Systems and methods for mixed reality

1. A virtual image generation system comprising:

a planar optical waveguide having opposing first and second faces;

an in-coupling (IC) element configured for optically coupling a collimated light beam from an image projection assembly into the planar optical waveguide as an in-coupled light beam;

a first orthogonal pupil expansion (OPE) element associated with the first face of the planar optical waveguide for splitting the in-coupled light beam into a first set of orthogonal light beamlets;

a second orthogonal pupil expansion (OPE) element associated with the second face of the planar optical waveguide for splitting the in-coupled light beam into a second set of orthogonal light beamlets; and

an exit pupil expansion (EPE) element associated with the planar optical waveguide for splitting the first and second sets of orthogonal light beamlets into an array of out-coupled light beamlets that exit the planar optical waveguide.

2. The virtual image generation system of claim 1 , where planar optical waveguide is formed of a single unitary substrate.

3. The virtual image generation system of claim 1 , wherein the first OPE element is disposed on the first face of the planar optical waveguide, and the second OPE element is disposed on the second face of the planar optical waveguide.

4. The virtual image generation system of claim 1 , wherein the EPE element is disposed on one of the first and second surfaces of the planar optical waveguide.

5. The virtual image generation system of claim 1 , wherein the IC element is configured for optically coupling the collimated light beam from the image projection assembly as the in-coupled light beam for propagation within the planar optical waveguide via total internal reflection (TIR) along a first optical path that alternately intersects the first OPE element and the second OPE element, such that portions of the in-coupled light beam are deflected as the respective first set of orthogonal light beamlets and the second set of orthogonal light beamlets that propagate within the planar optical waveguide via TIR along second parallel optical paths.

6. The virtual image generation system of claim 5 , wherein the second parallel optical paths are orthogonal to the first optical path.

7. The virtual image generation system of claim 1 , wherein the first set of orthogonal light beamlets and the second set of orthogonal light beamlets intersect the EPE element, such that portions of the first set of orthogonal light beamlets and the second set of orthogonal light beamlets are deflected as the out-coupled light beamlet array out of the planar optical waveguide.

8. The virtual image generation system of claim 1 , wherein the EPE element is configured for imparting a convex wavefront profile on the out-coupled light beamlet array exiting the planar optical waveguide, the convex wavefront profile having a center of radius at a focal point to produce an image at a given focal plane.

9. The virtual image generation system of claim 1 , wherein the collimated light beam defines an entrance pupil, and the out-coupled light beamlet array defines an exit pupil larger than the entrance pupil.

10. The virtual image generation system of claim 9 , wherein the exit pupil is at least ten times larger than the entrance pupil.

11. The virtual image generation system of claim 9 , wherein the exit pupil is at least one hundred times larger than the entrance pupil.

12. The virtual image generation system of claim 1 , wherein each of the IC element, OPE element, and EPE element is diffractive.

13. The virtual image generation system of claim 1 , wherein the out-coupled light beamlet array is a two-dimensional out-coupled light beamlet array.

14. The virtual image generation system of claim 1 , further comprising the image projection assembly.

15. The virtual image generation system of claim 14 , wherein the image projection assembly comprises a scanning device configured for scanning the collimated light beam.