Very high refractive index eyepiece substrate-based viewing optics assembly architectures

Abstract

To provide viewing optics assembly architectures.SOLUTION: There are provided herein, very high refractive index eyepiece substrate-based viewing optics assembly architectures. Very high refractive index (n>2.2) lightguide substrates enable production of 70° field-of-view eyepieces with all three color primaries in a single eyepiece layer. Disclosed herein are viewing optics assembly architectures that make use of such eyepieces to reduce a size and cost, simplifying manufacture and assembly, and better accommodating novel microdisplay designs.SELECTED DRAWING: Figure 12

Description

[Technical Field]

[0001] (Priority Claim) This application claims the benefit of priority to U.S. Provisional Patent Application No. 62 / 641,976, filed March 12, 2018, which is incorporated herein by reference in its entirety. (Cited by reference)

[0002] This application incorporates by reference the entirety of each of the following patent applications: U.S. Patent Application Publication No. 2018 / 0284585, published on October 4, 2018, entitled "LOW-PROFILE BEAM SPLITTER" (Attorney Docket No. MLEAP.111A); U.S. Patent Application No. 62 / 474543, filed on March 21, 2017; and U.S. Patent Application No. 62 / 570995, filed on October 11, 2017; and U.S. Patent Application No. 62 / 570995, published on December 13, 2018, entitled "AUGMENTED REALITY DISPLAY HAVING MULTI-ELEMENT ADAPTIVE LENS FOR CHANGING DEPTH" (Attorney Docket No. MLEAP.111A). U.S. Patent Application Publication No. 2018 / 0356639, filed June 12, 2017, entitled "WAVEGUIDE PLANES" (Attorney Docket No. MLEAP.119A), U.S. Patent Application No. 62 / 518539, filed July 25, 2017, U.S. Patent Application No. 62 / 536872, filed October 27, 2017, U.S. Patent Application No. 15 / 796,669, filed December 10, 2018, entitled "WAVEGUIDE PLANES" (Attorney Docket No. MLEAP.119A), This application incorporates U.S. patent application Ser. No. 16 / 215,477, published on __________ as U.S. Application Publication No. ___________, entitled "A MICROPHOSPHATE ILLUMINATOR" (Attorney Docket No. MLEAP.154A), and U.S. patent application Ser. No. 62 / 597,359, filed December 11, 2017, U.S. patent application Ser. No. 62 / 624,109, filed January 30, 2018, and U.S. patent application Ser. No. 16 / 262,659, published on __________ as U.S. Application Publication No. ___________, and U.S. patent application Ser. No. 62 / 624,762, filed January 31, 2018. The contents of each of the above-identified applications are incorporated herein by reference.

[0003] This application relates to viewing optics assemblies, and more particularly to viewing optics assembly architectures configured to utilize ultra-high refractive index light guide substrates. The viewing optics assemblies can be used in optical systems, including augmented reality imaging and visualization systems. [Background technology]

[0004] Modern computing and display technology has facilitated the development of systems for so-called "virtual reality" or "augmented reality" experiences, in which digitally reproduced images or portions thereof are presented to a user in a manner that appears or can be perceived as real. Virtual reality, or "VR," scenarios typically involve the presentation of digital or virtual image information without transparency to other actual real-world visual input, while augmented reality, or "AR," scenarios typically involve the presentation of digital or virtual image information as an augmentation to the user's visualization of the real world around them. Mixed reality, or "MR," scenarios are a type of AR scenario that typically involve virtual objects integrated into and responsive to the natural world. For example, MR scenarios may include AR image content that appears blocked by or is perceived to otherwise interact with objects in the real world.

[0005] Referring to FIG. 1 , an augmented reality scene 10 is depicted. A user of the AR technology sees a real-world park-like setting 20 featuring people, trees, a building in the background, and a concrete platform 30. The user also perceives that they are "seeing" "virtual content," such as a robotic figure 40 standing on the real-world platform 30 and a flying, cartoon-like avatar character 50 that appears to be an anthropomorphic bumblebee. These elements 50, 40 are "virtual" in that they do not exist in the real world. The human visual perception system is complex, making it difficult to create AR technology that facilitates a comfortable, natural-feeling, and rich presentation of virtual image elements among other virtual or real-world image elements.

[0006] The systems and methods disclosed herein address various challenges associated with AR or VR technology. Summary of the Invention [Means for solving the problem]

[0007] The head-mounted display system may be configured to project light into the user's eye and display augmented reality image content within the user's field of view. The head-mounted display system may include a frame configured to be supported on the user's head. The head-mounted display system may also include an eyepiece disposed on the frame. At least a portion of the eyepiece may be transparent and / or the transparent portion may be positioned in front of the user's eye when the user wears the head-mounted display such that light from an environment in front of the user passes through to the user's eye to provide a view of the environment in front of the user. The eyepiece may include one or more waveguides positioned to direct light into the user's eye and form the augmented reality image content.

[0008] Various embodiments of head-mounted display systems include at least one projector having one or more pupils that outputs light (e.g., image light) having multiple colors or wavelength ranges (e.g., two or three colors or wavelength ranges) to generate different color images or image components, such as a red image component, a green image component, and a blue image component. Such image components can be combined to provide a virtually full-color image. These color components can be directed into a user's eye to display augmented reality or virtual image content. In some implementations, an eyepiece in a head-mounted display system includes a waveguide assembly that includes multiple waveguides stacked over one another.

[0009] Various implementations of the display devices contemplated herein include one or more waveguides including a material with a refractive index greater than that of glass. For example, one or more waveguides in various embodiments of the display devices contemplated herein can include lithium niobate (LiNbO) or silicon carbide (SiC). In various embodiments, one or more waveguides in various embodiments of the display devices contemplated herein can include a material that is transparent to visible light and has a refractive index greater than that of glass (e.g., a refractive index of about 1.79 or greater). One or more waveguides including a material with a relatively high refractive index (e.g., a refractive index greater than that of glass and / or a refractive index of about 1.79 or greater) can advantageously increase the field of view of image content from a projector output to a user's eye by the one or more waveguides, compared to waveguides including glass and / or a material with a refractive index less than about 1.79. Advantageously, various implementations of display devices allow multiple colors or wavelengths of light (e.g., red, green, and / or blue wavelengths of light) to be internally coupled in parallel into and guided within a single waveguide comprising a material with a relatively high refractive index (e.g., a refractive index greater than that of glass and / or a refractive index of about 1.79 or greater), and then externally coupled therefrom into a user's eye with similar angular output for each color or wavelength. Thus, for example, a single waveguide may be employed to propagate three color components of an image from a projector, as opposed to using three waveguides, one for each of three colors (e.g., red, green, and blue). Such a reduction in the number of waveguides can potentially have one or more advantages, such as, for example, reducing the weight, overall eyepiece thickness, complexity, form factor, and / or increasing light transmission and / or image quality.

[0010] In some implementations, instead of three colors, two color components of the image content from the projector can be internally coupled into a single waveguide, guided therein, and externally coupled to the user's eye. In some such designs, two waveguides may be used to accommodate three colors. For example, a first waveguide can receive and guide two colors (e.g., red and green, red and blue, or green and blue), and a second waveguide can receive, guide, and output a third color (e.g., blue, green, and red, respectively) to the user. In some implementations, a first waveguide can receive and guide two colors (e.g., red and green, red and blue, green and blue), and a second waveguide can receive, guide, and output a single third color or color component (e.g., blue, green, and red, respectively) to the user. In other implementations, a first waveguide can receive and guide two colors (e.g., red and green), and a second waveguide can receive, guide, and outcouple two colors or color components to a viewer, one of the color components being different from the image color components (e.g., green and blue) guided within the first waveguide. Using two waveguides instead of three (e.g., per depth or depth plane) can still reduce thickness, complexity, and potentially provide one or more of the advantages disclosed herein.

[0011] Similarly, different waveguides among the multiple waveguides may include internal coupling optical elements configured to internally couple light of one of a color or wavelength range from light output from the projector pupil. In some implementations, for example, a single internal coupling optical element within a waveguide is used to couple three colors or color components into the waveguide to be guided therein. In some implementations, a single internal coupling optical element within a waveguide is used to couple two colors or color components into the waveguide to be guided therein. In other implementations, different internal coupling optical elements are used to couple separate, distinct colors or color components into a single waveguide to be guided therein. For example, three internal coupling optical elements may be used to couple three separate colors or color components into a single waveguide. Similarly, two internal coupling optical elements may be used to combine two separate colors or color components into a single waveguide.

[0012] Thus, in one or more implementations, two or more colors (e.g., two or three colors) can be coupled into a single waveguide including a material with a relatively high refractive index (e.g., a refractive index greater than that of glass and / or a refractive index greater than or equal to about 1.79) using one or more internal coupling optical elements, such that the internally coupled two or more colors can propagate within the single waveguide including a material with a relatively high refractive index (e.g., a refractive index greater than that of glass and / or a refractive index greater than or equal to about 1.79) via total internal reflection and be externally coupled to a viewer for presenting virtual image content. In some implementations, the single internal coupling optical element can be configured to receive two or more colors of light containing image information from an imaging system (e.g., a projection device) and internally couple the received two or more colors of light containing image information into a single waveguide including a material with a relatively high refractive index (e.g., a refractive index greater than that of glass and / or a refractive index greater than or equal to about 1.79), such that the light of the two or more colors containing image information propagates through the single waveguide by total internal reflection and is externally coupled to a viewer for presenting virtual image content. In some implementations, the two or more internal coupling optical elements can be configured to receive two or more colors of light containing image information from an imaging system (e.g., a projection device) and internally couple the two or more colors of received light containing image information into a single waveguide including a material with a relatively high refractive index (e.g., a refractive index greater than that of glass and / or a refractive index of about 1.79 or greater), such that the two or more colors of light containing image information propagate through the single waveguide by total internal reflection and are externally coupled to a viewer to present virtual image content. The one or more internal coupling optical elements can be aligned with one or more exit pupils of the projector or imaging system that emit the two or more colors of light containing image information.

[0013] The systems, methods, and devices disclosed herein each have several innovative aspects, no one of which is solely responsible for the desirable attributes disclosed herein. Various exemplary systems and methods are provided below.

[0014] (Embodiment 1) A display system, comprising: an image projection device configured to emit a multiplexed light stream comprising a first light stream of a first color, a second light stream of a second color, and a third light stream of a third color, wherein the first, second, and third colors are different, and the first, second, and third light streams comprise image content; a waveguide comprising a material having a refractive index greater than 1.79, the waveguide being configured to receive multiplexed light streams emitted from an image projection device such that a first light stream, a second light stream, and a third light stream are guided within the waveguide by multiple total internal reflections; A display device comprising:

[0015] (Embodiment 2) A display system according to embodiment 1, wherein the waveguide comprises a material having a refractive index of 2.2 or greater.

[0016] (Embodiment 3) A display system according to any one of embodiments 1-2, wherein the waveguide comprises a material having a refractive index of 2.3 or greater.

[0017] (Embodiment 4) A display system according to any one of embodiments 1-3, wherein the waveguide comprises lithium niobate.

[0018] (Embodiment 5) A display system described in any one of embodiments 1-4, wherein the waveguide has a field of view greater than about 30 degrees horizontally and greater than about 24 degrees vertically.

[0019] (Embodiment 6) A display system as described in embodiment 5, wherein the field of view of the waveguide is approximately 45 degrees horizontally and approximately 56 degrees vertically.

[0020] (Embodiment 7) A display system described in any of embodiments 1-6, further comprising at least one variable-focus optical element arranged to receive the multiplexed light stream output from the waveguide so that at least a portion of the multiplexed light stream is directed toward the user's eye, the variable-focus optical element configured to vary the depth at which light from the waveguide appears to originate.

[0021] (Embodiment 8) A display system described in any of embodiments 1-6, wherein the multiplexed light stream comprises a first multiplexed light stream comprising image information associated with a first depth plane.

[0022] (Embodiment 9) A display system as described in embodiment 8, wherein the waveguide comprises a first waveguide associated with a first depth plane, and light emitted from the first waveguide is configured to direct the first multiplexed light stream toward a viewer and generate an image that appears to arise from the first depth plane.

[0023] (Embodiment 10) A display system described in any of embodiments 8-9, wherein the image projection device is further configured to output a second multiplexed light stream comprising image information associated with a second depth plane, the second multiplexed light stream comprising a plurality of light streams having a first color, a second color, and a third color, the first, second, and third colors being different.

[0024] (Embodiment 11) The display system described in embodiment 10 further comprises a second waveguide associated with a second depth plane, the second waveguide comprising a material having a refractive index greater than 1.79, and configured to receive a second multiplexed light stream emitted from an image projection device such that multiple light streams associated with the second multiplexed light stream are guided through the second waveguide by multiple total internal reflections.

[0025] (Embodiment 12) A display system as described in embodiment 11, wherein light emitted from the second waveguide is configured to direct the second multiplexed light stream toward a viewer and generate an image that appears to arise from a first depth plane.

[0026] (Embodiment 13) A display system described in any of embodiments 11-12, wherein the second waveguide is included within the eyepiece of the head-mounted display.

[0027] (Embodiment 14) A display system described in any of embodiments 9-13, wherein the first waveguide is included within the eyepiece of the head-mounted display.

[0028] (Embodiment 15) A display system described in any of embodiments 1-7, wherein the waveguide is included within the eyepiece of a head-mounted display.

[0029] (Embodiment 16) A display system described in any of embodiments 1-7 and 15, further comprising an internal coupling optical element configured to receive multiplexed light streams emitted from an image projection device and internally couple each of the first light stream, the second light stream, and the third light stream into a waveguide so as to be guided therein by multiple total internal reflections.

[0030] (Embodiment 17) A display system described in any one of embodiments 1-16, wherein the image projection device comprises a light modulation device.

[0031] (Embodiment 18) A display system, comprising: an image projection device configured to emit a multiplexed light stream comprising a first light stream of a first color, a second light stream of a second color, and a third light stream of a third color, wherein the first, second, and third colors are different, and the first, second, and third light streams comprise image content; first and second waveguides comprising a material having a refractive index greater than 1.79; wherein a first waveguide is configured to receive a first color and a second color, and a second waveguide is configured to receive a third color, and the different colors or color combinations are combined into the two waveguides such that the first and second light streams are guided in the first waveguide by multiple total internal reflections, and the third light stream is guided in the second waveguide by multiple total internal reflections. Display system.

[0032] (Embodiment 19) A display system as described in embodiment 18, wherein the second waveguide is also configured to receive the first color such that the first light stream is guided within the second waveguide by multiple total internal reflections.

[0033] (Embodiment 20) A display system as described in embodiment 18, wherein the second waveguide is also configured to receive a second color such that a second light stream is guided within the second waveguide by multiple total internal reflections.

[0034] (Embodiment 21) A display system as described in embodiment 18, wherein the second waveguide is not configured to internally couple the first or second colors such that the third light stream is guided within the second waveguide primarily by multiple total internal reflections.

[0035] (Embodiment 22) A display system described in any of embodiments 18-21, further comprising a first internal coupling optical element within the first waveguide configured to internally couple both the first and second light streams into the first waveguide so that the first and second light streams are guided within the first waveguide by multiple total internal reflections.

[0036] (Embodiment 23) A display system described in any of embodiments 18-21, further comprising first and second internal coupling optical elements within the first waveguide, each configured to internally couple both the first and second light streams into the first waveguide so that the first and second light streams are guided within the first waveguide by multiple total internal reflections.

[0037] (Embodiment 24) A display system described in any of embodiments 18-21, further comprising a third internal coupling optical element within the second waveguide configured to internally couple the third light stream into the second waveguide so that the third light stream is guided within the second waveguide by multiple total internal reflections.

[0038] (Embodiment 25) A display system as described in embodiment 24, wherein the third internal coupling optical element is also configured to internally couple either the first or second light stream into the second waveguide so that either the first or second light stream is guided within the second waveguide by multiple total internal reflections.

[0039] (Embodiment 26) A display system as described in embodiment 24, further comprising a fourth internal coupling optical element configured to internally couple either the first or second light stream into the second waveguide so that either the first or second light stream is guided within the second waveguide by multiple total internal reflections.

[0040] (Embodiment 27) A method for manufacturing a diffractive optical element, comprising the steps of: providing a substrate comprising a material having a refractive index greater than 1.79 that is transparent to visible light; disposing a patternable layer over a surface of a substrate; patterning the patternable layer, the pattern comprising a plurality of features; Etching a surface of the substrate through the patternable layer to fabricate a structure on the surface of the substrate, the structure comprising diffractive features configured to diffract visible light.

[0041] (Embodiment 28) The method of embodiment 27, wherein the transparent material includes LiNbO3.

[0042] (Embodiment 29) The method of embodiment 27 or 28, wherein disposing the patternable layer over the surface of the substrate comprises jet-depositing the patternable layer over the surface of the substrate.

[0043] (Embodiment 30) The method of any of embodiments 27-29, wherein the surface of the substrate is discharged prior to depositing the patternable layer.

[0044] (Embodiment 31) The method of any one of embodiments 27-30, wherein the patternable layer comprises a resist or a polymer.

[0045] (Embodiment 32) A method for manufacturing a diffractive optical element, comprising the steps of: providing a substrate comprising a material having a refractive index greater than 1.79 that is transparent to visible light; disposing a patternable layer over a surface of a substrate; patterning the patternable layer, the pattern comprising a plurality of features; wherein the plurality of features of the patterned patternable layer are configured to diffract visible light as guided therein into the substrate or to diffract visible light guided within the substrate out of the substrate; method.

[0046] (Embodiment 33) The method of embodiment 32, wherein the transparent material includes LiNbO3.

[0047] (Embodiment 34) The method of embodiment 32 or 33, wherein disposing the patternable layer over the surface of the substrate comprises jet-depositing the patternable layer over the surface of the substrate.

[0048] (Embodiment 35) The method of any of embodiments 32-34, wherein the surface of the substrate is discharged prior to depositing the patternable layer.

[0049] (Embodiment 36) The method of any one of embodiments 32-35, wherein the patternable layer comprises a resist or a polymer.

[0050] (Embodiment 37) A method for manufacturing a diffractive optical element, comprising the steps of: providing a substrate comprising a material having a refractive index greater than 1.79 that is transparent to visible light; jet-depositing a patternable layer over a surface of a substrate; patterning the patternable layer, the pattern comprising a plurality of features; A method comprising:

[0051] (Embodiment 38) The method of embodiment 37, wherein the transparent material includes LiNbO3.

[0052] (Embodiment 39) The method of embodiment 37 or 38, wherein the surface of the substrate is discharged prior to depositing the patternable layer.

[0053] (Embodiment 40) The method of any one of embodiments 37-39, wherein the patternable layer comprises a resist or a polymer.

[0054] (Embodiment 41) A waveguide for propagating image content therein by total internal reflection, comprising: a substrate comprising a material having a refractive index greater than 1.79 that is transparent to visible light, and capable of propagating image content therein by total internal reflection; a layer over a surface of a substrate, the layer comprising a material having a lower refractive index than the substrate, the layer comprising a pattern comprising a plurality of features; wherein the plurality of features of the patterned patternable layer are configured to diffract visible light as guided therein into the substrate or to diffract visible light guided within the substrate out of the substrate. waveguide.

[0055] (Embodiment 42) A waveguide as described in embodiment 41, wherein the transparent material includes LiNbO3.

[0056] (Embodiment 43) A waveguide as described in embodiment 41 or 42, wherein the surface of the substrate is discharged prior to depositing the patternable layer.

[0057] (Embodiment 44) A waveguide described in any of embodiments 41-43, wherein the patternable layer comprises a resist.

[0058] (Embodiment 45) A waveguide described in any of embodiments 41-44, wherein the patternable layer comprises a polymer.

[0059] (Embodiment 46) A head-mounted display device, an eyepiece comprising at least one waveguide comprising a material having a refractive index greater than 1.79, the waveguide having a first major surface, a second major surface opposite the first major surface, and a plurality of edges between the first and second major surfaces; a plurality of diffractive features formed on at least one of the first major surface or the second major surface; A head-mounted display device comprising:

[0060] (Embodiment 47) A head-mounted display device as described in embodiment 46, wherein the plurality of diffractive features are formed on at least one of the first major surface or the second major surface by etching at least one of the first major surface or the second major surface.

[0061] (Embodiment 48) A head-mounted display device as described in embodiment 46 or 47, wherein the waveguide comprises a material having a refractive index greater than 2.2.

[0062] (Embodiment 49) A head-mounted display device described in any of embodiments 46-48, wherein the waveguide comprises lithium niobate.

[0063] (Embodiment 50) A head-mounted display device described in any of embodiments 46-48, wherein the waveguide comprises silicon carbide.

[0064] (Embodiment 51) A head-mounted display device described in any of embodiments 46-50, wherein at least some of the multiple diffractive features are configured to internally couple incident image light so that the internally coupled image light propagates through the waveguide by multiple total internal reflections at the first and second major surfaces.

[0065] (Embodiment 52) ​​A head-mounted display device described in any of embodiments 46-52, further comprising a variable-focus lens between the waveguide and the viewer, the variable-focus lens configured to vary the focal plane of image light propagating through the waveguide by multiple total internal reflections at the first and second major surfaces that are externally coupled from the waveguide toward the viewer.

[0066] (Embodiment 53) A head-mounted display device as described in embodiment 52, wherein the variable focus lens comprises a negative lens.

[0067] (Embodiment 54) A head-mounted display device described in any of embodiments 52-53, wherein the variable focus lens comprises a liquid-filled lens.

[0068] (Embodiment 55) A head-mounted display device described in any of embodiments 52-53, wherein the variable focus lens includes a liquid crystal.

[0069] (Embodiment 56) Any head-mounted display device described in embodiment 52, 53, or 55, wherein the variable focus lens comprises a geometric phase lens.

[0070] (Embodiment 57) A head-mounted display device described in any of embodiments 46-51, further comprising a negative lens between the waveguide and the viewer, such that the negative lens receives light propagating through the waveguide by multiple total internal reflections at the first and second major surfaces, which is outcoupled from the waveguide toward the viewer.

[0071] (Embodiment 58) A head-mounted display device as described in embodiment 57, wherein the negative lens comprises a static lens.

[0072] (Embodiment 59) A head-mounted display device described in embodiment 57 or 58, wherein the waveguide and negative lens are contained within a stacked waveguide assembly.

[0073] (Embodiment 60) A head-mounted display device described in any of embodiments 57-59, further comprising an additional waveguide paired with an additional negative lens.

[0074] (Embodiment 61) A head-mounted display device described in any of embodiments 57-60, further comprising a positive lens positioned between the waveguide and the real world.

[0075] (Embodiment 62) A head-mounted display device described in any of embodiments 46-61, further comprising a polarizer stacked with the waveguide.

[0076] (Embodiment 63) A head-mounted display device described in any of embodiments 46-62, wherein at least some of the plurality of diffractive features are configured to outcouple image light propagating through the waveguide toward a viewer by multiple total internal reflections at the first and second major surfaces.

[0077] (Embodiment 64) A head-mounted display device described in any of embodiments 46-62, further comprising an imaging system configured to provide image light.

