherein said steps of exposing said plate to said third source are carried out by:

positioning a mask in a first position between said third source and said plate to expose said plate, and repositioning said mask to a second position between said third source and said plate to expose said plate, respectively.

4. The method of claim 3 wherein said mask contains a plurality of apertures spaced from each other by the width of said aperture, and wherein said repositioning step is carried out by moving said mask an aperture width, along a direction line in which the width is measured.

5. The method of claim 3 wherein Said mask contains a plurality of apertures spaced from each other by a distance greater than the width of an aperture, and wherein said repositioning step is carried out by moving said mask an aperture width, along a direction line in which the width is measured.

6. A method of fabricating a holographic viewing screen for use in an unaided stereo viewing system comprising the steps of:

splitting a single beam of light to obtain three light sources, positioning the third source so that its optical axis is perpendicular to a photographic plate, positioning the first and second reference sources so that their optical axes form an angle which is bisected by said third source'"'"''"'"'s optical axis, exposing said photographic plate to light from said first reference source, simultaneously exposing said plate to light from said third source coherent with said first reference source, and on the same side of said plate as said first source, said first pair of exposure steps being achieved by simultaneously blocking said second reference source and masking a first portion of said third source, exposing said plate to light from a second reference source, and simultaneously exposing said plate to the light of said third source, coherent with the second reference source and on the same side of said plate as said second source, said second pair of exposure steps being achieved by simultaneously blocking said first reference source and masking a second portion of the third source instead of said first portion thereof.

7. A holographic viewing screen for use in a rear projection unaided stereo viewing system comprising:

a film having recorded thereon;

a first set of interference patterns of a first light beam and a third light beam for diffracting light in a first direction, a second set of interference patterns of a second light beam and said third light beam for diffracting light in a second direction, and wherein said first and second set of interference patterns are mutually incoherent so as to provide two angles of diffraction.

8. An apparatus for producing a holographic viewing screen for transmission diffracting use in an unaided stereo viewing system comprising:

first light means for transmitting a first reference light beam, second light means for transmitting a second reference light beam, third light means for transmitting a diffuse third light beam, light sensitive recording means for recording said three light beams, blocking means for interrupting said recording of said first and second reference light beams individually, said unblocked reference light beam being coherent with said third light beam, and masking means for interrupting the recording of an areal portion of said diffuse third light beam during blocking of said first reference light beam and for interrupting the recording of a different areal portion of said diffuse third light beam during said blocking of said second reference light beam, said three light beams approaching said recording means from the same side.

9. An apparatus for producing a holographic viewing screen for use in an unaided stereo viewing system comprising:

first light means for transmitting a first reference light beam, second light means for transmitting a second reference light beam, third light means for transmitting a third light beam, light sensitive recording means for recording said three light beams, blocking means for interrupting said recording of said first and second reference light beams individually, and masking means for interrupting recording of a portion of said third light beam wherein said three light beams emanate from the same side of said recording means, and wherein;

said third light means has its optical axis perpendicular to said recording means, and said first and second light means'"'"''"'"' optical axes form an angle which is bisected by said third light means'"'"''"'"' optical axis.

10. ApparatUs of claim 9 wherein said first, second and third light means comprises:

light source means for producing a single beam of light, beam splitter means for splitting said single beam of light into three beams of light, and optic means for directing said light beams'"'"''"'"' optical axes.

11. Apparatus of claim 9 wherein said masking means includes a mask with a plurality of apertures spaced from each other by the width of said aperture, whereby said masking means interrupts and transmits equal amounts of said third light beam.

12. Apparatus of claim 9 wherein said masking means includes a mask with a plurality of apertures spaced from each other by distances greater than the width of an aperture.

13. A method of projecting an unaided stereo image comprising the steps of:

providing a transmission surface on which two mutually noncoherent superimposed diffraction holograms are recorded, the first of said holograms corresponding to a right eye image and the second corresponding to a left eye image, projecting a right stereo image onto said transmission surface using a first readout beam, projecting a left stereo image onto the same side of said transmission surface using a second readout beam, and transmitting to a viewing station on the other side of said transmission surface a pair of mutually exclusive stereo image projections, each of said projections occupying a different transverse area at said viewing station, whereby the right eye of a viewer at said station sees said right stereo image and his left eye sees said left stereo image, each of said eyes being in a different one of said different transverse areas.

14. A method of claim 13 wherein said transmitting step generates a plurality of pairs of mutually exclusive spaced apart stereo image projections to be viewed by a plurality of viewers.

15. A method of claim 13 wherein said transmission surface comprises a hologram with two sets of interference patterns of a first and a second reference beam individually with a third beam recorded in a mutually incoherent manner.

16. A method of claim 15 wherein said first and second reference beams are the conjugate of said first and second readout beams respectively.

17. An unaided stereo viewer comprising:

projection means for obliquely projecting a pair of stereo scenes, and holographic screen means for receiving said projections on one side of said screen means and for transmitting and diffracting each of said stereo scenes in different directions to reconstruct an image of a first of said scenes in a first region and to reconstruct an image of the second of said scenes in a second region, both of said regions being on the other side of said screen means from said projection means, whereby an observer positioned with one eye in said first region and the other eye in said second region sees only the first of said images in the first eye and only the second of said images in the second eye.

18. A viewer as in claim 17 wherein said screen means comprises a hologram means with two sets of interference patterns recorded in a mutually incoherent manner.

19. A viewer as in claim 18 wherein each of said sets of interference patterns transmits only a corresponding member of said pair of projected stereo images.

20. A viewer as in claim 17 wherein said projection means comprises:

first and second light source means for illuminating the rear of said screen means, and a pair of stereo transparencies positioned singularly between a corresponding first and second light source means and said screen means.

21. A viewer as in claim 20 wherein said screen means comprises:

a hologram means with two sets of interference patterns recorded thereon, each of said sets of interference patterns transmits only a corresponding light source means, and its corresponding transparency image.

22. A viewer as in claim 21 wherein said sets of interference patterns are recorded in a mutually incoherent mannEr in said hologram means and thus diffract mutually exclusive stereo images to corresponding eyes of an observer.

23. A viewer as in claim 21 wherein said sets of interference patterns comprise a plurality of interference patterns which diffract a plurality of mutually exclusive stereo images to the corresponding eyes of a plurality of observers.

24. A viewer as in claim 23 wherein said stereo images define a plurality of contiguous viewing zones.

25. A viewer as in claim 23 wherein said stereo images define a plurality of spaced viewing zones.