Two-active-layer waveguide architecture with two or more split reflective and transmissive IC pupils for the visible light spectrum

Abstract

The eyepiece waveguide stack includes a first eyepiece waveguide including a first incoupling diffractive optical element and a first compound pupil dilator, and a second eyepiece waveguide including a second incoupling diffractive optical element and a second compound pupil dilator, the second incoupling diffractive optical element being laterally offset from the first incoupling diffractive optical element.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Patent Application No. 63 / 421,044, filed October 31, 2022, the disclosure of which is incorporated herein by reference in its entirety for all purposes. [Background technology]

[0002]

[0002] Modern computing and display technologies have 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 viewer in such a way that they appear to be 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. Augmented reality, or "AR," scenarios typically involve the presentation of digital or virtual image information as an extension to the visualization of the real world around the viewer.

[0003] Referring to FIG. 1, an augmented reality scene 10 is shown. A user of AR technology views a real-world, park-like setting 120 featuring people, trees, background buildings, and a concrete platform 30. The user also perceives 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. Due to the complexity of the human visual perception system, it is challenging to create AR technology that facilitates the comfortable, natural-feeling, and rich presentation of virtual image elements among other virtual or real-world image elements. Summary of the Invention

[0004]

[0004] Embodiments of the present invention relate to systems having two active layers that utilize varying thicknesses of each active layer in combination with split and in-line pupil architectures. Further, embodiments relate to systems that use diffractive structures with specific pitches between blue and green for blue and green, and pitches between green and red for both green and red, in specific refractive index waveguides.

[0005] According to one embodiment of the present invention, a system is provided that utilizes a two-active-layer waveguide architecture with a split-pupil design in conjunction with a projection system for use in an AR / MR wearable. By using a waveguide with an ICG design that operates in both reflective and transmissive modes, several combinations are possible that utilize a split-pupil design in conjunction with a waveguide for optimized diffraction pitch, different waveguide substrate thicknesses, and thickness variation profiles that fit within a specific eyepiece waveguide stack thickness range, and optimal RGB white output for a specific field of view. Furthermore, in some embodiments, a diffraction grating pitch for incoupling and outcoupling that falls between two of the three colors utilized for virtual image creation, such as red, green, and blue, is implemented, including projection of the visible color spectrum in the waveguide and two active layers.

[0006]

[0006] In some eyepiece waveguide designs suitable for augmented reality (AR) applications, individual active layers of specific colors are used in a split-pupil configuration to achieve a high performance eyepiece and achieve a large field of view (FoV). The embodiments described herein utilize two active layers, providing a stack that is less complex, lighter, thinner, and features such as lower backside rainbow and backside reflection, while maintaining sufficient optical performance such as efficiency and color uniformity, thereby providing a thinner wearable. [Brief explanation of the drawings]

[0007] [Figure 1] 1 illustrates a user's view of an augmented reality (AR) device. [Figure 2]1 illustrates a conventional display system for simulating a three-dimensional image for a user. [Figure 3A] The relationship between the radius of curvature and the radius of the focal point is shown. [Figure 3B] The relationship between the radius of curvature and the radius of the focal point is shown. [Figure 3C] The relationship between the radius of curvature and the radius of the focal point is shown. [Figure 4A] Figure 1 shows the representation of accommodative vergence movements in the human visual system. [Figure 4B] 1 shows examples of different accommodation and convergence states of a pair of eyes of a user. [Figure 4C] 1 illustrates an example of a top-view representation of a user viewing content through a display system. [Figure 4D] 10 illustrates another example of a top-view representation of a user viewing content through a display system. [Figure 5] 1 illustrates aspects of a technique for simulating three-dimensional images by correcting for wavefront divergence. [Figure 6] 1 illustrates an example of a waveguide stack for outputting image information to a user. [Figure 7] 1 shows an example of an output beam output by a waveguide. [Figure 8] 1 illustrates an example of a stacked waveguide assembly in which each depth plane contains an image formed using multiple different component colors. [Figure 9A] 1 shows a cross-sectional side view of an example set of stacked waveguides, each containing an incoupling optical element. [Figure 9B] 9B shows a perspective view of an example of one or more stacked waveguides of FIG. 9A. [Figure 9C] 9C shows a top plan view of one example of the stacked waveguide(s) of FIGS. 9A and 9B. FIG. [Figure 9D] 1 illustrates an example of a wearable display system. [Figure 10] FIG. 1 is a side view of a projector assembly including a polarizing beam splitter with a light source injecting light onto one side of the beam splitter and projection optics receiving light from the other side of the beam splitter. [Figure 11A] 1 is a side view of an augmented reality display system including a light source, a spatial light modulator, optical elements for illuminating the spatial light modulator and projecting an image of the spatial light modulator (SLM), and a waveguide for outputting image information to a user. The system includes in-coupling optical elements for coupling light from the optical elements into the waveguide, and out-coupling optical elements for coupling light from the waveguide to the eye. [Figure 11B] 11B is a top view of the augmented reality display system shown in FIG. 11A showing a waveguide with incoupling and outcoupling optics and a light source disposed thereon. The top view also shows an orthogonal pupil dilator. [Figure 11C] FIG. 11B is a side view of the augmented reality display system of FIG. 11A with a shared polarizer / analyzer and polarization-based spatial light modulator (e.g., liquid crystal on silicon SLM). [Figure 11D] 1 illustrates an example of a waveguide with a combined OPE / EPE, according to one embodiment of the present invention. [Figure 12A] FIG. 1 is a side view of an augmented reality display system including a multicolor light source (e.g., a time-multiplexed RGB LED or laser diode), a spatial light modulator, optical elements for illuminating the spatial light modulator and projecting the image of the spatial light modulator into the eye, a stack of waveguides, and different waveguides including incoupling and outcoupling optical elements with different color selectivity. [Figure 12B] 12B is a side view of the augmented reality display system of FIG. 12A further including a MEMS (micro-electromechanical) based SLM such as an array of movable mirrors (e.g., digital light processing (DLP™) technology) and a light dump. [Figure 12C] 12C is a top view of a portion of the augmented reality display system of FIG. 12B, schematically illustrating one of the incoupling optics and the lateral arrangement of the light dump and light source. [Figure 13A]FIG. 1 is a perspective view of an augmented reality display system including a stack of waveguides, the incoupling optical elements of which are laterally displaced relative to one another. One or more light sources, also laterally displaced relative to one another, are positioned to direct light to the respective incoupling optical elements by passing the light through the optical elements, reflecting the light off a spatial light modulator, and passing the reflected light back through the optical elements. [Figure 13B] FIG. 13B is a side view of the example shown in FIG. 13A showing laterally displaced incoupling optics and light source, and optical elements and spatial light modulator. [Figure 13C] FIG. 13C is a top view of the augmented reality display system shown in FIGS. 13A and 13B, showing one or more laterally displaced incoupling optical elements and one or more associated laterally displaced light sources. [Figure 14A] FIG. 1 is a side view of an augmented reality display system including a waveguide stack, different waveguides including different incoupling optical elements laterally displaced from each other (in this example, the lateral displacement occurs in the z-direction). [Figure 14B] FIG. 14B is a top view of the display system shown in FIG. 14A showing laterally displaced incoupling optics and light sources. [Figure 14C] 14C is an orthogonal side view of the display system shown in FIGS. 14A and 14B. FIG. [Figure 15] 14A-14C are top views of an augmented reality display system including a set of stacked waveguides, different waveguides including different incoupling optics, where the light sources and incoupling optics are arranged in an alternative configuration to that shown in FIGS. [Figure 16A] FIG. 1 is a side view of an augmented reality display system including a group of laterally displaced incoupling optical elements relative to one another, each of the groups including one or more color-selective incoupling optical elements. [Figure 16B] FIG. 16B is a top view of the display system of FIG. 16A. [Figure 17]1 is a side view of an augmented reality display system including a waveguide split by a reflective surface that can couple light guided from a portion of the waveguide to an optical element toward a portion of the waveguide near the light source and a spatial light modulator, in this example the optical element and the light source are shown located on the same side of the waveguide. [Figure 18] 1 is a side view of an augmented reality display system including a waveguide for receiving light from a light source and directing the light guided in the waveguide into an optical element and toward a spatial light modulator. The display system further includes a waveguide for receiving light from the spatial light modulator where it passes back through the optical element. The waveguide includes a reflective surface for outcoupling light. The waveguide also includes a reflective surface for incoupling light. In this example, the optical element and the light source are shown disposed on the same side of the waveguide. [Figure 19]

[0013] Figure 1 illustrates a side view of an augmented reality display system including adaptive or variable-focus optical elements. A first variable optical element between the stack of waveguides and the eye can vary the divergence and collimation of the combined light exiting the waveguides and directed toward the eye to change the depth at which an object appears to be located. A second variable optical element on the other side of the stack of waveguides can compensate for the effect of the first optical element on light received from the augmented reality display system and the environment in front of the user. The augmented reality display system further includes prescription lenses to provide ophthalmic correction, such as refractive correction, for users with myopia, hyperopia, astigmatism, etc. [Figure 20A] 1 is a side view of an augmented reality display system including a color filter array, where one or more laterally displaced incoupling optical elements are disposed on different waveguides, and laterally displaced color filters are aligned with each incoupling optical element. [Figure 20B] 20B shows the augmented reality display system of FIG. 20A, in which the analyzer is disposed between the optical element and the spatial light modulator. [Figure 20C]20A and 20B show an augmented reality display system similar to that shown in FIGS. 20A and 20B but using a deflection-based spatial light modulator, such as a movable micromirror-based spatial light modulator. [Figure 20D] 20D is a top view of a portion of the augmented reality display system as shown in FIG. 20C, schematically illustrating laterally displaced light sources and corresponding laterally displaced incoupling optics above the color filter array. [Figure 20E] 20D illustrates how a deflection-based spatial light modulator directs light onto a mask surrounding the filters, away from corresponding incoupling optics in a filter array for the augmented reality display system of FIG. 20D. [Figure 20F] FIG. 1 is a side view of an augmented reality display system including a cover glass positioned on the user side of the stack of waveguides and a light source positioned on the front side of the cover glass. [Figure 20G] FIG. 1 is a side view of an augmented reality display system including a cover glass disposed on the front side of a stack of waveguides and a light source disposed on the front side of the cover glass. [Figure 21] FIG. 1 is a side view of an augmented reality display system including a light source equipped with a light recycler configured to recycle light, such as light of one polarization. [Figure 22] 1 is a side view of one or more light sources propagating light through one or more apertures and corresponding collection optics. The light may also propagate through a diffuser positioned proximate the one or more apertures. [Figure 23A] FIG. 1 is a side view of a portion of an augmented reality display system including a light source, an optical element having optical power, and a waveguide for receiving and outputting image information to a user's eye, wherein the system further includes one or more retarders and polarizers configured to reduce reflections from optical surfaces that may be input to the waveguide as ghost images. [Figure 23B] FIG. 23B is a side view of a portion of an augmented reality display system as shown in FIG. 23A with additional retarders and polarizers configured to reduce reflections that can create ghost images. [Figure 23C] FIG. 23C is a side view of an augmented reality display system as shown in FIGS. 23A and 23B with reduced retarders and polarizers configured to reduce reflections that can create ghost images. [Figure 24] FIG. 1 is a side view of an augmented reality display system that utilizes an inclined surface, such as an inclined surface on a cover glass, to direct reflections away from the user's eyes, potentially reducing ghost reflections. [Figure 25] 25 illustrates an embodiment of the system of FIG. 24 in which a beveled surface on the cover glass is configured to direct reflections toward a light dump that absorbs the light. [Figure 26A] FIG. 1 shows a plan view of an eyepiece waveguide using a two active layer architecture according to an embodiment of the present invention. [Figure 26B] 26B shows an exploded view of the eyepiece waveguide shown in FIG. 26A. [Figure 26C] 26B shows a cross-sectional view of the eyepiece waveguide shown in FIG. 26A. [Figure 27A] FIG. 10 shows a plan view of an eyepiece waveguide using a two active layer architecture according to another embodiment of the present invention. [Figure 27B] 27B shows an exploded view of the eyepiece waveguide shown in FIG. 27A. [Figure 27C] 27B shows a cross-sectional view of the eyepiece waveguide shown in FIG. 27A. [Figure 28A] 1A-1C show cross-sectional views of two active layer eyepiece waveguides according to various embodiments of the present invention. [Figure 28B] 1A-1C show cross-sectional views of two active layer eyepiece waveguides according to various embodiments of the present invention. [Figure 28C] 1A-1C show cross-sectional views of two active layer eyepiece waveguides according to various embodiments of the present invention. [Figure 29A] FIG. 10 shows a plan view of an eyepiece waveguide using a two active layer architecture with both split and in-line ICG according to an embodiment of the present invention. [Figure 29B] 29B shows an exploded view of the eyepiece waveguide shown in FIG. 29A. [Figure 29C] 29B shows a cross-sectional view of the eyepiece waveguide shown in FIG. 29A. [Figure 30A] FIG. 1 shows a plan view of an eyepiece waveguide using a two active layer architecture according to an embodiment of the present invention. [Figure 30B] 30B shows an exploded view of the eyepiece waveguide shown in FIG. 30A. [Figure 30C] 30B shows a cross-sectional view of the eyepiece waveguide shown in FIG. 30A. [Figure 31A] FIG. 10 shows a plan view of an eyepiece waveguide using a two active layer architecture according to another embodiment of the present invention. [Figure 31B] 31B shows an exploded view of the eyepiece waveguide shown in FIG. 31A. [Figure 31C] 31B shows a cross-sectional view of the eyepiece waveguide shown in FIG. 31A. [Figure 32A] FIG. 1 shows a cross-sectional view of an eyepiece waveguide according to an embodiment of the present invention. [Figure 32B] 32B shows a plan view of the ICG of the eyepiece waveguide shown in FIG. 32A. [Figure 32C] 32B shows a plan view of an alternative ICG that can be utilized in the eyepiece waveguide shown in FIG. 32A. [Figure 32D] 13 shows a cross-sectional view of an eyepiece waveguide according to an alternative embodiment of the present invention. [Figure 32E] A plan view of the ICG of the eyepiece waveguide shown in Figure 32D is shown. [Figure 32F] 32D shows a plan view of an alternative ICG that can be utilized in the eyepiece waveguide shown in FIG. 32D. [Figure 33A] FIG. 10 shows a plan view of an eyepiece waveguide with a three pupil layout according to an embodiment of the present invention. [Figure 33B] 33B illustrates the incoupling and propagation of light using a cross-sectional view of the eyepiece waveguide shown in FIG. 33A. [Figure 33C] 33B is a field of view image produced by the eyepiece waveguide shown in FIG. 33A. [Figure 33D] 33B is a field of view image produced by the eyepiece waveguide shown in FIG. 33A. [Figure 33E] 33B is a field of view image produced by the eyepiece waveguide shown in FIG. 33A. [Figure 34A]10 is a spectral plot showing the diffractive pitches used in two active layer architectures according to one embodiment of the present invention. [Figure 34B] FIG. 2 is a simplified cross-sectional view of a two active layer architecture according to one embodiment of the present invention. [Figure 34C] FIG. 2 is a simplified cross-sectional view of a two active layer architecture according to one embodiment of the present invention. [Figure 35A] FIG. 1 shows a cross-sectional view of an eyepiece waveguide using a two active layer architecture according to one embodiment of the present invention. [Figure 35B] 35B shows a plan view of the user side eyepiece waveguide layer of the eyepiece waveguide shown in FIG. 35A. [Figure 35C] 35B shows a plan view of the user side eyepiece waveguide layer of the eyepiece waveguide shown in FIG. 35A. [Figure 35D] FIG. 35B shows a plan view of the eyepiece waveguide layer on the front side of the eyepiece waveguide shown in FIG. 35A. [Figure 35E] FIG. 35B shows a plan view of the eyepiece waveguide layer on the front side of the eyepiece waveguide shown in FIG. 35A. [Figure 36A] 10A-10C illustrate various grating structures that can be utilized in an incoupling grating, an orthogonal pupil dilator grating, an exit pupil dilator grating, or a compound pupil dilator grating according to an embodiment of the present invention. [Figure 36B] 10A-10C illustrate various grating structures that can be utilized in an incoupling grating, an orthogonal pupil dilator grating, an exit pupil dilator grating, or a compound pupil dilator grating according to an embodiment of the present invention. [Figure 36C] 10A-10C illustrate various grating structures that can be utilized in an incoupling grating, an orthogonal pupil dilator grating, an exit pupil dilator grating, or a compound pupil dilator grating according to an embodiment of the present invention. [Figure 36D] 10A-10C illustrate various grating structures that can be utilized in an incoupling grating, an orthogonal pupil dilator grating, an exit pupil dilator grating, or a compound pupil dilator grating according to an embodiment of the present invention. [Figure 36E] 10A-10C illustrate various grating structures that can be utilized in an incoupling grating, an orthogonal pupil dilator grating, an exit pupil dilator grating, or a compound pupil dilator grating according to an embodiment of the present invention. [Figure 36F] 10A-10C illustrate various grating structures that can be utilized in an incoupling grating, an orthogonal pupil dilator grating, an exit pupil dilator grating, or a compound pupil dilator grating according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0008]

