System for synthesizing strip-multiplexed holograms

• US 4,206,965 A
• Filed: 08/23/1976
• Issued: 06/10/1980
• Est. Priority Date: 08/23/1976
• Status: Expired due to Term

• Current Assignee: Stephen P. Mcgrew
• Original Assignee: Stephen P. Mcgrew
• Inventors: McGrew, Stephen P.
• Primary Examiner(s): Corbin, John K.
• Assistant Examiner(s): Lee, John D.
• Application Number:
  US05/716,463
• Time in Patent Office: 1,387 Days
• Field of Search: 350/3.5, 350/173, 350/3.66, 350/3.76, 350/3.84
• US Class Current: 359/9
• CPC Class Codes: G03H 1/0406 Image plane or focused image holograms, i.e. an image of the object or holobject is formed on, in or across the recording plane
• CPC Class Codes: G03H 1/0486 Improving or monitoring the quality of the record, e.g. by compensating distortions, aberrations
• CPC Class Codes: G03H 1/06 using incoherent light
• CPC Class Codes: G03H 1/0891 Processes or apparatus adapted to convert digital holographic data into a hologram G03H1/2294 takes precedence
• CPC Class Codes: G03H 1/24 using white light , e.g. rainbow holograms
• CPC Class Codes: G03H 1/26 Processes or apparatus specially adapted to produce multiple sub- holograms or to obtain images from them, e.g. multicolour technique
• CPC Class Codes: G03H 2001/2685 One step recording process
• CPC Class Codes: G03H 2001/2695 Dedicated printer holographic printers G03H1/0476

Abstract

A system for synthesizing strip-multiplexed holograms, with or without coherent light, from a plurality of two-dimensional images. The two-dimensional images may be formed by a motion picture film of a rotating subject such that each image is a view of the subject from a different angle. The images are then non-diffusely and anamorphically projected by a lens system which compresses the image in a first direction and expands the image in a second direction orthogonal to the first direction. The projected image or object beam is then superimposed on the reference beam by a lens-beamsplitter which transforms the substantially planar object beam into a substantially cylindrical wavefront and projects it and the reference beam onto a holographic recording medium. As each two-dimensional image is sequentially projected, the holographic recording medium is shifted so that a plurality of laterally displaced strips are recorded. Alternate embodiments of the system utilize a holographic diffraction grating contact printed by means of the object beam onto the holographic recording medium instead of a reference beam to produce an interference pattern, a video projection system instead of a cinema film projection system, a three-color image of coherent or nondiffuse light instead of a monochromatic image, and/or three separate holographic diffraction gratings produced by three different monochromatic sources of coherent light instead of a single holographic diffraction grating in order to produce multicolor holograms, or a reference beam or reflective surface relief diffraction grating or Fresnel mirror behind the holographic recording medium for synthesis of reflection holograms instead of transmission holograms. The system is capable of synthesizing image plane holograms by using a variety of disclosed processes. Techniques are also disclosed for synthesizing holograms which can be displayed flat and illuminated with a point light source without introducing image distortion.

Claims

1. A system for synthesizing strip-multiplexed transmission holograms, comprising:

image projection means for sequentially generating a plurality of two-dimensional images of coherent, substantially non-diffuse light;

anamorphic projection means for compressing said images in a first direction and expanding said images in a second direction to form an elongated object beam, said second direction being orthogonal to said first direction, said anamorphic projection means being positioned directly beyond said image projection means before said object beam has significantly diverged;

lens-beamsplitter means spaced apart from said anamorphic projection means, said lens-beamsplitter means being relatively narrow in said first direction and relatively long in said second direction, said lens-beamsplitter transforming said image beam incident on a first face into a substantially cylindrical wavefront, superimposing a second beam incident on a second face onto said cylindrical wavefront, and projecting said cylindrical wavefront and said second beam in a direction perpendicular to a third face;

reference beam generator means for projecting an elongated beam of coherent, substantially nondiffuse light onto the second face of said lens-beamsplitter means during the projection of said object beam onto said lens-beamsplitter means; and

holographic recording medium transport means positioned directly beyond the third face of said lens-beamsplitter for sequentially advancing a holographic recording medium in a predetermined direction by a predetermined increment for each two-dimensional image generated by said image projection means such that at least one strip hologram is recorded on said recording medium for each of said two-dimensional images to form a strip-multiplexed hologram.