[0078] (Embodiment 65) A head-mounted display device as described in embodiment 64, wherein the imaging system is outside the field of view of the viewer viewing the waveguide.

[0079] (Embodiment 66) The imaging system comprises: A lighting system; a modulation element configured to receive unmodulated light from the illumination system; a projection optics system configured to transmit image light output by the modulation element; A head-mounted display device as described in any of embodiments 64-65, comprising:

[0080] (Embodiment 67) A head-mounted display device as described in embodiment 66, wherein the modulation element is reflective.

[0081] (Embodiment 68) A head-mounted display device as described in embodiment 67, in which unmodulated image light from the illumination system is transmitted through the projection optical system toward a reflective modulation element, reflected from the modulation element, and transmitted back into the waveguide through the projection optical system.

[0082] (Embodiment 69) The lighting system includes: a light source configured to output visible light; and a light pipe configured to receive visible light output from the light source; a light redirecting element; Equipped with the light pipe is configured to transmit light output from the light source toward the light redirecting element by multiple total internal reflections; the light redirecting element is configured to redirect light propagating in the light pipe towards the modulation element; 69. A head mounted display device according to any one of claims 66-68.

[0083] (Embodiment 70) A head-mounted display device as described in embodiment 69, wherein the light source comprises a plurality of light-emitting elements configured to emit light in a plurality of colors.

[0084] (Embodiment 71) A head-mounted display device as described in embodiment 70, wherein the plurality of light-emitting elements comprise light-emitting diodes or lasers.

[0085] (Embodiment 72) A head-mounted display device described in any of embodiments 70-71, further comprising an optical element configured to combine light emitted by multiple light-emitting elements.

[0086] (Embodiment 73) A head-mounted display device as described in embodiment 72, wherein the optical element is a dichroic beam combiner.

[0087] (Embodiment 74) A head-mounted display device described in any of embodiments 69-73, wherein the light redirecting element is configured to redirect light propagating in the light pipe through the waveguide towards the modulation element.

[0088] (Embodiment 75) A head-mounted display device described in any of embodiments 69-74, wherein the waveguide further comprises a light adjusting optical system configured to adjust the distribution of light redirected by the light redirecting element.

[0089] (Embodiment 76) A head-mounted display device, an image projection device; an eyepiece comprising a waveguide comprising silicon carbide, the waveguide having a first major surface, a second major surface opposite the first major surface, and a plurality of edges between the first major surface and the second major surface; wherein the waveguide is configured to receive and guide light from the image projection device and direct the image into an eye of a wearer of the head mounted display.

[0090] (Embodiment 77) A head-mounted display device as described in embodiment 76, further comprising a plurality of diffractive features disposed on at least one of the first major surface or the second major surface.

[0091] (Embodiment 78) A head-mounted display device as described in embodiment 77, wherein the plurality of diffractive features are formed on at least one of the first major surface or the second major surface by etching at least one of the first major surface or the second major surface.

[0092] (Embodiment 79) A head-mounted display device described in any of embodiments 77-78, wherein at least some of the multiple diffractive features are configured to internally couple incident image light so that the internally coupled image light propagates through the waveguide by multiple total internal reflections at the first and second major surfaces.

[0093] (Embodiment 80) A head-mounted display device described in any of embodiments 76-79, further comprising a variable-focus lens between the waveguide and the viewer, the variable-focus lens configured to vary the focal plane of image light propagating through the waveguide by multiple total internal reflections at the first and second major surfaces that are externally coupled from the waveguide toward the viewer.

[0094] (Embodiment 81) A head-mounted display device as described in embodiment 80, wherein the variable focus lens comprises a negative lens.

[0095] (Embodiment 82) A head-mounted display device described in any of embodiments 80-81, wherein the variable focus lens comprises a liquid-filled lens.

[0096] (Embodiment 83) A head-mounted display device described in any of embodiments 80-81, wherein the variable focus lens includes a liquid crystal.

[0097] (Embodiment 84) A head-mounted display device described in any of embodiments 80, 81, or 83, wherein the variable focus lens comprises a geometric phase lens.

[0098] (Embodiment 85) A head-mounted display device described in any of embodiments 76-79, further comprising a negative lens between the waveguide and the viewer, such that the negative lens receives light propagating through the waveguide by multiple total internal reflections at the first and second major surfaces, which is outcoupled from the waveguide toward the viewer.

[0099] (Embodiment 86) A head-mounted display device as described in embodiment 85, wherein the negative lens comprises a static lens.

[0100] (Embodiment 87) A head-mounted display device described in embodiment 85 or 86, wherein the waveguide and negative lens are contained within a stacked waveguide assembly.

[0101] (Embodiment 88) A head-mounted display device described in any of embodiments 85-87, further comprising an additional waveguide paired with an additional negative lens.

[0102] (Embodiment 89) A head-mounted display device described in any of embodiments 85-88, further comprising a positive lens positioned between the waveguide and the real world.

[0103] (Embodiment 90) A head-mounted display device described in any of embodiments 76-89, further comprising a polarizer stacked with the waveguide.

[0104] (Embodiment 91) A head-mounted display device described in any of embodiments 76-90, wherein at least some of the multiple diffractive features are configured to outcouple image light propagating through the waveguide toward a viewer by multiple total internal reflections at the first and second major surfaces.

[0105] (Embodiment 92) A head-mounted display device described in any of embodiments 76-91, further comprising an imaging system configured to provide image light.

[0106] (Embodiment 93) A head-mounted display device as described in embodiment 92, wherein the imaging system is outside the field of view of the viewer viewing the waveguide.

[0107] (Embodiment 94) The imaging system comprises: A lighting system; a modulation element configured to receive unmodulated light from the illumination system; a projection optics system configured to transmit image light output by the modulation element; A head-mounted display device as described in any of embodiments 92-93, comprising:

[0108] (Embodiment 95) A head-mounted display device as described in embodiment 94, wherein the modulation element is reflective.

[0109] (Embodiment 96) A head-mounted display device as described in embodiment 95, wherein unmodulated image light from the illumination system is transmitted through the projection optical system toward a reflective modulation element, reflected from the modulation element, and transmitted back into the waveguide through the projection optical system.

[0110] (Embodiment 97) The lighting system includes: a light source configured to output visible light; and a light pipe configured to receive visible light output from the light source; a light redirecting element; Equipped with the light pipe is configured to transmit light output from the light source toward the light redirecting element by multiple total internal reflections; the light redirecting element is configured to redirect light propagating in the light pipe towards the modulation element; A head-mounted display device described in any of embodiments 94-96.

[0111] (Embodiment 98) A head-mounted display device as described in embodiment 98, wherein the light source comprises a plurality of light-emitting elements configured to emit light in a plurality of colors.

[0112] (Embodiment 99) A head-mounted display device as described in embodiment 98, wherein the plurality of light-emitting elements comprise light-emitting diodes or lasers.

[0113] (Embodiment 100) A head-mounted display device described in any of embodiments 98-99, further comprising an optical element configured to combine light emitted by multiple light-emitting elements.

[0114] (Embodiment 101) A head-mounted display device as described in embodiment 100, wherein the optical element is a dichroic beam combiner.

[0115] (Embodiment 102) A head-mounted display device described in any of embodiments 98-101, wherein the light redirecting element is configured to redirect light propagating in the light pipe through the waveguide towards the modulation element.

[0116] (Embodiment 103) A head-mounted display device described in any of embodiments 98-102, wherein the waveguide further comprises a light adjusting optical system configured to adjust the distribution of light redirected by the light redirecting element.

[0117] (Embodiment 104) A display system, comprising: an image projection device configured to emit multiplexed light streams comprising a first light stream comprising image content associated with a first color, a second light stream comprising image content associated with a second color, and a third light stream comprising image content associated with a third color; a waveguide comprising a material having a refractive index greater than 1.79; a first incoupling optical element configured to receive the multiplexed light streams emitted from the image projection device and incoupling the multiplexed light streams such that the first light stream, the second light stream, and the third light stream propagate through the waveguide by multiple total internal reflections; A display system comprising:

[0118] (Embodiment 105) A display system described in embodiment 104, wherein the waveguide comprises a material having a refractive index of 2.2 or greater.

[0119] (Embodiment 106) A display system described in any of embodiments 104-105, wherein the waveguide comprises a material having a refractive index of 2.3 or greater.

[0120] (Embodiment 107) A display system described in any of embodiments 104-106, wherein the waveguide comprises lithium niobate or silicon carbide.

[0121] (Embodiment 108) A display system described in any of embodiments 104-107, wherein the waveguide has a field of view that is greater than approximately 30 degrees horizontally and approximately 24.7 degrees vertically.

[0122] (Embodiment 109) A display system as described in embodiment 108, wherein the field of view of the waveguide is approximately 45.9 degrees horizontally and approximately 56.1 degrees vertically.

[0123] (Embodiment 110) A display system described in any of embodiments 104-109, wherein the multiplexed light stream comprises image information associated with a first depth plane.

[0124] (Embodiment 111) A display system as described in embodiment 110, wherein the waveguide is associated with a first depth plane and light emitted from the waveguide is configured to generate an image that appears to originate from the first depth plane.

[0125] (Embodiment 112) A display system described in any of embodiments 110-111, wherein the image projection device is further configured to output a second multiplexed light stream comprising image information associated with a second depth plane, the second multiplexed light stream comprising a plurality of light streams associated with a first color, a second color, and a third color.

[0126] (Embodiment 113) A second waveguide associated with a second depth plane, the second waveguide comprising a material having a refractive index greater than 1.79; a second incoupling optical element configured to receive the second multiplexed light streams emitted from the image projection device and incoupling the second multiplexed light streams such that the multiple light streams propagate through the second waveguide by multiple total internal reflections; 113. The display system of embodiment 112, further comprising:

[0127] (Embodiment 114) A display system as described in embodiment 113, wherein light emitted from the second waveguide is configured to generate an image that appears to arise from a second depth plane.

[0128] (Embodiment 115) A display system described in any of embodiments 114-115, wherein the second waveguide is included within the eyepiece of the head-mounted display.

[0129] (Embodiment 116) A display system described in any of embodiments 104-115, wherein the waveguide is contained within the eyepiece of a head-mounted display.

[0130] (Embodiment 117) A display system described in any of embodiments 115-116, wherein the head-mounted display is equipped with eyewear.

[0131] (Embodiment 118) A display system described in any of embodiments 104-117, wherein the image input device comprises a light modulation device.

[0132] (Embodiment 119) A display system, comprising: an image projection device configured to emit multiplexed light streams comprising a first light stream comprising image content associated with a first color, a second light stream comprising image content associated with a second color, and a third light stream comprising image content associated with a third color; a waveguide comprising a material having a refractive index greater than 1.79; a first plurality of in-coupling optical elements configured to receive the multiplexed light streams emitted from the image projection device and in-coupling the multiplexed light streams such that the first light stream, the second light stream, and the third light stream propagate through the waveguide by multiple total internal reflections; A display system comprising:

[0133] (Embodiment 120) A display system described in embodiment 119, wherein the waveguide comprises a material having a refractive index of 2.2 or greater.

[0134] (Embodiment 121) A display system described in any of embodiments 119-120, wherein the waveguide comprises a material having a refractive index of 2.3 or greater.

[0135] (Embodiment 122) A display system described in any of embodiments 119-121, wherein the waveguide comprises lithium niobate or silicon carbide.

[0136] (Embodiment 123) A display system described in any of embodiments 119-122, wherein the waveguide has a field of view that is greater than approximately 30 degrees horizontally and approximately 24.7 degrees vertically.

[0137] (Embodiment 124) A display system as described in embodiment 123, wherein the field of view of the waveguide is approximately 45.9 degrees horizontally and approximately 56.1 degrees vertically.

[0138] (Embodiment 125) The first plurality of internal coupling optical elements comprises: a first incoupling optical element configured to incoupling the first light stream; a second incoupling optical element configured to incoupling the second light stream; a third incoupling optical element configured to incoupling a third light stream; A display system described in any of embodiments 119-124, comprising:

[0139] (Embodiment 126) A display system described in any of embodiments 119-125, wherein the multiplexed light stream comprises image information associated with a first depth plane.

[0140] (Embodiment 127) A display system as described in embodiment 126, wherein the waveguide is associated with a first depth plane and light emitted from the waveguide is configured to generate an image that appears to originate from the first depth plane.

[0141] (Embodiment 128) A display system described in any of embodiments 125-127, wherein the image projection device is further configured to output a second multiplexed light stream comprising image information associated with a second depth plane, the second multiplexed light stream comprising a plurality of light streams associated with a first color, a second color, and a third color.

[0142] (Embodiment 129) a second waveguide associated with the second depth plane, the second waveguide comprising a material having a refractive index greater than 1.79; a second plurality of in-coupling optical elements configured to receive the second multiplexed light streams emitted from the image projection device and in-coupling the second multiplexed light streams such that the plurality of light streams propagate through the second waveguide by multiple total internal reflections; 129. The display system of embodiment 128, further comprising:

[0143] (Embodiment 130) A display system as described in embodiment 129, wherein light emitted from the second waveguide is configured to generate an image that appears to arise from a second depth plane.

[0144] (Embodiment 131) A display system described in any of embodiments 129-130, wherein the second waveguide is included within the eyepiece of the head-mounted display.

[0145] (Embodiment 132) A display system described in any of embodiments 119-131, wherein the waveguide is contained within the eyepiece of a head-mounted display.

[0146] (Embodiment 133) A display system described in any of embodiments 131-132, wherein the head-mounted display is equipped with eyewear.

[0147] (Embodiment 134) A display system described in any of embodiments 119-133, wherein the image input device comprises a light modulation device.

[0148] (Embodiment 135) A display system, comprising: an image projection device configured to emit multiplexed light streams comprising a first light stream comprising image content associated with a first color, a second light stream comprising image content associated with a second color, and a third light stream comprising image content associated with a third color; a first waveguide comprising a material having a refractive index greater than 1.79; a second waveguide comprising a material having a refractive index greater than 1.79; a first incoupling optical element configured to receive the multiplexed light streams emitted from the image projection device and to incoupling the first light stream and the second light stream into the first waveguide such that the first light stream and the second light stream propagate through the first waveguide by multiple total internal reflections; a second incoupling optical element configured to receive the multiplexed light streams emitted from the image projection device and incoupling the third light stream into the second waveguide such that the third light stream propagates through the second waveguide by multiple total internal reflections; A display system comprising:

[0149] (Embodiment 136) A display system as described in embodiment 135, wherein the second internal coupling optical element is further configured to internally couple the first light stream or the second light stream into the second waveguide so that the first light stream or the second light stream propagates through the first waveguide by multiple total internal reflections.

[0150] (Embodiment 137) A display system described in any of embodiments 135-136, wherein at least one of the first waveguide and the second waveguide comprises a material having a refractive index of 2.2 or greater.

[0151] (Embodiment 138) A display system described in any of embodiments 135-137, wherein at least one of the first waveguide and the second waveguide comprises a material having a refractive index of 2.3 or greater.

[0152] (Embodiment 139) A display system described in any of embodiments 135-137, wherein at least one of the first waveguide and the second waveguide comprises lithium niobate or silicon carbide.

[0153] (Embodiment 140) A display system described in any of embodiments 135-139, wherein at least one of the first waveguide and the second waveguide has a field of view that is greater than approximately 30 degrees horizontally and approximately 24.7 degrees vertically.

[0154] (Embodiment 141) A display system as described in embodiment 140, wherein the field of view of at least one of the first waveguide and the second waveguide is approximately 45.9 degrees horizontally and approximately 56.1 degrees vertically.

[0155] (Embodiment 142) A display system described in any of embodiments 135-141, wherein the multiplexed light stream comprises image information associated with a first depth plane.

[0156] (Embodiment 143) A display system as described in embodiment 142, wherein the first waveguide and the second waveguide are associated with a first depth plane, and light emitted from the first waveguide and the second waveguide is configured to generate an image that appears to originate from the first depth plane.

[0157] (Embodiment 144) A display system described in any of embodiments 135-143, wherein the image projection device is further configured to output a second multiplexed light stream comprising image information associated with a second depth plane, the second multiplexed light stream comprising a plurality of light streams associated with a first color, a second color, and a third color.

[0158] (Embodiment 145) Two waveguides associated with a second depth plane, the two waveguides comprising a material with a refractive index greater than 1.79; a third incoupling optical element configured to receive the second multiplexed light stream emitted from the image projection device and incoupling the light streams associated with the first color and the second color into the first of the two waveguides such that the light streams associated with the first color and the second color propagate through the first of the two waveguides by multiple total internal reflections; a fourth incoupling optical element configured to receive the multiplexed light streams emitted from the image projection device and incoupling the light stream associated with the third color into the second of the two waveguides such that the light stream associated with the third color propagates through the second of the two waveguides by multiple total internal reflections; 145. The display system of embodiment 144, further comprising:

[0159] (Embodiment 146) A display system as described in embodiment 145, wherein the fourth internal coupling optical element is further configured to internally couple a light stream associated with the first color or the second color into the second of the two waveguides so that the light stream associated with the first color or the second color propagates through the second of the two waveguides by multiple total internal reflections.

[0160] (Embodiment 147) A display system described in any of embodiments 145-146, wherein the light emitted from the two waveguides is configured to generate an image that appears to arise from a second depth plane.

[0161] (Embodiment 148) A display system described in any of embodiments 145-147, wherein the two waveguides associated with the second depth plane are contained within the eyepiece of the head-mounted display.

[0162] (Embodiment 149) A display system described in any of embodiments 135-148, wherein the first waveguide and the second waveguide are contained within the eyepiece of a head-mounted display.

[0163] (Embodiment 150) A display system described in any of embodiments 148-149, wherein the head-mounted display is equipped with eyewear.

[0164] (Embodiment 151) A display system described in any of embodiments 135-150, wherein the image input device comprises a light modulation device.

[0165] (Embodiment 152) A display system, comprising: an image projection device configured to emit multiplexed light streams comprising a first light stream comprising image content associated with a first color, a second light stream comprising image content associated with a second color, and a third light stream comprising image content associated with a third color; a first waveguide comprising a material having a refractive index greater than 1.79; a second waveguide comprising a material having a refractive index greater than 1.79; a first incoupling optical element configured to receive the multiplexed light stream emitted from the image projection device and incoupling the first light stream into the first waveguide such that the first light stream propagates through the first waveguide by multiple total internal reflections; a second incoupling optical element configured to receive the multiplexed light stream emitted from the image projection device and incoupling the second light stream into the first waveguide such that the second light stream propagates through the first waveguide by multiple total internal reflections; a third incoupling optical element configured to receive the multiplexed light stream emitted from the image projection device and incoupling the third light stream into the second waveguide such that the third light stream propagates through the second waveguide by multiple total internal reflections; A display system comprising:

[0166] (Embodiment 153) A display system as described in embodiment 152, wherein the third internal coupling optical element is further configured to internally couple the first light stream or the second light stream into the second waveguide so that the first light stream or the second light stream propagates through the first waveguide by multiple total internal reflections.

[0167] (Embodiment 154) A display system as described in embodiment 152, further comprising a fourth internal coupling optical element configured to internally couple the first light stream or the second light stream into the second waveguide so that the first light stream or the second light stream propagates through the first waveguide by multiple total internal reflections.

[0168] (Embodiment 155) A display system described in any of embodiments 152-154, wherein at least one of the first waveguide and the second waveguide comprises a material having a refractive index of 2.2 or greater.

[0169] (Embodiment 156) A display system described in any of embodiments 152-155, wherein at least one of the first waveguide and the second waveguide comprises a material having a refractive index of 2.3 or greater.

[0170] (Embodiment 157) A display system described in any of embodiments 152-156, wherein at least one of the first waveguide and the second waveguide comprises lithium niobate or silicon carbide.

[0171] (Embodiment 158) A display system described in any of embodiments 152-157, wherein at least one of the first waveguide and the second waveguide has a field of view that is greater than approximately 30 degrees horizontally and approximately 24.7 degrees vertically.

[0172] (Embodiment 159) A display system as described in embodiment 158, wherein the field of view of at least one of the first waveguide and the second waveguide is approximately 45.9 degrees horizontally and approximately 56.1 degrees vertically.

[0173] (Embodiment 160) A display system described in any of embodiments 152-159, wherein the multiplexed light stream comprises image information associated with a first depth plane.

[0174] (Embodiment 161) A display system as described in embodiment 160, wherein the first waveguide and the second waveguide are associated with a first depth plane, and light emitted from the first waveguide and the second waveguide is configured to generate an image that appears to originate from the first depth plane.

[0175] (Embodiment 162) A display system described in any of embodiments 152-161, wherein the image projection device is further configured to output a second multiplexed light stream comprising image information associated with a second depth plane, the second multiplexed light stream comprising a plurality of light streams associated with a first color, a second color, and a third color.

[0176] (Embodiment 163) Two waveguides associated with a second depth plane, the two waveguides comprising a material with a refractive index greater than 1.79; a fifth incoupling optical element configured to receive the second multiplexed light stream emitted from the image projection device and incoupling the light streams associated with the first color and the second color into the first of the two waveguides such that the light streams associated with the first color and the second color propagate through the first of the two waveguides by multiple total internal reflections; a sixth incoupling optical element configured to receive the multiplexed light streams emitted from the image projection device and incoupling the light stream associated with the third color into the second of the two waveguides such that the light stream associated with the third color propagates through the second of the two waveguides by multiple total internal reflections; 163. The display system of embodiment 162, further comprising:

[0177] (Embodiment 164) A display system as described in embodiment 163, wherein the sixth internal coupling optical element is further configured to internally couple a light stream associated with the first color or the second color into the second of the two waveguides so that the light stream associated with the first color or the second color propagates through the second of the two waveguides by multiple total internal reflections.

[0178] (Embodiment 165) A display system described in any of embodiments 163-165, wherein the light emitted from the two waveguides is configured to generate an image that appears to arise from a second depth plane.

[0179] (Embodiment 166) A display system described in any of embodiments 163-165, wherein the two waveguides associated with the second depth plane are contained within the eyepiece of the head-mounted display.

[0180] (Embodiment 167) A display system described in any of embodiments 152-166, wherein the first waveguide and the second waveguide are contained within the eyepiece of a head-mounted display.

[0181] (Embodiment 168) A display system described in any of embodiments 166-167, wherein the head-mounted display is equipped with eyewear.

[0182] (Embodiment 169) A display system described in any of embodiments 152-168, wherein the image input device comprises a light modulation device.

[0183] (Embodiment 170) A method for manufacturing a diffractive optical element, comprising: providing a substrate comprising a material having a refractive index greater than 1.79 that is transparent to visible light; disposing a patternable layer over a surface of a substrate; patterning the patternable layer, the pattern comprising a plurality of features; Etching a surface of the substrate through the patternable layer to fabricate a structure on the surface of the substrate, the structure comprising diffractive features configured to diffract visible light.

[0184] (Embodiment 171) The method described in embodiment 170, wherein the transparent material comprises LiNbO3 or silicon carbide.

[0185] (Embodiment 172) The method described in embodiment 170, wherein disposing a patternable layer over the surface of the substrate comprises jet-depositing the patternable layer over the surface of the substrate.

[0186] (Embodiment 173) The method of embodiment 170, wherein the surface of the substrate is discharged prior to depositing the patternable layer.