[0087] Reference will now be made to the drawings, in which like reference numerals refer to like parts throughout. Unless otherwise indicated, the drawings are schematic representations and are not necessarily drawn to scale.

[0009]

[0088] FIG. 2 illustrates a conventional display system for simulating a three-dimensional image for a user. It will be appreciated that a user's eyes are spaced apart, and when viewing real objects in space, each eye may see the object slightly differently, forming an image of the object at a different location on each eye's retina. This is sometimes referred to as binocular disparity and can be exploited by the human visual system to provide the perception of depth. Conventional display systems simulate binocular disparity by presenting two separate images 190, 200 in which the same virtual object appears slightly different, with one for each eye 210a, 210b corresponding to the view of the virtual object seen by each eye being a virtual object of the real object at a desired depth. These images provide binocular cues that the user's visual system can interpret to derive the perception of depth.

[0010]

[0089] Continuing with reference to FIG. 2 , the images 190 and 200 are spaced a distance 230 along the z-axis from the eyes 210a and 210b. The z-axis is parallel to the observer's optical axis, and the observer's eyes are fixed on an object at optical infinity directly in front of the observer. The images 190 and 200 are flat and at a fixed distance from the eyes 210a and 210b. Based on the slightly different views of the virtual object in the images presented to the eyes 210a and 210b, the eyes can naturally rotate to maintain single binocular vision, such that the image of the object is directed toward a corresponding point on each eye's retina. This rotation can converge the gaze of each eye 210a and 210b to a point in space where the virtual object is perceived to reside. As a result, providing three-dimensional images traditionally involves manipulating the convergence of the eyes 210a and 210b and providing binocular cues that the human visual system interprets to provide the perception of depth.

[0011]

[0090] However, creating a realistic and comfortable depth perception is difficult. It is understood that light from objects at different distances from the eye has wavefronts with different amounts of divergence. Figures 3A-3C illustrate the relationship between distance and divergence of light rays. The distances between the object and the eye 210 are represented by R1, R2, and R3, in order of decreasing distance. As shown in Figures 3A-3C, light rays become more divergent as the distance to the object decreases. Conversely, as the distance increases, the light rays become more parallel. In other words, the light field generated by a point (an object or portion of an object) has a spherical wavefront curvature, which is a function of how far the point is from the user's eye. The curvature increases as the distance between the object and the eye 210 decreases. While Figures 3A-3C and other figures herein show a single eye 210 for clarity, any discussion of eye 210 may apply to both eyes 210a and 210b.

[0012]

[0091] Continuing with reference to FIGS. 3A-3C , light from an object on which an observer's eye is fixated may have different degrees of wavefront divergence. Due to the different amounts of wavefront divergence, the light may be focused differently by the eye's lens, which may require the lens to assume different shapes to form a focused image on the eye's retina. If a focused image is not formed on the retina, the resulting retinal blur acts as an accommodative cue, causing the eye's lens to change shape until a focused image is formed on the retina. For example, the accommodative cue triggers the ciliary muscles surrounding the eye's lens to relax or contract, thereby adjusting the force applied to the suspensory ligaments that hold the lens, thereby changing the shape of the eye's lens until retinal blur of the fixation target is eliminated or minimized, thereby forming a focused image of the fixation target on the eye's retina (e.g., the fovea). The process by which the eye's lens changes shape may be referred to as accommodation, and the shape of the eye's lens required to form a focused image of the fixation target on the eye's retina (e.g., the fovea) may be referred to as the accommodative state.

[0013]

[0092] Referring now to FIG. 4A, a representation of accommodative vergence movements in the human visual system is shown. Eye movement to fixate on an object causes the eyes to receive light from the object, which forms an image on each retina of the eye. The presence of retinal blur in the image formed on the retina can provide a cue to accommodation, and the relative position of the image on the retina can provide a cue to convergence. The accommodation cue causes accommodation, resulting in each of the eye's lenses adopting a specific accommodation state to form a focused image of the object on the eye's retina (e.g., the fovea). Convergence cue, on the other hand, causes vergence movements (eye rotation) to occur so that the images formed on each retina of each eye are at corresponding retinal points that maintain single binocular vision. At these positions, the eyes can be said to have adopted a specific convergence state. Continuing to refer to FIG. 4A, accommodation can be understood as the process by which the eyes achieve a specific accommodation state, and convergence can be understood as the process by which the eyes achieve a specific convergence state. As shown in FIG. 4A, the accommodation state and convergence state of the eyes can change when a user fixates on a different object. For example, the accommodation state may change if the user fixates a new object at a different depth on the z-axis.

[0014]

[0093] Without being limited by theory, it is believed that a viewer of an object may perceive the object as "three-dimensional" through a combination of convergence and accommodation. As described above, the convergence movement of the two eyes relative to one another (e.g., rotating the eyes so that the pupils move toward or away from one another to converge the lines of sight and fixate on an object) is closely linked to accommodation of the eye's lenses. Under normal conditions, changing the shape of the eye's lenses to change focus from one object to another at different distances automatically results in a corresponding change in convergence at the same distance, under a relationship known as the "accommodation-vergence reflex." Similarly, a change in convergence causes a corresponding change in lens shape under normal conditions.

[0015]

[0094] 4B, examples of different states of accommodation and convergence of the eyes are shown. The pair of eyes 222a is fixed on an object at optical infinity, and the pair of eyes 222b is fixed on an object 221 at less than optical infinity. In particular, the convergence states of the pair of eyes are different when the pair of eyes 222a is looking straight ahead and when the pair of eyes 222 are converging on the object 221. Furthermore, as represented by the different shapes of the lenses 220a and 220b, the states of accommodation of the eyes forming the pair of eyes 222a and 222b are also different.

[0016]

[0095] Unfortunately, many users of conventional "3D" display systems may find such systems uncomfortable or may not perceive depth at all due to the mismatch between accommodation and vergence in these displays. As discussed above, many stereoscopic or "3D" display systems display a scene by providing slightly different images to each eye. Such systems are uncomfortable for many observers because, among other things, they simply provide different presentations of the scene, causing changes in the eyes' vergence state without a corresponding change in the eyes' accommodation state. Rather, images are presented by displays at a fixed distance from the eyes, causing the eyes to view all image information in a single state of accommodation. This arrangement acts against the "accommodation-vergence reflex" by causing changes in vergence state without a corresponding change in accommodation state. This mismatch is thought to cause discomfort to observers. Display systems that provide a better match between accommodation and vergence can create more realistic and comfortable simulations of three-dimensional images.

[0017]

[0096] 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 eyes with different presentations of images corresponding to each of these limited number of depth planes. In some embodiments, the different presentations can provide both vergence cues and matching accommodation cues, thereby providing physiologically correct accommodation-vergence matching.

[0018]

[0097] 4B, two depth planes 240 are shown corresponding to different distances in space from the eyes 210a, 210b. For a given depth plane 240, convergence cues can be provided by displaying images of different perspectives to each eye 210a, 210b as appropriate. Furthermore, for a given depth plane 240, the light forming the image provided to each eye 210a, 210b can have a wavefront divergence corresponding to the light field generated by points at that depth plane 240.

[0019]

[0098] In the illustrated embodiment, the distance along the z-axis of the depth plane 240 containing the object 221 is 1 m. As used herein, distance or depth along the z-axis can be measured at a zero point located at the exit pupil of the user's eye. Thus, a depth plane 240 located at a depth of 1 m corresponds to a distance of 1 m away from the exit pupil of the user's eye on the eye's optical axis when the eye is directed toward optical infinity. As an approximation, the depth or distance along the z-axis can be measured from the display in front of the user's eye (e.g., from the surface of the waveguide) plus the value of the distance between the device and the exit pupil of the user's eye. That value is sometimes referred to as the eye relief and corresponds to the distance between the exit pupil of the user's eye and the display held by the user in front of the display. In practice, the eye relief value may be a normalized value commonly used for all observers. For example, the eye relief can be assumed to be 20 mm, and a depth plane located at a depth of 1 m may be at a distance of 980 mm in front of the display.

[0020]

[0099] 4C and 4D, examples of matched and mismatched accommodation-vergence distances are shown, respectively. As shown in FIG. 4C, the display system can provide an image of a virtual object to each eye 210a, 210b. The image can cause the eyes 210a, 210b to assume a convergence state in which the eyes converge to point 15 on the depth plane 240. In addition, the image can be formed by light having a wavefront curvature corresponding to the real object on the depth plane 240. This causes both eyes 210a, 210b to assume an accommodation state in which the image is focused on the retinas of both eyes. Therefore, the user can perceive the virtual object as being at point 15 on the depth plane 240.

[0021]

[0100] It will be understood that each of the accommodation and convergence states of the eyes 210a, 210b is associated with a specific distance on the z-axis. For example, an object at a specific distance from the eyes 210a, 210b will cause the eyes to assume a specific accommodation state based on the object's distance. The distance associated with a specific accommodation state can be referred to as the accommodation distance Ad. Similarly, there is a specific convergence distance Vd, or position relative to one another, associated with the eyes in a specific convergence state. When the accommodation distance and the convergence distance match, the relationship between accommodation and convergence is said to be physiologically correct. This is considered to be the most comfortable scenario for the observer.

[0022]

[0101] However, in a stereoscopic display, the accommodation distance and the convergence distance may not necessarily coincide. For example, as shown in FIG. 4D , images displayed to the eyes 210a, 210b may be displayed with a wavefront divergence corresponding to the depth plane 240, allowing the eyes 210a, 210b to assume a particular accommodation state focused on points 15a, 15b on the depth plane. However, the images displayed to the eyes 210a, 210b may provide convergence cues that cause the eyes 210a, 210b to converge to points 15a, 15b that are not located on the depth plane 240. As a result, in some embodiments, the accommodation distance corresponds to the distance from the exit pupils of the eyes 210a, 210b to the depth plane 240, while the convergence distance corresponds to the longer distance from the exit pupils of the eyes 210a, 210b to point 15. The accommodation distance is different from the convergence distance. As a result, an accommodation-vergence mismatch exists. Such a mismatch may be considered undesirable and may cause discomfort to the user. It will be appreciated that the discrepancy corresponds to a distance (eg, VaAd) and can be characterized using diopters.

[0023]

[0102] It will be appreciated that in some embodiments, a reference point other than the exit pupil of the eyes 210 a, 210 b may be used to determine the distance for determining accommodation-vergence discrepancy, so long as the same reference point is used for accommodation distance and convergence distance. For example, the distance can be measured from the cornea to the depth plane, from the retina to the depth plane, from the eyepiece (e.g., a waveguide in a display device) to the depth plane, etc.

[0024]

[0103] Without being limited by theory, it is believed that a user may perceive an accommodation-vergence mismatch of up to about 0.25 diopters, up to about 0.33 diopters, and up to about 0.5 diopters as physiologically correct without the mismatch itself causing significant discomfort. In some embodiments, a display system disclosed herein (e.g., display system 250 of FIG. 6 ) presents images to a viewer with an accommodation-vergence mismatch of about 0.5 diopters or less. In some other embodiments, the accommodation-vergence mismatch of images provided by the display system is about 0.33 diopters or less. In still other embodiments, the accommodation-vergence mismatch of images provided by the display system is about 0.25 diopters or less, including about 0.1 diopters or less.

[0025]

[0104] FIG. 5 illustrates aspects of an approach for simulating a three-dimensional image by modifying wavefront divergence. The display system includes a waveguide 270 configured to receive light 770 encoded with image information and output the light to a user's eye 210. The waveguide 270 can output light 650 with a prescribed amount of wavefront divergence corresponding to the wavefront divergence of a light field generated by a point on a desired depth plane 240. In some embodiments, the same amount of wavefront divergence is provided for all objects presented on that depth plane. It is further shown that the user's other eye can be provided with image information from a similar waveguide.

[0026]

[0105] In some embodiments, a single waveguide may be configured to output light having a set amount of wavefront divergence corresponding to a single or limited number of depth planes, and / or the waveguide may be configured to output light in a limited wavelength range. As a result, in some embodiments, a stack of waveguides may be utilized to provide different amounts of wavefront divergence for different depth planes and / or output light in different wavelength ranges. As used herein, it will be understood that a depth plane may follow the contour of a planar or curved surface. In some embodiments, for simplicity, the depth plane may advantageously follow the contour of a planar surface.

[0027]

[0106] 6 shows 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 three-dimensional perception to the eye / brain using waveguides 270, 280, 290, 300, 310. It will be appreciated that in some embodiments, display system 250 can be considered a light field display. Waveguide assembly 260 can also be referred to as an eyepiece.

[0028]

[0107] In some embodiments, display system 250 may be configured to provide substantially continuous vergence cues and multiple discrete accommodation cues. Vergence cues may be provided by displaying different images to each eye of the user, and accommodation cues may be provided by outputting light forming images with selectable discrete amounts of wavefront divergence. Stated another way, display system 250 may be configured to output light having variable levels of wavefront divergence. In some embodiments, each discrete level of wavefront divergence corresponds to a particular depth plane and may be provided by a particular one of waveguides 270, 280, 290, 300, and 310.