2. The system of claim 1 wherein said image projection means comprise a cinema film projector system including cinema film transport means for sequentially advancing a strip of cinema film in single frame increments past a fixed projection aperture, and illumination means for projecting a beam of coherent, substantially nondiffuse light through said projection aperture thereby projecting a beam of coherent, substantially nondiffuse light modulated by the images on said cinema film onto said anamorphic projection system.

3. The system of claim 1 wherein said image projection means comprise:

a video projection kinescope including electron gun means directing electrons to the face of said video projection kinescope in accordance with a video signal; and

means for generating a beam of coherent, substantially nondiffuse light and projecting it onto the face of said video projection kinescope such that said face modulates the coherent, substantially nondiffuse light in accordance with the electron pattern on said face corresponding to said video signal.

4. The system of claim 1, wherein said image projection means comprise:

an incoherent-to-coherent image convertor including means for focusing a sequence of images onto the input face of said incoherent-to-coherent image convertor; and

means for generating a beam of coherent, substantially nondiffuse light and directing it onto said image convertor such that said image convertor spatially modulates said beam of light in accordance with said images focused onto the input face of said convertor.

5. The system of claim 1, wherein said anamorphic projection means comprise a cylindrical lens placed directly beyond said image projection means with the axis of said cylindrical lens extending along said second direction, said anamorphic projection means further including a spherical lens placed beyond the focal length of said cylindrical lens thereby causing said images to diverge along said second direction without diverging substantially along said first direction.

6. The system of claim 1, wherein said anamorphic projection means comprise a cylindrical lens positioned beyond said image projection means, said cylindrical lens having its axis extending along said first direction whereby said image diverges along said second direction without diverging substantially along said first direction.

7. The system of claim 1, wherein said anamorphic projection means comprise a spherical lens followed by a cylindrical lens having its axis extending along said first direction thereby diverging said image in said second direction without substantially diverging said image along said first direction.

8. The system of claim 1, wherein said lens-beamsplitter means comprise a pair of elongated triangular prisms separated by a partially reflective, partially transmissive layer, one of said prisms having an elongated cylindrical lens secured to one face thereof such that a wavefront incident on said cylindrical lens is transformed into a substantially cylindrical wavefront and superimposed on a wavefront transmitted through an adjacent face of one of said prisms.

9. The system of claim 1, wherein said lens-beamsplitter means comprise a pair of elongated triangular prisms separated by a partially reflective, partially transmissive layer, said prisms having an elongated cylindrical lens secured to three faces of said prisms.

10. The system of claim 1, wherein said lens-beamsplitter means comprise:

a first elongated prism having first and second planar faces and a third concave face therebetween; and

a second elongated prism having first and second planar faces and a third convex face therebetween, the concave face of said first prism and the convex face of said second prism flushly contacting opposite sides of a partially reflective, partially transmissive layer.

11. The system of claim 1, wherein said lens-beamsplitter means comprise an elongated cylindrical lens followed by an elongated beamsplitter oriented so that a wavefront transformed by the cylindrical lens is superimposed upon another wavefront by means of the beam combining property of the beamsplitter.

12. The system of claim 1, further including means for synthesizing holograms viewable flat without significant distortion using a point light source comprising reference beam control means for adjusting the angle of incidence of said reference beam on said lens-beamsplitter means as each image is recorded on said holographic recording medium such that the angle of incidence of said reference beam on said holographic recording medium for each strip hologram corresponds to the angle at which said point light source strikes each strip hologram when said hologram is displayed flat.

13. The system of claim 12, wherein said reference beam control means comprise:

a mounting platform including means for moving said platform along an axis parallel to the second face and perpendicular to the first face of said lens-beamsplitter means in precisely controlled increments;

a turntable rotatably mounted on said mounting platform including means for rotating said turntable in precisely controlled increments; and

a reference beam projector fixedly mounted on said turntable for projecting said reference beam onto said lens-beamsplitter from a position controlled by the position of said mounting platform and at an angle controlled by the angle of said turntable.

14. The system of claim 1, further including means for synthesizing multicolor holograms comprising a movable reference beam projector for controlling the angle at which a particular color component of the recorded image is reconstructed.

