# US 10,371,876 B2 · Reflective diffractive gratings with variable reflectivity and display systems having the same

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- Number: US 10,371,876 B2
- Document ID: US10371876B2
- Status: Granted
- Kind: B2
- Application number: 16/042,996
- Filed: 2018-07-23
- Published: 2018-11-15
- Granted: 2019-08-06
- Earliest claimed: 2017-04-18
- Assignees: Magic Leap, Inc.
- Applicants: Magic Leap, Inc.
- Inventors: Marlon Edward Menezes; Jeffrey Dean Schmulen; Neal Paul Ricks; Victor Kai Liu; Zongxing Wang; David Carl Jurbergs
- Web page: https://patentgrep.com/patent/US10371876B2

## CPC

- G02B 6/0016: {Grooves, prisms, gratings, scattering particles or rough surfaces}
- G02B 6/0065: {Manufacturing aspects; Material aspects}
- G02B 6/0076: {Stacked arrangements of multiple light guides of the same or different cross-sectional area}
- G02B 27/0172: {characterised by optical features}
- G02B 5/0808: {having a single reflecting layer (G02B5/0883, G02B5/0891 take precedence)}
- G02B 5/1861: {Reflection gratings characterised by their structure, e.g. step profile, contours of substrate or grooves, pitch variations, materials (G02B5/1809, G02B5/1828, G02B5/1833, G02B5/1838 and G02B5/1847 take precedence)}
- G02B 6/34: utilising prism or grating {(G02B6/293 takes precedence)}
- G02B 27/0075: {with means for altering, e.g. increasing, the depth of field or depth of focus}
- G02B 2027/0125: {Field-of-view increase by wavefront division}
- G02B 2027/0185: {Displaying image at variable distance}
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

In some embodiments, compositions and methods comprising reflective flowable materials, e.g., reflective liquids including reflective inks and/or liquid metals, are described. In some embodiments, a surface is contacted with a reflective flowable material, thereby forming a reflective layer on the surface. In some embodiments, the surface is a surface of a waveguide, for example a waveguide for a display device, and the flowable material coats surfaces of protrusions on the surface to form reflective diffractive optical elements. Some embodiments include a display device comprising a reflective layer of reflective flowable material.

## Claims

### Claim 1

An optical device comprising:
an optical waveguide structure comprising:
an incoupling optical element configured to redirect incident light at angles such that the incident light propagates through the optical waveguide structure by total internal reflection, wherein the incoupling optical element comprises:
a diffractive optical grating structure comprising:
a plurality of protrusions; and
a reflective layer on surfaces of the protrusions, and
wherein at least one parameter of the reflective layer varies across an area occupied by the plurality of protrusions, and
wherein a reflectivity of the diffractive optical grating structure varies with the at least one parameter of the reflective layer across the area occupied by the plurality of protrusions.

### Claim 2 (depends on 1)

The optical device of claim 1, wherein the at least one parameter is a thickness of the reflective layer across the area occupied by the plurality of protrusions.

### Claim 3 (depends on 2)

The optical device of claim 2, wherein the thickness of the reflective layer varies by 25% or more across the area occupied by the plurality of protrusions.

### Claim 4 (depends on 1)

The optical device of claim 1, wherein the at least one parameter is a composition of the reflective layer across the area occupied by the plurality of protrusions.

### Claim 5 (depends on 1)

The optical device of claim 1, wherein the at least one parameter is the coverage over the reflective layer, and wherein the reflective layer covers less than an entirety of the area occupied by the plurality of protrusions.

### Claim 6 (depends on 1)

The optical device of claim 1, wherein the reflective layer comprises metal.

### Claim 7 (depends on 6)

The optical device of claim 6, wherein the metal is a liquid metal.

### Claim 8 (depends on 7)

The optical device of claim 7, wherein the liquid metal is selected from the group consisting of: gallium; indium; mercury; gallium-indium eutectic; gallium-indium alloy; gallium indium tin alloy; Ga, In, Sn and Zn alloy; Ga, In, and Sn alloy; sodium-potassium alloy; gallium, indium and stannum; gallium-indium-zinc-copper metallic; and silver indium gallium.

### Claim 9 (depends on 6)

The optical device of claim 6, wherein the metal forms a reflective ink.

### Claim 10 (depends on 9)

The optical device of claim 9, wherein the metal is aluminum, silver, or a combination thereof.

### Claim 11 (depends on 9)

The optical device of claim 9, wherein the reflective ink is a particle-free ink.

### Claim 12 (depends on 1)

The optical device of claim 1, wherein the optical waveguide structure comprises a first waveguide configured to propagate light therein by total internal reflection.

### Claim 13 (depends on 12)

The optical device of claim 12, wherein the optical waveguide structure comprises at least one additional waveguide, wherein the first waveguide and the at least one additional waveguide form a waveguide stack.

### Claim 14 (depends on 13)

The optical device of claim 13, wherein the area occupied by the diffractive optical grating is delineated by walls or barriers on the surface of the optical waveguide structure, wherein the walls or barriers extend vertically to a height above the plurality of protrusions, and wherein the walls or barriers are configured to function as spacers to provide a gap between the first waveguide and the at least one additional waveguide in the stack of waveguides.

### Claim 15 (depends on 13)

The optical device of claim 13, wherein the diffractive optical grating structure is configured to incouple the incident light into the first waveguide, and wherein the at least one additional waveguide has associated additional incoupling optical elements.

### Claim 16 (depends on 15)

The optical device of claim 15, wherein the incoupling optical element and the additional incoupling optical elements are configured to incouple light of different ranges of wavelengths.

### Claim 17 (depends on 13)

The optical device of claim 13, wherein the waveguide stack is optically coupled to a spatial light modulator, wherein the spatial light modulator is configured to inject light into the waveguide stack.

### Claim 18 (depends on 13)

The optical device of claim 13, wherein the first waveguide and the at least one additional waveguide each comprise associated outcoupling optical elements, wherein the respective associated outcoupling optical elements are configured to redirect light out of the first waveguide and the at least one additional waveguide with different amounts of wavefront divergence.

### Claim 19 (depends on 13)

The optical device of claim 13, wherein the incoupling optical element and the additional incoupling optical elements are laterally offset from one another in a top-down view.

### Claim 20 (depends on 13)

The optical device of claim 13, wherein the optical device is an augmented reality display, wherein the first waveguide and the at least one additional waveguide are configured to transmit light from an ambient environment.

### Claim 21 (depends on 1)

The optical device of claim 1, further comprising an image injection device configured to direct light with image information to the incoupling optical element.