[0029]

[0108] 6 , the waveguide assembly 260 may also include 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 features (e.g., lenses) 320, 330, 340, 350 may be configured to transmit image information to the eye at 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. Image injection devices 360, 370, 380, 390, 400 may function as light sources for the waveguides and may be utilized to inject image information into waveguides 270, 280, 290, 300, 310, each of which may be configured to distribute incident light across a respective waveguide for output toward eye 210, as described herein. Light exits output faces 410, 420, 430, 440, 450 of image injection devices 360, 370, 380, 390, 400 and is injected into corresponding input faces 460, 470, 480, 490, 500 of waveguides 270, 280, 290, 300, 310. In some embodiments, each of the input faces 460, 470, 480, 490, 500 may be an edge of the corresponding waveguide or may be a portion of a major surface of the corresponding waveguide (i.e., the table 510 or one of the waveguide surfaces directly facing the observer's eye 210). In some embodiments, a single light beam (e.g., a collimated beam) may be injected into each waveguide to output a full field of cloned collimated beams directed toward the eye 210 at a particular angle (and amount of divergence) corresponding to the depth plane associated with the particular waveguide. In some embodiments, a single one of the image injectors 360, 370, 380, 390, 400 may be associated with and inject light into one or more (e.g., three) of the waveguides 270, 280, 290, 300, 310.

[0030]

[0109] In some embodiments, the image injection devices 360, 370, 380, 390, 400 are individual displays that each generate image information for injection into a respective waveguide 270, 280, 290, 300, 310. In some other embodiments, the image injection devices 360, 370, 380, 390, 400 are the output of a single multiplexed display that can, for example, send image information via one or more optical conduits (such as fiber optic cables) to each of the image injection devices 360, 370, 380, 390, 400. It is understood that the image information provided by the image injection devices 360, 370, 380, 390, 400 may include light of different wavelengths or colors (e.g., different component colors as described herein).

[0031]

[0110] In some embodiments, light injected into the waveguides 270, 280, 290, 300, 310 is provided by a light projector system 520 that includes a light module 530, which may include light emitters such as light emitting diodes (LEDs). Light from the light module 530 may be directed through a beam splitter 550 to and modified by a light modulator 540, such as a spatial light modulator. The light modulator 540 may be configured to change the perceived intensity of the light injected into the waveguides 270, 280, 290, 300, 310 to encode the light with image information. Examples of spatial light modulators include liquid crystal displays (LCDs), including liquid crystal on silicon (LCoS) displays. It will be understood that image injection devices 360, 370, 380, 390, 400 are shown schematically, and in some embodiments, these image injection devices can represent different light paths and positions within a common projection system configured to output light to associated ones of waveguides 270, 280, 290, 300, 310. In some embodiments, the waveguides of waveguide assembly 260 can function as ideal lenses while relaying light injected into the waveguides to the user's eye. In this concept, the object can be a spatial light modulator 540, and the image can be an image on a depth plane.

[0032]

[0111] In some embodiments, display system 250 may be a scanning fiber display including 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 into the observer's eye 210. In some embodiments, the illustrated image injection devices 360, 370, 380, 390, 400 may generally represent a single scanning fiber or a bundle of scanning fibers configured to inject light into one or more of waveguides 270, 280, 290, 300, 310. In some embodiments, the illustrated image injection devices 360, 370, 380, 390, 400 may generally represent one or more scanning fibers or a bundle of one or more scanning fibers, each configured to inject light into an associated one of waveguides 270, 280, 290, 300, 310. It will be appreciated that the one or more optical fibers may be configured to transmit light from the optical module 530 to one or more of the waveguides 270, 280, 290, 300, 310. It will be appreciated that one or more intervening optical structures may be provided between the scanning fiber or fibers and the one or more waveguides 270, 280, 290, 300, 310, for example, to redirect light exiting the scanning fiber to the one or more waveguides 270, 280, 290, 300, 310.

[0033]

[0112] Controller 560 controls the operation of one or more of stacked waveguide assembly 260, including the operation of image injection devices 360, 370, 380, 390, 400, light source 530, and light modulator 540. In some embodiments, controller 560 is part of local data processing module 140. Controller 560 includes 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 wired or wireless communication channels. In some embodiments, controller 560 may be part of processing module 140 or 150 (FIG. 9D).

[0034]

[0113] Continuing with reference to FIG. 6 , the waveguides 270, 280, 290, 300, and 310 can be configured to propagate light within their respective waveguides by total internal reflection (TIR). The waveguides 270, 280, 290, 300, and 310 can each be planar or have another shape (e.g., curved) and have top and bottom major surfaces and edges extending between their top and bottom major surfaces. In the illustrated configuration, the waveguides 270, 280, 290, 300, and 310 can each include outcoupling optics 570, 580, 590, 600, and 610 configured to extract light from the waveguide by redirecting light propagating within the respective waveguide from the waveguide to output image information to the eye 210. While referred to throughout this specification as “outcoupling optics,” the outcoupling optics need not be optical elements and can be non-optical elements. The extracted light may also be referred to as outcoupled light, and the outcoupling optic may also be referred to as a light extraction optic. The extracted light beam may be output by the waveguide where light propagating within the waveguide strikes the light extraction optic. The outcoupling optic 570, 580, 590, 600, 610 may be, for example, a grating including diffractive optical features, as described further herein. While shown disposed on the bottom major surface of the waveguide 270, 280, 290, 300, 310 in some embodiments for ease of explanation and clarity of drawings, the outcoupling optic 570, 580, 590, 600, 610 may also be disposed on the top and / or bottom major surfaces and / or directly within the volume of the waveguide 270, 280, 290, 300, 310, as described further herein. In some embodiments, the outcoupling optical elements 570, 580, 590, 600, 610 may be formed in a layer of material attached to a transparent substrate to form 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.

[0035]

[0114] Continuing with reference to FIG. 6 , as described herein, each waveguide 270, 280, 290, 300, 310 is configured to output light to 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 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 a first lens 350 may be configured to create a slightly convex wavefront curvature so that the eye / brain interprets light coming from the next waveguide 280 as coming from a first focal plane closer inward from optical infinity toward the eye 210. Similarly, the third upper waveguide 290 passes its output light through both the first lens 350 and the second lens 340 before reaching the eye 210. The combined optical power of the first lens 350 and the second lens 340 may be configured to create another incremental amount of wavefront curvature such that the eye / brain interprets the light coming from the third waveguide 290 as coming from a second focal plane that is further inward from optical infinity towards the person than the light from the next upper waveguide 280.

[0036]

[0115] The other waveguide layers 300, 310 and lenses 330, 320 are similarly configured, with the highest waveguide 310 in the stack transmitting its output through all lenses between the eyes for a total focal power representing the focal plane closest to the person. To compensate the stack of lenses 320, 330, 340, 350 when viewing / interpreting light coming from the opposite surface 510 of the stacked waveguide assembly 260, a compensating lens layer 620 can be placed on top of the stack to compensate for the total power of the lens stacks 320, 330, 340, 350 below. Such a configuration provides as many perceived focal planes as there are available waveguide / lens combinations. Both the outcoupling optics of the waveguides and the focusing aspects of the lenses may be static (i.e., not dynamic or electrically active). In some alternative embodiments, either or both may be dynamic using an electrically active feature.

[0037]

[0116] In some embodiments, two or more of the waveguides 270, 280, 290, 300, 310 can have the same associated depth plane. For example, multiple waveguides 270, 280, 290, 300, 310 may be configured to output images set in the same depth plane, or multiple subsets of waveguides 270, 280, 290, 300, 310, one set for each depth plane, may be configured to output images set in the same one or more depth planes. This can provide advantages for forming tiled images to provide an extended field of view in those depth planes.

[0038]

[0117] Continuing with reference to FIG. 6 , the outcoupling optics 570, 580, 590, 600, 610 can be configured to redirect light from 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 can have different configurations of outcoupling optics 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 optics 570, 580, 590, 600, 610 can be volume or surface features that can be configured to output light at a particular angle. For example, the light extraction optics 570, 580, 590, 600, 610 can be volume holograms, surface holograms, and / or diffraction gratings. In some embodiments, features 320, 330, 340, 350 may not be lenses, but rather may simply be spacers (eg, cladding layers and / or structures that form air gaps).

[0039]

[0118] In some embodiments, the outcoupling optical elements 570, 580, 590, 600, 610 are diffractive features that form a diffraction pattern or "diffractive optical element" (also referred to herein as a "DOE"). Preferably, the DOE has 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, with the remainder continuing to travel through the waveguide via TIR. Thus, the light carrying the image information is split into several related output beams that exit the waveguide at multiple locations, resulting in a fairly uniform pattern of exit radiation toward the eye 210 for that particular collimated beam bouncing within the waveguide.

[0040]

[0119] 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 include a layer of polymer-dispersed liquid crystal, in which case the 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 appreciably diffract incident light), or the microdroplets may be switched to a refractive index that does not match the refractive index of the host medium (in which case the pattern actively diffracts incident light).

[0041]

[0120] In some embodiments, a camera assembly 630 (e.g., a digital camera including a visible light and infrared light camera) can be provided to capture images of the eye 210 and / or tissue surrounding the eye 210, for example, to detect user input and / or to monitor the user's physiological condition. As used herein, a camera may be any image capture device. In some embodiments, the camera assembly 630 can include an image capture device and a light source for projecting light (e.g., infrared light) onto the eye, which can then be reflected by the eye and detected by the image capture device. In some embodiments, the camera assembly 630 can be mounted on the frame 80 (FIG. 9D) and can be in electrical communication with processing modules 140 and / or 150 that can process image information from the camera assembly 630. In some embodiments, one camera assembly 630 can be utilized for each eye to monitor each eye separately.

[0042]

[0121] Referring now to FIG. 7 , an example of an output beam output by a waveguide is shown. While one waveguide is shown, it will be understood that if the waveguide assembly 260 includes multiple waveguides, other waveguides within the waveguide assembly 260 ( FIG. 6 ) may function similarly. Light 640 is injected into the waveguide 270 at the input face 460 of the waveguide 270 and propagates within the waveguide 270 by TIR. At the point where the light 640 impinges on the DOE 570, a portion of the light exits the waveguide as output beam 650. While output beam 650 is shown as substantially parallel, it may be redirected to propagate to the eye 210 at an angle (e.g., forming a diverging output beam) depending on the depth plane associated with the waveguide 270, as described herein. It will be understood that a substantially parallel exit beam can refer to a waveguide having outcoupling optics that outcouples light to form an image that appears to be set on a depth plane at a long distance (e.g., optical infinity) from the eye 210. Other waveguides or other sets of outcoupling optics can output a more divergent exit beam pattern, which requires the eye 210 to adjust to a closer distance to focus on the retina, and is interpreted by the brain as light from a distance closer to the eye 210 than optical infinity.

[0043]

[0122] In some embodiments, a full color image can be formed in each depth plane by overlaying images of each component color, for example, three or more component colors.

[0044]

[0123] FIG. 8 illustrates an example of a stacked waveguide assembly in which each depth plane includes an image formed using multiple different component colors. The illustrated embodiment shows depth planes 240a-240f, although more or fewer depths are contemplated. Each depth plane can have three or more component color images associated with it, including a first image of a first color, G, a second image of a second color, R, and a third image of a third color, B. The different depth planes are indicated in the diagram by different numbers in diopters (dpt) following the letters G, R, and B. By way of example, the number following each of these letters indicates the diopter (1 / m), or inverse distance, of the depth plane from the viewer, and each box in the diagram represents an individual component color image. In some embodiments, the exact placement of the different component color depth planes may vary to account for differences in the eye's focusing of different wavelengths of light. For example, different component color images for a given depth plane may be positioned on depth planes corresponding to different distances from the user. Such placement may improve visual acuity and user comfort and / or reduce chromatic aberrations.

[0045]

[0124] In some embodiments, light for each component 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, providing three component color images per depth plane. While the waveguides associated with each depth plane are shown adjacent to each other in this diagram for ease of illustration, it will 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 component colors may be output by the same waveguide, such that, for example, only a single waveguide may be provided per depth plane.

[0046]

[0125] 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 or substituted in addition to one or more of red, green, or blue.

[0047]

[0126] It will be understood that throughout this disclosure, references to light of a given color are understood to encompass light of one or more wavelengths within the wavelength range of light perceived by an observer as being of that given color. For example, red light may include light of one or more wavelengths in the range of about 620-780 nm, green light may include light of one or more wavelengths in the range of about 492-577 nm, and blue light may include light of one or more wavelengths in the range of about 435-493 nm.

[0048]

[0127] In some embodiments, the light source 530 (FIG. 6) may be configured to emit light at one or more wavelengths outside the visual range of an observer, such as infrared and / or ultraviolet wavelengths. Additionally, the waveguide incoupling, outcoupling, and other light redirection structures of the display 250 may be configured to emit this light from the display toward the eye 210, for example, for imaging and / or user stimulation applications.

[0049]

[0128] Referring now to FIG. 9A , in some embodiments, light impinging on a waveguide may need to be redirected to incouple the light into the waveguide. Incoupling optics may be used to redirect and incouple the light into its corresponding waveguide. Although referred to throughout this specification as “incoupling optics,” incoupling optics need not be optical elements and may be non-optical elements. FIG. 9A shows a cross-sectional side view of an example of a set 660 of stacked waveguides, each including an incoupling optic. Each of the waveguides may be configured to output light at one or more different wavelengths or one or more different wavelength ranges. It will be understood that stack 660 may correspond to stack 260 (FIG. 6), and the illustrated waveguides of stack 660 may correspond to portions 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 waveguides from locations where the light requires redirection for incoupling.

[0050]

[0129] The illustrated stacked waveguide set 660 includes waveguides 670, 680, and 690. Each waveguide includes associated incoupling optics (which may also be referred to as a light input region on the waveguide), having, for example, an incoupling optic 700 disposed on a major surface (e.g., the top major surface) of waveguide 670, an incoupling optic 710 disposed on a major surface (e.g., the top major surface) of waveguide 680, and an incoupling optic 720 disposed on a major surface (e.g., the top major surface) of waveguide 690. In some embodiments, one or more of incoupling optics 700, 710, 720 may be disposed on the bottom major surface of the respective waveguide 670, 680, 690 (particularly if one or more incoupling optics are reflective turning optics). As shown, the incoupling optical elements 700, 710, 720 may be disposed on the top major surfaces of their respective waveguides 670, 680, 690 (or on top of the next lower waveguide), particularly if the incoupling optical elements are transmissive polarizing optical elements. In some embodiments, the incoupling optical elements 700, 710, 720 may be disposed within the body of the respective waveguides 670, 680, 690. In some embodiments, as described herein, the incoupling optical elements 700, 710, 720 are wavelength selective, thereby selectively redirecting one or more wavelengths of light while transmitting other wavelengths of light. While shown on one side or corner of their respective waveguides 670, 680, 690, it will be understood that in some embodiments, the incoupling optical elements 700, 710, 720 may be disposed in other regions of their respective waveguides 670, 680, 690.