15. The system of claim 1, further including means for synthesizing multicolor holograms comprising a plurality of reference beam generator means for projecting a plurality of elongated beams of coherent, substantially nondiffuse light of differing colors onto the second face of said lens-beamsplitter means during coherent, substantially nondiffuse projection of said images in differing colors onto the first face of said lens-beamsplitter means.

16. The system of claim 1, further including a spatial filter placed at a point of focus of said object beam for enhancing and suppressing predetermined spatial frequencies in the two-dimensional images.

17. The system of claim 1, further including means for laterally displacing the image modulation for each of said strip holograms relative to its phase modulation such that the image modulation is displaced in the direction of the center of the strip-multiplexed hologram with respect to its grating pattern by an amount which varies with distance from the center of said hologram thereby generating a strip-multiplexed hologram which may be viewed flat without substantial distortion when illuminated with a point illumination source.

18. A system for synthesizing strip-multiplexed transmission holograms, comprising:

image projection means for sequentially generating a plurality of two-dimensional images of substantially nondiffuse light;

anamorphic projection means for compressing said images in a first direction and expanding said images in a second direction to form an elongated object beam, said second direction being orthogonal to said first direction, said anamorphic projection means being positioned directly beyond said image projection means before said object beam has significantly diverged;

an elongated cylindrical lens having its axis extending along said second direction, said lens being spaced apart from said anamorphic projection means and receiving said object beam thereby transforming said object beam into a substantially cylindrical wavefront;

a diffraction grating placed in the path of said cylindrical wavefront, said diffraction grating having a pattern corresponding to the interference pattern between a coherent, substantially nondiffuse reference beam and a coherent, substantially nondiffuse, cylindrical object beam; and

holographic recording medium transport means positioned directly beyond said diffraction grating for sequentially advancing a holographic recording medium in a predetermined direction by a predetermined increment for each two-dimensional image generated by image projection means such that a strip hologram is recorded on said recording medium for each of said two-dimensional images to form a strip-multiplexed hologram.

19. The system of claim 18 wherein said image projection means comprise a cinema film projector system including cinema film transport means for sequentially advancing a strip of cinema film in single frame increments past a fixed projection aperture, and illumination means for projecting a beam of substantially non diffuse light through said projection aperture thereby projecting a beam of substantially nondiffuse light modulated by the images on said cinema film onto said anamorphic projection means.

20. The system of claim 18, wherein said image projection means comprise:

a video projector kinescope including electron gun means directing electrons to the face of said video projection kinescope in accordance with a video signal; and

means for generating a beam of substantially nondiffuse light and projecting it onto the face of said video projection kinescope such that said face modulates the substantially nondiffuse light in accordance with the electron pattern on said face corresponding to said video signal.

21. The system of claim 18, wherein said image projection means comprise:

an image convertor including means for focusing a sequence of images onto the input face of said image convertor; and

means for generating a beam of substantially nondiffuse light and directing it onto said image convertor such that said convertor spatially modulates said beam of light in accordance with said images focused onto the input face of said convertor.

22. The system of claim 18, wherein said anamorphic projection means comprise a cylindrical lens placed directly in front of said image projection means with the axis of said cylindrical lens extending along said second direction, said anamorphic projection means further including a spherical lens placed beyond the focal length of said cylindrical lens thereby causing said images to diverge along said second direction without divering substantially along said first direction.

23. The system of claim 18, wherein said anamorphic projection means comprise a cylindrical lens positioned beyond said image projection means, said cylindrical lens having its axis extending along said first direction whereby said image diverges along said second direction without diverging substantially along said first direction.

24. The system of claim 18, wherein said anamorphic projection means comprise a spherical lens followed by a cylindrical lens having its axis extending along said first direction thereby causing said image to diverge in said second direction without substantially diverging along said first direction.

25. The system of claim 18, further including means for synthesizing holograms viewable flat without significant distortion using a point light source comprising a plurality of diffraction gratings mounting on transport means for sequentially placing each of said diffraction gratings adjacent said cylindrical lens, each of said diffraction gratings corresponding to the interference pattern between an unmodulated object beam and a reference beam having a different angle of incidence such that the diffraction grating thereby contact printed onto said holographic recording medium for each hologram strip corresponds to the angle at which light from said point light source strikes each strip hologram when said hologram is displayed flat.

