# US 10,371,951 B2 · Freeform nanostructured surface for virtual and augmented reality near eye display

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- Number: US 10,371,951 B2
- Document ID: US10371951B2
- Status: Granted
- Kind: B2
- Application number: 15/562,856
- Filed: 2016-03-31
- Published: 2018-04-26
- Granted: 2019-08-06
- Earliest claimed: 2015-04-02
- Assignees: University of Rochester
- Applicants: University of Rochester
- Inventors: Jannick Rolland; Nick Vamivakas; Alexander Kitt; Aaron Bauer
- Web page: https://patentgrep.com/patent/US10371951B2

## CPC

- G02B 27/0172: {characterised by optical features}
- G02B 6/0016: {Grooves, prisms, gratings, scattering particles or rough surfaces}
- 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}
- G02B 27/1066: {for enhancing image performance, like resolution, pixel numbers, dual magnifications or dynamic range, by tiling, slicing or overlapping fields of view}
- G02B 5/1809: {with pitch less than or comparable to the wavelength}
- G02B 5/1814: {structurally combined with one or more further optical elements, e.g. lenses, mirrors, prisms or other diffraction gratings (G02B5/189 takes precedence)}
- G02B 5/1876: {Diffractive Fresnel lenses; Zone plates; Kinoforms (G02B5/1842, G02B5/1847 take precedence; optical systems having diffractive correction means G02B27/0037; Fresnel lenses operating by refraction G02B3/08)}
- G02B 2027/011: {comprising device for correcting geometrical aberrations, distortion}
- G02B 2027/0125: {Field-of-view increase by wavefront division}
- G02B 2027/0174: {holographic}
- G02B 2027/0178: {Eyeglass type (eyeglass details G02C)}
- H04N 9/3129: {scanning a light beam on the display screen (scanning a light beam on a screen in displays other than projection devices G09G3/02; scanning systems in general G02B26/10; projectors using laser light sources in general H04N9/3161)}
- H04N 13/344: with head-mounted left-right displays
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION

## Abstract

A near eye display includes at least one of a combiner, a secondary mirror, and a waveguide having a freeform nanostructured surface. The freeform nanostructured surface encompasses a freeform surface, a nanostructured surface or a combination of both the freeform surface and the nanostructured surface. The freeform nanostructured surface can be incorporated into a combiner or a secondary mirror in the near eye display in a compact folded geometry, wherein an anamorphic or freeform optic can be optically intermediate an image source and the freeform nanostructured surface. The nanostructured surface can include a meta-grating operable across the visible spectrum. The meta-grating includes meta-atoms configured to provide a given efficiency at the desired wavelengths in reflection.

## Claims

### Claim 1

A near eye display assembly comprising:
(a) an image source; and
(b) at least one of a combiner, a mirror, and a waveguide optically coupled to the image source;
wherein the at least one of a combiner, a mirror, and a waveguide includes a nanostructured surface having a meta-grating at least partially defined by a unit cell having a plurality of meta-atoms.

### Claim 2 (depends on 1)

The near eye display assembly of claim 1, wherein the unit cell includes at least four meta-atoms.

### Claim 3 (depends on 1)

The near eye display assembly of claim 1, wherein each of the meta-atoms in the unit cell has a different length to width ratio.

### Claim 4 (depends on 1)

The near eye display assembly of claim 1, wherein the meta-grating is selected to have at least 20%+1 diffraction order absolute grating efficiency across the visible spectrum.

### Claim 5 (depends on 1)

The near eye display assembly of claim 1, comprising a combiner having a first reflective surface and a mirror having a second reflective surface optically coupled to the combiner, wherein the combiner and the secondary mirror are in an off-axis folded geometry and wherein at least one of the combiner and the mirror includes a nanostructured surface having a meta-grating at least partially defined by a unit cell having a plurality of meta-atoms.

### Claim 6 (depends on 1)

The near eye display assembly of claim 1, wherein each of the meta-atoms has a dimension greater than 1 nm.

### Claim 7 (depends on 6)

The near eye display assembly of claim 6, wherein each of the meta-atoms has a dimension greater than 10 nm.

### Claim 8 (depends on 1)

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

### Claim 9 (depends on 1)

The near eye display assembly of claim 1, wherein the meta-grating is selected to have at least 20%+1 diffraction order absolute grating efficiency across at least a 60° incident angle.

### Claim 10 (depends on 1)

The near eye display assembly of claim 1, comprising a combiner having a first reflective surface and a mirror having a second reflective surface, wherein both the combiner and the mirror include a freeform surface.

### Claim 11 (depends on 1)

The near eye display assembly of claim 1, wherein the unit cell has a length of approximately 555.5 nm and a width of approximately 221 nm and a first meta-atom has a length of approximately 105 nm and a width of approximately 84.6 nm, a second meta-atom has a length of approximately 105 nm and a width of approximately 47.7 nm, a third meta-atom has a length of approximately 50 nm and a width of approximately 177 nm and a fourth meta-atom has a length of approximately 105 nm and a width of approximately 150 nm.

### Claim 12 (depends on 1)

The near eye display assembly of claim 1, wherein the nanostructured surface includes a freeform surface.

### Claim 13 (depends on 1)

The near eye display assembly of claim 1, comprising a frame releasably engaging a head of a wearer, and a combiner having a first reflective surface and a mirror having a second reflective surface operably connected to the frame;
wherein at least one of the combiner and the secondary mirror includes a nanostructured surface having a meta-grating at least partially defined by a unit cell having a plurality of meta-atoms, the meta-atoms within the unit cell having different length to width ratios and sized and spaced to provide a given predetermined +1 diffraction order absolute grating efficiency over a majority of the visible light spectrum.

### Claim 14 (depends on 13)

The near eye display assembly of claim 13, wherein the image source is optically coupled to the mirror along an optical path and further comprising an optical element in the optical path, wherein the optical element is one of a spherical, aspheric, anamorphic, anamorphic aspheric, or freeform optic or lens.

### Claim 15 (depends on 13)

The near eye display assembly of claim 13, wherein the unit cell has four meta-atoms, each having a different length to width ratio.

### Claim 16 (depends on 13)

The near eye display assembly of claim 13, wherein each of the combiner and the mirror includes a nanostructured surface having a meta-grating at least partially defined by a unit cell having a plurality of meta-atoms, the meta-atoms within the unit cell having different length to width ratios and sized and spaced to provide an +1 diffraction order absolute grating efficiency of at least 20% over a majority of the visible light spectrum.

### Claim 17 (depends on 13)

The near eye display assembly of claim 13, wherein the nanostructured surface comprises a combination of both a freeform surface and a nanostructured surface.

### Claim 18 (depends on 1)

The near eye display assembly of claim 1, comprising: a frame; a combiner operably connected to the frame as a first reflective surface; and a mirror operably connected to the frame as a second reflective surface;
at least one of the combiner and the mirror including a nanostructured surface, and at least the other of the combiner and the mirror including a freeform surface, wherein the freeform component corrects optical aberrations induced by a tilting and decentering of the first reflective surface and the second reflective surface.

### Claim 19 (depends on 18)

The near eye display assembly of claim 18, wherein the nanostructured surface comprises a combination of both a freeform surface and a nanostructured surface.

### Claim 20 (depends on 1)

The near eye display assembly of claim 1, comprising a waveguide optically coupled to the image source;
wherein the waveguide includes a nanostructured surface having a meta-grating at least partially defined by a unit cell having a plurality of meta-atoms.