Planar holographic optical device for beam expansion and display

• US 6,169,613 B1
• Filed: 06/03/1997
• Issued: 01/02/2001
• Est. Priority Date: 02/26/1993
• Status: Expired due to Fees

• Current Assignee: YEDA Research & DEV Company Limited
• Original Assignee: YEDA Research & DEV Company Limited
• Inventors: Shariv, Isaac, Friesem, Asher Albert, Amitai, Yaakov
• Primary Examiner(s): HENRY, JON W
• Application Number:
  US08/868,007
• Time in Patent Office: 1,309 Days
• Field of Search: 359/19, 359/15, 359/16, 359/32, 359/33, 359/34, 359/565, 359/567
• US Class Current: 359/15
• CPC Class Codes: G02B 5/188 Plurality of such optical elements formed in or on a supporting substrate
• CPC Class Codes: G02B 5/32 Holograms used as optical elements
• CPC Class Codes: G02B 6/0016 Grooves, prisms, gratings, scattering particles or rough surfaces
• CPC Class Codes: G02B 6/0038 Linear indentations or grooves, e.g. arc-shaped grooves or meandering grooves, extending over the full length or width of the light guide
• CPC Class Codes: G02B 6/12007 forming wavelength selective elements, e.g. multiplexer, demultiplexer
• CPC Class Codes: G02B 6/124 Geodesic lenses or integrated gratings
• CPC Class Codes: G02B 6/2848 having refractive means, e.g. imaging elements between light guides as splitting, branching and/or combining devices, e.g. lenses, holograms
• CPC Class Codes: G02B 6/29323 Coupling to or out of the diffractive element through the lateral surface of the light guide evanescent grating couplers G02B6/29332
• CPC Class Codes: G02B 6/29325 of the slab or planar or plate like form, i.e. confinement in a single transverse dimension only integrated circuit planar waveguide arrangements G02B6/12007; specially adapted for lighting G02B6/0011
• CPC Class Codes: G02B 6/29328 Diffractive elements operating in reflection
• CPC Class Codes: G02B 6/29329 Diffractive elements operating in transmission
• CPC Class Codes: G02B 6/29373 utilising a bulk dispersive element, e.g. prism
• CPC Class Codes: G02B 6/2938 for multiplexing or demultiplexing, i.e. combining or separating wavelengths, e.g. 1xN, NxM
• CPC Class Codes: G02B 6/34 utilising prism or grating G02B6/293 takes precedence
• CPC Class Codes: G02B 6/43 Arrangements comprising a plurality of opto-electronic elements and associated optical interconnections
• CPC Class Codes: G03H 1/0005 Adaptation of holography to specific applications holographic optical element G02B5/32; holographic scanner G02B26/106; recognition using holographic mask G06V10/88; holographic memories G11B7/0065, G11C13/042
• CPC Class Codes: G03H 1/0408 Total internal reflection [TIR] holograms, e.g. edge lit or substrate mode holograms
• 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 2001/0439 for recording Holographic Optical Element [HOE] HOE per se G02B5/32
• CPC Class Codes: G03H 2227/05 Support holding the holographic record

Abstract

A holographic optical device includes a light transmissive substrate carrying first and second laternally separated holographic optical elements. The first holographic optical element diffracts incident light into the substrate where it is trapped by internal reflection so that light impinges more than once at different angles at different locations on at least one of the first and second holographic optical elements with a significantly higher efficiency for one angle of incidence. The second holographic optical element diffracts light out of the substrate. The second holographic optical element may be a display hologram for displaying a three-dimensional image.

Claims

1. A holographic optical device comprising:

a light transmissive substrate;

a first holographic optical element carried by said substrate; and

a second holographic optical element carried by said substrate laterally of said first holographic optical element;

wherein said first holographic optical element diffracts incident light into said substrate such that said light is trapped inside by internal reflection; and

wherein said second holographic optical element diffracts said light out of said substrate; and

wherein said light trapped inside said substrate undergoes multiple internal reflections, such that at least part of said light impinges more than once at different locations on at least one of said first and said second holographic optical elements; and

wherein at least part of said light impinges at different angles of incidence on at least one of said different locations; and

wherein said at least one of said first and said second holographic optical elements is constructed such that at said at least one of said different locations, it diffracts said light with significantly higher efficiency for one of said different angles of incidence than for any other angle of incidence.

2. The device according to claim 1, and wherein said at least one of said first and said second holographic optical elements is operative to produce angular discrimination in the diffraction of said light, according to the angle of incidence of said light on said element.

3. The device according to claim 1, and wherein said at least one of said first and said second holographic optical-elements is a Bragg hologram.

4. The device according to claim 1, and wherein at least one of said first and said second holographic optical elements is a surface blazed grating.

5. The device according to claim 1, and wherein said second holographic optical elements is a transmissive element.

6. The device according to claim 1, and wherein said second holographic optical elements is a reflective element.

7. The device according to claim 1, wherein said second holographic optical element is laterally larger than said first holographic optical element.

8. The device according to claim 7, wherein said light trapped inside said substrate comprises a diverging beam.

9. The device according to claim 1, wherein said second holographic optical element is laterally smaller than said first holographic optical element.

10. The device according to claim 9, wherein said light trapped inside said substrate comprises a converging beam.

11. The device according to claim 1, wherein said incident light is essentially monochromatic light.

12. The device according to claim 1, wherein said incident light is polychromatic.

13. The device according to claim 1, wherein said second holographic optical element is a display hologram illuminated by said light trapped inside said substrate by internal reflection so as to reconstruct a three-dimensional image.

14. The device according to claim 13, wherein said first holographic optical element is a holographic lens.

15. The device according to claim 14, wherein said holographic lens is of substantially smaller surface area than said display hologram.

19. The device according to claim 1, wherein the surface of the substrate aligned with the first holographic optical element, but opposite that receiving said incident light is opaque.

20. The device according to claim 1, wherein the surface of the substrate aligned with the second holographic optical element, but opposite that from which said second holographic optical element diffracts said light out of said substrate is opaque.

21. The device according to claim 1, wherein said first and second holographic optical elements are located substantially coplanar in said substrate.

22. The device according to claim 1, wherein said first and second holographic optical elements are located on opposite sides of said substrate.

16. The device according to claim 30, wherein said first and second holographic optical elements are both holographic lenses.

17. The device according to claim 16, wherein said first and second holographic lenses are constructed such that the lateral dimensions of the light beam emerging from the substrate at the second holographic lens is a magnification of the lateral dimensions of the light beam entering the substrate to the first holographic lens.

18. The device according to claim 17, wherein said first and second holographic lenses are constructed such that the lateral dimensions of the light beam emerging from the substrate at the second holographic lens is a de-magnification of the lateral dimensions of the light beam entering the substrate to the first holographic lens.