Systems and methods for optical systems with exit pupil expander

• US 10,481,399 B2
• Filed: 09/20/2017
• Issued: 11/19/2019
• Est. Priority Date: 09/21/2016
• Status: Active Grant

• Current Assignee: Magic Leap, Inc.
• Original Assignee: Magic Leap, Inc.
• Inventors: Macnamara, John Graham
• Primary Examiner(s): Sasinowski, Andrew
• Application Number:
  US15/710,055
• Publication Number:
  US 20180120566A1
• Time in Patent Office: 790 Days
• CPC Class Codes: G02B 2027/0125 Field-of-view increase by wavefront division
• CPC Class Codes: G02B 2027/0134 of stereoscopic type
• CPC Class Codes: G02B 2027/0154 with movable elements
• CPC Class Codes: G02B 2027/0178 Eyeglass type eyeglass details G02C
• CPC Class Codes: G02B 27/0081 with means for altering, e.g. enlarging, the entrance or exit pupil
• CPC Class Codes: G02B 27/0172 characterised by optical features
• CPC Class Codes: G02B 27/0176 characterised by mechanical features
• CPC Class Codes: G02B 6/0076 Stacked arrangements of multiple light guides of the same or different cross-sectional area
• CPC Class Codes: G02B 6/34 utilising prism or grating G02B6/293 takes precedence
• CPC Class Codes: G06T 19/006 Mixed reality object pose determination, tracking or camera calibration for mixed reality G06T7/00

Abstract

Architectures are provided for expanding the exit pupil of systems including one or more waveguides. Various embodiments include a display device including one or more waveguides. One or more physical/optical parameters of the one or more waveguides and/or a wavelength of light input to the waveguide can be varied as the angle at which incoming light is incident on the waveguide varies in order to maintain phase correlation between different beamlets of the output light beam emitted from the one or more waveguides.

Claims

1. An optical system comprising:

an image projection system, the image projection system configured to emit a coherent beam of light at a plurality of wavelengths in the visible spectral range;

a waveguide comprising a first edge, a second edge and a pair of reflective surfaces disposed between the first and the second edges, the pair of reflective surfaces separated by a gap having a gap height d, the waveguide comprising a material having a refractive index n, the pair of reflective surfaces having a reflectivity r, the beam emitted from the image projection system being coupled into the waveguide at an input angle θ

; and

a control system configured to vary at least one parameter selected from the group consisting of;

a wavelength from the plurality of wavelengths, the gap height d, the refractive index n and the reflectivity r, wherein the variation of the at least one parameter is correlated with variation in the input angle θ

such that the equation 2nd sin θ

=mλ

is satisfied for values of the input angle θ

, wherein m is an integer and λ

is wavelength of the beam.

2. The optical system of claim 1, wherein the image projection system is configured to vary the input angle θ

of emitted beam at a scan rate.

3. The optical system of claim 2 wherein the control system is configured to modulate the at least one parameter at a modulation rate substantially equal to the scan rate.

4. The optical system of claim 1, wherein the least one parameter is a wavelength from the plurality of wavelengths.

5. The optical system of claim 1, wherein the least one parameter is the gap height d.

6. The optical system of claim 1, wherein the least one parameter is the refractive index n.

7. The optical system of claim 1, wherein the least one parameter is the reflectivity r.

8. The optical system of claim 1, wherein the image projection system comprises a fiber.

9. The optical system of claim 1, wherein the emitted beam is collimated.

10. The optical system of claim 1, wherein the plurality of wavelengths comprises wavelengths in the red, green and blue spectral regions.

11. The optical system of claim 1, wherein the waveguide comprises an acousto-optic material.

12. The optical system of claim 1, wherein the waveguide comprises a piezo-electric material.

13. The optical system of claim 1, wherein the waveguide comprises an electro-optic material.

14. The optical system of claim 1, wherein the waveguide comprises a micro-electro mechanical system (MEMS).

15. The optical system of claim 1, wherein the waveguide is configured as an exit pupil expander that expands and multiplies the emitted beam.

16. The optical system of claim 1, wherein the waveguide is configured to expand the beam to a spot size greater than 1 mm.

17. The optical system of claim 1, integrated in an augmented reality (AR) device.

18. The optical system of claim 1, integrated in a virtual reality (VR) device.

19. The optical system of claim 1, integrated in a near-to-eye display device.

20. The optical system of claim 1, integrated in an eyewear comprising at least one of:

a frame, one or more lenses or ear stems.

21. An optical system comprising:

an image projection system, the image projection system configured to emit a coherent beam of light at a plurality of wavelengths in the visible spectral range; and

a plurality of stacked waveguides, each waveguide comprising;

a first edge, a second edge and a pair of reflective surfaces disposed between the first and the second edges, the pair of reflective surfaces separated by a gap having a gap height d, the waveguide comprising a material having a refractive index n, the pair of reflective surfaces having a reflectivity r; and

a control system configured to vary at least one parameter selected from the group consisting of;

a wavelength from the plurality of wavelengths, the gap height d, the refractive index n and the reflectivity r,

wherein the beam emitted from the image projection system is coupled into the waveguide at an input angle θ

, and wherein the variation of the at least one parameter is correlated with variation in the input angle θ

such that the equation 2nd sin θ

=mλ

is satisfied for values of the input angle θ

, wherein m is an integer and λ

is wavelength of the beam.

22. The optical system of claim 21, wherein each waveguide has an associated depth plane, wherein the beam emitted from each waveguide appears to originate from that waveguide'"'"'s associated depth plane.

23. The optical system of claim 21, wherein different waveguides from the plurality of stacked waveguides have different associated depth planes.

24. The optical system of claim 21, integrated in an augmented reality (AR) device.

25. The optical system of claim 21, integrated in a virtual reality (VR) device.

26. The optical system of claim 21, integrated in a near-to-eye display device.

27. The optical system of claim 21, integrated in an eyewear comprising at least one of:

a frame, one or more lenses or ear stems.