[0187] (Embodiment 174) The method of embodiment 170, wherein the patternable layer comprises a resist or a polymer.

[0188] (Embodiment 175) A method for manufacturing a diffractive optical element, comprising: providing a substrate comprising a material having a refractive index greater than 1.79 that is transparent to visible light; disposing a patternable layer over a surface of a substrate; patterning the patternable layer, the pattern comprising a plurality of features; wherein the plurality of features of the patterned patternable layer are configured to diffract visible light. method.

[0189] (Embodiment 176) The method of embodiment 175, wherein the transparent material comprises LiNbO3 or silicon carbide.

[0190] (Embodiment 177) The method described in embodiment 175, wherein disposing the patternable layer over the surface of the substrate comprises jet-depositing the patternable layer over the surface of the substrate.

[0191] (Embodiment 178) The method of embodiment 175, wherein the surface of the substrate is discharged prior to depositing the patternable layer.

[0192] (Embodiment 179) The method of embodiment 175, wherein the patternable layer comprises a resist or a polymer.

[0193] (Embodiment 180) A display system described in any of embodiments 1-26, wherein the waveguide material comprises silicon carbide.

[0194] (Embodiment 181) The method of any of embodiments 27-40, wherein the transparent material comprises silicon carbide.

[0195] (Embodiment 182) A waveguide described in any of embodiments 41-45, wherein the transparent material comprises silicon carbide.

[0196] (Embodiment 183) A head-mounted display device, an eyepiece comprising an image projection device and a waveguide comprising a material having a refractive index greater than 1.79, the waveguide having a first major surface, a second major surface opposite the first major surface, and a plurality of edges between the first and second major surfaces; wherein the waveguide is configured to receive and guide light from the image projection device and direct the image into the eye of a wearer of the head mounted display. Head-mounted display device.

[0197] (Embodiment 184) A head-mounted display device as described in embodiment 183, wherein the waveguide material has a refractive index of 2.2 or greater.

[0198] (Embodiment 185) A head-mounted display device described in any of embodiments 183-184, wherein the waveguide material has a refractive index of 2.3 or greater.

[0199] (Embodiment 186) A head-mounted display device described in any of embodiments 183-185, wherein the material comprises lithium niobate.

[0200] (Embodiment 187) A head-mounted display device described in any of embodiments 183-185, wherein the material comprises silicon carbide.

[0201] (Embodiment 188) A head-mounted display device described in any of embodiments 183-187, wherein the waveguide has a field of view greater than approximately 30 degrees horizontally and greater than approximately 24 degrees vertically.

[0202] (Embodiment 189) A head-mounted display device as described in embodiment 188, wherein the field of view of the waveguide is approximately 45 degrees horizontally and approximately 56 degrees vertically.

[0203] (Embodiment 190) A head-mounted display device described in any of embodiments 183-189, further comprising a plurality of diffractive features arranged on at least one of the first major surface or the second major surface.

[0204] (Embodiment 191) A head-mounted display device as described in embodiment 190, wherein the plurality of diffractive features are formed on at least one of the first major surface or the second major surface by etching at least one of the first major surface or the second major surface.

[0205] (Embodiment 192) A head-mounted display device described in any of embodiments 183-191, wherein at least some of the multiple diffractive features are configured to internally couple incident image light so that the internally coupled image light propagates through the waveguide by multiple total internal reflections at the first and second major surfaces.

[0206] (Embodiment 193) A head-mounted display device described in any of embodiments 183-192, further comprising a variable-focus lens between the waveguide and the viewer, the variable-focus lens configured to vary the focal plane of image light propagating through the waveguide by multiple total internal reflections at the first and second major surfaces that are externally coupled from the waveguide toward the viewer.

[0207] (Embodiment 194) A head-mounted display device as described in embodiment 193, wherein the variable focus lens comprises a negative lens.

[0208] (Embodiment 195) A head-mounted display device described in any of embodiments 193-194, wherein the variable focus lens comprises a liquid-filled lens.

[0209] (Embodiment 196) A head-mounted display device described in any of embodiments 193-195, wherein the variable focus lens includes a liquid crystal.

[0210] (Embodiment 197) A head-mounted display device described in any of embodiments 193, 194, or 196, wherein the variable focus lens comprises a geometric phase lens.

[0211] (Embodiment 198) A head-mounted display device described in any of embodiments 183-192, further comprising a negative lens between the waveguide and the viewer, such that the negative lens receives light propagating through the waveguide by multiple total internal reflections at the first and second major surfaces, which is outcoupled from the waveguide toward the viewer.

[0212] (Embodiment 199) A head-mounted display device as described in embodiment 198, wherein the negative lens comprises a static lens.

[0213] (Embodiment 200) A head-mounted display device described in embodiment 198 or 199, wherein the waveguide and negative lens are contained within a stacked waveguide assembly.

[0214] (Embodiment 201) A head-mounted display device described in any of embodiments 198-200, further comprising an additional waveguide paired with an additional negative lens.

[0215] (Embodiment 202) A head-mounted display device described in any of embodiments 198-201, further comprising a positive lens positioned between the waveguide and the real world.

[0216] (Embodiment 203) A head-mounted display device described in any of embodiments 183-202, further comprising a polarizer stacked with the waveguide.

[0217] (Embodiment 204) A head-mounted display device described in any of embodiments 183-203, wherein at least some of the plurality of diffractive features are configured to outcouple image light propagating through the waveguide toward a viewer by multiple total internal reflections at the first and second major surfaces.

[0218] (Embodiment 205) A head-mounted display device described in any of embodiments 183-204, further comprising an imaging system configured to provide image light.

[0219] (Embodiment 206) A head-mounted display device as described in embodiment 205, wherein the imaging system is outside the field of view of the viewer viewing the waveguide.

[0220] (Embodiment 207) The imaging system includes: A lighting system; a modulation element configured to receive unmodulated light from the illumination system; a projection optics system configured to transmit image light output by the modulation element; A head-mounted display device as described in any of embodiments 205-206, comprising:

[0221] (Embodiment 208) A head-mounted display device as described in embodiment 207, wherein the modulation element is reflective.

[0222] (Embodiment 209) A head-mounted display device as described in embodiment 208, in which unmodulated image light from the illumination system is transmitted through the projection optical system toward a reflective modulation element, reflected from the modulation element, and transmitted back into the waveguide through the projection optical system.

[0223] (Embodiment 210) The lighting system includes: a light source configured to output visible light; and a light pipe configured to receive visible light output from the light source; a light redirecting element; Equipped with the light pipe is configured to transmit light output from the light source toward the light redirecting element by multiple total internal reflections; the light redirecting element is configured to redirect light propagating in the light pipe towards the modulation element; A head-mounted display device described in any of embodiments 207-209.

[0224] (Embodiment 211) A head-mounted display device as described in embodiment 210, wherein the light source comprises a plurality of light-emitting elements configured to emit light in a plurality of colors.

[0225] (Embodiment 212) A head-mounted display device as described in embodiment 211, wherein the plurality of light-emitting elements comprise light-emitting diodes or lasers.

[0226] (Embodiment 213) A head-mounted display device described in any of embodiments 211-212, further comprising an optical element configured to combine light emitted by multiple light-emitting elements.

[0227] (Embodiment 214) A head-mounted display device as described in embodiment 213, wherein the optical element is a dichroic beam combiner.

[0228] (Embodiment 215) A head-mounted display device described in any of embodiments 210-214, wherein the light redirecting element is configured to redirect light propagating in the light pipe through the waveguide towards the modulation element.

[0229] (Embodiment 216) A head-mounted display device described in any of embodiments 210-215, wherein the waveguide further comprises a light adjusting optical system configured to adjust the distribution of light redirected by the light redirecting element.

[0230] (Embodiment 217) A head-mounted display device described in any of embodiments 183-216, further comprising a diffraction grating within or on the waveguide. The present specification also provides, for example, the following items: (Item 1) 1. A display system comprising: an image projection device configured to emit multiplexed light streams, the multiplexed light streams comprising a first light stream of a first color, a second light stream of a second color, and a third light stream of a third color, the first, second, and third colors being different, and the first, second, and third light streams comprising image content; a waveguide, the waveguide comprising a material having a refractive index greater than 1.79, the waveguide configured to receive the multiplexed light streams emitted from the image projection device such that the first light stream, the second light stream, and the third light stream are guided within the waveguide by multiple total internal reflections; A display system comprising: (Item 2) Item 10. The display system of item 1, wherein the waveguide comprises a material having a refractive index of 2.2 or greater. (Item 3) 3. The display system of any of items 1-2, wherein the waveguide comprises a material having a refractive index of 2.3 or greater. (Item 4) 4. The display system of any one of items 1-3, wherein the waveguide comprises lithium niobate. (Item 5) 5. The display system of any of items 1-4, wherein the waveguide has a field of view greater than about 30 degrees horizontally and greater than about 24 degrees vertically. (Item 6) Item 6. The display system of item 5, wherein the field of view of the waveguide is approximately 45 degrees in the horizontal direction and approximately 56 degrees in the vertical direction. (Item 7) A display system described in any of items 1-6, further comprising at least one variable-focus optical element, the at least one variable-focus optical element being positioned to receive the multiplexed light stream output from the waveguide so that at least a portion of the multiplexed light stream is directed toward a user's eye, the variable-focus optical element being configured to vary the depth at which light from the waveguide appears to originate. (Item 8) 7. A display system according to any one of items 1-6, wherein the multiplexed light stream comprises a first multiplexed light stream comprising image information associated with a first depth plane. (Item 9) Item 9. The display system of item 8, wherein the waveguide comprises a first waveguide associated with the first depth plane, and wherein light emitted from the first waveguide is configured to direct the first multiplexed light stream toward a viewer and generate an image that appears to originate from the first depth plane. (Item 10) 10. The display system of any of items 8-9, wherein the image projection device is further configured to output a second multiplexed light stream comprising image information associated with a second depth plane, the second multiplexed light stream comprising a plurality of light streams having the first color, the second color, and the third color, and the first, second, and third colors are different. (Item 11) Item 11. The display system of item 10, further comprising a second waveguide associated with the second depth plane, the second waveguide comprising a material having a refractive index greater than 1.79, and the second waveguide configured to receive the second multiplexed light stream emitted from the image projection device such that the multiple light streams associated with the second multiplexed light stream are guided through the second waveguide by multiple total internal reflections. (Item 12) Item 12. The display system of item 11, wherein light emitted from the second waveguide is configured to direct the second multiplexed light stream toward a viewer to generate an image that appears to arise from the first depth plane. (Item 13) 13. A display system according to any of items 11-12, wherein the second waveguide is included within an eyepiece of a head-mounted display. (Item 14) 14. A display system according to any one of items 9-13, wherein the first waveguide is included within an eyepiece of a head-mounted display. (Item 15) 8. A display system according to any one of items 1-7, wherein the waveguide is included within an eyepiece of a head-mounted display. (Item 16) 16. The display system of any of items 1-7 and 15, further comprising an internal coupling optical element configured to receive the multiplexed light streams emitted from the image projection device and internally couple each of the first light stream, the second light stream, and the third light stream into the waveguide so as to be guided therein by multiple total internal reflections. (Item 17) 17. A display system according to any one of items 1-16, wherein the image projection device comprises a light modulation device. (Item 18) 1. A display system comprising: an image projection device configured to emit multiplexed light streams, the multiplexed light streams comprising a first light stream of a first color, a second light stream of a second color, and a third light stream of a third color, the first, second, and third colors being different, and the first, second, and third light streams comprising image content; First and second waveguides, said first and second waveguides comprising a material having a refractive index greater than 1.79. Equipped with a first waveguide configured to receive the first color and the second color, and a second waveguide configured to receive the third color, wherein different colors or color combinations are combined into the two waveguides such that the first and second light streams are guided within the first waveguide by multiple total internal reflections and the third light stream is guided within the second waveguide by multiple total internal reflections. (Item 19) Item 19. The display system of item 18, wherein the second waveguide is also configured to receive the first color such that the first light stream is guided within the second waveguide by multiple total internal reflections. (Item 20) Item 19. The display system of item 18, wherein the second waveguide is also configured to receive the second color such that the second light stream is guided within the second waveguide by multiple total internal reflections. (Item 21) Item 19. The display system of item 18, wherein the second waveguide is not configured to internally couple the first or second colors such that the third light stream is guided within the second waveguide primarily by multiple total internal reflections. (Item 22) 22. A display system as described in any of items 18-21, further comprising a first internal coupling optical element in the first waveguide, the first internal coupling optical element in the first waveguide configured to internally couple both the first and second light streams into the first waveguide such that the first and second light streams are guided within the first waveguide by multiple total internal reflections. (Item 23) 22. A display system according to any of items 18-21, further comprising first and second internal coupling optical elements in the first waveguide, the first and second internal coupling optical elements in the first waveguide being configured to internally couple both the first and second light streams into the first waveguide, respectively, such that the first and second light streams are guided within the first waveguide by multiple total internal reflections. (Item 24) 22. A display system according to any one of items 18-21, further comprising a third internal coupling optical element in the second waveguide, the third internal coupling optical element in the second waveguide configured to internally couple the third light stream into the second waveguide such that the third light stream is guided within the second waveguide by multiple total internal reflections. (Item 25) Item 25. The display system of item 24, wherein the third internal coupling optical element is also configured to internally couple either the first or second light stream into the second waveguide such that either the first or second light stream is guided within the second waveguide by multiple total internal reflections. (Item 26) Item 25. The display system of item 24, further comprising a fourth internal coupling optical element, the fourth internal coupling optical element configured to internally couple either the first or second light stream into the second waveguide such that either the first or second light stream is guided within the second waveguide by multiple total internal reflections. (Item 27) 1. A method of manufacturing a diffractive optical element, the method comprising: providing a substrate comprising a material having a refractive index greater than 1.79 that is transparent to visible light; disposing a patternable layer over a surface of the substrate; patterning the patternable layer, the pattern comprising a plurality of features; etching the surface of the substrate through the patternable layer to fabricate structures on the surface of the substrate, the structures comprising diffractive features configured to diffract visible light; A method comprising: (Item 28) Item 28. The method of item 27, wherein the transparent material includes LiNbO3. (Item 29) 29. The method of claim 27 or 28, wherein disposing the patternable layer over the surface of the substrate comprises jet-depositing the patternable layer over the surface of the substrate. (Item 30) 30. The method of any of items 27-29, wherein the surface of the substrate is discharged prior to depositing the patternable layer. (Item 31) 31. The method of any of items 27-30, wherein the patternable layer comprises a resist or a polymer. (Item 32) 1. A method of manufacturing a diffractive optical element, the method comprising: providing a substrate comprising a material having a refractive index greater than 1.79 that is transparent to visible light; disposing a patternable layer over a surface of the substrate; patterning the patternable layer, the pattern comprising a plurality of features; Including, A method wherein a plurality of features of the patterned patternable layer are configured to diffract visible light as guided therein into the substrate or to diffract visible light guided within the substrate out of the substrate. (Item 33) Item 33. The method of item 32, wherein the transparent material includes LiNbO3. (Item 34) 34. The method of claim 32 or 33, wherein disposing the patternable layer over the surface of the substrate comprises jet-depositing the patternable layer over the surface of the substrate. (Item 35) 35. The method of any of items 32-34, wherein the surface of the substrate is discharged prior to depositing the patternable layer. (Item 36) 36. The method of any of items 32-35, wherein the patternable layer comprises a resist or a polymer. (Item 37) 1. A method of manufacturing a diffractive optical element, the method comprising: providing a substrate comprising a material having a refractive index greater than 1.79 that is transparent to visible light; jet-depositing a patternable layer over a surface of the substrate; patterning the patternable layer, the pattern comprising a plurality of features; A method comprising: (Item 38) Item 38. The method of item 37, wherein the transparent material includes LiNbO3. (Item 39) Item 39. The method of item 37 or 38, wherein the surface of the substrate is discharged prior to depositing the patternable layer. (Item 40) 40. The method of any of items 37-39, wherein the patternable layer comprises a resist or a polymer. (Item 41) 1. A waveguide for propagating image content therein by total internal reflection, said waveguide comprising: a substrate comprising a material having a refractive index greater than 1.79 that is transparent to visible light, said substrate being capable of propagating image content therein by total internal reflection; a layer over a surface of the substrate, the layer comprising a material having a lower refractive index than the substrate, the layer comprising a pattern comprising a plurality of features; Equipped with A waveguide, wherein a plurality of features of the patterned patternable layer are configured to diffract visible light as guided therein into the substrate or to diffract visible light guided within the substrate out of the substrate. (Item 42) Item 42. The waveguide of item 41, wherein the transparent material comprises LiNbO3. (Item 43) Item 43. The waveguide of item 41 or 42, wherein the surface of the substrate is discharged prior to depositing the patternable layer. (Item 44) 44. The waveguide of any of items 41-43, wherein the patternable layer comprises a resist. (Item 45) 45. The waveguide of any of items 41-44, wherein the patternable layer comprises a polymer. (Item 46) A head-mounted display device, an eyepiece comprising at least one waveguide comprising a material having a refractive index greater than 1.79, the waveguide having a first major surface, a second major surface opposite the first major surface, and a plurality of edges between the first major surface and the second major surface; a plurality of diffractive features formed on at least one of the first major surface or the second major surface; A head-mounted display device comprising: (Item 47) Item 47. The head-mounted display device of item 46, wherein the plurality of diffractive features are formed in at least one of the first major surface or the second major surface by etching at least one of the first major surface or the second major surface. (Item 48) Item 48. A head-mounted display device according to item 46 or 47, wherein the waveguide comprises a material having a refractive index greater than 2.2. (Item 49) 49. A head-mounted display device according to any one of items 46-48, wherein the waveguide comprises lithium niobate. (Item 50) 49. A head-mounted display device according to any one of items 46-48, wherein the waveguide comprises silicon carbide. (Item 51) A head-mounted display device as described in any of items 46-50, wherein at least some of the plurality of diffractive features are configured to internally couple incident image light such that the internally coupled image light propagates through the waveguide by multiple total internal reflections at the first and second major surfaces. (Item 52) A head-mounted display device described in any of items 46-52, further comprising a variable-focus lens between the waveguide and a viewer, the variable-focus lens configured to vary the focal plane of image light propagating through the waveguide by multiple total internal reflections at the first and second major surfaces that are outcoupled from the waveguide toward the viewer. (Item 53) Item 53. A head-mounted display device as described in item 52, wherein the variable focus lens comprises a negative lens. (Item 54) 54. A head-mounted display device according to any of items 52-53, wherein the variable focus lens comprises a liquid-filled lens. (Item 55) 54. A head-mounted display device according to any one of items 52-53, wherein the variable focus lens comprises a liquid crystal. (Item 56) 56. Any of the head-mounted display devices described in items 52, 53, or 55, wherein the variable focus lens comprises a geometric phase lens. (Item 57) Item 58. The head-mounted display device of any of Items 46-51, further comprising a negative lens between the waveguide and the viewer, the negative lens being such that the negative lens receives light propagating through the waveguide by multiple total internal reflections at the first and second major surfaces that are outcoupled from the waveguide toward the viewer. Item 58. A head-mounted display device as described in item 57, wherein the negative lens comprises a static lens. (Item 59) 59. A head-mounted display device according to item 57 or 58, wherein the waveguide and the negative lens are contained within a stacked waveguide assembly. (Item 60) 60. A head-mounted display device according to any of items 57-59, further comprising an additional waveguide paired with an additional negative lens. (Item 61) A head-mounted display device described in any of items 57-60, further comprising a positive lens positioned between the waveguide and the real world. (Item 62) 62. A head-mounted display device according to any one of items 46-61, further comprising a polarizer stacked with the waveguide. (Item 63) A head-mounted display device as described in any of items 46-62, wherein at least some of the plurality of diffractive features are configured to outcouple image light propagating through the waveguide toward the viewer by multiple total internal reflections at the first and second major surfaces. (Item 64) 63. A head-mounted display device according to any of items 46-62, further comprising an imaging system configured to provide image light. (Item 65) Item 65. A head-mounted display device as described in Item 64, wherein the imaging system is outside the field of view of a viewer viewing the waveguide. (Item 66) the imaging system A lighting system; a modulation element configured to receive unmodulated light from the illumination system; a projection optics system configured to transmit image light output by the modulation element; 66. A head-mounted display device according to any one of items 64-65, comprising: (Item 67) Item 68. The head-mounted display device of item 66, wherein the modulation element is reflective. Item 68. A head-mounted display device as described in Item 67, wherein unmodulated image light from the illumination system is transmitted through the projection optical system toward the reflective modulation element, reflected from the modulation element, and transmitted back into the waveguide through the projection optical system. (Item 69) The lighting system comprises: a light source configured to output visible light; a light pipe configured to receive the visible light output from the light source; Light redirecting elements and Equipped with the light pipe is configured to transmit the light output from the light source toward the light redirecting element by multiple total internal reflections; A head-mounted display device described in any of items 66-68, wherein the light redirecting element is configured to redirect light propagating within the light pipe towards the modulation element. (Item 70) 70. A head-mounted display device as described in item 69, wherein the light source comprises a plurality of light-emitting elements configured to emit light in a plurality of colors. (Item 71) Item 71. A head-mounted display device as described in Item 70, wherein the plurality of light-emitting elements comprise light-emitting diodes or lasers. (Item 72) A head-mounted display device described in any of items 70-71, further comprising an optical element configured to combine light emitted by the multiple light-emitting elements. (Item 73) Item 73. A head-mounted display device as described in Item 72, wherein the optical element is a dichroic beam combiner. (Item 74) A head-mounted display device described in any of items 69-73, wherein the light redirecting element is configured to redirect light propagating within the light pipe through the waveguide towards the modulation element. (Item 75) A head-mounted display device described in any of items 69-74, wherein the waveguide further comprises light adjusting optics configured to adjust the distribution of the light redirected by the light redirecting element. (Item 76) A head-mounted display device, an image projection device; an eyepiece comprising a waveguide comprising silicon carbide, the waveguide having a first major surface, a second major surface opposite the first major surface, and a plurality of edges between the first major surface and the second major surface; Equipped with A head-mounted display device, wherein the waveguide is configured to receive and guide light from the image projection device and direct an image into an eye of a wearer of the head-mounted display. (Item 77) Item 77. The head-mounted display device of item 76, further comprising a plurality of diffractive features disposed on at least one of the first major surface or the second major surface. (Item 78) Item 78. The head-mounted display device of item 77, wherein the plurality of diffractive features are formed in at least one of the first major surface or the second major surface by etching at least one of the first major surface or the second major surface. (Item 79) A head-mounted display device as described in any of items 77-78, wherein at least some of the plurality of diffractive features are configured to internally couple incident image light such that the internally coupled image light propagates through the waveguide by multiple total internal reflections at the first and second major surfaces. (Item 80) A head-mounted display device described in any of items 76-79, further comprising a variable-focus lens between the waveguide and a viewer, the variable-focus lens configured to vary the focal plane of image light propagating through the waveguide by multiple total internal reflections at the first and second major surfaces that are outcoupled from the waveguide toward the viewer. (Item 81) Item 81. A head-mounted display device as described in item 80, wherein the variable focus lens comprises a negative lens. (Item 82) 82. A head-mounted display device according to any of items 80-81, wherein the variable focus lens comprises a liquid-filled lens. (Item 83) 82. A head-mounted display device according to any one of items 80-81, wherein the variable focus lens comprises a liquid crystal. (Item 84) 84. A head-mounted display device according to any of items 80, 81, or 83, wherein the variable focus lens comprises a geometric phase lens. (Item 85) 80. A head-mounted display device as described in any of items 76-79, further comprising a negative lens between the waveguide and the viewer, such that the negative lens receives light propagating through the waveguide by multiple total internal reflections at the first and second major surfaces that are outcoupled from the waveguide toward the viewer. (Item 86) Item 86. A head-mounted display device as described in item 85, wherein the negative lens comprises a static lens. (Item 87) Item 87. A head-mounted display device as described in item 85 or 86, wherein the waveguide and the negative lens are contained within a stacked waveguide assembly. (Item 88) 88. A head-mounted display device according to any of items 85-87, further comprising an additional waveguide paired with an additional negative lens. (Item 89) 89. A head-mounted display device according to any of items 85-88, further comprising a positive lens positioned between the waveguide and the real world. (Item 90) A head-mounted display device described in any of items 76-89, further comprising a polarizer stacked with the waveguide. (Item 91) A head-mounted display device as described in any of items 76-90, wherein at least some of the plurality of diffractive features are configured to outcouple image light propagating through the waveguide toward the viewer by multiple total internal reflections at the first and second major surfaces. (Item 92) 92. A head-mounted display device according to any of items 76-91, further comprising an imaging system configured to provide image light. (Item 93) Item 93. A head-mounted display device as described in Item 92, wherein the imaging system is outside the field of view of a viewer viewing the waveguide. (Item 94) the imaging system A lighting system; a modulation element configured to receive unmodulated light from the illumination system; a projection optics system configured to transmit image light output by the modulation element; 94. A head-mounted display device according to any one of items 92-93, comprising: (Item 95) Item 95. A head-mounted display device as described in Item 94, wherein the modulation element is reflective. (Item 96) Item 96. A head-mounted display device as described in Item 95, wherein unmodulated image light from the illumination system is transmitted through the projection optical system toward the reflective modulation element, reflected from the modulation element, and transmitted back into the waveguide through the projection optical system. (Item 97) The lighting system comprises: a light source configured to output visible light; a light pipe configured to receive the visible light output from the light source; Light redirecting elements and Equipped with the light pipe is configured to transmit the light output from the light source toward the light redirecting element by multiple total internal reflections; A head-mounted display device described in any of items 94-96, wherein the light redirecting element is configured to redirect light propagating within the light pipe towards the modulation element. (Item 98) Item 99. A head-mounted display device as described in Item 98, wherein the light source comprises a plurality of light-emitting elements configured to emit light in a plurality of colors. (Item 99) Item 99. A head-mounted display device as described in Item 98, wherein the plurality of light-emitting elements comprise light-emitting diodes or lasers. (Item 100) A head-mounted display device described in any of items 98-99, further comprising an optical element configured to combine light emitted by the multiple light-emitting elements. (Item 101) Item 101. A head-mounted display device as described in item 100, wherein the optical element is a dichroic beam combiner. (Item 102) A head-mounted display device described in any of items 98-101, wherein the light redirecting element is configured to redirect light propagating within the light pipe through the waveguide towards the modulation element. (Item 103) A head-mounted display device described in any of items 98-102, wherein the waveguide further comprises light adjusting optics configured to adjust the distribution of the light redirected by the light redirecting element. (Item 104) 27. The display system of any of items 1-26, wherein the waveguide material comprises silicon carbide. (Item 105) 41. The method of any of items 27-40, wherein the transparent material comprises silicon carbide. (Item 106) 46. ​​The waveguide of any of items 41-45, wherein the transparent material comprises silicon carbide. [Brief explanation of the drawings]