[0051]

[0130] As shown, the incoupling optical elements 700, 710, 720 may be laterally offset from one another. In some embodiments, each incoupling optical element may be offset to receive light without the light passing through another incoupling optical element. For example, each incoupling optical element 700, 710, 720 may be configured to receive light from a different image injection device 360, 370, 380, 390, 400, as shown in FIG. 6 , and may be separated (e.g., laterally spaced) from the other incoupling optical elements 700, 710, 720, such that it does not receive substantially light from other ones of the incoupling optical elements 700, 710, 720.

[0052]

[0131] Each waveguide also includes associated light distribution elements, for example, a light distribution element 730 disposed on a major surface (e.g., the top major surface) of waveguide 670, a light distribution element 740 disposed on a major surface (e.g., the top major surface) of waveguide 680, and a light distribution element 750 disposed on a major surface (e.g., the top major surface) of waveguide 690. In some other embodiments, light distribution elements 730, 740, 750 may be disposed on the bottom major surface of the associated waveguide 670, 680, 690, respectively. In some other embodiments, light distribution elements 730, 740, 750 may be disposed on both the top and bottom major surfaces of the associated waveguide 670, 680, 690, respectively, or light distribution elements 730, 740, 750 may be disposed on different top and bottom major surfaces of different associated waveguides 670, 680, 690, respectively.

[0053]

[0132] The waveguides 670, 680, 690 may be spaced apart and separated by, for example, gas, liquid, and / or solid material layers. 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 one of the immediately adjacent waveguides 670, 680, 690). Preferably, the refractive index of the material forming layers 760a, 760b is 0.05 or more or 0.10 or less than the refractive index of the material forming waveguides 670, 680, 690. Advantageously, the low refractive index layers 760a, 760b can function as cladding layers that facilitate 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 will be understood that the top and bottom of the illustrated set of waveguides 660 can include immediately adjacent cladding layers.

[0054]

[0133] Preferably, for ease of fabrication and other considerations, the materials forming waveguides 670, 680, and 690 are similar or identical, and the materials forming layers 760a and 760b are similar or identical. In some embodiments, the materials forming waveguides 670, 680, and 690 may vary between one or more waveguides, and / or the materials forming layers 760a and 760b may be different while still maintaining the various refractive index relationships described above. Various materials can be used to form the waveguides. Glass is one material that can be used to fabricate the waveguides, but other materials can also be used, including LiNbO3, SiC, ZnS, and the like. These materials can be in the form of optical-quality single-crystal materials or optical-quality, but not single-crystal, materials. Additionally, multigrain ceramics of similar composition can be used to form the waveguides. As an example, nanocrystalline materials can be used to fabricate the waveguides.

[0055]

[0134] 9A, light rays 770, 780, 790 are incident on the set of waveguides 660. It will be appreciated that light rays 770, 780, 790 may be injected into the waveguides 670, 680, 690 by one or more image injectors 360, 370, 380, 390, 400 (FIG. 6).

[0056]

[0135] In some embodiments, light rays 770, 780, 790 have different properties, for example, different wavelengths or different wavelength ranges that may correspond to different colors. Each of the incoupling optics 700, 710, 720 deflects incident light such that the light propagates by TIR through a respective one of the waveguides 670, 680, 690. In some embodiments, each of the incoupling optics 700, 710, 720 selectively deflects one or more particular wavelengths of light while transmitting other wavelengths to the underlying waveguide and associated incoupling optic.

[0057]

[0136] For example, incoupling optic 700 may be configured to deflect light beam 770 having a first wavelength or wavelength range while simultaneously transmitting light beams 780 and 790 having different second and third wavelengths or wavelength ranges, respectively. Transmitted light beam 780 impinges on and is deflected by incoupling optic 710 configured to deflect light of the second wavelength or wavelength range. Light beam 790 is deflected by incoupling optic 720 configured to selectively deflect light of the third wavelength or wavelength range.

[0058]

[0137] 9A , the deflected light rays 770, 780, 790 are deflected such that they propagate through their corresponding waveguides 670, 680, 690. That is, the incoupling optical element 700, 710, 720 of each waveguide deflects the light into its corresponding waveguide 670, 680, 690, incoupling the light into its corresponding waveguide. The light rays 770, 780, 790 are deflected at an angle that causes the light to propagate through their respective waveguides 670, 680, 690 by TIR. The light rays 770, 780, 790 propagate through their respective waveguides 670, 680, 690 by TIR until they impinge on the waveguide's corresponding light distribution element 730, 740, 750.

[0059]

[0138] 9B, a perspective view of an example of the stacked waveguide of FIG. 9A is shown. As described above, incoupled light rays 770, 780, and 790 are deflected by incoupling optical elements 700, 710, and 720, respectively, and then propagate through waveguides 670, 680, and 690 by TIR. Light rays 770, 780, and 790 then impinge on light distribution elements 730, 740, and 750, respectively. Light distribution elements 730, 740, and 750 deflect light rays 770, 780, and 790 to propagate toward outcoupling optical elements 800, 810, and 820, respectively.

[0060]

[0139] In some embodiments, the light distribution elements 730, 740, 750 are orthogonal pupil dilators (OPEs). In some embodiments, the OPEs deflect or distribute light to the outcoupling optics 800, 810, 820, and in some embodiments, can also increase the beam or spot size of this light as it propagates to the outcoupling optics. In some embodiments, the light distribution elements 730, 740, 750 may be omitted, and the incoupling optics 700, 710, 720 may be configured to deflect light directly to the outcoupling optics 800, 810, 820. For example, with reference to FIG. 9A , the light distribution elements 730, 740, 750 may be replaced by the outcoupling optics 800, 810, 820. In some embodiments, the outcoupling optics 800, 810, 820 are exit pupils (EPs) or exit pupil dilators (EPEs) that direct light into the eye 210 ( FIG. 7 ). It will be appreciated that an OPE may be configured to increase the dimension of the eyebox in at least one axis, and an EPE may increase the eyebox in an axis intersecting the axis, e.g., perpendicular to the axis of the OPE. For example, each OPE may be configured to redirect a portion of the light striking it to an EPE of the same waveguide, while allowing the remaining portion of the light to continue propagating down the waveguide. Upon striking the OPE again, another portion of the remaining light is redirected to the EPE, which continues to propagate further down the waveguide, and so on. Similarly, upon striking the EPE, a portion of the striking light is redirected out of the waveguide to the user, and the remaining portion of that light continues to propagate through the waveguide until it again strikes the EPE, at which point another portion of the striking light is redirected out of the waveguide, and so on. As a result, a single beam of incoupled light may be "replicated" each time a portion of that light is redirected by the OPE or EPE, thereby forming a field of cloned light beams, as shown in FIG. 6. In some embodiments, the OPE and / or EPE may be configured to change the size of the light beam.

[0061]

[0140] 9A and 9B, in some embodiments, a waveguide set 660 includes waveguides 670, 680, 690, incoupling optics 700, 710, 720, light distribution elements (e.g., OPEs) 730, 740, 750, and outcoupling optics (e.g., EPs) 800, 810, 820 for each component color. The waveguides 670, 680, 690 may be stacked with an air gap / cladding layer between each. The incoupling optics 700, 710, 720 redirect or deflect incident light (with different incoupling optics receiving light of different wavelengths) into that waveguide. The light then propagates at an angle that results in TIR within each waveguide 670, 680, 690. In the illustrated example, light ray 770 (e.g., blue light) is deflected by the first incoupling optical element 700 and then continues bouncing down the waveguide, interacting with the light distribution element (e.g., OPE) 730 and then the outcoupling optical element (e.g., EP) 800 in the manner described above. Light rays 780 and 790 (e.g., green and red light, respectively) pass through the waveguide 670, with light ray 780 striking and being deflected by the incoupling optical element 710. Light ray 780 then bounces down the waveguide 680 via TIR, traveling to its light distribution element (e.g., OPE) 740 and then to the outcoupling optical element (e.g., EP) 810. Finally, light ray 790 (e.g., red light) passes through the waveguide 690 and impinges on the light incoupling optical element 720 of the waveguide 690. The light incoupling optic 720 deflects the light 790 to propagate by TIR to a light distribution element (e.g., OPE) 750, and then by TIR to a light outcoupling optic (e.g., EP) 820. The outcoupling optic 820 then finally outcouples the light ray 790 to an observer, who also receives outcoupled light from the other waveguides 670, 680.

[0062]

[0141] FIG. 9C shows a top plan view of one example of the stacked waveguides of FIGS. 9A and 9B. As shown, the waveguides 670, 680, 690, along with each waveguide's associated light distribution elements 730, 740, 750 and associated outcoupling optics 800, 810, 820, may be vertically aligned. However, as described herein, the incoupling optics 700, 710, 720 are not vertically aligned. Rather, the incoupling optics preferably do not overlap (e.g., are laterally spaced apart as seen in the top view). As further described herein, this non-overlapping spatial arrangement facilitates one-to-one injection of light from different sources into different waveguides, thereby enabling a specific light source to be uniquely coupled to a specific waveguide. In some embodiments, arrangements including non-overlapping, spatially separated incoupling optics may be referred to as shifted pupil systems, and the incoupling optics in these arrangements may correspond to sub-pupils.

[0063]

[0142] 9D shows an example of a wearable display system 60 into which the various waveguides and associated systems disclosed herein may be integrated. In some embodiments, the display system 60 is the system 250 of FIG. 6, which schematically illustrates some portions of the system 60 in more detail. For example, the waveguide assembly 260 of FIG. 6 may be part of the display 70.

[0064]

[0143] 9D , display system 60 includes display 70 and various mechanical and electronic modules and systems for supporting the functionality of display 70. Display 70 can be coupled to a frame 80 that is wearable by a user or observer 90 of the display system and configured to position display 70 in front of the user's 90 eyes. Display 70 can be considered eyewear in some embodiments. In some embodiments, speakers 100 are coupled to frame 80 and configured to be positioned adjacent to the user's 90 ear canals (in some embodiments, additional speakers, not shown, can optionally be positioned adjacent the user's other ear canals to provide stereo / shapeable sound control). Display system 60 can also include one or more microphones 110 or other devices for detecting sound. In some embodiments, the microphones can be configured to allow a user to provide input or commands to system 60 (e.g., selection of voice menu commands, natural language questions, etc.) and / or enable voice communication with others (e.g., with other users of similar display systems). The microphone may further be configured as an ambient sensor for collecting audio data (e.g., sounds from the user and / or the environment). In some embodiments, the display system 60 may further include one or more outward-facing environmental sensors 112 configured to detect objects, stimuli, people, animals, places, or other aspects of the world around the user. For example, the environmental sensors 112 may include one or more cameras, which may be positioned, for example, facing outward, to capture images similar to at least a portion of the user's 90's normal field of view. In some embodiments, the display system may also include ambient sensors 120a that are separate from the frame 80 and may be attached to the user's 90's body (e.g., the user's 90's head, torso, limbs, etc.). The ambient sensors 120a, in some embodiments, may be configured to acquire data characterizing the user's 90's physiological state.For example, the sensor 120a may be an electrode.

[0065]

[0144] 9D , display 70 is operably coupled by a communication link 130, such as a wired lead or a wireless connection, 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 in headphones, or otherwise removably attached to user 90 (e.g., in a backpack-type configuration, a belt-connected configuration). Similarly, sensor 120a may be operably coupled to local processor and data module 140 by a communication link 120b, such as a wired lead or a wireless connection. 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 assist in processing, caching, and storing data. Optionally, local processor and data module 140 may include one or more central processing units (CPUs), graphics processing units (GPUs), dedicated processing hardware, etc. The data may include a) captured from sensors (which may be operatively coupled to the frame 80 or otherwise attached to the user 90), such as image capture devices (such as cameras), microphones, inertial measurement units, accelerometers, compasses, GPS units, wireless devices, gyros, and / or other sensors disclosed herein, and / or b) data acquired and / or processed using a remote processing module 150 and / or a remote data repository 160 (including data related to the virtual content), possibly for transfer to the display 70 after such processing or acquisition. The local processing and data module 140 may be operatively coupled to each other and to the remote processing module 150 and the remote data repository 160 by communication links 170, 180, such as via wired or wireless communication links, that are available as resources to the local processing and data module 140.In some embodiments, 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 gyro. In some other embodiments, one or more of these sensors may be mounted to frame 80 or may be a stand-alone structure that communicates with local processing and data module 140 by a wired or wireless communication path.

[0066]

[0145] 9D , in some embodiments, remote processing module 150 can comprise one or more processors configured to analyze and process data and / or image information, including, for example, one or more central processing units (CPUs), graphics processing units (GPUs), dedicated processing hardware, etc. In some embodiments, remote data repository 160 can comprise a digital data storage facility that may be available via the Internet or other networking configuration in a “cloud” resource configuration. In some embodiments, remote data repository 160 can include one or more remote servers that provide information to local processing and data module 140 and / or remote processing module 150, e.g., information for generating augmented reality content. In some embodiments, all data is stored and all computations are performed in the local processing and data module, allowing for fully autonomous use from the remote module. Optionally, an external system (e.g., one or more processors, one or more computer systems) including a CPU, GPU, etc. can perform at least a portion of the processing (e.g., generating image information, processing data) and provide and receive information to modules 140, 150, 160, e.g., via a wireless or wired connection.

[0067]

[0146] FIG. 10 is a schematic diagram illustrating a projector assembly 1000 that utilizes a polarizing beam splitter (PBS) 1020 to illuminate a spatial light modulator (SLM) 1030 and redirect light from the SLM 1030 through projection optics 1040 to an eyepiece (not shown). The projector assembly 1000 includes an illumination source 1010, which may include, for example, a light-emitting diode (LED), a laser (e.g., a laser diode), or other types of light sources. This light may be collimated by collimating optics. The illumination source 1010 can emit polarized, unpolarized, or partially polarized light. In the illustrated design, the illumination source 1010 can emit polarized light 1012 having p-polarization. A first optical element 1015 (e.g., a pre-polarizer) is aligned to pass light having a first polarization (e.g., p-polarization).

[0068]

[0147] This light is directed toward the polarizing beam splitter 1020. Initially, the light passes through an interface 1022 (e.g., a polarizing interface) of the PBS 1020, which is configured to transmit light of a first polarization (e.g., p-polarized light). This allows the light to continue incident on the spatial light modulator 1030. As shown, the SLM 1030 is a reflective SLM configured to retroreflect and selectively modulate the incident light. The SLM 1030 includes, for example, one or more pixels that can have different states. Light incident on each pixel may be modulated based on the state of the pixel. Thus, the SLM 1030 can be driven to modulate the light to provide an image. In this example, the SLM 1030 may be a polarization-based SLM that modulates the polarization of light incident thereon. For example, in an on state, a pixel of the SLM 1030 changes the input light from a first polarization state (e.g., p-polarized state) to a second polarization state (e.g., s-polarized state) to indicate a bright state (e.g., a white pixel). The second polarization state may be the first polarization state modulated (e.g., rotated) by 90°. In the on state, light having the second polarization state is reflected by interface 1022 and propagates downstream to projector optics 1040. In the off state, SLM 1030 does not change the polarization state of light incident thereon, e.g., does not rotate the input light from the first polarization state, and thus exhibits a dark state (e.g., a black pixel). In the off state, light having the first polarization state is transmitted through interface 1022 and propagates upstream back to illumination source 1010, not reaching the user's eyes.

