Augmented reality display

1. A near eye display assembly comprising:

(a) frame;

(b) a combiner operably connected to the frame as a first reflective surface positionable in front of an eye of a user of the display assembly;

(c) a secondary mirror operably connected to the frame as a second reflective surface configured to be positioned proximate a side of a nose adjacent to the eye of a user of the display assembly when the first reflective surface is positioned in front of an eye of a user of the display assembly;

(d) an image source operably connected to the frame and optically coupled to the secondary mirror along an optical path; and

(e) an optical fold element between the image source and the secondary mirror in the optical path, and configured to be positioned proximate a temple adjacent to the eye of a user of the display assembly when the first reflective surface is positioned in front of an eye of a user of the display assembly;

wherein an intermediate image is formed in the optical path between the image source and the secondary mirror, wherein the combiner and the secondary mirror are in an off-axis folded geometry which directs images from the optical fold element to an eyebox of the near eye display assembly, and at least one of the combiner and the secondary mirror include a freeform surface, wherein a freeform component of the freeform surface corrects optical aberrations induced by a tilting and decentering of the first reflective surface and the second reflective surface, and wherein at least the combiner includes a nanostructured meta-surface which further provides wavefront control of an image from the image source to be directed to the eyebox and enables the combiner to be positioned at a tilt angle so that unobscured images are conveyable between the optical fold element and the secondary mirror while providing an FOV of at least 30 degrees and an eyebox width of at least 5 mm.

2. The near eye display assembly of claim 1 , wherein the nanostructured meta-surface comprises a meta-grating at least partially defined by a unit cell having a plurality of meta-atoms.

3. The near eye display assembly of claim 2 , wherein the unit cell includes at least three meta-atoms.

4. The near eye display assembly of claim 2 , wherein each of the meta-atoms in the unit cell has a different length to width ratio.

5. The near eye display assembly of claim 1 , wherein the optical fold element comprises one or more fold mirrors.

6. The near eye display assembly of claim 5 , further comprising a relay lens positioned between the optical fold element and the secondary mirror in the optical path.

7. The near eye display assembly of claim 5 , wherein the optical fold element comprises a fold mirror having a freeform surface.

8. The near eye display assembly of claim 1 , wherein the optical fold element comprises a fold prism comprising a first external refractive surface, an internal reflective surface, and a second external refractive surface.

9. The near eye display assembly of claim 8 , wherein at least one of the first external refractive surface, the internal reflective surface, and the second external refractive surface of the fold prism comprises a freeform surface.

10. The near eye display assembly of claim 1 , wherein the combiner includes a multitude of apertures sized and spaced to render the combiner substantially transparent to a viewer.

11. The near eye display assembly of claim 1 , wherein both the combiner and the secondary mirror include a freeform surface.

12. The near eye display assembly of claim 1 , further comprising an optical relay in the optical path between the image source and the optical fold element, wherein the optical relay includes at least one of a spherical, aspheric, anamorphic, anamorphic aspheric, or freeform optic or lens.

13. The near eye display assembly of claim 1 , wherein the combiner includes a freeform nanostructured surface having a meta-grating at least partially defined by a unit cell having a plurality of meta-atoms.

14. The near eye display assembly of claim 1 , wherein the combiner comprises a nanostructured meta-surface comprising metal nano-tokens coated with a protective dielectric layer to protect the meta-surface from metal oxidation and sample degradation.

15. The near eye display assembly of claim 14 , wherein protective dielectric layer comprises poly(methyl methacrylate).

16. The near eye display assembly of claim 1 , providing an FOV of at least 35 degrees.

17. The near eye display assembly of claim 1 , providing an FOV of at least 40 degrees.

18. The near eye display assembly of claim 1 , providing an FOV of 35-60 degrees.

19. The near eye display assembly of claim 1 , providing an FOV of 40-60 degrees.

20. The near eye display assembly of claim 1 , providing an eyebox width of at least 6 mm.

21. The near eye display assembly of claim 1 , providing an eyebox width of at least 7 mm.

22. The near eye display assembly of claim 1 , providing an eyebox width of at least 8 mm.

23. The near eye display assembly of claim 1 , providing an FOV of 35-60 degrees and an eyebox width of 5-8 mm.

24. The near eye display assembly of claim 1 , wherein the frame comprises left and right temples positionable over the ears and a nose piece positionable over the nose of a user.

25. The near eye display assembly of claim 24 , wherein a nosepiece to temple distance is from 35-60 mm.

26. The near eye display assembly of claim 1 , wherein the secondary mirror configured to be positioned proximate a side of the nose of a user and the optical fold element configured to be positioned proximate the temple of a user are separated by distance of from 35-60 mm.