[0231] [Figure 1] FIG. 1 illustrates a user's view of an augmented reality (AR) device, according to some embodiments.

[0232] [Figure 2] FIG. 2 illustrates an example of a wearable display system, according to some embodiments.

[0233] [Figure 3] FIG. 3 illustrates a display system for simulating a three-dimensional image for a user, according to some embodiments.

[0234] [Figure 4] FIG. 4 illustrates aspects of an approach for simulating a three-dimensional image using multiple depth planes, according to some embodiments.

[0235] [Figure 5] 5A-5C illustrate the relationship between the radius of curvature and the focal radius, according to some embodiments.

[0236] [Figure 6] FIG. 6 illustrates an example of a waveguide stack for outputting image information to a user, according to some embodiments.

[0237] [Figure 7] FIG. 7 illustrates an example of an output beam output by a waveguide, according to some embodiments.

[0238] [Figure 8] FIG. 8 illustrates an example of a stacked waveguide assembly in which each depth plane contains an image formed using multiple different primary colors, according to some embodiments.

[0239] [Figure 9A] FIG. 9A illustrates a cross-sectional side view of an example of a set of stacked waveguides, each including an internal coupling optical element, according to some embodiments.

[0240] [Figure 9B] FIG. 9B illustrates a perspective view of an example of the stacked waveguide set of FIG. 9A, according to some embodiments.

[0241] [Figure 9C] FIG. 9C illustrates a top-down plan view of the example set of stacked waveguides of FIGS. 9A and 9B, according to some embodiments.

[0242] [Figure 10] FIG. 10 illustrates an example of a display system comprising an imaging system, a waveguide including a high refractive index material, and multiple variable focus elements, e.g., a liquid-filled lens configured to provide images as they arise from multiple depth planes or depths.

[0243] [Figure 11] FIG. 11 illustrates an example of a display system comprising an imaging system, a waveguide including a high refractive index material, and multiple variable focus elements, e.g., a geometric phase (GP) lens configured to provide images as they arise from multiple depth planes or depths.

[0244] [Figure 12] FIG. 12 illustrates an example of a display system comprising an imaging system and two waveguides comprising a high refractive index material, the two waveguides being contained within a waveguide assembly configured to provide at least one focal plane or depth.

[0245] [Figure 13] Figure 13 illustrates an imaging system in which unmodulated illumination is input into the imaging system through a projection optics system toward a reflective modulation element, such that modulated light containing image information is reflected from the modulation element and transmitted back through the projection optics system toward the waveguide stack.

[0246] [Figure 14A-C] Figure 14A illustrates a display system with a constrained working distance for configuring first and second groups of waveguides for two depth planes, each with three waveguides. Figure 14B illustrates a similar display system as shown in Figure 14A, additionally including lenses included with the first and second groups of waveguides. Figure 14C illustrates a display system with an improved working distance for configuring the waveguides, according to some embodiments.

[0247] [Figure 14D-1] 14D-1, 14D-2, 14D-3, 14E-1, 14E-2, and 14E-3 illustrate various design considerations for configuring the working distance of a display system, according to some embodiments. [Figure 14D-2] 14D-1, 14D-2, 14D-3, 14E-1, 14E-2, and 14E-3 illustrate various design considerations for configuring the working distance of a display system, according to some embodiments. [Figure 14D-3] 14D-1, 14D-2, 14D-3, 14E-1, 14E-2, and 14E-3 illustrate various design considerations for configuring the working distance of a display system, according to some embodiments. [Figure 14E] 14D-1, 14D-2, 14D-3, 14E-1, 14E-2, and 14E-3 illustrate various design considerations for configuring the working distance of a display system, according to some embodiments.

[0248] [Figure 15] FIG. 15 illustrates an example of a display system comprising an imaging system and three waveguides comprising high refractive index material and configured to provide three focal planes or depths.

[0249] [Figure 16] FIG. 16 illustrates an embodiment of a display system comprising a light pipe 1630 .

[0250] [Figure 17] 17A and 17B show side and top views including individual light pipes configured to provide individual colored illumination to an embodiment of an imaging system.

[0251] [Figure 18] 18A and 18B illustrate flow charts of two different methods for fabricating a diffraction grating on the surface of a substrate (eg, a waveguide) comprising a high refractive index material.

[0252] The drawings are provided to illustrate example embodiments and are not intended to limit the scope of the present disclosure. Like reference numbers refer to like parts throughout. DETAILED DESCRIPTION OF THE INVENTION

[0253] VR and AR experiences can be provided by a display system having a display that provides a viewer with images corresponding to multiple depth planes. The images can be relayed from a projector by an exit pupil, where the exit pupil, associated with particular display optics (such as a waveguide), is configured to display the image from a particular depth plane. The display system thereby helps provide depth cues to the user based on accommodation of the eye, or similarly, provides accommodation cues based on the depth of the image or virtual content. Accommodation of the eye can focus different content located on different depth planes within a scene. As discussed herein, such depth cues help provide a reliable perception of depth by the viewer.

[0254] In some configurations, full-color images can be formed for various depth planes by overlaying component images, each having a particular component color. For example, red, green, and blue images can each be output to form a respective full-color image. As a result, each depth plane can have multiple component color images associated with it. As disclosed herein, the component color images can be output using a waveguide that incoupling light containing image information, dispersing the incoupling light across the waveguide, and then outcoupling the light toward a viewer. Light can be incoupling into the waveguide using an incoupling optical element, such as a diffractive element (e.g., a diffraction grating), and then outcoupling out of the waveguide using an outcoupling optical element, which can also be a diffractive element such as a grating.

[0255] In many cases, display systems providing VR and AR experiences, such as mixed reality or augmented reality (AR) eyepiece displays, are desirable to be lightweight, low-cost, have a small form factor, have a wide virtual image field of view, and be as transparent as possible to at least visible wavelengths of light. Additionally, in various implementations, it is desirable to have a configuration that presents virtual image information in multiple (e.g., two or more) focal planes to be practical for a wide variety of applications without exceeding tolerances for vergence-accommodation mismatch. Multiple focal planes may also be referred to herein as multiple depth planes or depths (e.g., at which image content appears to occur). While several architectures exist to achieve a subset of these goals, relatively few comprehensively address all of them. To achieve many of the objectives identified above, it may be desirable to pursue architectures that incorporate compact, or even as compact as possible, imaging systems, such as microdisplays (e.g., projectors), that contain a desired number of pixels for a given field of view. It may also be desirable to use a few, reduced, or minimal number of eyepieces required to convey a desired number of focal (or depth) planes or depths. Additionally, efficient, transparent, and / or low-cost focusing elements involved in imaging the designed focal or depth planes in their intended locations, and compact eyepiece designs to achieve the desired field of view and small form factor with light weight and high optical quality may be desired.

[0256] One architecture class of many combinations of viewing optical elements that can be used to generate mixed reality light fields incorporates static optical elements on either side of an infinity-focusing eyepiece that serve to present the viewer with an unmagnified real-world view in conjunction with a virtual image at some location (e.g., depth) other than infinity. This can be accomplished through the use of a positive / negative lens combination, where both lenses have equal refractive power.

[0257] One group of compact eyepiece solutions incorporates light guides that host leaky gratings (such as exit pupil expander ("EPE") / orthogonal pupil expander ("OPE") configurations) that redirect and replicate the entrance pupil from the imaging system, generate a wide field of view with a wide pupil, and facilitate comfortable, flexible multi-IPD (interpupillary distance) viewing and eye movement. In this application, the terms "light guide" and "waveguide" can be used interchangeably. In various embodiments, the light guide can comprise nanostructured or microstructured gratings. In some embodiments, the eyepiece comprises gratings or diffractive optical elements that form EPE / OPE combinations on both sides of the light guide (e.g., major surfaces, front and rear, etc.), and in some embodiments, the gratings or diffractive optical elements comprise compound pupil expanders (that both diffuse and outcouple light) formed on a single surface of the light guide.

[0258] For example, a compact imaging system for generating an image, such as a microdisplay, may include a spatial light modulator, an optical system (e.g., projection optics) for projecting an image formed by the spatial light modulator, and an illumination module for illuminating the spatial light modulator to generate the image. Other microdisplay technologies, such as multi-core or single-core optical fibers, or micro LED displays, may also be used as the light source or image source. It may be desirable for the illumination module to be compact and deliver reduced or minimal heating to the optical elements of the microdisplay.

[0259] The optical system (e.g., projection optics) may be configured to generate an exit pupil for the microdisplay. Without any loss of generality, the exit pupil may correspond to the pupil of the optical system through which light exits the optical system. Light emitted from the exit pupil of the microdisplay may be intersected by or be proximate to an internal coupling element (e.g., a grating) on ​​the light guide of the eyepiece. Several microdisplay solutions have been described and demonstrated that may be configured to generate separate sub-pupils for different color image light emitted from the imaging system. For example, one embodiment of an imaging system has a first set of three separate output sub-pupils for outputting light corresponding to red, green, and blue image components for a first depth or focal plane, and a second set of three separate output sub-pupils for outputting light corresponding to red, green, and blue image components for a second depth or focal plane. In some implementations, three input sub-pupils may be included within the eyepiece for each depth plane to receive red, green, and blue light from one or more light sources. However, such systems can be bulky and may not be practical to achieve the goals of small architectural form factor and reduced volume / weight.

[0260] The waveguides in the eyepieces may comprise a light guide material with a specific refractive index suitable for supporting the range of field angles desired for the system field of view. For example, due to the inability of a single eyepiece layer to support all of the grating vectors and field angles desired for displaying all three colors superimposed on one another, it may be preferable to have separate eyepiece layers employed for red, green, and blue image components. However, the cost of producing a waveguide stack in the eyepieces of a head-mounted VR and / or AR device may increase as the number of waveguides in the waveguide stack increases. The cost of producing a waveguide stack in the eyepieces of a head-mounted VR and / or AR device may also depend on the handedness (e.g., "left" or "right") of the waveguide stack. For example, the production cost for manufacturing different waveguide stacks configured to be positioned in front of the right and left eyes may be higher than a single waveguide stack that can be positioned in front of the left eye and a single waveguide stack that can be positioned in front of the right eye. As discussed above, various implementations of the waveguide stack of the eyepiece of a head-mounted VR and / or AR device can include six separate designs and six separate waveguides. The cost of manufacturing and assembling such a waveguide stack can be further increased due to the increased cost of monitoring the quality of the various waveguides in the waveguide stack during the manufacturing and assembly process. The cost of manufacturing and assembling such a waveguide stack can be further increased due to the higher likelihood that a waveguide stack with multiple waveguides will be rejected if the quality of a single waveguide in the waveguide stack does not meet standards. Furthermore, because each color component is desired to produce an image that matches the others in x, y, and z, there is an increased likelihood of reduced optical quality. In addition, variations in the total thickness of a waveguide stack with six waveguides can independently change the pixel positions of each of the color components, potentially causing some color components to be out of focus. Computationally extensive calibration / image warping can be implemented to correct for color component variations as a result of thickness variations.For these reasons, it may be desirable to have a waveguide stack with fewer waveguides, e.g., one or two waveguides, that can support the propagation of multiple different colored image components, such as three (e.g., red, green, and blue image components).

[0261] With wearable computing systems where power consumption is a priority, increased or maximum optical throughput of virtual image light may be desirable. Additionally, it may also be desirable to produce a system that increases or maximizes visibility of the external environment to the wearer of the wearable computing system, for example, to promote eye contact with others. It may also be desirable for the wearer of a wearable computing system, or the operator of a mixed or augmented reality system, to be able to perceive the real world with reduced or as little attenuation as possible to avoid hazards and promote everyday comfort and function. Without relying on any particular theory, the transmission of light from the external environment (e.g., the real world) may be reduced and / or compromised as the number of optical interfaces between the wearer's eyes and the real world increases. For this additional reason, it may be desirable to reduce or minimize the number of waveguide layers within the waveguide stack of the eyepiece that may scatter and / or absorb light from the external environment within the waveguides and / or other optical elements positioned between the wearer's eyes and the real world.

[0262] Additionally, a higher refractive index generally provides a larger field of view. Thus, in some designs described herein, the substrate may have a refractive index of about 1.79 or higher. One such material is lithium niobate (LiNbO), a crystalline material available in thin wafer form with a refractive index of about 2.3 within visible wavelengths. Another high-refractive-index material considered herein is silicon carbide (SiC). SiC is a high-refractive-index material that at least partially transmits visible light. Thus, one or more waveguides including SiC can be integrated into a display device (e.g., incorporated into the eyepiece of a head-mounted display device). Due to the high refractive index, two or more different colors of light propagating through a waveguide including SiC via total internal reflection can be emitted toward a viewer with a wide field of view. Waveguides comprising SiC can have the added advantage of being scratch resistant and / or less likely to break due to a high hardness modulus (e.g., about 9-10 Mohs), which can be beneficial for eyewear that is prone to being dropped or otherwise mishandled.

[0263] Various implementations described herein thus include an eyepiece comprising a waveguide including a material with a high refractive index (e.g., a material with a refractive index greater than that of glass and / or a material with a refractive index of about 1.79 or greater) that can support the guided propagation of multiple different colored image components (e.g., red, green, and blue image components) within a single waveguide, or within two waveguides where at least one waveguide supports the guided propagation of two color components. For example, two or more different colored light streams comprising image information (e.g., red, green, and blue colored image streams comprising image information) can be internally coupled into a single waveguide including a material with a refractive index greater than about 1.79 and / or 2.2 (e.g., lithium niobate) to propagate via total internal reflection within the waveguide. Additionally, the field of view of a display device comprising one or more waveguides with a high refractive index material (e.g., a material with a refractive index greater than that of glass and / or a material with a refractive index of about 1.79 or greater) may exceed the field of view of a display device comprising one or more glass waveguides or one or more waveguides comprising a material having a refractive index less than about 1.79.

[0264] Thus, various implementations of the display devices described herein comprise one or more waveguides including a material with a high refractive index (e.g., a material with a refractive index greater than that of glass and / or a material with a refractive index of about 1.79 or greater) that can efficiently in-couple red, green, and blue image light emitted from an imaging system (e.g., a microdisplay and / or a projector) and project red, green, and blue images toward a viewer with an increased field of view. For example, in some implementations of the display devices described herein, a single waveguide including a material with a high refractive index (e.g., a material with a refractive index greater than that of glass and / or a material with a refractive index of about 1.79 or greater) can efficiently in-couple two-color, e.g., red and green, or green and blue, or red and blue image light or image components emitted from an imaging system (e.g., a microdisplay and / or a projector) and project these images (e.g., red and green, or green and blue, or red and blue images) toward a viewer with an increased field of view. In some implementations of the display devices described herein, a single waveguide including a material with a high refractive index (e.g., a material with a refractive index greater than that of glass and / or a material with a refractive index of about 1.79 or greater) can efficiently combine three colors, e.g., red, green, and blue, image light or image components emitted from an imaging system (e.g., a microdisplay and / or projector) and project these images (e.g., red, green, and blue images) toward a viewer with an increased field of view.

[0265] Reference is now made to the drawings, wherein like reference numerals refer to like parts throughout.

[0266] FIG. 2 illustrates an example of a wearable display system 60. The display system 60 includes a display 70 and various mechanical and electronic modules and systems to support the functionality of the display 70. The display 70 may be coupled to a frame 80 that is wearable by a display system user or viewer 90 and configured to position the display 70 directly in front of the user's 90's eyes. The display 70 may, in some embodiments, be considered eyewear. In some embodiments, a speaker 100 is coupled to the frame 80 and configured to be positioned adjacent to the user's 90's ear canal (in some embodiments, another speaker, not shown, may optionally be positioned adjacent the user's other ear canal to provide stereo / shapeable sound control). The display system may also include one or more microphones 110 or other devices to detect sound. In some embodiments, the microphones may be configured to allow a user to provide input or commands (e.g., voice menu command selections, natural language queries, etc.) to the system 60 and / or enable audio communication with other persons (e.g., other users of similar display systems). The microphone may further be configured as an ambient sensor to collect audio data (e.g., sounds from the user and / or the environment). In some embodiments, the display system may also include ambient sensors 120a that are separate from the frame 80 and may be mounted on the body of the user 90 (e.g., the head, torso, limbs, etc. of the user 90). The ambient sensors 120a, in some embodiments, may be configured to obtain data that characterizes a physiological state of the user 90. For example, the sensors 120a may be electrodes.

[0267] 2 , display 70 is operably coupled by a communications link 130, such as by wired or wireless connectivity, to a local data processing module 140, which may be mounted in a variety of configurations, such as fixedly attached to frame 80, fixedly attached to a helmet or hat worn by a user, embedded within headphones, or otherwise removably attached to user 90 (e.g., in a backpack-style configuration, in a belt-coupled configuration). Similarly, sensor 120 a may be operably coupled to local data processing module 140 by a communications link 120 b, e.g., by wired or wireless connectivity. Local processing and data module 140 may comprise a hardware processor and digital memory, such as non-volatile memory (e.g., flash memory or a hard disk drive), both of which may be utilized to aid in processing, caching, and storing data. The data includes a) data captured from sensors (e.g., which may be operatively coupled to frame 80 or otherwise attached to user 90), such as image capture devices (such as cameras), microphones, inertial measurement units, accelerometers, compasses, GPS units, wireless devices, gyroscopes, and / or other sensors disclosed herein, and / or b) data obtained and / or processed using remote processing module 150 and / or remote data repository 160 (including data related to virtual content), possibly for processing or readout and then passage to display 70. Local processing and data module 140 may be operatively coupled to remote processing module 150 and remote data repository 160 by communication links 170, 180, such as via wired or wireless communication links, such that these remote modules 150, 160 are operatively coupled to each other and available as resources to local processing and data module 140. In some embodiments, the local processing and data module 140 may include one or more of an image capture device, a microphone, an inertial measurement unit, an accelerometer, a compass, a GPS unit, a wireless device, and / or a gyroscope.In some other embodiments, one or more of these sensors may be mounted on the frame 80 or may be freestanding structures that communicate with the local processing and data module 140 via wired or wireless communication paths.

[0268] 2 , in some embodiments, remote processing module 150 may comprise one or more processors configured to analyze and process data and / or image information. In some embodiments, remote data repository 160 may comprise a digital data storage facility that may be available through the Internet or other networking configuration in a “cloud” resource configuration. In some embodiments, remote data repository 160 may include one or more remote servers that provide information, e.g., information for generating augmented reality content, to local processing and data module 140 and / or remote processing module 150. In some embodiments, all data is stored and all computations are performed within the local processing and data module, allowing for fully autonomous use from the remote module.

[0269] Referring now to FIG. 3, the perception of an image as “three-dimensional” or “3-D” can be achieved by providing a slightly different presentation of the image to each eye of a viewer. FIG. 3 illustrates a conventional display system for simulating a three-dimensional image for a user. Two distinct images 190, 200 are output to the user, one for each eye 210, 220. The images 190, 200 are spaced from the eyes 210, 220 by a distance 230 along the optical or z-axis parallel to the viewer's line of sight. The images 190, 200 are flat, and the eyes 210, 220 can focus on the images by assuming a single accommodative state. Such a 3-D display system relies on the human visual system to combine the images 190, 200 and provide the perception of depth and / or scale of the combined image.

