Turning light pipe for a pupil expansion system and method

• US 10,698,203 B1
• Filed: 06/27/2018
• Issued: 06/30/2020
• Est. Priority Date: 05/18/2015
• Status: Active Grant

• Current Assignee: Rockwell Collins, Inc. (Raytheon Technologies Corporation d/b/a RTX)
• Original Assignee: Rockwell Collins, Inc. (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: Brown, Robert D., Stanley, James H., Stratton, Eric P., Yu, Ming
• Primary Examiner(s): Chwasz, Jade R
• Application Number:
  US16/020,125
• Publication Number:
  US 20200192087A1
• Time in Patent Office: 734 Days
• Field of Search: 359 13, 359 34, 359 35, 359 15
• CPC Class Codes: G02B 17/0884 having a pupil corrector
• CPC Class Codes: G02B 2027/0123 comprising devices increasing the field of view
• CPC Class Codes: G02B 2027/0154 with movable elements
• CPC Class Codes: G02B 2027/0174 holographic
• CPC Class Codes: G02B 27/0081 with means for altering, e.g. enlarging, the entrance or exit pupil
• CPC Class Codes: G02B 27/0103 comprising holographic elements
• CPC Class Codes: G02B 27/0172 characterised by optical features
• CPC Class Codes: G02B 27/0176 characterised by mechanical features
• CPC Class Codes: G02B 27/30 Collimators
• 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 6/0028 Light guide, e.g. taper
• CPC Class Codes: G02B 6/0036 2-D arrangement of prisms, protrusions, indentations or roughened surfaces

Abstract

A display system includes a light pipe including elongated surfaces. The light pipe is configured to expand the image in a first direction through one of the elongated surfaces. The display also includes a waveguide including an output grating, a first surface, a second surface, and a side surface. The first surface and the second surface have a larger area than the side surface, the output grating being configured to provide the image expanded in a second direction. The second direction is different than the first direction. The image enters the waveguide from the one of the elongated surfaces.

Claims

1. A near eye optical display, comprising:

a projector configured to provide an image;

a light pipe comprising a plurality of elongated surfaces, the light pipe being configured to expand the image in a first direction through one of the elongated surfaces, wherein light associated with the image travels through the light pipe by striking three or more of the elongated surfaces; and

a waveguide comprising an output grating, a first surface, a second surface, and a side surface, the first surface and the second surface being an opposing surfaces, and having a larger area than the side surface, the output grating being configured to provide the image expanded in a second direction, the second direction being different than the first direction, wherein the image enters the waveguide from the one of the elongated surfaces of the light pipe.

2. The near eye optical display of claim 1, wherein the first direction is orthogonal to the second direction.

3. The near eye optical display of claim 1, wherein the one elongated surface, the side surface, the first surface and the second surface are planar surfaces.

4. The near eye optical display of claim 1, wherein the projector:

is comprised of a display source comprising a collimating mirror, a pair of beam splitters, a light source, and a lens configured to provide the image as collimated light to the light pipe.

5. The near eye optical display of claim 1, further comprising:

a gradient reflective coating disposed on the one elongated surface.

6. The near eye optical display of claim 5, further comprising a beam splitting coating between an input coupler on the light pipe and the gradient reflective coating.

7. The near eye optical display of claim 6, wherein the input coupler is a volume hologram or a surface relief grating.

8. The near eye optical display of claim 1, wherein the light pipe is disposed at an angle less than 90 degrees and greater than 0 degrees between the one elongated surface and the first surface.

9. The near eye optical display of claim 8, wherein an input coupler associated with the light pipe and the output grating are disposed to compensate for the angle to the side surface.

10. The near eye optical display of claim 9, wherein angle orientations for the output grating and the input grating match.

11. A method of displaying information, the method comprising:

receiving light in a light pipe having at least four elongated surfaces, the light striking the four elongated surfaces and traveling at least partially by total internal reflection within the light pipe;

receiving the light from one of the at least four elongated surfaces in a waveguide having a first surface and a second surface;

providing the light to an output grating via total internal reflection between the first surface and the second surface; and

providing the light from the waveguide via the output grating, where the light is provided with dual axis pupil expansion with respect to the light received in the light pipe.

12. The method of claim 11, wherein the output grating is a volume hologram or surface relief grating.

13. The method of claim 11, further comprising beam splitting the light received in the light pipe before the light enters the waveguide.

14. The method of claim 11, wherein the light pipe includes an input coupler.

15. The method of claim 14, wherein the input coupler is a surface relief grating.

16. An apparatus for providing an image, the apparatus comprising:

a light pipe comprising at least four elongated surfaces, each elongated surface connecting to at least two other of the elongated surfaces, the light pipe being configured such that light associated with an image strikes the at least four elongated surfaces as the light travels in a corkscrew or helical fashion within the light pipe; and

a waveguide comprising an input surface and an output surface, wherein the light from the light pipe is received at the input surface and the light is ejected from the output surface of the waveguide by an output grating.

17. The apparatus of claim 16, wherein the apparatus provides dual axis pupil expansion.

18. The apparatus of claim 16, wherein the light pipe comprises an input grating.

19. The apparatus of claim 16, further comprising a first beam splitting coating disposed in the waveguide and a second beam splitting coating disposed in the light pipe.

20. The apparatus of claim 16, wherein the light pipe has a rectangular prismatic shape.