[0069]

[0148] After reflecting from the SLM 1030, a portion of the light 1014 (e.g., modulated light) is reflected from interface 1022 and exits the PBS 1020 toward the user's eye. The emitted light passes through projector optics 1040 and is imaged onto an incoupling grating (ICG) 1050 in the eyepiece (not shown).

[0070]

[0149] 11A shows a system (e.g., an augmented reality display system) 1100A for presenting an image to a user's eye 210 and viewing a table 510 having an alternative configuration to that shown in FIG. 10. The system 1100 includes a light source 1110, a spatial light modulator (SLM) 1140, and a waveguide 1120, also referred to as an eyepiece waveguide, arranged so that light from the light source 1110 illuminates the SLM 1140 and light reflected from the SLM 1140 is coupled into the waveguide 1120 to be directed toward the eye 210. The system 1100A includes an optical element 1130 arranged to illuminate the SLM 1140 and project an image of the SLM 1140. Light from the light source 1110 propagates, for example, through the optical element 1130 onto the SLM 1140 in a first direction, thereby illuminating the SLM 1140. Light reflected from SLM 1140 re-propagates through optical element 1130 in a second direction opposite to the first direction and is directed towards and coupled into waveguide 1120 .

[0071]

[0150] The light source 1110 can include a light-emitting diode (LED), a laser (e.g., a laser diode), or other types of light sources. The light source 1110 can be a polarized light source, but the light source 1110 need not be so limited. In some implementations, a polarizer 1115 can be positioned between the light source 1110 and the SLM 1140. As shown, the polarizer 1115 is between the light source 1110 and the waveguide 1120. This polarizer 1115 can also be a light recycler that transmits light of a first polarization and reflects light of a second polarization back to the light source 1110. Such a polarizer 1115 can be, for example, a wire grid polarizer. A coupling optic 1105, such as a non-imaging optical element (e.g., a cone, a compound parabolic concentrator (CPC, lens)), can be positioned relative to the light source 1110 to receive the light output from the light source 1110. The coupling optic 1105 can collect light from the light source 1110 and, in some cases, reduce the divergence of the light emitted from the light source 1110. The coupling optic 1105 can, for example, collimate the light output from the light source 1110. The coupling optic 1105 can collect light that matches the angular spectral field of view of the system 1100A. Thus, the coupling optic 1105 can match the angular spectrum of the light output by the light source 1110 to the field of view of the system 1100A. The coupling optic 1105 can have an asymmetric profile that operates asymmetrically on the light emitted from the light source 1110. For example, the coupling optic 1105 can reduce divergence by different amounts in orthogonal directions (e.g., x and z directions). Such asymmetry in the coupling optic 1105 can address, for example, asymmetry in the light emitted from the light source 1110, which may include a laser diode that emits light over a wider angular range in one direction (e.g., x or z, respectively) as opposed to an orthogonal direction (e.g., z or x, respectively).

[0072]

[0151] As described above, the system 1100A includes an optical element 1130 configured to illuminate the SLM 1140 and disposed in the optical path between the light source 1110 and the SLM 1140. The optical element 1130 may include a transmissive optical element that transmits light from the light source 1110 to the SLM 1140. The optical element 1130 may also be configured to project an image of the SLM 1140 or an image formed by the SLM 1140 onto the waveguide 1120. The image may be projected onto the eye 210. In some designs, the optical element 1130 may include one or more lenses or optical elements having optical power. The optical element 1130 may have, for example, positive optical power. The optical element 1130 may include one or more refractive optical elements, such as a refractive lens. Other types of optical elements could also possibly be used.

[0073]

[0152] The SLM 1140 may be reflective, modulating and reflecting light therefrom. The SLM 1140 may also be a polarization-based SLM configured to modulate polarization. The SLM 1140 may, for example, comprise a liquid crystal (LC) SLM (e.g., a liquid crystal on silicon (LCoS) SLM). The LC SLM may, for example, comprise a twisted nematic (TN) liquid crystal. The SLM 1140 may be substantially similar to the SLM 1030 with reference to FIG. 10 . The SLM 1140 may, for example, comprise one or more pixels configured to selectively modulate light incident thereon depending on the state of the pixel. For some types of SLM 1140, the pixels can modulate a beam incident thereon by changing the polarization state, for example, by rotating the polarization (e.g., rotating the orientation of linearly polarized light).

[0074]

[0153] As mentioned above, the SLM 1140 may be an LCoS SLM 1140. In a crossed polarizer configuration, the LCoS SLM 1140 may be nominally white. When the pixel is off (e.g., 0 voltage), it is in the bright state, and when the pixel is on (e.g., a voltage above a threshold turns on voltage), it is in the dark state. In this crossed polarizer configuration, leakage is minimized when the pixel is on and in the dark state.

[0075]

[0154] In the parallel polarizer configuration, the LCoS SLM 1140 is nominally black. When the pixel is off (e.g., 0 voltage), it is in the dark state, and when the pixel is on (e.g., a voltage above the threshold turns on the voltage), it is in the bright state. In this parallel polarizer configuration, leakage is minimized when the pixel is off and in the dark state. The dark state can be (re)optimized using the friction direction and compensator angle. The compensator angle can refer to the angle of the compensator, which can be between the optical element 1130 and the SLM 1140, for example, as shown in FIG. 20B.

[0076]

[0155] The dynamic range and throughput of the parallel polarizer configuration may be different from the dynamic range and throughput of the crossed polarizer configuration. Additionally, the parallel polarizer configuration may be optimized for a different contrast than the crossed polarizer configuration.

[0077]

[0156] The system 1100A includes a waveguide 1120 for outputting image information to the eye 210. The waveguide 1120 may be substantially similar to the waveguides 270, 280, 290, 300, 310, 670, 680, and 690 described above. The waveguide 1120 may include a substantially transparent material having a refractive index sufficient to guide light therethrough. As shown, the waveguide 1120 may include a first side 1121, a second side 1123 opposite the first side 1121, corresponding top and bottom major surfaces, and surrounding edges. The first and second major surfaces 1121, 1123 may be sufficiently flat so that image information can be preserved when propagating light from the SLM 1140 to the eye 210, such that an image formed by the SLM 1140 can be injected into the eye. The optical element 1130 and the SLM 1140 may be positioned on a first side 1121 of the waveguide 1120. The light source 1110 may be disposed on the second side 1123 such that light from the light source 1110 passes through the waveguide 1120 and enters the second side 1123 before passing through the optical element 1130 to the SLM 1140. Thus, the waveguide 1120 may be disposed between the light source 1110 and the optical element 1130. Furthermore, at least a portion of the waveguide 1120 may extend between the light source 1110 and the optical element 1130, such that light passes through a portion of the waveguide 1120 to the optical element 1130. Thus, light emitted from the light source 1110 can be directed through the waveguide 1120 into the optical element 1130, pass through the optical element, and enter the SLM 1140. SLM 1140 reflects the light back through optical element 1130 into waveguide 1120 .

[0078]

[0157] The system 1100A also includes an incoupling optical element 1160 to couple light from the optical element 1130 into the waveguide 1120. The incoupling optical element 1160 may be disposed on a major surface (e.g., the top major surface 1123) of the waveguide 1120. In some designs, the incoupling optical element 1160 may be disposed on the bottom major surface 1121 of the waveguide 1120. In some designs, the incoupling optical element 1160 may be disposed within the body of the waveguide 1120. Although shown on one side or corner of the waveguide 1120, the incoupling optical element 1160 may be disposed in / on other regions of the waveguide 1120. The incoupling optical element 1160 may be substantially similar to the incoupling optical elements 700, 710, 720 described above with reference to FIGS. 9A, 9B, and 9C. The incoupling optical element 1160 may be a diffractive optical element or a reflector. Other structures may be used as the incoupling optical element 1160. The incoupling optical element 1160 may be configured to direct light incident thereon into the waveguide 1120 at a sufficiently large grazing angle (e.g., greater than the critical angle) relative to the upper and lower major surfaces 1123, 1121 of the waveguide 1120, and guide it therein by total internal reflection. Furthermore, the incoupling optical element 1160 may operate over a wide range of wavelengths and thus be configured to couple multiple colors of light into the waveguide 1120. For example, the incoupling optical element 1160 may be configured to couple red, green, and blue light into the waveguide 1120. The light source 1110 may emit red, green, and blue light at different times.

[0079]

[0158] The system 1100A includes a light distribution element 1170 disposed on or within the waveguide 1120. The light distribution element 1170 may be substantially similar to the light distribution elements 730, 740, and 750 described above with respect to FIG. 9B. For example, the light distribution element 1170 may be an orthogonal pupil dilator (OPE). The light distribution element 1170 may be configured to spread light within the waveguide 1120 by redirecting light propagating in the x-direction, for example, in the z-direction shown in the top view of FIG. 11B. Thus, the light distribution element 1170 may be configured to increase the dimension of the eyebox along the z-axis; see FIG. 11B. The light distribution element 1170 may include, for example, one or more diffractive optical elements configured to diffract light propagating within the waveguide 1120 that is incident on the diffractive optical element and redirect the light, for example, in a substantially orthogonal direction. Other configurations are possible.

[0080]

[0159] 11B , the system 1100 can also include an outcoupling optic 1180 for coupling light from the waveguide 1120 to the eye 210. The outcoupling optic 1180 can be configured to redirect light propagating within the waveguide 1120 by total internal reflection (TIR) ​​at an angle more perpendicular to the top 1123 and / or bottom 1121 major surfaces of the waveguide 1120, such that the light is not guided within the waveguide 1120. Instead, the light is redirected from the waveguide 1120, for example, through the bottom 1121. The outcoupling optic 1180 can include, for example, one or more diffractive optical elements configured to diffract light propagating within the waveguide 1120 that is incident on the diffractive optical element, thereby redirecting the light, for example, from the waveguide 1120. Other configurations are possible.

[0081]

[0160] Also shown in Figure 11B is the position of the incoupling optic 1160, which is disposed laterally relative to the light distribution optic (e.g., orthogonal pupil dilator) 1170 and the outcoupling optic 1180. Also shown in Figure 11B is the position of the light source 1110, which is disposed laterally relative to the incoupling optic 1160, the light distribution optic (e.g., orthogonal pupil dilator) 1170 and the outcoupling optic 1180.

[0082]

[0161] During operation, the light source 1110 of the system 1100A emits light into the coupling optic 1105 through the polarizer 1115. This light may therefore be polarized, for example, linearly polarized in a first direction. This polarization may be transmitted through the waveguide 1120, enter the second major surface of the waveguide 1120, and exit the first major surface of the waveguide 1120. This light may propagate through the optical element 1130 to the SLM 1140. The optical element 1130 quasi-collimates and / or selects the light from the light source 1110 to illuminate the SLM 1140, which may include a polarization-based modulator that modulates the polarization of the light incident thereon, such as by selectively rotating the orientation of the modulator on a pixel-by-pixel basis depending on the state of the pixel. For example, a first pixel may be in a first state and rotate the polarization, while a second pixel may be in a second state and not rotate the polarization. Light between the coupling optic 1105 and the optical element 1130 can illuminate the SLM 1140 fairly uniformly. After entering the SLM 1140, the light is reflected back through the optical element 1130. The optical element 1130 can be configured to project an image from the SLM 1140 to the waveguide 1120 and ultimately to the eye 210 so that the image is visible to the eye 210. In some designs, the retina of the eye 210 is light conjugated to the SLM 1140 and / or an image formed by and / or on the SLM 1140. The output of the optical element 1130 can facilitate the projection of the image on the SLM 1140 into and onto the retina of the eye 210. In some implementations, optical power provided by, for example, the outcoupling optic 1180, can assist and / or influence the image ultimately formed in the eye 210. Optical element 1130 functions as a projection lens as light reflected from SLM 1140 passes through the optical element towards waveguide 1120. The optical element can function approximately as a Fourier transform of the image on SLM 1140 onto a plane within waveguide 1120 near incoupling optical element 1160.Together, both passing through the optical element 1130 (the first from the light source 1110 to the SLM 1140, and the second from the SLM 1140 to the waveguide 1120) can act to roughly image the pupil of the coupling optic 1105. The alignment and orientation of the light source 1110 (and possibly also the coupling optic 1105 and / or polarizer 1115), optical element 1130, and SLM 1140 are such that light from the light source 1110 reflected from the SLM 1140 is directed onto the incoupling optic 1160. The pupil associated with the coupling optic 1105 may be aligned with the incoupling optic 1160. The light can pass through an analyzer 1150 (e.g., a polarizer) in the optical path between the SLM 1140 and the eye 210. As shown in FIG. 11A , an analyzer (e.g., a polarizer) 1150 may be disposed in the optical path between the optical element 1130 and the incoupling optical element 1160. The analyzer 1150 may be, for example, a linear polarizer oriented to transmit light of a first polarization (p-polarized) and block light of a second polarization (s-polarized), or vice versa. The analyzer 1150 may be a purifying polarizer or may further block light of a polarization blocked by another polarizer between the SLM 1140 and the analyzer 1150 or within the SLM 1140. The analyzer 1150 may be, for example, a circular polarizer that acts as an isolator to mitigate reflections from the waveguide 1120, specifically the incoupling optical element 1160, back toward the SLM 1140. The analyzer 1150 may include a wire grid polarizer, such as an absorptive wire grid polarizer, as any of the polarizers disclosed herein. Such a polarizer may result in significant absorption of undesired light and thus increased contrast. Some such polarizers can be fabricated to include one or more dielectric layers over the wires and / or multilayers. In some implementations, the SLM 1140 may be a liquid crystal on silicon (LCoS) SLM and may include an LC cell and a retarder (e.g., a compensator).In some implementations, the analyzer 1150 may be a compensator intended to provide a more consistent polarization rotation (e.g., 90°) of the SLM 1140 for different angles of incidence and different wavelengths. A compensator can be used to improve the contrast of a display by improving the circular polarization of incident light across a spread of angles and wavelengths. The SLM 1140 may include, for example, a TN LCoS configured to rotate incident light of a first polarization (e.g., s-polarized) to a second polarization (e.g., p-polarized) for a first pixel to generate a bright pixel state when the light passes through the analyzer 1150. Conversely, the SLM 1140 may be configured not to rotate incident light of a first polarization (e.g., s-polarized) to a second polarization (e.g., p-polarized) for a second pixel so that the reflected light remains at the first polarization to generate a dark pixel state when the light is attenuated or blocked by the analyzer 1150. In such a configuration, the polarizer 1115, which is closer along the optical path to the light source 1110, may be oriented differently (e.g., orthogonal) relative to the analyzer 1150, which is farther along the optical path from the light source 1110. Other, e.g., reverse, configurations are also possible.