[0270] However, it should be appreciated that the human visual system is more complex and providing a realistic perception of depth is more difficult. For example, many viewers of conventional “3-D” display systems find such systems uncomfortable or may not perceive any sensation of depth at all. Without being limited by theory, it is believed that viewers of an object may perceive the object as “three-dimensional” due to a combination of vergence and accommodation. Vergence movement of the two eyes relative to one another (i.e., eye rotation such that the pupils move toward or away from one another, converging the eyes’ gazes, and fixating on an object) is closely coupled to the focusing (or “accommodation”) of the eye lens and pupil. Under normal conditions, changing the focus of the eye lens, or accommodating the eye to change focus from one object to another at a different distance, will automatically produce a corresponding change in vergence to the same distance, under a relationship known as the “accommodation-vergence reflex” and pupil dilation or constriction. Similarly, changes in vergence-divergence will, under normal conditions, induce corresponding changes in accommodation in lens shape and pupil size. As described herein, many stereoscopic or "3-D" display systems display a scene using slightly different presentations (and therefore slightly different images) to each eye so that a three-dimensional perspective is perceived by the human visual system. However, such systems are uncomfortable for many viewers because, among other things, they simply provide different presentations of the scene, but the eyes view all image information in a single, accommodated state, working against the "accommodation-vergence-divergence reflex." Display systems that provide better correspondence between accommodation and vergence-divergence may produce more realistic and comfortable simulations of three-dimensional images.

[0271] FIG. 4 illustrates aspects of an approach for simulating a three-dimensional image using multiple depth planes. With reference to FIG. 4 , objects at various distances from the eyes 210, 220 on the z-axis are accommodated by the eyes 210, 220 so that the objects are in focus. The eyes 210, 220 assume particular accommodated states and focus on objects at different distances along the z-axis. As a result, a particular accommodated state may be said to be associated with a particular one of the depth planes 240 having an associated focal length such that an object or portion of an object at a particular depth plane is in focus when the eye is in the accommodated state for that depth plane. In some embodiments, a three-dimensional image may be simulated by providing a different presentation of an image for each eye 210, 220 and by providing a different presentation of an image corresponding to each of the depth planes. While shown as separate for clarity of illustration, it should be understood that the fields of view of the eyes 210, 220 may overlap, for example, as the distance along the z-axis increases. Additionally, although shown as flat for ease of illustration, it should be understood that the contour of the depth plane may be curved in physical space so that all features within the depth plane are in focus with the eye in a particular accommodative state.

[0272] The distance between an object and the eye 210 or 220 can also change the amount of divergence of light from the object as viewed by that eye. Figures 5A-5C illustrate the relationship between distance and divergence of light rays. The distance between the object and the eye 210 is represented by decreasing distances R1, R2, and R3. As shown in Figures 5A-5C, light rays become more divergent as the distance to the object decreases. As the distance increases, the light rays become more collimated. In other words, the light field generated by a point (an object or part of an object) can be said to have a spherical wavefront curvature that is a function of the distance the point is from the user's eye. The curvature increases as the distance between the object and the eye 210 decreases. As a result, the divergence of light rays at different depth planes also differs, and the divergence increases as the distance between the depth plane and the viewer's eye 210 decreases. While only a single eye 210 is illustrated in Figures 5A-5C and other figures herein for clarity of illustration, it should be understood that the discussion regarding eye 210 may apply to both eyes 210 and 220 of a viewer.

[0273] Without being limited by theory, it is believed that the human eye can typically interpret a finite number of depth planes to provide depth perception. As a result, a highly realistic simulation of perceived depth can be achieved by providing the eye with different representations of images corresponding to each of these limited number of depth planes. The different representations can be focused separately by the viewer's eyes, thereby serving to provide depth cues to the user based on the ocular accommodation required to focus different image features for a scene located on different depth planes and / or based on the observation of different image features on different depth planes that are out of focus.

[0274] FIG. 6 illustrates an example of a waveguide stack for outputting image information to a user. Display system 250 includes a stack of waveguides or stacked waveguide assembly 260 that can be utilized to provide a three-dimensional perception to the eye / brain using multiple waveguides 270, 280, 290, 300, 310. In some embodiments, display system 250 is system 60 of FIG. 2 , and FIG. 6 diagrammatically illustrates some portions of system 60 in greater detail. For example, waveguide assembly 260 may be part of display 70 of FIG. 2 . It should be understood that display system 250 may be considered a light field display in some embodiments. Additionally, waveguide assembly 260 may also be referred to as an eyepiece.

[0275] Continuing with reference to FIG. 6 , the waveguide assembly 260 may also include multiple features 320, 330, 340, 350 between the waveguides. In some embodiments, the features 320, 330, 340, 350 may be one or more lenses. The waveguides 270, 280, 290, 300, 310 and / or multiple lenses 320, 330, 340, 350 may be configured to transmit image information to the eye with various levels of wavefront curvature or ray divergence. Each waveguide level may be associated with a particular depth plane and configured to output image information corresponding to that depth plane. The image injection devices 360, 370, 380, 390, 400 may act as light sources for the waveguides and may be utilized to inject image information into the waveguides 270, 280, 290, 300, 310, each configured to distribute incident light across each individual waveguide for output toward the eye 210, as described herein. Light exits output surfaces 410, 420, 430, 440, 450 of the image injection devices 360, 370, 380, 390, 400 and is injected into corresponding input surfaces 460, 470, 480, 490, 500 of the waveguides 270, 280, 290, 300, 310. In some embodiments, each input surface 460, 470, 480, 490, 500 may be an edge of the corresponding waveguide or a portion of a major surface of the corresponding waveguide (i.e., one of the waveguide surfaces that directly faces the world 510 or the viewer's eye 210). In some embodiments, a single light beam (e.g., a collimated beam) may be launched into each waveguide, outputting a total field of cloned collimated beams directed toward the eye 210 at a particular angle (and divergence) corresponding to the depth plane associated with the particular waveguide. In some embodiments, a single one of the image launch devices 360, 370, 380, 390, 400 may be associated with and launch light into multiple (e.g., three) waveguides 270, 280, 290, 300, 310.

[0276] In some embodiments, each of the image input devices 360, 370, 380, 390, 400 is a discrete display that generates image information for input into a corresponding waveguide 270, 280, 290, 300, 310. In some other embodiments, the image input devices 360, 370, 380, 390, 400 are the output of a single multiplexed display that may, for example, send image information via one or more optical conduits (such as fiber optic cables) to each of the image input devices 360, 370, 380, 390, 400. It should be understood that the image information provided by the image input devices 360, 370, 380, 390, 400 may include light of different wavelengths or colors (e.g., different primary colors as discussed herein).

[0277] In some embodiments, the light injected into the waveguides 270, 280, 290, 300, 310 may be provided by a light projector system 520 including a light module 540, which may include a light emitter such as a light emitting diode (LED). Light from the light module 540 may be directed via a beam splitter 550 to and modified by a light modulator 530, such as a spatial light modulator. The light modulator 530 may be configured to change the perceived intensity of the light injected into the waveguides 270, 280, 290, 300, 310. Examples of spatial light modulators include liquid crystal displays (LCDs), including liquid crystal on silicon (LCOS) displays. It should be understood that image input devices 360, 370, 380, 390, 400 are illustrated diagrammatically and in some embodiments these image input devices may represent different light paths and locations within a common projection system that are configured to output light into associated ones of waveguides 270, 280, 290, 300, 310.

[0278] In some embodiments, the display system 250 may be a scanning fiber display comprising one or more scanning fibers configured to project light in various patterns (e.g., raster scan, spiral scan, Lissajous pattern, etc.) into one or more waveguides 270, 280, 290, 300, 310 and ultimately to the viewer's eye 210. In some embodiments, the illustrated image injection devices 360, 370, 380, 390, 400 may diagrammatically represent a single scanning fiber or a bundle of scanning fibers configured to inject light into one or more waveguides 270, 280, 290, 300, 310. In some other embodiments, the illustrated image injection devices 360, 370, 380, 390, 400 may diagrammatically represent multiple scanning fibers or multiple bundles of scanning fibers, each configured to inject light into an associated one of the waveguides 270, 280, 290, 300, 310. It should be understood that one or more optical fibers may be configured to transmit light from the optical module 540 to one or more waveguides 270, 280, 290, 300, 310. It should be understood that one or more intervening optical structures may be provided between the scanning fiber or fibers and one or more waveguides 270, 280, 290, 300, 310, for example, to redirect light exiting the scanning fiber into one or more waveguides 270, 280, 290, 300, 310.

[0279] Controller 560 controls the operation of one or more of stacked waveguide assemblies 260, including the operation of image input devices 360, 370, 380, 390, 400, light source 540, and light modulator 530. In some embodiments, controller 560 is part of local data processing module 140. Controller 560 contains programming (e.g., instructions in a non-transitory medium) that coordinates the timing and provision of image information to waveguides 270, 280, 290, 300, 310, for example, according to any of the various schemes disclosed herein. In some embodiments, the controller may be a single integrated device or a distributed system connected by a wired or wireless communication channel. Controller 560 may, in some embodiments, be part of processing module 140 or 150 (FIG. 2).

[0280] Continuing with reference to FIG. 6 , waveguides 270, 280, 290, 300, 310 may be configured to propagate light within each individual waveguide by total internal reflection (TIR). Each of waveguides 270, 280, 290, 300, 310 may be planar or have another shape (e.g., curved), with major top and bottom surfaces and edges extending between the major top and bottom surfaces. In the illustrated configuration, waveguides 270, 280, 290, 300, 310 may each include outcoupling optical elements 570, 580, 590, 600, 610 configured to extract light from the waveguide by redirecting light propagating within each individual waveguide out of the waveguide and outputting image information to eye 210. Extracted light may also be referred to as outcoupled light, and optical elements that outcouple light may also be referred to as light extraction optical elements. The extracted beam of light may be output by the waveguide at a location where light propagating within the waveguide strikes the light extraction optical element. The outcoupling optical element 570, 580, 590, 600, 610 may be a grating, for example, including diffractive optical features as discussed further herein. While shown disposed on the bottom major surface of the waveguides 270, 280, 290, 300, 310 for ease of explanation and clarity of the drawings, in some embodiments the outcoupling optical element 570, 580, 590, 600, 610 may be disposed on the top and / or bottom major surfaces and / or directly within the volume of the waveguides 270, 280, 290, 300, 310, as discussed further herein. In some embodiments, the outcoupling optical elements 570, 580, 590, 600, 610 may be formed within a layer of material attached to a transparent substrate and forming the waveguides 270, 280, 290, 300, 310. In some other embodiments, the waveguides 270, 280, 290, 300, 310 may be a monolithic piece of material, and the outcoupling optical elements 570, 580, 590, 600, 610 may be formed on and / or within that piece of material.

[0281] Continuing with reference to FIG. 6 , as discussed herein, each waveguide 270, 280, 290, 300, 310 is configured to output light and form an image corresponding to a particular depth plane. For example, the waveguide 270 closest to the eye may be configured to deliver collimated light (injected into such waveguide 270) to the eye 210. The collimated light may represent an optical infinity focal plane. The next upper waveguide 280 may be configured to send collimated light that passes through a first lens 350 (e.g., a negative lens) before reaching the eye 210. Such first lens 350 may be configured to generate a slight convex wavefront curvature so that the eye / brain interprets light emerging from the next upper waveguide 280 as emerging from a first focal plane closer inward from optical infinity toward the eye 210. Similarly, the third upper waveguide 290 may pass its output light through both the first lens 350 and the second lens 340 before reaching the eye 210, and the combined refractive power of the first lens 350 and the second lens 340 may be configured to create another increasing amount of wavefront curvature such that the eye / brain interprets the light emerging from the third waveguide 290 as originating from a second focal plane closer inward towards the person from optical infinity, which was the light from the next upper waveguide 280.

[0282] The other waveguide layers 300, 310 and lenses 330, 320 are similarly configured, with the highest waveguide 310 in the stack sending its output through all of the lenses between it and the eye for a collective focal power representing the focal plane closest to the person. To compensate for the stack of lenses 320, 330, 340, 350 when viewing / interpreting light originating from the world 510 on the other side of the stacked waveguide assembly 260, a compensating lens layer 620 may be placed on top of the stack to compensate for the collective power of the lower lens stacks 320, 330, 340, 350. Such a configuration provides as many perceived focal planes as there are available waveguide / lens pairs. Both the waveguide outcoupling optical elements and the focusing sides of the lenses may be static (i.e., not dynamic or electro-active). In some alternative embodiments, either or both may be dynamic using electro-active features.

[0283] In some embodiments, two or more of the waveguides 270, 280, 290, 300, 310 may have the same associated depth plane. For example, multiple waveguides 270, 280, 290, 300, 310 may be configured to output images set at the same depth plane, or multiple subsets of the waveguides 270, 280, 290, 300, 310 may be configured to output images set at the same multiple depth planes, with one set per depth plane. This may provide advantages for forming tiled images to provide an extended field of view at those depth planes.

[0284] Continuing with reference to FIG. 6 , the outcoupling optical elements 570, 580, 590, 600, 610 may be configured to redirect light out of their respective waveguides and output this light with the appropriate amount of divergence or collimation for the particular depth plane associated with the waveguide. As a result, waveguides with different associated depth planes may have different configurations of the outcoupling optical elements 570, 580, 590, 600, 610 that output light with different amounts of divergence depending on the associated depth plane. In some embodiments, the light-extraction optical elements 570, 580, 590, 600, 610 may be volume or surface features that can be configured to output light at specific angles. For example, the light-extraction optical elements 570, 580, 590, 600, 610 may be volume holograms, surface holograms, and / or diffraction gratings. In some embodiments, features 320, 330, 340, 350 may not be lenses; rather, they may simply be spacers (eg, cladding layers and / or structures for forming air gaps).

[0285] In some embodiments, the outcoupling optical elements 570, 580, 590, 600, 610 are diffractive features or "diffractive optical elements" (also referred to herein as "DOEs") that form a diffraction pattern. Preferably, the DOEs have a sufficiently low diffraction efficiency so that only a portion of the light in the beam is deflected toward the eye 210 at each intersection of the DOE, while the remainder continues traveling through the waveguide via TIR. The light carrying the image information is thus split into several related output beams that exit the waveguide at various locations, resulting in a very uniform pattern of output emission toward the eye 210 for this particular collimated beam bouncing within the waveguide.

[0286] In some embodiments, one or more DOEs may be switchable between an "on" state in which they actively diffract and an "off" state in which they do not significantly diffract. For example, a switchable DOE may comprise a layer of polymer-dispersed liquid crystal in which microdroplets comprise a diffractive pattern in a host medium, and the refractive index of the microdroplets may be switched to substantially match the refractive index of the host material (in which case the pattern does not significantly diffract incident light), or the microdroplets may be switched to a refractive index that does not match that of the host medium (in which case the pattern actively diffracts incident light).

[0287] In some embodiments, a camera assembly 630 (e.g., a digital camera, including a visible light and infrared light camera) may be provided to capture images of the eye 210 and / or tissue surrounding the eye 210, for example, to detect user input and / or monitor the physiological state of the user. As used herein, a camera may be any image capture device. In some embodiments, the camera assembly 630 may include an image capture device and a light source for projecting light (e.g., infrared light) onto the eye that can be reflected by the eye and detected by the image capture device. In some embodiments, the camera assembly 630 may be mounted on the frame 80 ( FIG. 2 ) and may be in electrical communication with the processing modules 140 and / or 150, which may process image information from the camera assembly 630. In some embodiments, one camera assembly 630 may be utilized per eye, monitoring each eye separately.

[0288] 7, an example of an output beam output by a waveguide is shown. While one waveguide is illustrated, it should be understood that other waveguides in waveguide assembly 260 (FIG. 6) may function similarly, and that waveguide assembly 260 includes multiple waveguides. Light 640 is launched into waveguide 270 at input surface 460 of waveguide 270 and propagates within waveguide 270 by TIR. At the point where light 640 impinges on DOE 570, a portion of the light exits the waveguide as output beam 650. Output beam 650 is illustrated as being approximately parallel, but may be redirected to propagate to eye 210 at an angle (e.g., forming a diverging output beam), as discussed herein and depending on the depth plane associated with waveguide 270. It should be understood that a nearly collimated exit beam may refer to a waveguide with outcoupling optics that outcouples light to form an image that appears to be set at a depth plane at a large distance (e.g., optical infinity) from the eye 210. Other waveguides or other sets of outcoupling optics may output a more divergent exit beam pattern, which would require the eye 210 to accommodate to a closer distance and focus on the retina, and would be interpreted by the brain as light from a distance closer to the eye 210 than optical infinity.

[0289] In some embodiments, a full-color image may be formed at each depth plane by overlaying an image in each of the primary colors, for example, three or more primary colors. FIG. 8 illustrates an example of a stacked waveguide assembly in which each depth plane includes an image formed using multiple different primary colors. The illustrated embodiment shows depth planes 240a-240f, but more or fewer depths are also contemplated. Each depth plane may have three or more primary color images associated with it, including a first image in a first color G, a second image in a second color R, and a third image in a third color B. Different depth planes are indicated in the diagram by different numbers for diopters (dpt) following the letters G, R, and B. By way of example only, the number following each of these letters indicates the diopter (1 / m), i.e., the inverse distance of the depth plane from the viewer, and each box in the diagram represents an individual primary color image. In some embodiments, the exact locations of the depth planes for different primary colors may be varied to account for differences in the eye's focusing of light of different wavelengths. For example, different primary color images for a given depth plane may be placed on depth planes corresponding to different distances from the user. Such an arrangement may increase visual acuity and user comfort and / or reduce chromatic aberrations.

[0290] In some embodiments, light for each primary color may be output by a single dedicated waveguide, such that each depth plane may have multiple waveguides associated with it. In such embodiments, each box in the diagram containing the letter G, R, or B may be understood to represent an individual waveguide, and three waveguides may be provided per depth plane, with three primary color images provided per depth plane. While the waveguides associated with each depth plane are shown adjacent to each other in this drawing for ease of illustration, it should be understood that in a physical device, the waveguides may all be arranged in a stack with one waveguide per level. In some other embodiments, multiple primary colors may be output by the same waveguide, such that, for example, only a single waveguide may be provided per depth plane.

[0291] 8, in some embodiments, G is green, R is red, and B is blue. In some other embodiments, other colors associated with other wavelengths of light, including magenta and cyan, may be used in addition to or replace one or more of red, green, or blue.

[0292] It should be understood that references throughout this disclosure to a given color of light will be understood to encompass light of one or more wavelengths within the range of wavelengths of light that are perceived by a viewer as being of that given color. For example, red light may include one or more wavelengths of light in the range of about 620-780 nm, green light may include one or more wavelengths of light in the range of about 492-577 nm, and blue light may include one or more wavelengths of light in the range of about 435-493 nm.

[0293] In some embodiments, light source 540 (FIG. 6) may be configured to emit light at one or more wavelengths outside the range of a viewer's visual perception, e.g., infrared and / or ultraviolet wavelengths. Additionally, the waveguide incoupling, outcoupling, and other light redirecting structures of display 250 may be configured to direct and emit this light from the display toward the user's eye 210, e.g., for imaging and / or user stimulation applications.

[0294] Referring now to FIG. 9A , in some embodiments, light impinging on a waveguide may need to be redirected to incoupling the light into the waveguide. An incoupling optical element may be used to redirect and incoupling the light into its corresponding waveguide. FIG. 9A illustrates a cross-sectional side view of an example of a plurality or set 660 of stacked waveguides, each including an incoupling optical element. The waveguides may each be configured to output light of one or more different wavelengths or one or more different wavelength ranges. It should be understood that stack 660 may correspond to stack 260 ( FIG. 6 ), and the illustrated waveguides of stack 660 may correspond to portions of the plurality of waveguides 270, 280, 290, 300, 310, except that light from one or more of image injection devices 360, 370, 380, 390, 400 is injected into the waveguide from a location requiring the light to be redirected for incoupling.

[0295] The illustrated set 660 of stacked waveguides includes waveguides 670, 680, and 690. Waveguide 670 is in front of, or closer to, the image light source than, waveguide 680, and waveguide 690 is behind, or farther from, the image light source than, waveguide 680. Each waveguide includes an associated internal coupling optical element (which may also be referred to as the light input area on the waveguide), for example, internal coupling optical element 700 is disposed on a major surface (e.g., upper major surface) of waveguide 670, internal coupling optical element 710 is disposed on a major surface (e.g., upper major surface) of waveguide 680, and internal coupling optical element 720 is disposed on a major surface (e.g., upper major surface) of waveguide 690. In some embodiments, one or more of the internal coupling optical elements 700, 710, 720 may be disposed on the bottom major surfaces of the respective waveguides 670, 680, 690 (particularly, one or more of the internal coupling optical elements are reflective polarizing optical elements). As shown, the internal coupling optical elements 700, 710, 720 may be disposed on the upper major surfaces of the respective waveguides 670, 680, 690 (or on top of the next lower waveguide), and particularly, the internal coupling optical elements are transmissive polarizing optical elements. In some embodiments, the internal coupling optical elements 700, 710, 720 may be disposed within the body of the respective waveguides 670, 680, 690. In some embodiments, as discussed herein, the internal coupling optical elements 700, 710, 720 are wavelength selective so as to selectively redirect one or more wavelengths of light while transmitting other wavelengths of light. Although illustrated on one side or corner of the respective waveguides 670, 680, 690, it should be understood that the internal coupling optical elements 700, 710, 720 may be located within other areas of the respective waveguides 670, 680, 690 in some embodiments.

[0296] As shown, the in-coupling optical elements 700, 710, 720 may be laterally offset from one another. In some embodiments, each in-coupling optical element may be offset to receive light without that light passing through another in-coupling optical element. For example, each in-coupling optical element 700, 710, 720 may be configured to receive light from a different image input device 360, 370, 380, 390, and 400, as shown in FIG. 6 , and may be separated (e.g., laterally spaced) from the other in-coupling optical elements 700, 710, 720 so as to receive substantially no light from others of the in-coupling optical elements 700, 710, 720.

[0297] Each waveguide also includes an associated optically dispersive element, for example, optically dispersive element 730 is disposed on a major surface (e.g., the top major surface) of waveguide 670, optically dispersive element 740 is disposed on a major surface (e.g., the top major surface) of waveguide 680, and optically dispersive element 750 is disposed on a major surface (e.g., the top major surface) of waveguide 690. In some other embodiments, optically dispersive elements 730, 740, 750 may be disposed on the bottom major surfaces of the associated waveguides 670, 680, 690, respectively. In some other embodiments, the optically dispersive elements 730, 740, 750 may be disposed on both the top and bottom major surfaces of the associated waveguides 670, 680, 690, respectively, or the optically dispersive elements 730, 740, 750 may be disposed on different ones of the top and bottom major surfaces in different associated waveguides 670, 680, 690, respectively.

