Diffraction optics diffusing screen laminate for full color on-axis viewing

• US 4,960,314 A
• Filed: 07/05/1988
• Issued: 10/02/1990
• Est. Priority Date: 07/05/1988
• Status: Expired due to Term

• Current Assignee: Dai Nippon Printing Company Limited
• Original Assignee: Hughes Aircraft Company (Rtx Corporation)
• Inventors: Smith, Ronald T., Hegg, Ronald G.
• Primary Examiner(s): Bovernick, Rodney B.
• Assistant Examiner(s): SHAFER, RICKY D
• Application Number:
  US07/214,986
• Time in Patent Office: 819 Days
• Field of Search: 350/3.7, 350/3.85, 350/3.86, 350/3.77, 350/162.11
• US Class Current: 359/15
• CPC Class Codes: G02B 5/00 Optical elements other than lenses light guides G02B6/00; optical logic elements G02F3/00
• CPC Class Codes: G02B 5/32 Holograms used as optical elements
• CPC Class Codes: G03H 1/0256 having specific functional layer
• CPC Class Codes: G03H 1/2205 using downstream optical component
• CPC Class Codes: G03H 1/2249 Holobject properties
• CPC Class Codes: G03H 1/24 using white light , e.g. rainbow holograms
• CPC Class Codes: G03H 2001/2234 Transmission reconstruction
• CPC Class Codes: G03H 2001/2263 Multicoloured holobject
• CPC Class Codes: G03H 2001/2265 Achromatic holobject
• CPC Class Codes: G03H 2001/264 One hologram being a HOE
• CPC Class Codes: G03H 2223/12 Amplitude mask, e.g. diaphragm, Louver filter
• CPC Class Codes: G03H 2260/10 Dichromated gelatine or equivalents

Abstract

An optical screen module for full-color, on axis viewing is described. The module has a transmission holographic optical element, a louver filter, and a diffraction optics diffusion screen. Input light is diffracted off-axis by the transmission holographic element, passed through the louver filter and rediffracted on-axis by the diffusion screen. The module can handle full-color light because the dispersion in the transmission hologram is compensated by that in the diffusion screen. The louver filter blocks the undiffracted zero-order light while allowing the light diffracted by the transmission hologram to pass through.

Claims

1. An optical apparatus comprising:

a transmission holographic optical element comprising means for diffracting a portion of a beam of multi-color light incident on said element to redirect the diffracted light so that it exits from said element at acute angles relative to the remaining portion of the incident beam;

an optical louver filter positioned with respect to said transmission holographic element so that light passing through said element is incident on said louver filter, said filter comprising a plurality of transparent cells separated by opaque louvers, said louvers being cooperatively arranged with respect to the diffracted light from said transmission holographic optical element so that diffracted multi-color light passes unimpeded through said filter and zero-order light is blocked by said louvers; and

a diffraction optics holographic optical diffusion screen supported adjacent said louver filter and comprising means for diffusively diffracting light exiting said filter toward a predetermined exit pupil so that light diffracted by said optical diffusion screen is substantially directed toward and illuminates said exit pupil.

2. The optical apparatus of claim 1 wherein said transmission holographic element is supported on a first rigid glass substrate, and said diffraction optics holographic diffusion screen is supported on a second rigid glass substrate, and wherein said first and second substrates sandwich said transmission holographic element, said louver filter and said diffraction optics diffusion screen.

3. The optical apparatus of claim 1 wherein said means for diffracting a portion of a beam of light incident on said transmission holographic optical element comprises a holographic dichromated gelatin film.

4. The optical apparatus of claim 1 wherein said means for diffusively diffracting light exiting said filter comprises a holographic dichromated gelatin film.

9. The optical apparatus of claim 1 wherein light is incident on said apparatus along an incident axis which is substantially normal to said transmission holographic optical element, and said louvers are slanted with respect to said incident axis and are spaced apart by a distance such that the multi-color light diffracted by said transmission holographic optical element passes through said louver filter without reflection by said louvers, and the zero-order light is blocked by said louvers.

10. The optical apparatus of claim 9 wherein the angle at which said louvers are slanted with respect to said incident axis is about 30 degrees.

11. The optical apparatus of claim 1 wherein said louvers are spaced apart by about 0.005 inches.

12. The optical apparatus of claim 1 wherein said optical louver filter has a thickness in the range of 0.030 to 0.050 inches.

13. The optical apparatus of claim 1 wherein said beam of light is incident on said optical apparatus along a projection axis which is substantially normal to said transmission holographic optical element, and said exit pupil lies on a viewing axis extending substantially normal to said diffusion screen.

5. An optical apparatus comprising:

a full-color image source projector for projecting a beam of full-color image-information-bearing light;

a transmission holographic optical element comprising means disposed with respect to said image source projector for diffracting a portion of said beam to redirect said diffracted light beam so that it exits from said element at acute angles relative to the remaining portion of said beam incident on said transmission holographic optical element;

an optical louver filter positioned with respect to said transmission holographic element so that light passing through said element is incident on said louver filter, said filter comprising a plurality of transparent cells separated by opaque louvers, said louvers being cooperatively arranged with respect to the diffracted light from said transmission holographic optical element so that the diffracted light passes unimpeded through said filter and zero-order light is blocked by said louvers; and

a diffraction optics holographic optical diffusion screen supported adjacent said louver filter and comprising means for diffusively diffracting light exiting said filter toward a predetermined exit pupil so that light diffracted by said optical diffusion screen is substantially directed toward and illuminates said exit pupil.

6. The optical apparatus of claim 5 wherein said transmission holographic element is supported on a first rigid glass substrate, and said diffraction optics holographic diffusion screen is supported on a second rigid glass substrate, and wherein said first and second substrates sandwich said transmission holographic element, said louver filter and said diffraction optics diffusion screen.