26. The system of claim 18, including means for synthesizing holograms viewable flat without significant distortion using a point light source comprising means for laterally displacing the image modulation for each of said strip holograms relative to its phase modulation such that the image modulation is displaced in the direction of the center of the strip-multiplexed hologram with respect to its grating pattern by an amount which varies with distance from the center of said hologram thereby generating a strip-multiplexed hologram which may be viewed flat without substantial distortion when illuminated with a point illumination source.

27. The system of claim 18, further including means for synthesizing multicolor holograms comprising a plurality of holographic gratings, each having a grating pattern corresponding to the interference between an unmodulated object beam of a specific color and a reference beam of the same specific color such that the specific color for each of the plurality of gratings is different, and means for positioning a predetermined grating in the path of said cylindrical wavefront for each exposure.

28. A system for synthesizing strip-multiplexed reflection holograms, comprising:

image projection means for sequentially generating a pluraltiy of two-dimensional images of coherent, substantially nondiffuse light;

anamorphic projection means for compressing said images in a first direction and expanding said images in a second direction to form an elongated object beam, said second direction being orthogonal to said first direction, said anamorphic projection means being positioned directly beyond said image projection means before said object beam has significantly diverged;

an elongated cylindrical lens having its axis extending along said second direction, said lens being spaced apart from said anamorphic projection means and receiving said object beam thereby transforming said object beam into a substantially cylindrical wavefront;

holographic recording medium transport means positioned directly beyond said cylindrical lens for sequentially advancing a holographic recording medium in a predetermined direction by a predetermined increment for each two-dimensional image generated by said image projection means; and

reference beam generator means for projecting an elongated beam of coherent, substantially nondiffuse light onto the opposite surface of said holographic recording medium that said object beam is incident on, said beams being directly adjacent to each other such that a strip reflection hologram is recorded on said recording medium for each of said two-dimensional images to form a strip-multiplexed reflection hologram.

29. The system of claim 28, wherein said image projection means comprise a cinema film projector system including cinema film transport means for sequentially advancing a strip of cinema film in single frame increments past a fixed projection aperture, and illumination means for projecting a beam of coherent, substantially nondiffuse light through said projection aperture thereby projecting a beam of coherent, substantially nondiffuse light modulated by the images on said film onto said anamorphic projection system.

30. The system of claim 28, wherein said image projection means comprise:

a video projector kinescope including electron gun means directing electrons to the face of said video projection kinescope in accordance with a video signal; and

means for generating a beam of coherent, substantially nondiffuse light and projecting it onto the face of said video projection kinescope such that said face modulates the coherent, substantially nondiffuse light in accordance with the electron pattern on said face corresponding to said video signal.

31. The system of claim 28, wherein said image projection means comprise:

an incoherent-to-coherent image convertor including means for focusing a sequence of images onto the input face of said incoherent-to-coherent image convertor; and

means for generating a beam of coherent, substantially nondiffuse light and directing it onto said incoherent-to-coherent image convertor such that said convertor spatially modulates said beam of light in accordance with said images focused onto the input face of said convertor.

32. The system of claim 28, wherein said anamorphic projection means comprise a cylindrical lens placed directly beyond said image projection means with the axis of said cylindrical lens extending along said second direction, said anamorphic projection means further including a spherical lens placed beyond the focal length of said cylindrical lens thereby causing said object beam to diverge along said second direction without diverging substantially along said first direction.

33. The system of claim 28, wherein said anamorphic projection means comprise a cylindrical lens positioned beyond said image projection means, said cylindrical lens having its axis extending along said first direction whereby said object beam diverges along said second direction without diverging substantially along said first direction.

34. The system of claim 28, wherein said anamorphic projection means comprise a spherical lens followed by a cylindrical lens having its axis extending along said first direction thereby diverging said object beam in said second direction without substantially diverging said object beam along said first direction.

35. The system of claim 28, further including means for synthesizing holograms viewable flat without significant distortion using a point light source comprising reference beam control means for adjusting the angle of incidence of said reference beam on said holographic recording medium as each image is recorded on said holographic recording medium such that the angle of incidence of said reference beam on said recording medium for each strip hologram corresponds to the angle at which said point light source strikes each strip hologram when said hologram is displayed flat.