[0298] Waveguides 670, 680, 690 may be spaced apart and separated, for example, by gas, liquid, and / or solid layers of material. For example, as shown, layer 760a may separate waveguides 670 and 680, and layer 760b may separate waveguides 680 and 690. In some embodiments, layers 760a and 760b are formed from a low refractive index material (i.e., a material having a lower refractive index than the material forming the immediately adjacent ones of waveguides 670, 680, 690). Preferably, the refractive index of the material forming layers 760a, 760b is 0.05 or greater, or 0.10 or less, relative to the refractive index of the material forming waveguides 670, 680, 690. Advantageously, the lower refractive index layers 760a, 760b may function as cladding layers that promote total internal reflection (TIR) ​​of light through the waveguides 670, 680, 690 (e.g., TIR between the top and bottom major surfaces of each waveguide). In some embodiments, the layers 760a, 760b are formed from air. Although not shown, it should be understood that the top and bottom of the illustrated set of waveguides 660 may include immediate cladding layers.

[0299] Preferably, for ease of manufacturing and other considerations, the materials forming waveguides 670, 680, 690 are similar or the same, and the materials forming layers 760a, 760b are similar or the same. In some embodiments, the materials forming waveguides 670, 680, 690 may vary between one or more waveguides, and / or the materials forming layers 760a, 760b may vary while still maintaining the various refractive index relationships described above.

[0300] 9A , light rays 770, 780, 790 enter waveguide set 660. It should be understood that light rays 770, 780, 790 may be launched into waveguides 670, 680, 690 by one or more image launch devices 360, 370, 380, 390, 400 ( FIG. 6 ). Light rays 770, 780, 790 may constitute image light, i.e., light encoded with image information. For example, the light may be spatially modulated or otherwise provided with different intensities and / or different wavelengths at different locations, e.g., to form pixels that form an image.

[0301] In some embodiments, light rays 770, 780, 790 have different properties, e.g., different wavelengths or different wavelength ranges, which may correspond to different colors. Each of the incoupling optical elements 700, 710, 720 deflects incident light such that the light propagates through a respective one of the waveguides 670, 680, 690 by TIR. In some embodiments, each of the incoupling optical elements 700, 710, 720 selectively deflects one or more particular wavelengths of light while transmitting other wavelengths to the underlying waveguide and associated incoupling optical element.

[0302] For example, in-coupling optical element 700 may be configured to deflect light ray 770 having a first wavelength or wavelength range while transmitting light rays 780 and 790 having different second and third wavelengths or wavelength ranges, respectively. Transmitted light ray 780 impinges on and is deflected by in-coupling optical element 710, which is configured to deflect light of the second wavelength or wavelength range. Light ray 790 is deflected by in-coupling optical element 720, which is configured to selectively deflect light of the third wavelength or wavelength range.

[0303] 9A , the deflected light rays 770, 780, 790 are deflected to propagate through the corresponding waveguides 670, 680, 690. That is, the in-coupling optical element 700, 710, 720 of each waveguide deflects the light into its corresponding waveguide 670, 680, 690 and in-couples the light into its corresponding waveguide. The light rays 770, 780, 790 are deflected at an angle that causes the light to propagate through the respective waveguides 670, 680, 690 by TIR. The light rays 770, 780, 790 propagate through the respective waveguides 670, 680, 690 by TIR until they impinge on the waveguide's corresponding optical dispersive element 730, 740, 750.

[0304] 9B, a perspective view of the multiple stacked waveguide embodiment of FIG. 9A is illustrated. As described above, in-coupled light rays 770, 780, 790 are deflected by in-coupling optical elements 700, 710, 720, respectively, and then propagate by TIR within waveguides 670, 680, 690, respectively. Light rays 770, 780, 790 then impinge on optically dispersive elements 730, 740, 750, respectively. Optically dispersive elements 730, 740, 750 deflect light rays 770, 780, 790 to propagate toward out-coupling optical elements 800, 810, 820, respectively.

[0305] In some embodiments, the optically dispersive elements 730, 740, 750 are orthogonal pupil expanders (OPEs). In some embodiments, the OPEs deflect or disperse light into the out-coupling optical elements 800, 810, 820, and in some embodiments, may also increase the beam or spot size of this light as it propagates into the out-coupling optical elements. In some embodiments, the optically dispersive elements 730, 740, 750 may be omitted, and the in-coupling optical elements 700, 710, 720 may be configured to deflect light directly into the out-coupling optical elements 800, 810, 820. For example, with reference to FIG. 9A , the optically dispersive elements 730, 740, 750 may be replaced with the out-coupling optical elements 800, 810, 820, respectively. In some embodiments, the outcoupling optical elements 800, 810, 820 are exit pupils (EPs) or exit pupil expanders (EPEs) that direct light toward the viewer's eye 210 ( FIG. 7 ). It should be understood that an OPE can be configured to increase the size of the eyebox in at least one axis, and that an EPE can increase the eyebox in an axis that intersects the axis of the OPE, e.g., orthogonal to the axis of the OPE. For example, each OPE may be configured to redirect a portion of the light striking the OPE to an EPE in the same waveguide while allowing the remaining portion of the light to continue propagating down the waveguide. In response to striking the OPE again, another portion of the remaining light is redirected to the EPE, and the remainder of that portion continues to propagate further down the waveguide, etc. Similarly, in response to striking the EPE, a portion of the impinging light is directed out of the waveguide toward the user, and the remaining portion of that light continues to propagate through the waveguide until it again strikes an EP, at which point another portion of the impinging light is directed out of the waveguide, etc. As a result, a single beam of internally coupled light may be "replicated" each time a portion of that light is redirected by an OPE or EPE, thereby forming a cloned beam field of light, as shown in Figure 6. In some embodiments, the OPE and / or EPE may be configured to modify the size of the beam of light.

[0306] 9A and 9B, in some embodiments, a waveguide set 660 includes, for each primary color, waveguides 670, 680, 690, in-coupling optical elements 700, 710, 720, optically dispersive elements (e.g., OPEs) 730, 740, 750, and out-coupling optical elements (e.g., EPs) 800, 810, 820. The waveguides 670, 680, 690 may be stacked with an air gap / cladding layer between each one. The in-coupling optical elements 700, 710, 720 redirect or deflect incident light into that waveguide (with different in-coupling optical elements receiving light of different wavelengths). The light then propagates at an angle that will result in TIR within the individual waveguides 670, 680, 690. In the example shown, light ray 770 (e.g., blue light) is deflected by the first in-coupling optical element 700 in the manner described above, then continues bouncing down the waveguide, interacting with the optically dispersive element (e.g., OPE) 730 and then the out-coupling optical element (e.g., EP) 800. Light rays 780 and 790 (e.g., green and red light, respectively) pass through the waveguide 670, with light ray 780 impinging on and being deflected by the in-coupling optical element 710. Light ray 780 will then, via TIR, bounce down the waveguide 680, to its optically dispersive element (e.g., OPE) 740 and then the out-coupling optical element (e.g., EP) 810. Finally, light ray 790 (e.g., red light) passes through the waveguide 690 and impinges on the optically in-coupling optical element 720 of the waveguide 690. The light in-coupling optical element 720 deflects the light ray 790 so that it propagates by TIR to the light dispersive element (e.g., OPE) 750 and then by TIR to the out-coupling optical element (e.g., EP) 820. The out-coupling optical element 820 then finally out-couples the light ray 790 to a viewer that also receives out-coupled light from the other waveguides 670, 680.

[0307] FIG. 9C illustrates a top-down plan view of an example of the multiple stacked waveguides of FIGS. 9A and 9B. As shown, waveguides 670, 680, 690 may be vertically aligned, along with each waveguide's associated optically dispersive element 730, 740, 750 and associated out-coupling optical elements 800, 810, 820. However, as discussed herein, the in-coupling optical elements 700, 710, 720 are not vertically aligned. Rather, the in-coupling optical elements are preferably non-overlapping (e.g., laterally spaced apart, as seen in the top-down view). As discussed further herein, this non-overlapping spatial arrangement facilitates the injection of light from different sources into different waveguides on a one-to-one basis, thereby allowing a specific light source to be uniquely coupled to a specific waveguide. In some embodiments, arrays including non-overlapping, spatially separated in-coupling optical elements may be referred to as shifted or split-pupil systems, and the in-coupling optical elements in these arrays may correspond to sub-pupils.

[0308] As discussed above, various embodiments of display system 60 or display system 250 can include waveguides with high refractive index materials. For example, various embodiments of display system 60 or display system 250 can include one or more waveguides with a material having a refractive index greater than that of glass. Various embodiments of display system 60 or display system 250 can include one or more waveguides with a material having a refractive index greater than or equal to about 1.79 and less than or equal to about 4.5. For example, various embodiments of display system 60 or display system 250 can include one or more waveguides with a material having a refractive index greater than or equal to 1.8 and less than or equal to 2.1, 2.1 and less than or equal to 2.2, 2.2 and less than or equal to 2.3, 2.3 and less than or equal to 2.4, 2.4 and less than or equal to 2.5, 2.5 and less than or equal to 2.6, 2.6 and less than or equal to 2.7, 2.7 and less than or equal to 2.8, 2.8 and less than or equal to 2.9, 2.9 and less than or equal to 3.0, 3.0 and less than or equal to 3.1, 3.1 and less than or equal to 3.2, 3.2 or more, and 4.5 or less. The optical waveguide may include one or more waveguides with a material having a refractive index of 3.3 or less, 3.3 or more and 3.4 or less, 3.4 or more and 3.5 or less, 3.5 or more and 3.6 or less, 3.6 or more and 3.7 or less, 3.7 or more and 3.8 or less, 3.8 or more and 3.9 or less, 3.9 or more and 4.0 or less, 4.0 or more and 4.2 or less, 4.0 or more and 4.4 or less, 4.0 or more and 4.5 or less, or any value within any range / subrange defined by these values. Without any loss of generality, the high refractive index materials contemplated herein may be transparent to visible light. For example, the high refractive index materials contemplated in some implementations herein may be configured to transmit visible light in the spectral range between about 450 nm and about 750 nm with an efficiency of about 80% or 90% or more. However, Fresnel reflection may occur at the interfaces of the waveguide in some implementations.

[0309] As discussed above, various embodiments of display system 60 or display system 250 that include one or more waveguides with a high refractive index material (e.g., with a refractive index greater than that of glass and / or with a refractive index of about 1.79 or greater) can have an increased field of view compared to embodiments of display system 60 or display system 250 that include one or more waveguides with glass and / or a material with a refractive index less than about 1.79. Furthermore, as discussed above, multiple colors or wavelengths of light (e.g., two or potentially three colors) can be coupled in parallel into a single waveguide that includes a high refractive index material. Thus, various embodiments of display system 60 or display system 250 can include different waveguides associated with different depth planes. In some implementations, the waveguides associated with the depth planes can include a high refractive index material such that incident light of different colors, such as three colors (e.g., red, green, and blue wavelengths), can be coupled into and guided within that single waveguide. Thus, the associated waveguides have the ability to project a multicolor image comprising light of different wavelengths (e.g., red, green, and blue wavelengths) toward the viewer. Similarly, in some implementations, one waveguide associated with a depth plane may include a high-index material such that incident light of different colors, such as two colors (e.g., red and green or green and blue wavelengths), can be coupled into and guided within that single waveguide. Another waveguide associated with that depth plane may be configured such that at least one different color (e.g., blue or red, respectively) can be coupled into and guided within that single waveguide. This waveguide may also include a high-index material. The combination of waveguides for that depth plane or depth thus has the ability to project a multicolor image comprising light of different wavelengths (e.g., red, green, and blue wavelengths) toward the viewer. One or more other waveguide configurations may also be used for other depth planes or depths.Various high refractive index materials contemplated herein include materials such as lithium niobate (LiNbO), which has a refractive index of about 2.3, or silicon carbide, which has a refractive index greater than 2.7, or other similar materials, and possibly even higher.

[0310] As discussed above, one or more waveguides in various implementations of display system 60 or display system 250 can include in-coupling optical elements (e.g., in-coupling optical elements 700, 710, 720) for in-coupling light into one or more waveguides and / or out-coupling optical elements (e.g., 570, 580, 590, 800, 810, 820) from one or more waveguides. In various embodiments of display system 60 or display system 250, one or more waveguides can include optically dispersive elements (e.g., optically dispersive elements 730, 740, 750). In various embodiments, the light-dispersive element (e.g., light-dispersive elements 730, 740, 750) can be configured as an orthogonal pupil expander (OPE), and / or the outcoupling element (e.g., 800, 810, 820) can be configured as an exit pupil expander (EPE) or as a compound pupil expander (CPE) that exhibits both orthogonal expansion and outcoupling functionality. An eyepiece may include any one or combination of an incoupling optical element (ICG), an orthogonal pupil expander (OPE), an exit pupil expander (EPE), and a compound pupil expander (CPE). Thus, a wide range of configurations is possible. For example, some eyepieces do not include an orthogonal pupil expander (OPE). The incoupling optical element, the outcoupling optical element, and the light-dispersive element can comprise diffractive features. The diffractive optical element can comprise microscale and / or nanoscale features. Without any loss of generality, in-coupling optical elements, out-coupling optical elements, and / or light dispersive elements may be provided on one or both surfaces (e.g., major surfaces, front and rear surfaces, etc.) of the waveguide in different embodiments of display system 60 or display system 250. For example, various embodiments of the waveguides described herein may have diffractive structures disposed on both surfaces (e.g., major surfaces, front and rear surfaces, etc.) of the waveguide, or all disposed on a single surface, or even overlapping on a single surface.

[0311] The use of one or more waveguides comprising a high refractive index material (e.g., a refractive index above that of glass and / or above about 1.79) within a viewing optics assembly architecture for a mixed reality system can advantageously provide a waveguide stack with a reduced number of optical interfaces and waveguide layers, enable the use of potentially lower cost and lighter weight virtual image focal length shifting elements, increase or maximize the transparency of the waveguide stack, reduce or minimize manufacturing costs, or reduce or minimize the form factor, weight, and / or mass of the waveguide stack, or potentially provide any combination of these features.

[0312] Thus, various embodiments of the display systems (e.g., head-mounted AR / VR display devices) described herein comprise one or more waveguides including a high refractive index material (e.g., a refractive index greater than 1.79, such as a refractive index of about 2.3 or greater). The one or more waveguides comprise top and bottom major surfaces and multiple edges between the top and bottom major surfaces. The one or more waveguides can further comprise an in-coupling optical element (e.g., an in-coupling optical element similar to in-coupling optical elements 700, 710, 720) configured to in-coupling different colored image light emitted from an imaging system (e.g., a microdisplay and / or projector), and an out-coupling optical element (e.g., an out-coupling optical element similar to elements 570, 580, 590, 800, 810, 820) configured to project the in-coupling light toward the wearer's eye. In some embodiments, one or more waveguides may further comprise an optically dispersive element (e.g., an optically dispersive element similar to optically dispersive elements 730, 740, 750). As discussed above, one or more of the internal coupling optical element, the external coupling optical element, and the optically dispersive element may comprise a diffraction grating. In various embodiments, the diffraction grating may comprise microscale or nanoscale features. The diffraction grating may comprise surface features or volume features. Without any loss of generality, the internal coupling optical element, the external coupling optical element, and the optically dispersive element may be provided on one or both of the major surfaces of the one or more waveguides.

[0313] As discussed above, in various embodiments of the display systems (e.g., head-mounted AR / VR display devices) described herein, one or more internal coupling optical elements can be configured to internally couple two or more differently colored light streams containing image information emitted from an imaging system (e.g., a microdisplay and / or projector) into a single waveguide comprising a high refractive index material (e.g., a refractive index greater than 1.79, such as a refractive index of about 2.3 or greater), such that the internally coupled light of the different colors propagates within the single waveguide by total internal reflection. For example, in some embodiments, first, second, and third (e.g., red, green, and blue) colored light streams containing image information can be internally coupled into one or two waveguides comprising a high refractive index material (e.g., a refractive index greater than 1.79, such as a refractive index of about 2.3 or greater), such that the internally coupled first, second, and third (e.g., red, green, and blue) light propagates within the corresponding waveguides by total internal reflection. For example, in some such embodiments, first, second, and third (e.g., red, green, and blue) colored light streams containing image information can be internally combined into a single waveguide containing a high refractive index material (e.g., a refractive index greater than 1.79, such as a refractive index of about 2.3 or greater).

[0314] As discussed above, light projected out of a waveguide with a high refractive index (e.g., a refractive index greater than 1.79, such as a refractive index of about 2.3 or greater) can have an increased field of view through which the light is output by the waveguide and, as a result, through which the virtual image content can be seen by a viewer. The field of view can vary based on the refractive index of the waveguide material and the number of wavelengths internally coupled into the waveguide. Tables 1A and 1B below include calculated values ​​of the vertical and horizontal fields of view in degrees provided by various embodiments of waveguides for head-mounted AR / VR display devices, including materials with refractive indices of about 1.73 to about 2.3, when one or single color, two or dual color (e.g., green and blue or red and blue), and three or triple color (e.g., red, green, and blue) light is internally coupled into the waveguide. [Table 1-1] [Table 1-2]

[0315] Note from Tables 1A and 1B that as the refractive index of the waveguide material increases, the vertical and horizontal fields of view in degrees also increase. For example, a waveguide including a material with a refractive index greater than about 1.79 has a horizontal field of view greater than about 20.2 degrees and a vertical field of view greater than about 20.2 degrees, depending on whether one or single color, two or dual colors (e.g., green and blue or red and blue), and three or triple colors (e.g., red, green, and blue) light are internally coupled into the waveguide. Further, note from Table 1A that when all three colors (e.g., red, green, and blue) light are internally coupled into the waveguide, the vertical and horizontal fields of view in degrees provided by various embodiments of a waveguide for a head-mounted AR / VR display device including a material with a refractive index of about 2.3 (e.g., lithium niobate) are approximately about 45.9 and 56.1, respectively, which is a diagonal field of view of about 70 degrees. Therefore, embodiments of the eyepiece lens comprising a waveguide comprising a material with a refractive index of about 2.3 (e.g., lithium niobate) or higher (e.g., silicon carbide) are attractive solutions for obtaining display devices with increased fields of view.

[0316] In addition to its high refractive index, lithium niobate has other advantages. For example, lithium niobate is commonly available in wafer form, is optically transparent to visible light, and has low scattering. While lithium niobate may not have previously been considered a prime candidate as a substrate material on which large-area surface-relief leaky grating structures, such as those used in ICGs, EPEs, and OPEs for mixed reality eyepieces, can be fabricated, as described herein, for use in head-mounted displays. One reason lithium niobate may be less desirable as a substrate material on which grating structures used in ICGs, EPEs, and OPEs can be fabricated may be due, at least in part, to the difficulty of economically producing large-area grating structures. The ferroelectric and pyroelectric properties of lithium niobate present challenges in fabricating large-area grating structures using an etch mask obtained by jet deposition and patterning of a resist layer. Nevertheless, lithium niobate processing methods, as described herein, can be used to fabricate large-area grating structures. Additional discussion of methods for fabricating lithium niobate is included below.

[0317] Such a high-index waveguide may be advantageously included in an optical system used in a head-mounted display, such as that shown in FIG. 10. FIG. 10 illustrates an example of a display system 1000 comprising an imaging system 1001, a waveguide 1003 comprising a high-index material (e.g., a refractive index greater than about 1.79), and multiple variable-focus elements 1005a and 1005b. The imaging system 1001 comprises a projection optics system 1009, an illumination optics system 1011 that provides three colors (e.g., red, green, and blue light), and a spatial light modulation element 1013 that modulates the light (e.g., red, green, and blue light) emitted from the illumination optics system 1011 to form a light stream containing image information. The three different color (e.g., red, green, and blue) light streams modulated by the spatial light modulator that contain the image information are output from a single exit pupil of the projection optics system 1009. The three different color (e.g., red, green, and blue) light streams containing image information that exit the single exit pupil of the projection optics system 1009 are received by one or more internal coupling optical elements associated with the waveguide 1003 and diffracted such that the three color (e.g., red, green, and blue) light streams containing image information are internally coupled into the waveguide 1003. As discussed above, in various implementations, the one or more internal coupling optical elements can be aligned (e.g., vertically aligned) with the single exit pupil of the projection optics system 1009 such that at least a portion of the one or more internal coupling optical elements overlaps with the single exit pupil of the projection optics system 1009 in a top-down view.

[0318] In some implementations, imaging system 1001 can comprise a low-mass, compact microdisplay. In some implementations, imaging system 1001 can comprise either a blending color pupil, a set of closely spaced red-green-blue ("RGB") sub-pupils, or an internal pupil (such as an MEMs system, where the pupil resides at the scanning mirror plane). In various embodiments, imaging system 1001 can have features similar to any of the imaging systems discussed below with reference to FIGS. 11-17B.

[0319] The waveguide 1003 can include a material having a refractive index of about 2.3 or greater, such as, for example, lithium niobate. When the waveguide 1003 includes lithium niobate, the diagonal field of view of light output from the waveguide can be about 70° for red, green, and blue wavelengths. In some implementations, the display system 1000 can include two waveguides instead of a single waveguide 1003. For example, a first of the two waveguides can be configured to internally couple one or two different colored light streams containing image information (e.g., a red-colored image stream, or red and green-colored image streams), and a second of the two waveguides can be configured to internally couple another one or two different colored light streams containing image information (e.g., blue and green-colored image streams, or a blue-colored image stream, respectively). In some implementations where the first waveguide contains two different colored light streams, the second of the two waveguides can be configured to internally combine one colored light stream that is different from the color in the first waveguide and one light stream that is the same or similar color as that contained in the first waveguide (e.g., green and blue colored image streams, or red and blue colored image streams).

[0320] System 1000 can be configured as an infinity-focusing system that presents a real-world view without magnification to the viewer or the viewer's eye 1007, along with a virtual image at a location other than infinity. Variable-focus elements 1005a and 1005b provide the ability to shift the virtual image focal plane. Variable-focus element 1005a can be configured as a positive continuously variable-focus element, and variable-focus element 1005b can be configured as a negative continuously variable-focus element. In various embodiments, variable-focus elements 1005a and 1005b can comprise liquid-filled variable-focus lens pairs. In some embodiments, variable-focus elements 1005a and 1005b can include liquid crystal (LC) based programmable Fresnel lens pairs configured with pixels. The negative focus element 1005b can be configured to shift the virtual image position, and the positive focus element 1005a can be configured to simultaneously neutralize the refractive power of the negative focus element 1005b with respect to the real world as seen through the pair of variable-focus elements 1005a and 1005b. Light projected out from the waveguide 1003 traverses only the negative focus element 1005b. This approach and combination of elements can generate a range of focal planes, depth planes, or depths, depending on the specific capabilities of the variable-focus elements 1005a and 1005b. Exemplary near and far planes are shown in FIG. 10. A switch or control module that coordinates the spatial light modulator 1013 with the variable-focus elements 1005a and 1005b so that various images are presented at the appropriate depths is shown diagrammatically. The integrated stack comprising the variable-focus elements 1005a and 1005b and the single waveguide 1003 can be made sufficiently thin and low mass, depending primarily on the ability to miniaturize the variable-focus elements 1005a and 1005b. Without any loss of generality, the integrated stack comprising the variable-focus elements 1005a and 1005b and the single waveguide 1003 can be referred to as an eyepiece when the display system 1000 is included in a head-mounted display. In some implementations, the eyepiece may be an infinity-focus eyepiece designed to have a focus at a far distance in at least one state.