[0083]

[0162] The light is then deflected, e.g., rotated, by the incoupling optics 1160 so that it is guided within the waveguide 1120 where it propagates by TIR. The light then strikes the light distribution element 1170, which directs the light in another direction (e.g., more toward the z-direction), increasing the size of the eyebox along the z-axis, as shown in FIG. 11B. Thus, the light is deflected toward the outcoupling optics 1180, which directs the light from the waveguide 1120 toward the eye 210 (e.g., the user's eye as shown). The coupled light exiting along the z-direction by different portions of the outcoupling optics 1180 increases the size of the eyebox at least along a direction parallel to the z-axis, as defined in FIG. 11B. Notably, in this configuration, the optical element 1130 is used both to illuminate the SLM 1140 and to project an image onto the incoupling optics 1160. Thus, the optical element 1130 can function as both a projection optic that distributes light from the light source 1110 (e.g., uniformly) as well as an imaging optic that provides an image of the SLM 1140 and / or an image formed in the eye by the SLM 1140. The system 1100A of FIGS. 11A / B may, in some cases, be more compact than the system 1000 of FIG. 10. In some cases, the cost and / or size of the system can be reduced by not using the PBS 1020 shown in FIG. 10. Furthermore, without the PBS 1020, the system may be more symmetrical and easier to design by shortening the back focal length of the optical element 1130.

[0084]

[0163] As mentioned above, alternative configurations are possible. Referring to FIG. 11C , for example, in some designs, system 1100C may be configured to pass light having a polarization that is not rotated by SLM 1140. In one implementation, for example, SLM 1140 is a liquid crystal (LC)-based SLM and may include a vertically aligned (VA)LC-on-silicon (LCoS) device. SLM 1140 may have a first pixel in a first state that does not rotate the polarization and a second pixel in a second state that rotates the polarization. In the configuration shown in FIG. 11C , a single shared analyzer / polarizer 1155 is utilized. This analyzer 1155 can transmit light of a first polarization (e.g., s-polarized) and attenuate or reduce transmission of light of a second polarization (e.g., p-polarized). As a result, light incident on the first pixel in a first state that does not rotate the polarization orientation (e.g., s-polarized light) is reflected by the SLM 1140 and passes through the analyzer 1155 to the waveguide 1120. Conversely, light incident on the second pixel in a second state that rotates the polarization orientation (e.g., s-polarized light) is reflected by the SLM 1140 and passes through the analyzer 1155 to be attenuated, reduced, or not passed to the waveguide 1120. As a result, the polarizer 1115 and analyzer 1150 shown in FIG. 11A can be combined into a shared optical element, analyzer 1155, shown in FIG. 11C, simplifying the system 1100 of FIGS. 11A / B by reducing the number of optical components. The analyzer 1155 may be located between the waveguide 1120 and the optical element 1130. In other implementations, separate analyzers / polarizers and analyzer / polarizers can be used, as shown in the system 1100 of FIGS. 11A / B. 11A and 11B show a polarizer 1115 between the light source 1110 and the waveguide 1120, and an analyzer SLM 1140 between the optical element 1130 and the waveguide 1120. FIG.

[0085]

[0164] FIG. 11D illustrates an example of a waveguide having a combined OPE / EPE according to one embodiment of the present invention. Referring to FIG. 11D , a waveguide 1190 having a combined OPE / EPE region 1191 includes gratings corresponding to both the OPE and the EPE that spatially overlap in the x and y directions. In some embodiments, the gratings corresponding to both the OPE and the EPE are disposed on the same side of the substrate, such that the OPE grating is overlaid on the EPE grating, or the EPE grating is overlaid on the OPE grating (or both). In other embodiments, the OPE grating is disposed on the opposite side of the substrate from the EPE grating, such that the gratings spatially overlap in the x and y directions but are separated from each other in the z direction (i.e., in different planes). Thus, the combined OPE / EPE region 1191 can be implemented in either a single-sided or double-sided configuration.

[0086]

[0165] The light path within the eyepiece waveguide 1190 includes incident light 1194 that is coupled into the eyepiece waveguide 1190 at ICG 1193. The incoupled light propagates within substrate 1192 toward the combined OPE / EPE 1191 by total internal reflection. When these light rays encounter the combined OPE / EPE 1191, also referred to as a compound pupil dilator (CPE), the light is diffracted in the +y direction and then in the -z direction along optical path 1195 out of the waveguide toward the user's eye. Similarly, the incoupled light may alternatively encounter the combined OPE / EPE 1191 and be diffracted in the -y direction and then in the -z direction out of the waveguide toward the user's eye along optical path 1195.

[0087]

[0166] As described more fully herein, embodiments of the present invention utilize eyepiece waveguides having optical path length differences, such as the thickness of the eyepiece waveguide as a function of lateral position, i.e., position in the x-y plane. In some embodiments, the portion of the eyepiece waveguide in which the ICG is formed is thicker than the portion of the eyepiece waveguide in which the CPE is formed. Furthermore, in some embodiments, the thickness of the CPE varies, with the portion adjacent to the ICG being thicker than the portion distal to the ICG. In other embodiments, the physical thickness is uniform, but the refractive index varies as a function of lateral position, resulting in an optical path length difference that characterizes the eyepiece waveguide as a function of lateral position.

[0088]

[0167] A wide variety of other configurations can be employed that utilize optical element 1130 for both illuminating SLM 1140 and capturing images formed by SLM 1140. For example, while Figures 11A-11D show a single waveguide 1120, one or more waveguides, such as a stack of waveguides (possibly different waveguides for different color light), may be used.

[0089]

[0168] 12A shows a cross-sectional side view of an exemplary system 1200A including a stack 1205 including waveguides 1120, 1122, and 1124, each including an incoupling optical element 1260, 1262, and 1264. The waveguides 1120, 1122, and 1124 may each be configured to output light at one or more different wavelengths or in one or more different wavelength ranges. The stack 1205 may be substantially similar to stacks 260 and 660 (FIGS. 6 and 9A), and the illustrated waveguides 1120, 1122, and 1124 of the stack 1205 may correspond to portions of the waveguides 670, 680, and 690, although the stack 1205 and the waveguides 1120, 1122, and 1124 need not be so limited. As shown in FIG. 12A , the incoupling optical elements 1260, 1262, and 1264 may be associated with, included in, or located on the waveguides 1120, 1122, and 1124, respectively, for example. The incoupling optical elements 1260, 1262, and 1264 may be color-selective and primarily redirect or redirect specific wavelengths to be guided into the corresponding waveguides 1120, 1122, and 1124. As shown, because the incoupling optical elements 1260, 1262, and 1264 are color-selective, the incoupling optical elements 1260, 1262, and 1264 do not need to be laterally displaced but may be stacked on top of each other. Wavelength multiplexing may be employed to couple specific colors into the corresponding waveguides. For example, a red incoupling optical element may incouple red light into a waveguide designated to propagate red light, but will not incoupling blue or green light, which will instead be coupled into other waveguides by other blue and green selective waveguides, respectively.

[0090]

[0169] In some implementations, the light source 1110 may be a multicolor light source capable of emitting different colors of light at different times. For example, the light source 1110 may emit red, green, and blue (RGB) light and may be configured to emit red and negligible amounts of green and blue during a first period, green and negligible amounts of red and blue during a second period, and blue and negligible amounts of red and green during a third period. These cycles may be repeated, and the SLM 1140 may generate a pattern of pixel states appropriate for a particular color (red, green, or blue) to provide the appropriate image color components for a given image frame. Different waveguides 1120, 1122, and 1124 of the stack 1205 may each be configured to output light of a different respective color. For example, as shown in FIG. 12A, the waveguides 1120, 1122, and 1124 may be configured to output blue, green, and red light, respectively. Of course, other colors are possible; for example, the light source 1110 may emit other colors, and the color-selective incoupling optics 1260, 1262, 1264, outcoupling optics, etc. may be configured for such other colors. Furthermore, individual red, green, and blue emitters may be positioned close enough together to effectively function as a single pupil light source. Red, green, and blue emitters can be combined with lenses and dichroic splitters to form a single red, green, and blue pupil light source. Single-pupil multiplexing may be extended beyond or in addition to color selectivity and may include the use of polarization-sensitive gratings and polarization switching. These color or polarization gratings can also be used in combination with multiple display pupils to increase the number of layers that can be addressed.

[0091]

[0170] The different incoupling optical elements 1260, 1262, 1264 in the different waveguides 1120, 1122, 1124 may be disposed above and / or below one another and laterally aligned (e.g., in the x and z directions shown in FIG. 12A ), as opposed to being laterally displaced and misaligned with one another. Thus, in some implementations, for example, the different incoupling optical elements 1260, 1262, 1264 may be configured such that light of a first color can be coupled into and guided into the waveguide 1120 by the incoupling optical element 1260, and light of a second color different from the first color can pass through the incoupling optical element 1260 to the next incoupling optical element 1262 and be coupled into and guided into the waveguide 1122 by the incoupling optical element 1262. Light of a third color, different from the first and second colors, may pass through incoupling optical elements 1260 and 1262 to incoupling optical element 1264 and be coupled into and guided into waveguide 1124. Furthermore, incoupling optical elements 1260, 1262, 1264 may be polarization-selective. For example, different incoupling optical elements 1260, 1262, 1264 may be configured such that light of a particular polarization is coupled into the waveguide by the corresponding polarization-selective incoupling optical element 1260, 1262, 1264 or passes through the incoupling optical element 1260, 1262, 1264.

[0092]

[0171] Depending on the configuration, SLM 1140 may include a polarization-based SLM that modulates polarization. System 1200A may include, for example, a polarizer and / or analyzer to modulate the light injected into stack 1205 for each pixel depending on the state of the respective pixel (e.g., whether the pixel rotates the polarization orientation or not). Various aspects of such systems employing polarization-based SLMs are described above, and any one of such features may be employed in combination with any other feature described herein. However, other designs are still possible.

[0093]

[0172] For example, a deflection-based SLM 1140 can be employed. For example, the SLM 1140 can include one or more movable optical elements, such as movable mirrors, that can reflect and / or deflect light along different directions depending on the state of the optical element. The SLM 1140 can include one or more pixels that include optical elements, such as micromirrors or reflectors. The SLM 1140 can incorporate digital light processing (DLP™) technology, for example, using a digital micromirror device (DMD). An example of a system 1200B using such a deflection-based SLM 1140 is shown in FIG. 12B. The system 1200B includes the deflection-based SLM 1140 and a light dump 1250. The light dump 1250 can include an absorptive material or structure configured to absorb light. The deflection-based SLM 1140 can include one or more micro-movable mirrors that can be selectively tilted to deflect light in different directions. For example, the deflection-based SLM 1140 may be configured to deflect light from the light source 1110 incident thereon to the incoupling optics 1260, 1262, 1264 when a given pixel is in a bright state. Thus, as described above, this light is coupled by one of the incoupling optics 1260, 1262, 1264 into one of the respective waveguides 1120, 1122, 1124, depending on, for example, the color of the light, and directed toward the eye 210. Conversely, when a given pixel is in a dark state, the light from the light source 1110 can be deflected to the light dump 1250, such that the light is not coupled by one of the incoupling optics 1260, 1262, 1264 into one of the respective waveguides 1120, 1122, 1124, and directed toward the eye 210. Alternatively, the light may be absorbed by an absorbing material comprising the light dump 1250. In some implementations, the analyzer 1150 may be a polarizer (e.g., a "cleaning" polarizer) used to remove unwanted reflections from the incoupling optics 1260, 1262, 1264. This polarizer may be useful because the optics 1130 may include plastic optical elements that have birefringence and can change the polarization of light.The "purifying" polarizer can attenuate or eliminate light with undesired polarizations (e.g., reflections) from being directed into the waveguides 1120, 1122, 1124. Other types of light conditioning elements may be disposed between the SLM 1140 and the waveguides 1120, 1122, 1124, such as between the optical element 1130 and the waveguides 1120, 1122, 1124. For example, such light conditioning elements may also include circular polarizers (i.e., linear polarization and retardation plates such as quarter-wave plates). The circular polarizer can reduce the amount of reflection from the waveguides 1120, 1122, 1124 or from the incoupling optical elements 1260, 1262, 1264 that re-enter and are coupled into the waveguides 1120, 1122, 1124. The reflected light may be circularly polarized or may have the opposite circular polarization to that of the incident light (e.g., right-handed circularly polarized light is converted to left-handed circularly polarized light upon reflection, or vice versa). A retarder in the circular polarizer can convert circularly polarized light to linearly polarized light, such as the polarizer's orthogonal polarization, which is attenuated, e.g., absorbed, by the circular polarizer's linear polarizer. Purifying polarizers can be used with polarization-independent modulators, such as DMDs. As mentioned above, purifying polarizers can be useful to suppress reflections and / or improve the coupling of light into the incoupling optics 1260, 1262, 1264 with optimal polarization states.

[0094]

[0173] 12B shows a side or cross-sectional view of such a system 1200B, and FIG. 12C shows a top view of the lateral arrangement of the incoupling optics 1264, the light dump 1250, and the light source 1110. The SLM 1140 is configured to reflect, deflect, and / or direct light from the light source 1110 either to the incoupling optics 1264 (as well as other incoupling optics 1260, 1262) or to the lateral position of the light dump 1250, depending on the state of a particular pixel.

[0095]

[0174] In certain designs, the light dump 1250 may include an energy harvesting system. The light dump 1250 may include, for example, a light energy conversion element configured to convert light energy into electrical energy. The light energy conversion element may include, for example, a solar cell. The light energy conversion element may include, for example, a photovoltaic detector that generates an electrical output when light is incident on it. The light energy conversion element may be electrically connected to an electrical component, for example, a conductive wire, to direct the electrical output to power the system 1200B and / or possibly charge one or more batteries.

[0096]

[0175] Certain designs may use laterally displaced, non-color-selective, or broadband or multicolor incoupling optics. FIG. 13A is a perspective view of a system 1300 including, for example, a stack 1305 including waveguides. The stack 1305 may be substantially similar to the stack 1205, with reference to FIG. 12A. Each waveguide in the stack 1305 may include an incoupling optic 1360, 1362, 1364, but in contrast to the design shown in FIG. 12A, the incoupling optics 1360, 1362, 1364 are laterally displaced relative to one another. 13A, 13B, and 13C, the light sources 1110, 1112, 1114 may also be laterally displaced relative to one another and positioned to direct light to respective incoupling optics 1360, 1362, 1364 by passing the light through optical element 1130, reflecting the light off the SLM 1140, and passing the reflected light back through optical element 1130. The system 1300 in FIG. 13B is shown with light source 1114 located behind light source 1110 and therefore not shown in FIG. 13B. The light sources 1110, 1112, 1114 may correspond to incoupling optics 1360, 1362, 1364, respectively. In one design, for example, the light sources 1110, 1112, 1114 and corresponding incoupling optics 1360, 1362, 1364 are positioned approximately equidistant (symmetrically) from the center of the optical element 1130 along a common (optical) axis. The common (optical) axis may intersect the center of the optical element 1130. In one design, for example, the light sources 1110, 1112, 1114 and corresponding incoupling optics 1360, 1362, 1364 are not positioned equidistant (symmetrically) from the center of the optical element 1130 along the common (optical) axis.