36. The system of claim 28, further including means for increasing the vertical viewing angle of said reflection holograms comprising a unilateral diffusing screen placed between the elongated cylindrical lens and the holographic recording medium such that the object beam is diffused in the direction parallel to the axis of the elongated cylindrical lens, thereby forming a strip-multiplexed reflection hologram viewable over an extended range of vertical angles.

37. The system of claim 28, wherein said image projection means projects coherent, substantially nondiffuse, multicolor images, and wherein said reference beam generator means projects a coherent, substantially nondiffuse, multicolor reference beam, and wherein said image projection means and said reference beam generator means project the same set of colors, and wherein the corresponding color components in the two means are mutually coherent, thereby synthesizing multicolor strip-multiplexed reflection holograms.

38. A system for synthesizing strip-multiplexed reflection holograms, comprising:

image projection means for sequentially generating a plurality of two-dimensional images of substantially nondiffuse light;

anamorphic projection means for compressing said images in a first direction and expanding said images in a second direction to form an elongated object beam, said second direction being orthogonal to said first direction, said anamorphic pprojection means being positioned directly beyond said image projection means before said object beam has significantly diverged;

an elongated cylindrical lens having its axis extending along said second direction, said lens being spaced apart from said anamorphic projection means and receiving said object beam thereby transforming said object beam into a substantially cylindrical wavefront;

holographic recording medium transport means positioned directly beyond said cylindrical lens for sequentially advancing a holographic recording medium in a predetermined direction by a predetermined increment for each two-dimensional image generated by said image projection means, said holographic recording medium transport means having a reflecting and transforming means positioned on the opposite side of said recording medium from said cylindrical lens; and

means for reflecting said cylindrical wavefront after it emerges from the opposite side of the holographic recording medium, and transforming said cylindrical wavefront into another wavefront having a shape and direction such that the interference between the reflected, transformed wavefront and the cylindrical wavefront forms a strip reflection hologram in the holographic recording medium and such that a sequence of such strip holograms recorded adjacently forms a strip-multiplexed reflection hologram.

39. The system of claim 38, wherein said image projection means comprise:

a cinema film projector system including cinema film transport means for sequentially advancing a strip of cinema film in single frame increments past a fixed projection aperture, and illumination means for projecting a beam of substantially nondiffuse light through said projection aperture thereby projecting a beam of substantially nondiffuse light modulated by the images on said film onto said anamorphic projection system.

40. The system of claim 38, wherein said image projection means comprise:

a video projection kinescope including electron gun means directing electrons to the face of said video projection kinescope in accordance with a video signal; and

means for generating a beam of substantially nondiffuse light and projecting it onto the face of said video projection kinescope such that said face modulates the substantially nondiffuse light in accordance with the electron pattern on said face corresponding to said video signal.

41. The system of claim 38, wherein said image projection means comprise:

an image convertor including means for focusing a sequence of images onto the input face of said image convertor; and

means for generating a beam of substantially nondiffuse light and directing it onto said image convertor such that said convertor spatially modulates said beam of light in accordance with said images focused onto the input face of said convertor.

42. The system of claim 38, wherein said anamorphic projection means comprise a cylindrical lens placed directly beyond said image projection means with the axis of said cylindrical lens extending along said second direction, said anamorphic projection means further including a spherical lens placed beyond the focal length of said cylindrical lens thereby causing said object beam to diverge along said second direction without diverging along said first direction.

43. The system of claim 38, wherein said anamorphic projection means comprise a cylindrical lens positioned beyond said image projection means, said cylindrical lens having its axis extending along said first direction whereby said object beam diverges along said second direction without diverging substantially along said first direction.

44. The system of claim 38, wherein said anamorphic projection means comprise a spherical lens followed by a cylindrical lens having its axis extending along said first direction thereby diverging said object beam in said second direction without substantially diverging said beam along said first direction.

45. The system of claim 38, further including means for synthesizing holograms viewable flat without significant distortion using a point light source comprising a plurality of reflecting and transforming means mounted on transport means for sequentially advancing each of said reflecting and transforming means, each of said reflecting and transforming means producing a reflected and transformed wavefront corresponding to a reference beam having a different angle of incidence such that the interference pattern recorded in said holographic recording medium for each strip hologram corresponds to the angle at which said point light source strikes each strip hologram when said hologram is displayed flat.