[0321] The design of display system 1000 illustrated in FIG. 10 can advantageously provide a substantially compact microdisplay because only a single pupil with color mixing is used, and focal plane shifting is accomplished entirely by a liquid lens pair or a liquid crystal (“LC”)-based programmable lens pair. However, in some implementations, the weight of display system 1000 may increase as a result of the increased weight of the liquid lens or programmable Fresnel lens system. In addition, the use of a liquid lens or programmable Fresnel lens system may increase optical distortion. Additionally, the thickness of the integrated stack comprising waveguide 1003 and variable-focus elements 1005 a and 1005 b may be increased due to the frame required to support variable-focus elements 1005 a and 1005 b.

[0322] FIG. 11 illustrates another embodiment of a display system 1100. The display system 1100 employs the imaging system 1001 and waveguide 1003 discussed above. Thus, various elements of the display system 1100 may be similar to corresponding elements of the display system 1000. In the display system 1100, a switchable geometric phase (GP) lens stack is used as the variable-focus elements 1005a and 1005b instead of a liquid-filled lens pair or a programmable Fresnel lens pair configured with LC-based pixels. The display system 1100 may potentially be thinner and lighter than the display system 1000. However, because the geometric phase (GP) lens stack operates only on polarized light, the display system 1100 may include a polarizer to filter real-world light entering the system. The incorporation of a polarizer may result in a reduction in the brightness of the real-world light entering the system. For example, the incorporation of a polarizer may result in a brightness reduction of approximately 50% in some embodiments. Combined with other losses from the GP lens stack, the total throughput of real-world light may fall below 30% in some implementations. Additionally, scattering from the lenses in the GP lens stack may reduce optical performance below desirable levels in some embodiments. Additionally, the attenuating nature of the display system 1100 may partially obscure the wearer's eyes to at least nearby people, potentially similar to the scenario of an individual wearing sunglasses, thereby making eye contact more difficult. The display system 1100 may also introduce other artifacts induced by leakage of undiffracted light, which may involve the use of switchable waveplates to vary the relative refractive power across two to four available depth planes. In some embodiments, the display system 1100 may include two waveguides instead of a single waveguide 1003.The first of the two waveguides can be configured, for example, to internally combine one or two different colored light streams containing image information (e.g., a red-colored image stream, or red- and green-colored image streams), and the second of the two waveguides can be configured to internally combine another one or two different colored light streams containing image information (e.g., blue- and green-colored image streams, or blue-colored image streams, respectively). In some implementations where the first waveguide contains two different colored light streams, the second of the two waveguides can be configured to internally combine one colored light stream different from the color in the first waveguide and one light stream of the same or similar color as that contained in the first waveguide (e.g., green- and blue-colored image streams, or red- and blue-colored image streams).

[0323] 12 illustrates another embodiment of a display system 1200 comprising an imaging system 1201 and a waveguide including a high refractive index material. Various components of imaging system 1201 may be similar to corresponding components of imaging system 1001. However, projection optics system 1209 is configured to have two exit pupils configured to emit three colors, e.g., first, second, and third colors (e.g., red, green, and blue), respectively. The first output projector exit pupil is configured to emit first, second, and third (e.g., red, green, and blue) light streams comprising image information for a first depth or focal plane, and the second projector exit pupil is configured to emit first, second, and third (e.g., red, green, and blue) light streams comprising image information for a second depth or focal plane. First, second, and third (e.g., red, green, and blue) light streams emanating from a first exit pupil and comprising image information for a first depth or focal plane are internally coupled into a first waveguide 1203a of the waveguide assembly 1203. First, second, and third (e.g., red, green, and blue) light streams emanating from a second exit pupil and comprising image information for a second depth or focal plane are internally coupled into a second waveguide 1203b of the waveguide assembly 1203. Thus, embodiments of the display system 1200 are configured as a two depth plane system, with each depth plane addressed by a separate waveguide pairing (pairing a waveguide with a refractive power component such as a refractive lens or an optical element disposed on a surface of the waveguide to impart a refractive power associated with the depth plane). Waveguides 1203a and 1203b can be identical to one another in some embodiments. Like waveguide 1003, waveguides 1203a and 1203b can comprise a material having a high refractive index (e.g., a refractive index greater than about 1.79, such as about 2.3). For example, in some embodiments, waveguides 1203a and 1203b can comprise lithium niobate or silicon carbide. Like waveguide 1003, waveguides 1203a and 1203b can be infinity-focused.The variability in the focal position of the light emitted from waveguides 1203a and 1203b can be provided by static refractive lenses 1205a, 1205b, and 1205c (e.g., thin refractive lenses) similar to those commonly used in eyeglasses, for example. Static refractive lens 1205b is positioned between first waveguide 1203a and the wearer's eye 1207, static refractive lens 1205c is positioned between first waveguide 1203a and second waveguide 1203b, and static refractive lens 1205a is positioned between the outside world and second waveguide 1203b. In some implementations, the gap between the first waveguide 1203a and the second waveguide 1203b may be large enough to accommodate the static refractive lens 1205c, but small enough to reduce the form factor of the eyepiece comprising the waveguides 1203a and 1203b and provide flexibility in working distance configuration and tolerances. For example, the gap between the first waveguide 1203a and the second waveguide 1203b may be about 1.0 mm to about 1.5 mm in some implementations.

[0324] Refractive lenses 1205b and 1205c can be configured as negative power lenses, and refractive lens 1205a is configured as a positive power lens. In the embodiment of display system 1200 illustrated in FIG. 12, refractive lens 1205b is a plano-concave lens with a refractive power of −0.5 diopters, refractive lens 1205c is a plano-concave lens with a refractive power of −1.5 diopters, and refractive lens 1205a is a plano-convex lens with a refractive power of +2.0 diopters. In some embodiments, static refractive lenses may be molded. In some embodiments, static refractive lenses can be formed by other manufacturing techniques. In some embodiments, static refractive lenses can be mass-produced from polymers (e.g., high refractive index polymers). In various embodiments, an anti-reflective layer can be disposed over static refractive lenses comprising polymers. For example, in some embodiments, static refractive lenses comprising polymers can be coated with anti-reflective layers / coatings using inexpensive methods. Light from the first waveguide 1203a passes through a single negative refractive lens 1205b and is focused in distance by the refractive power of the single negative refractive lens 1205b. Light from the second waveguide 1203b passes through two negative refractive lenses 1205b and 1205c and is focused in distance by the combined refractive power of the two negative refractive lenses 1205b and 1205c. The outer positive refractive lens 1205a negates the combination of the two negative refractive lenses 1205b and 1205c, resulting in a real world view that is unaffected by lenses 1205b and 1205c.

[0325] The embodiment of display system 1200 illustrated in FIG. 12 can utilize a multi-pupil microdisplay to address each layer independently (thus, each depth plane or depth can have unique image content). As discussed above, in an example embodiment, imaging system 1201 comprises two RGB mixing exit pupils that output image content for two depth planes. It should be appreciated that in various embodiments, imaging system 1201 can be configured to output the red (R), green (G), and blue (B) color components of an image for a particular depth plane through geometrically offset and separated R, G, and B sub-pupils, or at least partially combined RGB sub-pupils (at least two colors are input into the same waveguide using the same internal coupling optical element). As discussed above, reducing the number of output sub-pupils in an imaging system can generally result in significantly more compact projection optics and a correspondingly more compact imaging system, which can be advantageous for wearable systems. In various embodiments of the display system 1200, the imaging system 1201 can include two independent single-pupil microdisplays. The independent single-pupil microdisplays can be LCOS-based single-pupil systems or independent MEMs scanner projectors. In such embodiments, each independent single-pupil microdisplay is configured to direct image light to a corresponding waveguide.

[0326] In some embodiments, display system 1200 can include two waveguide assemblies per depth plane instead of one waveguide per depth plane. For each depth plane, a first of the two waveguides can be configured to interconnect one or two different colored light streams (e.g., a red-colored image stream, or a red- and green-colored image stream) that contain image information for that depth plane, and a second of the two waveguides can be configured to interconnect another one or two different colored light streams (e.g., a blue- and green-colored image stream, or a blue-colored image stream, respectively) that contain image information for that depth plane. In some implementations where the first waveguide contains two different colored light streams, the second of the two waveguides can be configured to interconnect one colored light stream that is different from the color in the first waveguide and one light stream that is the same or similar in color to that contained in the first waveguide (e.g., a green- and blue-colored image stream, or a red- and blue-colored image stream).

[0327] FIG. 13 illustrates an embodiment of an imaging system 1300 configured to provide a multicolored light stream comprising image information to a stack 1303 comprising one or more waveguides disposed on eyewear, such as a head-mounted display, to be positioned in front of a wearer's eyes. In some embodiments, the one or more waveguides can comprise a high refractive index material (e.g., a refractive index greater than about 1.79). In various embodiments, the stack 1303 can comprise one or more waveguides (e.g., a waveguide comprising a high refractive index material) per depth plane. For example, the stack 1303 can comprise one waveguide comprising a high refractive index material per depth plane. The two waveguides can be configured to internally couple image light output from the imaging system 1300 having one or more different wavelengths such that the internally coupled image light propagates within the waveguides by total internal reflection. The one or more waveguides comprising a high refractive index material can further be configured to project the internally coupled light to a viewer over a wide field of view (e.g., a horizontal field of view greater than about 20 degrees and a vertical field of view greater than about 20 degrees).

[0328] The imaging system is configured as a front-illuminated imaging system in which polychromatic, unmodulated illumination light is input into the imaging system through one or more entrance pupils through a projection optics system 1307 toward a modulation element 1305. The modulation element 1305 is reflective and is front-illuminated by the illumination light from the projection optics system 1307. The modulated light containing the image information is reflected from the modulation element 1305 and transmitted through the projection optics system 1307 back toward the waveguide stack 1303 through one or more exit pupils. In various embodiments, the imaging system 1300 can be configured with two entrance pupils, each configured to provide polychromatic illumination and generate images for two different depths or focal planes. In some such embodiments, the imaging system 1300 can be configured with two exit pupils, each configured to output polychromatic image light for two different depths or focal planes. Polychromatic image light for two different depths or focal planes emitted from the two exit pupils can be directed towards corresponding waveguides in stack 1303. The imaging system illustrated in Figure 13 has several advantages, including, but not limited to, a small size and / or potentially reduced number of pupils.

[0329] Other configurations are possible. For example, stack 1303 can include two waveguides including high refractive index material for each depth plane. In one illustrative design, for example, a first of the two waveguides can be configured to internally couple one or more of the first, second, or third colors, such as red-, green-, and blue-colored image light (e.g., red-colored image light, or red and green-colored image light, or red and blue-colored image light), output from imaging system 1300, such that the internally coupled image light propagates within the waveguide by total internal reflection, and a second of the two waveguides can be configured to internally couple one or more of the first, second, or third colors, such as red-, green-, and blue-colored image light (e.g., blue-colored image light, or blue and green-colored image light, or blue and red-colored image light), output from imaging system 1300, such that the internally coupled image light propagates within the waveguide by total internal reflection.

[0330] As discussed above, designing a projection optics system (e.g., projection optics systems 1107, 1207, and 1307) can be challenging, especially when it is desired that light from the projection optics system be output by multiple waveguides or waveguide assemblies. One difficulty encountered in designing such a projection optics system is a limited working distance (e.g., the distance from the last optical surface of the projection optics system to the surface of the relevant waveguide). As discussed above, one advantage of employing waveguides comprising a high refractive index material (e.g., a refractive index greater than about 1.79) is a reduction in the number of waveguides used per depth or focal plane (e.g., potentially reducing the number of waveguides from three per depth plane to one or two per depth plane). The reduction in the number of waveguides resulting from using a high refractive index material can provide additional working distance gains that may enable projection lens design options that were not practical with systems or eyepieces involving a large number of waveguides. Obtaining such additional working distance, and embodiments of display systems configured for optimal working distance of their components, are further described below with reference to Figures 14A-14E-3.

[0331] 14A illustrates a display system (e.g., an eyepiece of a head-mounted system) having first and second groups of waveguides 1401 and 1403 for two depth planes. Each group of waveguides 1401, 1403 has three waveguides configured to receive multiple light beams from projection optics across a wide range of angles and internally couple the light into the waveguides for propagation by total internal reflection. For example, the multiple light beams may be first, second, and third colors (red, blue, and green light comprising image information for that depth plane) across a range of angles associated with the field of view of the display system.

[0332] Each waveguide in Figure 14A can be considered to have an individual working distance (the distance from the last optical surface of the projection optics system 1405 to the surface of that waveguide proximal to the sub-pupil, which can be a waveguide surface closer or further from the projection optics system 1405). As depicted in Figure 14A, the sub-pupils for the multiple light beams in the leftmost and rightmost waveguides are larger compared to the sub-pupils in waveguides closer to the center of the waveguide stack because the light beams are steered by the projection optics by narrowing and then widening the light beam bundles carrying image data at the angle of the field. Therefore, the internal coupling elements for these leftmost and rightmost waveguides must be correspondingly larger to capture all of the light in the individual sub-pupils.

[0333] However, large internal coupling elements may introduce imaging efficiency issues, such as reflecting some of the light coupled into the waveguide through the same internal coupling element before propagation by total internal reflection begins. FIG. 14E-1 illustrates an example of a waveguide 1403 with an internal coupling element 1416a that is large enough to reflect a portion of the light internally coupled out of the waveguide 1403 through the same internal coupling element 1416a. The phenomenon of outcoupling light internally coupled through the same internal coupling element is referred to herein as “rebouncing.” One way to reduce the risk of outcoupling light internally coupled through the same internal coupling element is to make the internal coupling element smaller. FIG. 14E-2 illustrates an example of a waveguide 1403 with an internal coupling element 1416b that is smaller than the internal coupling element 1416a. However, simply reducing the size of the internal coupling element to reduce rebouncing may reduce the amount of light the internal coupling element can receive. For example, if the sub-pupil in a waveguide is larger than the internal coupling element in the same waveguide, the portion of the received light that does not enter the internal coupling element will not be internally coupled and will be lost.

[0334] Additionally, with each bounce during total internal reflection, imperfections in the waveguide structure introduce aberrations into the optical path, such that the greater the number of bounces per waveguide, the more image quality degrades. This problem can be reduced by using a thicker waveguide, which can induce fewer bounces through total internal reflection. FIG. 14E-3 shows an example of a waveguide 1403c that is thicker than the waveguide 1403 of FIGS. 14E-1 and 14E-2. A thicker waveguide can have a sufficiently large internal coupling element to receive all of the incident light while reducing the risk of outcoupling light incoupling through the internal coupling element. However, increasing the thickness of any one waveguide (much less all of them) would place the leftmost waveguide of the waveguide assembly 1401 of FIG. 14A further from the projection optics system 1405, resulting in a larger sub-pupil size and requiring a larger internal coupling element, which would further exacerbate the efficiency problem described above. Therefore, as noted from FIG. 14A, the waveguide assemblies of 1401 and 1403 have an overall limited working distance, as any changes to the waveguide metrics (such as the thickness of the waveguide, or the distance of the waveguide from the projection optics system 1405) can adversely affect the resulting increase in sub-pupil size.

[0335] Figure 14B illustrates this when a refractive lens 1409a is introduced between the waveguide assemblies 1401 and 1403. By placing the refractive lens 1409a between the waveguide assemblies, the sub-pupil intersection on the waveguide assembly 1401 would be further away than in Figure 14A, requiring a thinner waveguide to maintain form factor (increasing aberrations in the image due to increased bounce) and / or a larger internal coupling element to receive all angles at the new sub-pupil distance (reducing the efficiency of the waveguide). In other words, the placement of the refractive lens 1409a, which would otherwise support and improve depth cues for the viewer, results in degraded image quality from increased working distances.

[0336] By replacing the waveguides in the first and second groups 1401 and 1403 with waveguides comprising a high refractive index material, the number of waveguides in each group can be reduced from three per depth plane to one per depth plane, as shown in FIG. 14C. In some embodiments, the number of waveguides can be reduced from three per depth plane to two per depth plane. This configuration can reduce the working distance of any one waveguide because the overall waveguide assembly is now thinner. Assuming a waveguide thickness of approximately 300-400 microns per waveguide, FIG. 14C illustrates the "recovery" or "regaining" of up to 1.2 mm of working distance as a result of reducing the number of waveguides per depth plane with the high refractive index waveguides of FIG. 14C. The configuration illustrated in FIG. 14C can have several additional benefits from the improved working distance. For example, a smaller internal coupling grating can be employed to internally couple light within the waveguide due to a smaller working distance (such as between the waveguide and the projector); alternatively, a smaller beam size entering the waveguide can be used; or the thickness of the waveguide can be increased (which can actually increase the working distance) to refine the number of bounces due to total internal reflection and reduce the number of angles susceptible to the "rebounce" problem of FIG. 14E-1. Such an increase in waveguide thickness would previously have been undesirable due to the increased working distance relative to continuous waveguides in the stack, but may have a negligible performance effect since the working distance has already been shortened. As another example, one or more additional depth planes could potentially be incorporated into the system, as shown in FIG. 15 below.

[0337] 14D-1, 14D-2, and 14D-3 illustrate embodiments of display systems comprising two waveguide pairs (waveguides and refractive lenses). Fig. 14D-1 illustrates a display system with transmissive internal coupling elements 1414 and 1416, where light passes through the elements before the waveguides, while Fig. 14D-2 illustrates a display system with reflective internal coupling elements 1414-1 and 1416-1, where light enters the waveguides before interacting with the elements, and Fig. 14D-3 illustrates a display system utilizing both transmissive and reflective internal coupling elements.

[0338] FIGS. 14D-1, 14D-2, and 14D-3 each depict a projection optics system having a final lens 1405 for projecting multiple light beams from an entire projector (not depicted) at multiple angles, the multiple angles associated with the image comprising the field of view. The range of angles encompasses light beam 1412 through light beam 1410. The projection optics system thus generates a narrowing and then widening cone of multiple light beams over the range of angles. While only one range of angles is depicted, it should be understood that FIGS. 14D-1, 14D-2, and 14D-3 may also work for a multi-pupil projector (such as FIG. 14C), and the single pupil of FIGS. 14D-1, 14D-2, and 14D-3 is illustrated for ease of explanation.

[0339] Waveguides 1401 and 1403 intersect the sub-pupil cone at different locations. Waveguide 1401 is positioned where the cone widens, and waveguide 1403 is placed where the cone narrows. In some embodiments, a refractive lens is placed between waveguides 1401 and 1403.

[0340] Internal coupling elements (e.g., diffraction gratings) are positioned on waveguides 1401 and 1403 where their major surfaces intersect the sub-pupils. In FIG. 14D-1 , which depicts a transmissive internal coupling element, the internal coupling element is positioned on a surface of the waveguide closer to the final lens 1405 of the projection optics system. In FIG. 14D-2 , which depicts a reflective internal coupling element, the internal coupling element is positioned on a surface of the waveguide farther from the final lens 1405 of the projection optics system. It should be understood that the size of the internal coupling element may depend on the surface on which it is positioned and the waveguide on which it is positioned. As shown in FIG. 14D-1 , internal coupling element 1414 is smaller than internal coupling element 1416, while the opposite is true in FIG. 14D-2 . Increasing or decreasing the waveguide working distance 1410 or 1412 can adjust the size of the internal coupling element required to capture the range of the light beam. 14D-3 illustrates an embodiment in which the internal coupling element is located on the near or far side to increase or optimize the internal coupling element size for each waveguide. In other words, the surface locations of the internal coupling elements in FIGS. 14D-1 and 14D-2 are not mutually exclusive and may be interchangeable.

[0341] Waveguide display systems within the art can minimize form factor and maximize overall efficiency by placing the waveguide as close to the projector as possible and minimizing in-coupling size. By implementing the high index waveguides described herein, optimization of working distance can instead be linked to ideal in-coupling element size, which in turn can optimize waveguide thickness and the presence of beneficial intermediate optics such as refractive or variable focus lenses.

[0342] FIG. 14D-1 illustrates a first waveguide 1403 having an internal coupling element 1416 on its proximal surface at a first working distance 1412, as measured from the internal coupling element 1414 to the last lens 1405 in the projection optics system. A second waveguide 1401, also having an internal coupling element 1416 on its proximal surface, is located at a second working distance 1410, as measured from the internal coupling element 1414 to the last lens 1405 in the projection optics system. FIGS. 14D-2 and 14D-3 illustrate similar embodiments with variations on the internal coupling element surface locations and corresponding changes to the working distances; it should be noted that FIG. 14D-3 may use a first working distance 1412-1 and a second working distance 1410, and not necessarily a unique working distance for that particular variable configuration of internal coupling element surface arrangements.

[0343] In some embodiments, at least one refractive lens 1420 is disposed between waveguides 1401 and 1403, and is configured to provide depth cues to light passing therethrough. In some embodiments, refractive lens 1420 has an optical prescription or optical power. It should be understood that in some implementations, the thicker lens 1420 may be, the greater the optical power it may exert, and that increasing the thickness of lens 1420 will also increase at least the second working distance.

[0344] In some embodiments, the waveguides 1401 and 1403 (or at least their respective internal coupling elements 1414 or 1414-1 and 1416 or 1416-1) are located on opposite sides of a sub-pupil transition point 1418, where the angular range of the multiple light beams comprising the image data of the field of view transitions from a narrowing cone to a widening cone. In some embodiments, the waveguides (or at least their respective internal coupling elements) are located on a common side of the sub-pupil transition point 1418. Figures 14D-1, 14D-2, and 14D-3 illustrate the former, but those skilled in the art will understand the applicability of the latter from the description provided herein. Furthermore, it should be noted that the sub-pupil transition point 1418, or the working distance as applied herein, is not necessarily co-located with the optical pupil of the projector.

[0345] Benefits of the various systems, architectures, and designs disclosed herein, such as the embodiments illustrated in Figures 10, 12, 13, 14C, 14D-1, and 14D-2, include, but are not limited to, high transmission, relatively small form factor and thickness (e.g., nominal eyepiece thickness of less than about 5 mm), reduced manufacturing costs, and lower mass compared to other two-depth plane architectures. The mass of a full-color eyepiece with a single waveguide with a high refractive index material (e.g., refractive index greater than 1.79 and / or refractive index greater than 2.2) can be reduced compared to a full-color eyepiece with three glass waveguides due to the integration of three waveguides into one waveguide.