[0097]

[0176] The incoupling optical elements 1360, 1362, 1364 may be configured to couple light of multiple colors into their respective waveguides. Accordingly, these incoupling optical elements 1360, 1362, 1364 may be referred to herein as broadband, multicolor, or non-color-selective incoupling optical elements 1360, 1362, 1364. For example, in some cases, these incoupling optical elements 1360, 1362, 1364 are configured to incouple red light, green light, and blue light into the associated waveguide in which the incoupling optical element 1360, 1362, 1364 is included, such that light of such colors is guided within the waveguide by TIR. Such broadband incoupling optical elements 1360, 1362, 1364 may operate over a wide range of wavelengths, for example, within the visible range, or may select wavelengths or wavelength regions that span, for example, the visible range. Thus, such broadband or multicolor or non-color-selective incoupling optics 1360, 1362, 1364 may be configured to convert light of a variety of different colors (e.g., red, green, and blue) into a waveguide and guide it by TIR. Although red, green, and blue (RGB) are referenced herein in connection with light sources, incoupling optics, waveguides, etc., other colors or color systems, such as, for example, but not limited to, magenta, cyan, and yellow (CMY), may additionally or alternatively be used.

[0098]

[0177] As shown in FIG. 13A, light sources 1110, 1112, and 1114 are shown above the top waveguide and are displaced relative to one another (e.g., in the x and z directions). Similarly, three incoupling optical elements 1360, 1362, and 1364 are shown above the three respective waveguides and are displaced relative to one another (e.g., in the x, y, and z directions). FIG. 13B is a side view of the system 1300 shown in FIG. 13A, showing the incoupling optical elements 1360, 1362, and 1364 spatially displaced laterally relative to one another (e.g., in the x and z directions), as well as some of the light sources 1110, 1112, and 1114 laterally displaced relative to one another (e.g., in the x and z directions). FIG. 13B also shows the optical element 1130 and the SLM 1140.

[0099]

[0178] 13C is a top view of the augmented reality display system shown in FIGS. 13A and 13B , showing the incoupling optical elements 1360, 1362, 1364 and associated light sources 1110, 1112, 1114. In this design, the incoupling optical elements 1360, 1362, 1364 and associated light sources 1110, 1112, 1114 are arranged in a ring-like pattern around a center point of a common (optical) axis. As shown, the light sources 1110, 1112, 1114 and corresponding incoupling optical elements 1360, 1362, 1364 are, and should be, approximately equidistantly arranged around the center point of the common (optical) axis. In some designs, this center point may correspond to the center of the optical element 1130 and / or the center of the optical element 1130 along the common (optical) axis that intersects with the position of the optical element 1130 along the optical axis. Also as a result, the non-color-selective incoupling optics 1360, 1362, 1364 and the light sources 1110, 1112, 1114 are laterally displaced relative to one another (eg, in the x and z directions).

[0100]

[0179] Other arrangements of lateral placement are possible. Figures 14A-14C show alternative configurations of a system 1400 including a stack 1405 including waveguides in which incoupling optical elements 1360, 1362, 1364 and light sources 1110, 1112, 1114 are laterally displaced relative to one another. Figure 14A is a side view, and Figure 14B is a top view of the system 1400 shown in Figure 14A, showing the laterally displaced incoupling optical elements 1360, 1362, 1364 and light sources 1110, 1112, 1114. Figure 14C is an orthogonal side view of the system 1400 shown in Figures 14A and 14B.

[0101]

[0180] The side views of Figures 14A and 14C show how incoupling optical elements 1360, 1362, 1364 are positioned on separate waveguides in stack 1405 so that light can be coupled into corresponding waveguides by each laterally displaced incoupling optical element 1360, 1362, 1364. The incoupling optical elements 1360, 1362, 1364 are shown positioned on the upper major surfaces of the waveguides in Figures 14A and 14C. However, the incoupling optical elements 1360, 1362, 1364 may alternatively be positioned on the lower major surfaces of the respective waveguides or within the bulk of the waveguides. A wide variety of configurations are possible.

[0102]

[0181] 14B, the incoupling optics 1360, 1362, 1364 are arranged in a column that is laterally displaced relative to one another along the z-direction but not along the x-direction. Similarly, the light sources 1110, 1112, 1114 are arranged in a column that is also laterally displaced relative to one another along the z-direction but not along the x-direction. The incoupling optics 1360, 1362, 1364 are laterally displaced in the x-direction relative to the light sources 1110, 1112, 1114.

[0103]

[0182] Still other configurations are possible. Figure 15 is a top view of a system 1500 illustrating an alternative configuration of light sources 1110, 1112, 1114 and incoupling optics 1360, 1362, 1364. In contrast to Figure 13C, in which all of the light sources 1110, 1112, 1114 are generally on one side (e.g., in a ring-like pattern) and all of the incoupling optics 1360, 1362, 1364 are generally on one side (i.e., opposite sides), the light sources 1110, 1112, 1114 and incoupling optics 1360, 1362, 1364 are interspersed or alternating around the circumference of a ring-like pattern.

[0104]

[0183] However, in some implementations, the incoupling optical elements 1360, 1362, 1364 and associated light sources 1110, 1112, 1114 are also arranged in a ring-like pattern around a center point. As a result, the light sources 1110, 1112, 1114 and corresponding incoupling optical elements 1360, 1362, 1364 may be arranged approximately equidistant from the center. In some designs, this center may correspond to the center of the optical element 1130 and / or the center of the optical element 1130 along a common central axis that intersects the position along the optical axis of the optical element 1130. Thus, light from the first light source 1110 may be coupled into the incoupling optical element 1360 through the optical element 1130, transverse to the center or central axis or optical axis of the optical element 1130 (as can be seen from the top view in FIG. 15 ). Similarly, light from the second light source 1112 may be coupled through the optical element 1130 to the incoupling optic 1362 across the center or central axis or optical axis of the optical element 1130. Similarly, light from the third light source 1114 may be coupled through the optical element 1130 to the incoupling optic 1364 across the center or central axis or optical axis of the optical element 1130. Also, as a result, the non-color-selective incoupling optics 1360, 1362, 1364 and the light sources 1110, 1112, 1114 are laterally displaced relative to one another (e.g., in the x and z directions). The optical element 1130 can be designed so that the focal point is closer within the stack 1405, so that the positions of the sub-pupil and the incoupling optics 1360, 1362, 1364 are closer together in the y direction. In this configuration, the incoupling optics 1360, 1362, 1364 may be smaller because they are closer to the focal point of the optical element 1130. The light source 1110 may be on the user side of the stack 1405 (e.g., similar to FIGS. 17 and 18), thus reducing the distance or optical path between the light source 1110 and the optical element 1130.

[0105]

[0184] In various implementations described above, such as those shown in FIGS. 12A-15 , stacks (e.g., stacks 1205, 1305, 1405) including multiple waveguides (e.g., stack 1205 including waveguides 1120, 1122, 1124; stack 1305 including a waveguide (not numbered); and stack 1405 including a waveguide (not numbered)) may be included to handle different colors (e.g., red, green, and blue). Different waveguides may be for different colors. Similarly, multiple stacks can be included to provide different optical properties to the light outcoupled from each stack. For example, waveguides 1120, 1122, 1124 of stack 1205 in FIGS. 12A-12B may be configured to output light with optical properties (e.g., optical power to provide a particular wavefront shape) perhaps associated with the apparent depth from which the light appears to diverge. For example, wavefronts with different amounts of divergence, convergence, or collimation may appear to be projected from different distances from the eye 210. Thus, multiple stacks may be included, with different stacks configured so that light outcoupled by the outcoupling optics has different amounts of convergence, divergence, or collimation and therefore appears to originate from different depths. In some designs, the different stacks may include different lenses, such as diffractive lenses or other diffractive optical elements, to provide different amounts of optical power to the different stacks. As a result, the different stacks produce different amounts of convergence, divergence, or collimation, and therefore, the light from the different stacks appears to be associated with different depth surfaces or objects that are different distances from the eye 210.

[0106]

[0185] FIG. 16A is a side view of a system 1600 including stacks 1605, 1610, and 1620. As shown in FIG. 16A, the system 1600 includes three stacks 1605, 1610, and 1620, but this need not be the case. Systems may be conceived with fewer or more stacks. Each of the stacks 1605, 1610, and 1620 includes one or more (e.g., three) waveguides. FIG. 16A also shows groups 1630, 1640, and 1650 of incoupling optical elements. The first group 1630 is associated with the first stack 1605, the second group 1640 is associated with the second stack 1610, and the third group 1650 is associated with the third stack 1620. The groups 1630, 1640, and 1650 are laterally displaced relative to each other. Each of the groups 1630, 1640, and 1650 includes color-selective incoupling optical elements configured to incouple different respective colors, substantially similar to the incoupling optical elements 1260, 1262, and 1264 of FIG. 12A . As shown in FIG. 16A , the incoupling optical elements within each group 1630, 1640, and 1650 are not laterally displaced relative to one another, but this need not be the case. Systems may be devised in which the incoupling optical elements within a group are laterally displaced relative to one another. The system 1600 can be configured so that the light outcoupled from each of the stacks 1605, 1610, and 1620 has different amounts of optical power. For example, the waveguides within the stacks can have outcoupling optical elements or diffractive lenses with a given optical power. The optical powers for the different stacks 1605, 1610, and 1615 can be different so that light from one stack can appear to originate at a different depth than light from another stack. For example, the optical power of one stack may collimate the light from that stack, while the optical power of another stack may diverge the light from that stack. The diverging light may appear to emanate from an object that is a close distance from the eye 210, while the collimated light may appear to emanate from an object that is a far distance.Thus, the light outcoupled from the first stack 1605, the second stack 1610, and the third stack 1620 may have different amounts of convergence, divergence, and / or collimation and therefore appear to originate from different depths. In some implementations, the light outcoupled from one of the stacks may be collimated, while the light outcoupled by a different stack may diverge. The light outcoupled from one of the other stacks may also diverge, but by a different amount.

[0107]

[0186] As shown in FIG. 16A , light source 1110 may be positioned relative to optical elements 1130 and SLM 1140 to direct light to group 1630 of incoupling optical elements, light source 1112 may be positioned relative to optical elements 1130 and SLM 1140 to direct light to group 1640 of incoupling optical elements, and light source 1114 may be positioned relative to optical elements 1130 and SLM 1140 to direct light to group 1650 of incoupling optical elements. Light sources 1110, 1112, and 1114 may be configured to emit light of different colors at different times. Similarly, light of different respective colors may be coupled into different waveguides within the stack as a result of color-selective incoupling optical elements in the manner described above. For example, if blue light is emitted from second light source 1112, optical element 1130 and SLM 1140 direct the blue light to second group 1640 of incoupling optical elements. The light may pass through a first red incoupling optical element and a second green incoupling optical element in the second group 1640 and be directed by a third blue incoupling optical element in the second group 1640 to a third waveguide in the second stack 1610. The waveguide in the second stack 1610 may include an outcoupling optical element or other optical element with optical power (e.g., a diffractive lens) to provide a beam to an eye 210 associated with a particular depth plane or object distance associated with the second stack 1610.

[0108]

[0187] Figure 16B is a top view of the system 1600 of Figure 16A. Different groups of incoupling optical elements 1630, 1640, 1650 are shown laterally displaced relative to one another (e.g., in the x-direction). Similarly, light sources 1110, 1112, 1114 are shown laterally displaced relative to one another (e.g., in the x-direction).

[0109]

[0188] A wide variety of different variations on the above-described systems are possible. For example, the position of the light source 1110 relative to the waveguide(s) and optical element 1130 may be different. FIG. 17, for example, is a side view of a system 1700 having a different position of the light source 1110 relative to the waveguide 1720 and optical element 1130 than those shown in FIGS. 11-16B. Furthermore, FIG. 17 shows a design in which the waveguide 1720 is split into a first portion 1720a and a second portion 1720b. The waveguide 1720 may further include a reflector 1730 configured within the first portion 1720a proximal to the light source 1110 to couple light guided from the first portion 1720a into the optical element 1130 toward the SLM 1140. Additionally or alternatively, the system 1700 may include a diffractive outcoupling optical element for outcoupling light in the first portion 1720a of the waveguide 1720 into the optical element 1130 toward the SLM 1140. This reflector 1730 may be opaque and may include an isolator to reduce crosstalk between the first portion 1720a and the second portion 1720b. The waveguide 1720 has a first side 1721 and a second side 1723 opposite the first side 1721, and the optical element 1130 and the SLM 1140 are positioned on the first side 1721 such that light from the SLM 1140 is directed toward the first side 1721. In this example, the light source 1110 may be positioned on the first side 1721 of the waveguide 1720 such that light from the light source 1110 enters the first side 1721 before passing through the optical element 1130 to the SLM 1140. The system 1700 may further include an incoupling optic 1710 disposed on or in the first portion 1720a. The incoupling optic 1710 may be configured to receive light from the light source 1110 and couple the light into the first portion 1720a. The incoupling optic 1710 may include a diffractive optical element or a reflector configured to direct incident light toward the first portion 1720a at an angle that is guided therein by TIR.

[0110]

[0189] The reflector 1730 may be configured to direct light guided into the first portion 1720a from the first portion 1720a toward the optical element 1130 and the SLM 1140. (As mentioned above, in some implementations, a diffractive optical element may additionally or alternatively be used to direct light in the first portion 1720a from the first portion 1720a toward the optical element 1130 and the SLM 1140.) Thus, the reflector 1730 may be a mirror, a reflective grating, or one or more coatings that reflect light from the waveguide 1720 toward the SLM 1140. Light emitted from the first portion 1720a by the reflector 1730 passes through the optical element 1130 to enter the SLM 1140, and then passes through the optical element 1130 again to enter the second portion 1720b. As described above, light reflected from SLM 1140 that is transmitted through optical element 1130 may be incident on incoupling optical element 1160, which may direct the light to be guided into second portion 1720b. Light that is guided into second portion 1720b may be outcoupled therefrom by outcoupling optical element 1180 (not shown) and directed toward eye 210.

[0111]

[0190] As described above, the reflector 1730 may be an isolator that reduces crosstalk between the first portion 1720 a and the second portion 1720 b. The reflector 1730 may include an opaque and / or reflective surface. The reflector 1730 may be disposed within the waveguide 1720 and, in some cases, may define sides of the first portion 1720 a and the second portion 1720 b.

[0112]

[0191] Instead of having first and second portions 1720a and 1720b of the waveguide 1720, separate waveguides may be used. Figure 18 is a side view of a system 1800 including a first waveguide 1822 for receiving light from the light source 1110 and directing the light guided therein to the optical element 1130 and the SLM 1140. The system 1800 further includes a second waveguide 1820 that receives light from the SLM 1140 after the light passes through the optical element 1130 again. The first waveguide 1822 includes incoupling and outcoupling optical elements 1730a and 1730b, respectively. These incoupling and outcoupling optical elements 1730a and 1730b may include reflective surfaces oriented to incoupling and outcoupling light into and out of the waveguide 1822. The incoupling optical element 1730a may, for example, be positioned to receive light from the light source 1110 and may include a reflective surface oriented (e.g., tilted) to direct the light into the waveguide 1822 at an angle such that it is guided therein by TIR. The outcoupling optical element 1730b may, for example, include a reflective surface oriented (e.g., tilted) to direct the light guided into the waveguide 1822 at an angle such that it is emitted from the waveguide 1822. The outcoupling optical element 1730b may be positioned such that light exiting the waveguide 1822 is directed into the optical element 1130, reflected from the SLM 1140, passes through the optical element 1130 again, and is incident on the incoupling optical element 1730c of the second waveguide 1820.

