Full-color zero-order suppressed diffraction optics diffusing screen/louver filter laminate

• US 5,016,950 A
• Filed: 07/05/1988
• Issued: 05/21/1991
• Est. Priority Date: 07/05/1988
• Status: Expired due to Fees

• Current Assignee: Palomar Technologies Incorporated
• Original Assignee: Hughes Aircraft Company (Rtx Corporation)
• Inventors: Smith, Ronald T.
• Primary Examiner(s): Dzierzynski, Paul M.
• Assistant Examiner(s): SHAFER, RICKY D
• Application Number:
  US07/215,474
• Time in Patent Office: 1,050 Days
• Field of Search: 350/3.7, 350/3.85, 350/3.86, 350/174, 350/3.72, 350/3.83, 350/3.84, 350/3.6
• US Class Current: 359/15
• CPC Class Codes: G02B 2207/123 Optical louvre elements, e.g. for directional light blocking
• CPC Class Codes: G02B 27/42 Diffraction optics , i.e. systems including a diffractive element being designed for providing a diffractive effectG02B27/60 takes precedence
• CPC Class Codes: G02B 5/0252 using holographic or diffractive means
• CPC Class Codes: G02B 5/32 Holograms used as optical elements
• CPC Class Codes: G03H 1/0465 Particular recording light; Beam shape or geometry G03H1/06 takes precedence

Abstract

A full-color holographic screen laminate is disclosed, having a well-defined exit pupil, off-axis viewing capabilities, high and uniform gain, and low backscatter, and in addition the capabilities of blocking the zero-order beam and allowing full-color viewing. The laminate in one preferred form includes several layers, including a plano-convex focusing lens, a directional diffraction optics diffusing screen, and a thin plane-parallel laminate consisting of a plano-concave cylindrical lens, a slanted louver filter, and a plano-convex cylindrical lens. The lenses can be made out of contrast enhancement material. The louver filter is curved so that the louvers are oriented parallel to the line of sight across the entire louver surface. The plano-convex lens focuses the light, the diffusion screen bends and diffuses the light, the louver filter passes the diffracted light but blocks the zero-order light from entering the ambient, and the contrast enhancement lens increases the overall contrast of the screen.

Claims

1. An optical apparatus, comprising:

a first plano-convex lens for focusing light incident thereon;

a holographic optical element positioned adjacent to said plano-convex lens to receive said focused light and comprising means for diffracting a beam of white light incident upon any particular point on said holographic optical element from a predetermined direction toward substantially overlapping red, green and blue exit pupils;

a louver filter positioned with respect to said holographic element so that light passing through said element impinges on said filter, the diffracted light being transmitted through said filter and the undiffracted light being blocked by said filter, said filter comprising a thin flexible translucent substrate and a plurality of opaque louvers which are aligned parallel to each other when the substrate is planer; and

a plano-concave lens and a second plano-convex lens, said louver filter being laminated between said respective lens, the curvature of the respective concave and convex surfaces of said lens being selected so that each of the louvers comprising said louver filter are aligned with a viewer'"'"'s line of sight at the exit pupil.

2. The optical apparatus of claim 1 further comprising a full color image projector for generating full color image light substantially from a point source, and wherein said first plano-convex lens comprises means for focusing image light from said projector.

3. An optical apparatus comprising:

a diffusion holographic optical element comprising means for diffracting a beam of white light incident upon any particular point on said holographic optical element from a predetermined direction toward substantially overlapping red, green and blue exit pupils;

a louver filter positioned with respect to said holographic element so that light passing through said element impinges on said filter, the diffracted light being transmitted through said filter and the undiffracted light being blocked by said louver filter, said filter comprising a plurality of transparent cells separated by opaque louvers; and

means for positioning said louver filter so that said louvers are each respectively aligned with a viewer'"'"'s line of sight, said means for positioning comprising a plano-concave lens disposed on a first side of said filter and a plano-convex lens disposed on a second side of said filter for laminating said filter therebetween.

4. The optical apparatus of claim 3 wherein said plano-concave lens and said plano-convex lens are fabricated from an absorptive material and comprise a contrast enhancement filter.