46. The system of claim 38, further including means for synthesizing multicolor holograms comprising a multicolor coded reference beam holographic grating having an interference pattern corresponding to a plurality of reference beams of coherent, nondiffuse light of differing colors.

47. The system of claim 38, further including a plurality of said means for reflecting and transforming said cylindrical wavefront mounted on transport means for sequentially placing each of said reflecting means on the opposite side of said recording medium from said cylindrical lens as the images are sequentially recorded, each of said reflecting means configured such that the reflected and transformed wavefront travels in a direction corresponding to the angle at which light from a point illumination source strikes each strip hologram when said strip-multiplexed hologram is displayed flat, so that the resulting strip-multiplexed hologram may be displayed flat without distortion when illuminated with a point light source.

48. The system of claim 38, further including means for synthesizing holograms viewable flat without significant distortion using a point light source comprising means for displacing the reflective means relative to the cylindrical wavefront by an amount which varies with distance from the center of the strip-multiplexed hologram so that said reflected and transformed beam travels in a direction corresponding to the angle at which light from a point illumination source strikes each strip hologram when said strip-multiplexed hologram is displayed flat, so that the resulting strip-multiplexed hologram may be displayed flat without distortion when illuminated with a point light source.

49. The system of claim 38, further including means for synthesizing holograms with an extended vertical viewing angle comprising:

a unilateral diffusing screen placed between the elongated cylindrical lens and the holographic recording medium such that the object beam is diffused in the direction parallel to the axis of the elongated cylindrical lens; and

reflecting means to transform the diffuse object beam into a substantially nondiffuse beam such that the interference between the reflected wavefront and the cylindrical wavefront forms a strip hologram in the recording medium, such reflecting means comprising a reflective hologram formed by the interference between a longitudinally diffuse cylindrical wave and a nondiffuse reference beam, such that the reflected and transformed beam is a reconstruction of the nondiffuse reference beam.

50. The system of claim 38, further including means for synthesizing multicolor holograms comprising:

projection means utilizing a multicolor source of nondiffuse light; and

reflecting and transforming means such that all color components of the object beam are reflected and transformed into the same predetermined shape and direction, so that all color components of the object beam are simultaneously recorded as superimposed strip holograms, thereby forming multicolor strip holograms.

51. A method of synthesizing image plane strip-multiplexed holograms comprising:

generating a sequence of images representing views from a series of perspectives along a line in the vicinity of the object; and

recording the images as a series of laterally spaced strip holograms in a holographic recording medium in order to form an image plane strip-multiplexed hologram whose surface corresponds to the locus of the views represented by the sequence of images.

52. The method of claim 51, wherein the sequence of images is generated by recording the images of the object as reflected in a concave cylindrical mirror which is relatively large compared to the object.

53. The method of claim 51, wherein the sequence of images is generated by recording the images of the object as reflected in a concave ellipsoidal mirror which is relatively large compared to the object.

54. The method of claim 51, wherein the sequence of images is generated by recording the images of the object as reflected in an anamorphic Fresnel reflector which is relatively large compared to the object.

55. The method of claim 51, wherein the sequence of images is generaged by recording the images of the object as transformed by an anamorphic Fresnel lens which is relatively large compared to the object.

56. The method of claim 51, wherein the sequence of images is generated by recording the images of the object as transformed by a cylindrical lens which is relatively large compared to the object.

57. The method of claim 51, wherein said step of generating a sequence of images comprises:

recording a first sequence of images of an object from a sequence of points along a line relatively distant from the object; and

generating a second sequence of images from the first sequence by the process of assembling each of the second sequence of images from vertical strips from the first sequence of images such that the second sequence represents a series of views from perspectives along a second line in the vicinity of the object.

58. A method of synthesizing strip-multiplexed transmission holograms comprising:

generating a sequence of images representing views from a series of perspectives along a line relative to the object wherein the object in said images is offset laterally relative to the center of said images by an amount and in a direction so as to compensate for the error in reconstruction angle of each image resulting from the laterally varying angle of incidence of illumination light from a point source onto the intended shape of the hologram; and

synthesizing a strip-multiplexed hologram from said sequence of images using a fixed reference beam, such that the image offset in said sequence compensates for the difference in relationship between the hologram and reference beam, and the hologram and point illumination source.