7. The optical apparatus of claim 5 wherein said means for diffracting a portion of said beam of light comprises a holographic dichromated gelatin film.

8. The optical apparatus of claim 5 wherein said means for diffusively diffracting light exiting said filter comprises a holographic dichromated gelatin film.

14. The optical apparatus of claim 5 wherein said louvers are spaced apart by about 0.005 inches.

15. The optical apparatus of claim 5 wherein said optical louver filter has a thickness in the range of 0.030 to 0.050 inches.

16. The optical apparatus of claim 5 wherein said beam of light is incident on said optical apparatus along a projection axis which is substantially normal to said transmission holographic optical element, and said exit pupil lies on a viewing axis extending substantially normal to said diffusion screen.

17. The optical apparatus of claim 5 wherein light is incident on said apparatus along an incident axis which is substantially normal to said transmission holographic optical element, and said louvers are slanted with respect to said incident axis and are spaced apart by a distance such that the full-color light diffracted by said transmission holographic optical element passes through said louver filter without reflection by said louvers, and the zero-order light is blocked by said louvers.

18. The optical apparatus of claim 17 wherein the angle at which said louvers are slanted with respect to said incident axis is about 30 degrees.

19. A diffraction optics diffusing screen laminate for full-color on-axis viewing, comprising:

a transmission holographic optical element comprising means for diffracting a portion of a beam of full-color light incident on said element along an incident axis substantially normal to said element to redirect the diffracted light so that it exits from said element at acute angles relative to the remaining portion of the incident beam;

an optical louver filter positioned with respect to said transmission holographic element so that light passing through said element is incident on said louver filter, said filter comprising a plurality of transparent cells separated by opaque louvers, said louvers being cooperatively arranged with respect to the diffracted light from said transmission holographic optical element so that diffracted full-color light passes unimpeded through said filter and zero-order light is blocked by said louvers; and

a diffraction optics holographic optical diffusion screen supported adjacent said louver filter and comprising means for diffusively diffracting light exiting said filter toward a predetermined exit pupil lying on a viewing axis extending substantially normal to said screen so that light diffracted by said optical diffusion is substantially directed toward and illuminates said exit pupil.

20. The screen laminate of claim 19 wherein said transmission holographic element is supported on a first rigid glass substrate, and said diffraction optics holographic diffusion screen is supported on a second rigid glass substrate, and wherein said first and second substrates sandwich said transmission holographic optics diffusion screen.

21. The screen laminate of claim 19 wherein said means for diffracting a portion of a beam of light incident on said transmission holographic optical element comprises a holographic dichromated gelatin film.

22. The screen laminate of claim 19 wherein said means for diffusively diffracting light exiting said filter comprises a holographic dichromated gelatin film.

23. The optical apparatus of claim 19 wherein said louvers are spaced apart by about 0.005 inches.

24. The optical apparatus of claim 19 wherein said optical louver filter has a thickness in the range of 0.030 to 0.050 inches.

25. The optical apparatus of claim 19 wherein light is incident on said apparatus along an incident axis which is substantially normal to said transmission holographic optical element, and said louvers are slanted with respect to said incident axis and are spaced apart by a distance such that the full-color light diffracted by said transmission holographic optical element passes through said louver filter without reflection by said louvers, and the zero-order light is blocked by said louvers.

26. The optical apparatus of claim 25 wherein the angle at which said louvers are slanted with respect to said incident axis is about 30 degrees.

27. A diffraction optics multi-color on-axis display system, comprising:

a multi-color image source projector for projecting a beam of multi-color image-information-bearing light along a projection axis;

a transmission holographic optical element comprising means disposed with respect to said image source projector for diffracting a portion of said beam to redirect said diffracted light beam so that it exits from said element at acute angles relative to the remaining portion of said beam incident on said transmission holographic optical element, said projection axis extending substantially normal to said optical element;

an optical louver filter positioned with respect to said transmission holographic element so that light passing through said element is incident on said louver filter, said filter comprising a plurality of transparent cells separated by opaque louvers, said louvers being cooperatively arranged with respect to the diffracted light from said transmission holographic optical element so that diffracted light passes unimpeded through said filter and zero-order light is blocked by said louvers; and

a diffraction optics holographic optical diffusion screen supported adjacent said louver filter and comprising means for diffusively diffracting light exiting said filter toward a predetermined exit pupil lying on a viewing axis extending substantially normal to said screen and substantially parallel to said projection axis so that light diffracted by said optical diffusion screen is substantially directed toward and illuminates said exit pupil.

28. The display system of claim 27 wherein said transmission holographic element is supported on a first rigid glass substrate, and said diffraction optics holographic diffusion screen is supported on a second rigid glass substrate, and wherein said first and second substrates sandwich said transmission holographic element, said louver filter and said diffraction optics diffusion screen.

29. The display system of claim 27 wherein said means for diffracting a portion of said beam of light comprises a holographic dichromated gelatin film.

30. The display system of claim 27 wherein said means for diffusively diffracting light exiting said filter comprises a holographic dichromated gelatin film.

31. The display system of claim 27 wherein said louvers are spaced apart by about 0.005 inches.

32. The display system of claim 27 wherein said optical louver filter has a thickness in the range of 0.030 to 0.050 inches.

33. The display system of claim 27 wherein light is incident on said apparatus along an incident axis which is substantially normal to said transmission holographic optical element, and said louvers are slanted with respect to said incident axis and are spaced apart by a distance such that the multi-color light diffracted by said transmission holographic optical element passes through said louver filter without reflection by said louvers, and the zero-order light is blocked by said louvers.

34. The display system of claim 33 wherein the angle at which said louvers are slanted with respect to said incident axis is about 30 degrees.