[0346] As discussed above, employing waveguides comprising a high-index material (e.g., a refractive index greater than 1.79 and / or a refractive index greater than 2.2) can reduce the number of waveguides per depth plane, enabling the possibility of including one or more additional depth planes. FIG. 15 illustrates an embodiment of a display system 1500 comprising an eyepiece comprising a stack 1518 comprising multiple waveguides 1520, 1522, and 1524. Each waveguide 1520, 1522, and 1524 can be associated with a corresponding depth plane. (In some other embodiments, two waveguides can be associated with each depth.) In some implementations, the gap between the waveguides is approximately 0.3 mm. The waveguides may comprise a substrate of approximately 400 microns in some cases. Light comprising image information for each depth plane can be emitted from one or more exit pupils of the imaging system 1501. For example, in the embodiment illustrated in FIG. 15 , the imaging system 1501 can include three exit pupils, each configured to output polychromatic image light for a corresponding depth plane. (For similar systems used to provide depth or depth planes, two exit pupils may be used, as opposed to three.) In various embodiments, the waveguides in the stack 1518 can be infinity-focused or can include fixed-distance multifocal elements. Notably, in some such embodiments, the stack 1518 can include multiple negative static geometric phase 1530 (“GP”) lenses (e.g., liquid crystal polarization gratings) positioned between the depth planes and the wearer's eye 1507 to vary the focal position of virtual images projected from waveguides associated with different depth planes. The stack 1518 can further include a positive GP lens 1526 positioned between the outside world and the wearer's eye 1507 to compensate for the refractive power introduced by the negative GP lens. Using static GP lenses can reduce the thickness and weight of the stack 1518 compared to using other types of variable focus lenses. Many embodiments of GP lenses can be polarization sensitive.Thus, stack 1518 can further comprise a polarizer 1528 (e.g., a circular polarizer or a polarizer-based variable attenuator, e.g., comprising one or more liquid crystal layers and a polarizer) to ensure proper functionality of display system 1500. One drawback of incorporating a polarizer into stack 1518 is a reduction in optical throughput or brightness. For example, incorporating a polarizer into stack 1518 can, in some embodiments, reduce optical throughput by about 50%. In some embodiments, a combination of a liquid crystal-based variable attenuator and polarizer can be integrated into stack 1518.

[0347] The present application contemplates variations and combinations of the display systems and imaging systems described above, including hybrid combinations of refractive and diffractive (GP) lenses.

[0348] For example, in various embodiments of a front-illuminated imaging system, such as the imaging system 1300 illustrated in FIG. 13, a light pipe or light pipe can be used to provide illumination light to the modulation element 1305 of the imaging system. FIG. 16 illustrates an embodiment of a display system 1600 including a light pipe 1630. The display system 1600 includes a stack 1603 including one or more waveguides that can be integrated into eyewear or a head-mounted display. The light pipe 1630 may be disposed between the waveguides in the stack 1603. In some designs, the separation of the waveguides, which can be affected by the thickness of one or more lens elements between the waveguides, can be 1 to 1.2 mm wide in some cases. Light from the imaging system, including the modulation element 1605 and the projection optics system 1607, is directed toward the stack 1603 and is incoupled into the waveguides using an incoupling optical element as described herein. The display system 1600 further includes one or more monochromatic or polychromatic individual light sources (e.g., lasers or LEDs) 1632a-1632c. In the illustrated implementation, the individual light sources 1632a-1632c include first, second, and third color sources, such as red, green, and blue light. Light from the individual light sources 1632a-1632c is combined with a dichroic beam splitter 1634 to generate a white beam and launched into the light pipe 1630. In some embodiments, a white light source (e.g., a white LED) can be used to direct the white light down the light pipe 1630. In such embodiments, the beam-combining dichroic beam splitter 1634 can be eliminated. The incoming white light beam may be redirected using a light redirector or turning element 1636 (e.g., a wedge and / or mirror) to exit the pipe 1630. In some embodiments, this light is redirected in a direction nominally perpendicular to the major surfaces of the light pipe 1630 and / or the waveguides of the stack 1603 and directed through the projection optics system 1607 and one or more waveguides of the stack 1603 towards the modulation element 1605.The light is reflected from the modulation element 1605, and the modulated light stream is passed back through the projection optics 1607 and in-coupled into the waveguide within the stack 1603. In some embodiments, the redirected light can be modified or modulated using conditioning optics 1638, which comprise a diverging lens or a diffractive optical element designed to produce a desired light distribution on the modulation element 1605 after propagation through the projection optics system 1607. The conditioning optics 1638, in some implementations, may comprise a top-hat beam profile diffractive optical element. In some cases, the conditioning optics 1638 can efficiently adjust the light distribution to any arbitrary design depending on the needs of the display system 1600. The conditioning optics 1638 may be provided on one or both major surfaces of the waveguide. In some embodiments, the conditioning optics, which comprise a diffractive optical element, can be fabricated simultaneously with the in-coupling and out-coupling optical elements fabricated on the surfaces of the waveguide. An added benefit of employing a light pipe illuminator configuration is that it moves the light source away from the waveguide, which may generally be sensitive to thermal fluctuations or high temperatures.

[0349] In some embodiments, separate light pipes may be used to provide illumination light of different colors. Figures 17A and 17B show side and top views of individual light pipes 1730a, 1730b, and 1730c configured to provide individual colored illumination to the imaging system. In contrast to the design shown in Figure 16, a dichroic beam splitter 1634 is not used; light is coupled into the light pipe 1630 from the end of the light pipe in the implementation shown in Figures 17A and 17B. In the illustrated implementation, light pipe 1730a is configured to provide a first color (e.g., red) illumination, light pipe 1730b is configured to provide a first color (e.g., green) illumination, and light pipe 1730c is configured to provide a third color (e.g., blue) illumination. Light pipes for any combination of colors may be used. In such embodiments, separate diffractive optical elements (DOEs) designed or optimized for each color can be used to condition the illumination light before it is modulated. Additionally, the internal coupling gratings that receive the image light from the imaging system can also be designed or optimized for each individual color, for example, to increase the internal coupling efficiency. In various embodiments, the waveguides can be tapered to allow for closer spacing. One waveguide per depth plane

[0350] Various embodiments of the display devices described above include a single waveguide including a high refractive index material (e.g., a refractive index of about 1.79 or greater) per depth plane. A multiplexed stream of light including light of a first color, a second color, and a third color comprising image information for the depth plane is incoupled into the waveguide for that depth plane using at least one incoupling optical element. Without any loss of generality, the first color, the second color, and the third color can be selected from a group including red, green, and blue. In some embodiments, the single incoupling optical element can be configured to redirect (e.g., diffract) the light of the first color, the second color, and the third color comprising image information for the depth plane into the waveguide. In other embodiments, two incoupling optical elements can be configured to redirect (e.g., diffract) the light of the first color, the second color, and the third color comprising image information for the depth plane into the waveguide, with different colors or color combinations being coupled into the waveguide by the two incoupling optical elements. For example, in some embodiments, a first of the two internal coupling optical elements can be configured to redirect (e.g., diffract) light of the first color and the second color, and a second of the two internal coupling optical elements can be configured to redirect (e.g., diffract) light of the third color, respectively. In other embodiments, a first of the two internal coupling optical elements can be configured to redirect (e.g., diffract) light of the first color and the second color, and a second of the two internal coupling optical elements can be configured to redirect (e.g., diffract) light of the third color and light of one of the first or second colors, respectively. In some embodiments, three internal coupling optical elements, i.e., the first, second, and third internal coupling optical elements, can be configured to redirect (e.g., diffract) light of the first color, the second color, and the third color, which includes image information for the depth plane, into the waveguide.For example, in some embodiments, a first of the three internal coupling optical elements can be configured to redirect (e.g., diffract) light of a first color, a second of the three internal coupling optical elements can be configured to redirect (e.g., diffract) light of a second color, and a third of the three internal coupling optical elements can be configured to redirect (e.g., diffract) light of a third color, respectively. Two waveguides per depth plane

[0351] Various embodiments of the display device described above can include two waveguides including a high refractive index material (e.g., a refractive index of about 1.79 or greater) per depth plane. A multiplexed stream of light including light of a first color, a second color, and a third color that includes image information for the depth plane is internally coupled into the two waveguides, and the first and second different colors or color combinations are coupled into the two waveguides. Without any loss of generality, the first color, the second color, and the third color can be selected from a group including red, green, and blue. In some embodiments, the first waveguide can be configured to receive and guide therein the first color and the second color that include image information for the depth plane, and the second waveguide can be configured to receive and guide therein the third color that includes image information for the depth plane, respectively. In other embodiments, the first waveguide can be configured to receive and direct within it a first color and a second color comprising image information for the depth plane, and the second waveguide can be configured to receive and direct within it a third color and one of the first or second colors comprising image information for the depth plane, respectively. For example, the first waveguide can be configured to receive and direct within it red and green, and the second waveguide can be configured to receive and direct within it green and blue or red and blue, respectively.

[0352] In various implementations, a multiplexed stream of light including light of a first color, a second color, and a third color containing image information for the depth plane is incoupled into two waveguides using at least two incoupling optical elements. In some embodiments, the first incoupling optical element can be configured to redirect (e.g., diffract) the first and second color light containing image information for the depth plane into the first waveguide, and the second incoupling optical element can be configured to redirect (e.g., diffract) the third color light containing image information for the depth plane into the second waveguide, respectively. In some embodiments, the second incoupling optical element can also be configured to redirect (e.g., diffract) the first color or the second color light into the second waveguide. In some embodiments, the first inward coupling optical element can be configured to redirect (e.g., diffract) light of a first color containing image information for a depth plane into the first waveguide, and the second inward coupling optical element can be configured to redirect (e.g., diffract) light of a second color containing image information for a depth plane into the first waveguide. The third inward coupling optical element can be configured to redirect (e.g., diffract) light of a third color containing image information for a depth plane into the second waveguide for that depth plane. In some embodiments, the second inward coupling optical element can further be configured to redirect (e.g., diffract) light of the first color or the second color into the second waveguide. In some other embodiments, the fourth inward coupling optical element can be configured to redirect (e.g., diffract) light of the first color or the second color into the second waveguide. Method for fabricating a grating on a high index waveguide

[0353] Various embodiments of display devices including a waveguide including a high refractive index material (e.g., a refractive index of about 1.79 or greater) discussed herein can include a diffractive structure disposed on the surface of the waveguide. As discussed above, a waveguide including a high refractive index material (e.g., a refractive index of about 1.79 or greater) with a diffractive structure can be configured to incouple polychromatic light containing image information emitted from an imaging system (e.g., a microdisplay or projector), disperse the incoupled light along one or more desired directions, and / or outcouple the incoupled light toward a viewer. Different methods for fabricating a waveguide including a high refractive index material (e.g., a refractive index of about 1.79 or greater) with a diffractive structure are described below.

[0354] 18A and 18B illustrate flowcharts of two different methods for fabricating a diffraction grating on a surface of a substrate (e.g., a waveguide) comprising a high refractive index material (e.g., a refractive index greater than 1.79). In some implementations, the substrate can comprise lithium niobate (LiNbO) or silicon carbide (SiC). The method includes providing a high refractive index substrate, as shown in block 1801. The method further includes disposing a layer of patternable material on the surface of the substrate, as shown in block 1803. In some embodiments, the patternable material can comprise a resist. In some embodiments, the patternable material can comprise a polymer. For example, the patternable layer can comprise an ultraviolet (UV) curable polymer. The patternable layer can have a refractive index less than that of the material of the substrate (e.g., a refractive index less than 1.79). For example, the refractive index of the patternable layer can be from about 1.2 to about 1.8. In various embodiments, the refractive index of the patternable layer can be about 1.2 or more and about 1.3 or less, about 1.3 or more and about 1.4 or less, about 1.4 or more and about 1.5 or less, about 1.5 or more and about 1.6 or less, about 1.6 or more and about 1.7 or less, about 1.7 or more and about 1.79 or less, or any range / subrange between any of these values. In various embodiments, the patternable layer can have a thickness of about 10 nm to about 1000 nm.

[0355] The patternable layer can be disposed across the surface of the substrate using jet deposition techniques (e.g., inkjet deposition). As discussed above, some high refractive index materials, such as lithium niobate (LiNbO), can be piezoelectric, ferroelectric, and / or pyroelectric and can generate a substantial surface charge when prepared for deposition of the patternable material. It may be impractical to deposit the patternable material across a charged surface of the substrate using jet deposition techniques. Thus, in some embodiments, the charged surface of the substrate, including the high refractive index material, can be discharged prior to depositing the patternable material using jet deposition techniques.

[0356] The patternable layer can be patterned with a desired (e.g., grating or diffractive optical element) pattern, as shown in block 1805. The patterned layer can be used as an etch mask to etch a surface of a substrate comprising a high refractive index material (e.g., a refractive index of about 1.79 or greater) and fabricate diffractive structures on the surface of the substrate, as shown in block 1807.

[0357] In some embodiments, the patterned layer can be deposited on a surface of a substrate that includes a high refractive index material (e.g., a refractive index of about 1.79 or greater). In such embodiments, the patterned layer can be configured to function as a diffractive optical element. Thus, the patterned layer can be configured to function as a functional layer.

[0358] Various exemplary embodiments of the present invention are described herein. Reference is made to these examples in a non-limiting sense. They are provided to illustrate the more broadly applicable aspects of the present invention. Various changes may be made to the invention described, and equivalents may be substituted without departing from the true spirit and scope of the invention. In addition, many modifications may be made to adapt a particular situation, material, composition of matter, process, process acts or steps to the objective, spirit, or scope of the present invention. Moreover, as will be understood by those skilled in the art, each of the individual variations described and illustrated herein has discrete components and features that can be readily separated from or combined with the features of any of the other several embodiments without departing from the scope or spirit of the present invention. All such modifications are intended to be within the scope of the claims associated with this disclosure.

[0359] The present invention includes methods that may be implemented using the present devices. The methods may include the act of providing such suitable devices. Such provisioning may be performed by an end user. In other words, the act of "providing" simply requires the end user to obtain, access, approach, locate, configure, activate, power on, or otherwise act to provide the requisite devices in the present methods. The methods described herein may be carried out in any order of the described events, and in the described order of events, that is logically possible.

[0360] Exemplary aspects of the invention have been described above, along with details regarding material selection and manufacturing. As for other details of the invention, these will be understood in connection with the above-referenced patents and publications, and may generally be grasped or understood by those skilled in the art. The same may be true with respect to the method-based aspects of the invention in terms of additional acts as commonly or logically adopted. In addition, while the present invention has been described with reference to several embodiments optionally incorporating various features, the invention is not limited to those described or shown as being contemplated with respect to each variation of the invention. Various modifications may be made to the described invention and equivalents (whether described herein or not included for purposes of brevity) may be substituted without departing from the true spirit and scope of the invention. In addition, when a range of values ​​is provided, it is understood that every intervening value between the upper and lower limits of that range and any other stated or intervening value within that stated range is encompassed within the present disclosure.

[0361] It is also contemplated that any optional features of the described inventive variations may be set forth and claimed independently or in combination with any one or more of the features described herein. Reference to a singular item includes the possibility that there are plural of the same items. More specifically, as used in this specification and the claims associated therewith, the singular forms "a," "an," "said," and "the" include plural referents unless specifically stated otherwise. In other words, the use of articles allows for "at least one" of the present items in the above description and in the claims associated with this disclosure. Furthermore, it should be noted that such claims may be drafted to exclude any optional element. Accordingly, this statement is intended to serve as a predicate for the use of exclusive terminology such as "solely," "only," and the like in connection with the recitation of claim elements, or the use of a "negative" limitation.

[0362] Without using such exclusive terminology, the term "comprising" in the claims associated with this disclosure shall be construed as permitting the inclusion of any additional elements, regardless of whether a given number of elements are recited in such claim, or the addition of features may be considered to change the nature of the elements recited in such claim. Except as specifically defined herein, all technical and scientific terms used herein shall be given the broadest possible commonly understood meaning while maintaining the validity of the claims.

[0363] The scope of the present invention is not limited to the examples provided and / or this specification, but rather is limited only by the scope of the terms of the claims associated with this disclosure.

[0364] Various examples of devices (e.g., optical devices, display devices, illuminators, integrated optical devices, etc.) and systems (e.g., illumination systems) have been provided. Any of these devices and / or systems may be included within a head-mounted display system to couple light (e.g., using one or more internal coupling optical elements) into a waveguide and / or eyepiece to form an image. In addition, the devices and / or systems may be relatively small (e.g., less than 1 cm) such that one or more of the devices and / or systems may be included within a head-mounted display system. For example, the devices and / or systems may be small relative to the eyepiece (e.g., less than one-third the length and / or width of the eyepiece).

[0365] In the foregoing specification, the invention has been described with reference to specific embodiments thereof. It will, however, be apparent that various modifications and changes can be made therein without departing from the broader spirit and scope of the invention. The specification and drawings are, therefore, to be regarded in an illustrative rather than a restrictive sense.

[0366] Indeed, it should be understood that the systems and methods of the present disclosure each have several innovative aspects, no single one of which is solely responsible for or required for the desirable attributes disclosed herein. The various features and processes described above may be used independently of one another or may be combined in various ways. All possible combinations and subcombinations are intended to fall within the scope of the present disclosure.

[0367] Certain features described herein in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may also be implemented in multiple embodiments separately or in any suitable subcombination. Furthermore, while features may be described above as acting in a combination and may even be initially exemplified as such, one or more features from the exemplified combination may, in some cases, be deleted from the combination, and the exemplified combination may be directed to a subcombination or variation of the subcombination. No single feature or group of features is required or essential for every embodiment.

[0368] It should be understood that conditional language used herein, such as, among other things, "can," "could," "might," "may," "eg," and the like, is generally intended to convey that certain embodiments include certain features, elements, and / or steps, while other embodiments do not, unless specifically stated otherwise or understood otherwise within the context as used. Thus, such conditional language is generally not intended to imply that features, elements, and / or steps are in any way required for one or more embodiments, or that one or more embodiments necessarily include logic for determining whether those features, elements, and / or steps are included or performed in any particular embodiment, with or without authorial input or prompting. The terms "comprising," "including," "having," and the like, are synonymous and used inclusively in a non-limiting manner and do not exclude additional elements, features, acts, operations, etc. Also, the term "or," when used, for example, to connect a list of elements, is used in its inclusive sense (and not its exclusive sense), so as to mean one, some, or all of the elements in the list. Additionally, the articles "a," "an," and "the," as used in this application and the appended claims, shall be interpreted to mean "one or more" or "at least one," unless otherwise specified. Similarly, while operations may be depicted in the figures in a particular order, it should be recognized that such operations need not be performed in the particular order shown, or in sequential order, or that all illustrated operations need not be performed, to achieve desirable results. Furthermore, the figures may diagrammatically depict one or more exemplary processes in the form of a flowchart. However, other operations not depicted may also be incorporated within the diagrammatically illustrated exemplary methods and processes.For example, one or more additional operations may be performed before, after, simultaneously with, or between any of the illustrated operations. Additionally, operations may be rearranged or reordered in other embodiments. In some situations, multitasking and parallel processing may be advantageous. Furthermore, the separation of various system components in the embodiments described above should not be understood as requiring such separation in all embodiments, and it should be understood that the described program components and systems may generally be integrated together in a single software product or packaged in multiple software products. Additionally, other embodiments are within the scope of the following examples. In some cases, the actions recited in the examples may be performed in a different order and still achieve desirable results.

[0369] Thus, the present disclosure is not intended to be limited to the implementations shown herein but is to be accorded the widest scope consistent with the present disclosure, the principles and novel features disclosed herein.

Claims

1. A head-mounted display device, The head mounted display device comprises: an eyepiece comprising at least one waveguide comprising a material having a refractive index greater than 1.79, the waveguide having a first major surface, a second major surface opposite the first major surface, and a plurality of edges between the first major surface and the second major surface; a plurality of diffractive features formed on at least one of the first major surface or the second major surface; A head-mounted display device comprising:

2. A head-mounted display device as described in claim 1, wherein the plurality of diffractive features are formed on at least one of the first major surface or the second major surface by etching at least one of the first major surface or the second major surface.

3. A head-mounted display device as described in claim 1, wherein the waveguide comprises a material having a refractive index greater than 2.

2.

4. A head-mounted display device as described in claim 1, wherein the waveguide includes lithium niobate.

5. A head-mounted display device as described in claim 1, wherein the waveguide comprises silicon carbide.

6. A head-mounted display device as described in claim 1, wherein at least some of the plurality of diffractive features are configured to internally couple incident image light such that the internally coupled image light propagates through the waveguide by multiple total internal reflections at the first and second major surfaces.

7. A head-mounted display device as described in claim 1, further comprising a variable focus lens between the waveguide and a viewer, the variable focus lens configured to vary the focal plane of image light propagating through the waveguide by multiple total internal reflections at the first and second major surfaces that are externally coupled from the waveguide toward the viewer.

8. A head-mounted display device as described in claim 7, wherein the variable focus lens comprises a negative lens.

9. A head-mounted display device as described in claim 7, wherein the variable focus lens comprises a liquid-filled lens.

10. A head-mounted display device as described in claim 7, wherein the variable focus lens includes a liquid crystal.

11. A head-mounted display device as described in claim 7, wherein the variable focus lens comprises a geometric phase lens.

12. A head-mounted display device as described in claim 1, further comprising a negative lens between the waveguide and a viewer, the negative lens being such that the negative lens receives light propagating through the waveguide by multiple total internal reflections at the first and second major surfaces that are externally coupled from the waveguide toward the viewer.

13. A head-mounted display device as described in claim 12, wherein the negative lens comprises a static lens.

14. A head-mounted display device as described in claim 12, wherein the waveguide and the negative lens are contained within a stacked waveguide assembly.

15. A head-mounted display device as described in claim 12, further comprising an additional waveguide paired with an additional negative lens.

16. A head-mounted display device as described in claim 12, further comprising a positive lens positioned between the waveguide and the real world.

17. A head-mounted display device as described in claim 1, further comprising a polarizer stacked with the waveguide.

18. A head-mounted display device as described in claim 1, wherein at least some of the plurality of diffractive features are configured to outcouple image light propagating through the waveguide toward a viewer by multiple total internal reflections at the first and second major surfaces.

19. A head-mounted display device as described in claim 1, further comprising an imaging system configured to provide image light.

20. A head-mounted display device as described in claim 19, wherein the imaging system is outside the field of view of a viewer viewing the waveguide.

21. The imaging system, A lighting system; a modulation element configured to receive unmodulated light from the illumination system; a projection optics system configured to transmit image light output by the modulation element; 20. The head mounted display device of claim 19, comprising:

22. A head-mounted display device as described in claim 21, wherein the modulation element is reflective.

23. A head-mounted display device as described in claim 22, wherein unmodulated image light from the illumination system is transmitted through the projection optical system toward a reflective modulation element, reflected from the modulation element, and transmitted back into the waveguide through the projection optical system.

24. The lighting system, a light source configured to generate a visible light output; a light pipe configured to receive the visible light output from the light source; Light redirecting elements and Equipped with the light pipe is configured to transmit the visible light output from the light source towards the light redirecting element by multiple total internal reflections; 22. The head mounted display device of claim 21, wherein the light redirecting element is configured to redirect light propagating within the light pipe towards the modulation element.

25. A head-mounted display device as described in claim 24, wherein the light source comprises a plurality of light-emitting elements configured to emit light in a plurality of colors.

26. A head-mounted display device as described in claim 25, wherein the plurality of light-emitting elements comprise light-emitting diodes or lasers.

27. ​​A head-mounted display device as described in claim 25, further comprising an optical element configured to combine light emitted by the plurality of light-emitting elements.

28. A head-mounted display device as described in claim 27, wherein the optical element is a dichroic beam combiner.

29. A head-mounted display device as described in claim 24, wherein the light redirecting element is configured to redirect light propagating within the light pipe through the waveguide towards the modulation element.

30. A head-mounted display device as described in claim 24, wherein the waveguide further comprises light adjusting optics configured to adjust the distribution of the light redirected by the light redirecting element.

Images