[0113]

[0192] The incoupling optical element 1730c in the second waveguide 1820 may include a reflective surface that may be positioned and oriented (e.g., tilted) to direct light received from the SLM 1140 so that it is guided into the second waveguide 1820 by TIR. FIG. 18 shows the optical element 1130 and the light source 1110 positioned on the same side of the waveguides 1820, 1822. The system 1800 may further include an isolator to reduce crosstalk between the waveguide 1822 and the waveguide 1820. The isolator may include an opaque and / or reflective surface. The isolator may be positioned in or on at least one of the waveguides 1820, 1822.

[0114]

[0193] Various designs, such as those described above, can include additional features or components. FIG. 19, for example, shows a side view of a system 1900 including variable-focus optical elements (or adaptive optical elements) 1910, 1920. The variable-focus optical elements 1910, 1920 can include optical elements configured to be altered to provide variable optical power. The variable-focus optical elements 1910, 1920 can include multiple states, such as a first state and a second state, where in the first state, the variable-focus optical elements 1910, 1920 have a different optical power than in the second state. For example, the variable-focus optical elements 1910, 1920 can have a negative optical power in the first state and zero optical power in the second state. In some implementations, the variable-focus optical elements 1910, 1920 have a positive optical power in the first state and zero optical power in the second state. In some implementations, the variable-focus optic 1910, 1920 has a first negative or positive optical power in a first state and a second, different negative or positive optical power in a second state. Some adaptive or variable-focus optics 1910, 1920 can have more than two states, and in some cases can provide a continuous distribution of optical power.

[0115]

[0194] The variable-focus optical elements 1910, 1920 may include lenses (e.g., variable lenses) and may be transmissive. Transmissive or transparent adaptive or variable-focus optical elements 1910, 1920 are shown in FIG. 7. The variable-focus optical elements 1910, 1920 may include liquid lenses (e.g., movable membranes and / or electrowetting). The variable-focus lenses may also include liquid crystal lenses, such as switchable liquid crystal lenses, e.g., switchable liquid crystal polarized lenses, which may include diffractive lenses. Alverez lenses may also be used. Other types of variable-focus optical elements 1910, 1920 may be employed in some cases. Examples of variable-focus optical elements can be found in U.S. Patent Application No. 62 / 518,539, filed June 12, 2017, entitled "AUGMENTED REALITY DISPLAY HAVING MULTI-ELEMENT ADAPTIVE LENS FOR CHANGING DEPTH PLANES," the entire contents of which are incorporated herein by reference. The variable-focus optical elements 1910, 1920 can have electrical inputs that receive electrical signals that control the amount of optical power exhibited by the variable-focus optical elements 1910, 1920. The variable-focus optical elements 1910, 1920 can have positive and / or negative optical power. In addition to variable-focus elements (e.g., polarization switches, geometric phase (GP) lenses, fluid lenses, etc.), the variable-focus elements 1910, 1920 can include fixed lenses (e.g., diffractive lenses, refractive lenses, etc.) to generate desired depth planes in the light field.

[0116]

[0195] A first variable-focus optical element 1910 may be disposed between the stack 1905 and the eye 210. The stack 1905 may include different waveguides for different colors, as described above. The first variable-focus optical element 1910 may be configured to introduce different amounts of optical power, negative and / or positive optical power. The variable optical power can be used to vary the divergence and / or collimation of light coupled out of the stack 1905 to vary the depth at which a virtual object projected by the system 1900 into the eye 210 appears to be located. Accordingly, a four-dimensional (4D) light field can be created.

[0117]

[0196] The second variable-focus optical element 1920 is on the opposite side of the stack 1905 from the first variable-focus optical element 1920. Thus, the second variable-focus optical element 1920 can compensate for the effect of the first optical element 1910 on light received from the system 1900 and the table 510 in front of the eye 210. Thus, the worldview can be effectively unchanged or altered, as desired.

[0118]

[0197] The system 1900 may further include a static or variable prescription or corrective lens 1930. Such a lens 1930 can provide refractive correction for the eye 210. Furthermore, if the prescription lens 1930 is a variable lens, it can provide different refractive corrections for multiple users. Variable focus lenses are described above. The eye 210 may have, for example, myopia, hyperopia, and / or astigmatism. The lens 1930 can have a prescription (e.g., optical power) to reduce the refractive error of the eye 210. The lens 1930 may be spherical and / or cylindrical and may be positive or negative. The lens 1930 may be positioned between the stack 1905 and the eye 210 such that light from both the table 510 and the stack 1905 receives the correction provided by the lens 1930. In some implementations, the lens 1930 may be positioned between the eye 210 and the first variable focus optic 1910. Other positions of the lens 1930 are also possible. In some embodiments, the prescription lenses may be variable, allowing multiple user prescriptions to be implemented.

[0119]

[0198] In some designs, the system 1900 may include an adjustable dimmer 1940. In some implementations, this adjustable dimmer 1940 may be located on a side of the stack of waveguides 1900 opposite the eye 210 (e.g., the front side). Thus, this adjustable dimmer 1940 may be located between the stack of waveguides 1900 and the front 510. The adjustable dimmer 1940 may include an optical element that provides variable attenuation of light transmitted therethrough. The adjustable dimmer 1940 may include an electrical input for controlling the level of attenuation. In some cases, the adjustable dimmer 1940 is configured to increase the attenuation when the eye 210 is exposed to bright light, such as when the user goes outdoors. Thus, the system 1900 may include a light sensor that senses the brightness of ambient light and may control electronics to drive the adjustable dimmer 1940 to vary the attenuation based on the light level sensed by the light sensor.

[0120]

[0199] Different types of adjustable dimmer 1940 can be employed. Such adjustable dimmer 1940 can include a variable liquid crystal switch with a polarizer, an electrochromic material, a photochromic material, or the like. The adjustable dimmer 1940 can be configured to adjust the amount of light entering from the table 510 and / or transmitted through the stack 1905. The adjustable dimmer 1940 can be used to reduce the amount of ambient light passing through the waveguide stack 1900 to the eye 210, which in some cases can otherwise provide glare and reduce the user's ability to perceive virtual objects / images injected into the eye 210 from the stack 1905. Such an adjustable dimmer 1940 can reduce incoming bright ambient light from washing out the image projected into the eye 210. Thus, the contrast of the virtual object / image presented to the eye 210 can be increased with the adjustable dimmer 1940. In contrast, when ambient light is low, the adjustable dimmer 1940 may be adjusted to reduce attenuation so that the eye 210 can more easily see objects in the table 510 in front of the user. Dimming or attenuation may be system-wide or localized to one or more portions of the system. For example, multiple local portions may be dimmed or set to attenuate light from the table 510 in front of the user's eye 210. These local portions may be separated from each other by portions without such increased dimming or attenuation. In some cases, only one portion is dimmed or made to provide increased attenuation relative to other portions of the eyepiece. Other components may be added with different designs. Also, the placement of the components may be different. Similarly, one or more components may be excluded from the system.

[0121]

[0200] Another exemplary configuration is shown in Figure 20A. Figure 20A shows a side view of a system 2000 including laterally displaced incoupling optical elements 1360, 1362, 1364 on different waveguides and a color filter array 2030 including laterally displaced color filters 2040, 2042, 2044 aligned with the respective incoupling optical elements 1360, 1362, 1364. The color filter array 2030 may be disposed on a side of the stack 2005 proximate the eye 210 and the optical element 1130. The color filter array 2030 may be between the stack 2005 and the optical element 1130. The color filter array 2030 may be disposed in or on a cover glass 2050 disposed between the stack 2005 and the optical element 1130. The color filter array 2030 can include one or more different color filters 2040, 2042, 2044, such as red, green, and blue color filters, arranged laterally relative to one another. The system 2000 includes light sources 1110, 1112, 1114 laterally displaced relative to one another. These light sources 1110, 1112, 1114 can include light sources of different colors, such as red, green, and blue light sources. The color filters 2040, 2042, 2044 can be transmissive or transparent filters. In some implementations, the color filters 2040, 2042, 2044 include absorptive filters, although the color filters 2040, 2042, 2044 can also include reflective filters. The color filters 2040, 2042, 2044 in the color filter array 2030 can be separated and / or surrounded by masks, such as opaque masks, that reduce the propagation of stray light. The filters in the color filter array 2030 may be used to reduce or eliminate unwanted reflections within the system, such as from the waveguides and / or incoupling optical elements 1360, 1362, 1364, from re-entering the waveguides used for different colors via the incoupling optical elements 1360, 1362, 1364 for different colors.Examples of color filter arrays can be found in U.S. Patent Application No. 15 / 683,412, filed August 22, 2017, entitled "PROJECTOR ARCHITECTURE INCORPORATING ARTIFACT MITIGATION," and U.S. Patent Application No. 62 / 592,607, filed November 30, 2017, entitled "PROJECTOR ARCHITECTURE INCORPORATING ARTIFACT MITIGATION," both of which are incorporated by reference in their entireties. The mask may be a black mask or may include an absorbing material to reduce stray light propagation and reflection. The light sources 1110, 1112, and 1114 can be positioned relative to the optical element 1130 and the SLM 1140 to couple light into corresponding color filters 2040, 2042, and 2044 in the color filter array 2030. For example, the color filter array 2030 may include first, second, and third (e.g., red, green, and blue) color filters 2040, 2042, 2044 arranged to receive light from the first, second, and third light sources 1110, 1112, 1114, respectively. The first, second, and third (e.g., red, green, and blue) color filters 2040, 2042, 2044 may be aligned (e.g., in the x and z directions) with the respective incoupling optical elements 1360, 1362, 1364. Thus, light from the first light source 1110 is directed through a first color filter 2040 to a first incoupling optical element 1360, light from the second light source 1112 is directed through a second color filter 2042 to a second incoupling optical element 1362, and light from the third light source 1114 is directed through a third color filter 2044 to a third incoupling optical element 1364. In some implementations, the incoupling optical elements 1360, 1362, 1364 may be color-specific. For example, the first and second incoupling optical elements 1360, 1362 may be configured to couple light of respective first and second colors into the first and second waveguides, respectively.Similarly, the first, second, and third incoupling optical elements 1360, 1362, 1364 may be configured to couple light of the respective first, second, and third colors into the first, second, and third waveguides, respectively. The first incoupling optical element 1360 may be configured to couple more light of the first color into the first waveguide than the second color (or third color). The second incoupling optical element 1362 may be configured to couple more light of the second color into the second waveguide than the first color (or third color). The third incoupling optical element 1364 may be configured to couple more light of the third color into the second waveguide than the first or second colors. In other configurations, the incoupling optical elements 1360, 1362, 1364 may be broadband. For example, the first incoupling optical element 1360 may be configured to couple light of the first, second, and third colors into the first waveguide. The second incoupling optical element 1362 may be configured to couple light of the first, second, and third colors into the second waveguide. The third incoupling optical element 1364 may be configured to couple light of the first, second, and third colors into the third waveguide. However, the multiple color filters 2040, 2042, 2044 may be color-specific, selectively transmitting light of a particular color. For example, the first color filter 2040 may transmit more of the first color than the second color (and the third color). The second color filter 2042 may transmit more of the second color than the first color (and the third color). The third color filter 2044 may transmit more of the third color than the first and second colors. Similarly, the first, second, and third color filters 2040, 2042, 2044 may be color filters that selectively transmit the first, second, and third colors, respectively. Thus, the first, second, and third color filters 2040, 2042, 2044 may be bandpass filters that selectively pass the first, second, and third colors, respectively. In some implementations, the first, second, and third light sources 1110, 1112, 1114 may selectively emit the first, second, and third colors, respectively.For example, the first light source 1110 may emit more of the first color than the second color (and the third color). The second light source 2042 may emit more of the second color than the first color (and the third color). The third light source 2044 may transmit more of the third color than the first and second colors. The color filters 2040, 2042, 2044 can reduce the amount of stray light inadvertently directed toward a particular incoupling optic. In other implementations, one or more of the light sources 1110, 1112, 1114 are broadband light sources. For example, the first light source 1110 may emit the first and second colors (and possibly a third color). The second light source 1112 may also emit the first and second (and possibly a third) colors. The third light source 1114 may also emit the first and second (and possibly a third) colors. Although three filters are shown in FIGS. 20A-20G, more or fewer filters may be included. For example, in some implementations, two filters (rather than three) may be used. Thus, two colors corresponding to the two color filters may be selectively transmitted by the filters. In some such implementations, two corresponding incoupling optical elements may be used and aligned with the two filters. In some implementations, the two incoupling optical elements each selectively couple two colors into two respective waveguides. In some implementations, two light sources may be used instead of three. Other variations and other numbers of components may be used. Also, the color filters 2040, 2042, 2044 may or may not be integrated into a single array.

[0122]

[0201] As mentioned above, the components and their positions and arrangements may vary. For example, while FIG. 20A shows the analyzer 1150 positioned between the optical element 1130 and the stack 1905, the analyzer 1150 may be positioned in a different location. FIG. 20B also shows the analyzer 1150 positioned between the optical element 1130 and the SLM 1140. In some designs, the analyzer (e.g., a polarizer) 1150 may be directly attached to the SLM 1140. For example, the analyzer 1150 may be glued or mechanically coupled to the SLM 1140. For example, the analyzer 1150 may be glued or bonded to the SLM 1140 (e.g., to a window of the SLM) using an adhesive. Thus, while FIG. 20B shows an air gap between the analyzer 1150 and the SLM 1140, in some designs, there is no air gap between the analyzer 1150 and the SLM 1140. The analyzer 1150 may be mechanically fixed to the SLM 1140 (e.g., using a mechanical fixture), in which case there may or may not be an air gap between the analyzer 1150 and the SLM 1140. Birefringence from the optical element 1130 can be purified by positioning a polarizer directly on the SLM 1140, as described above. In some implementations, the analyzer 1150 positioned between the optical element 1130 and the incoupling optical elements 1360, 1362, 1364 can also be included to purify the polarization of light outgoing from the optical element 1130 (e.g., as shown by the dashed lines in FIG. 20B ). Additionally, a retarder (not shown), such as a quarter-wave plate, may be included proximate the SLM 1140, e.g., between the optical element 1130 and the SLM 1140. As used herein, a quarter-wave plate can refer to a quarter-wave retarder, regardless of whether the quarter-wave retarder includes a plate, film, or other structure to provide the quarter-wave of the retarder. In FIG. 20B, for example, a retarder (e.g., a quarter-wave plate) may be disposed between the analyzer 1150 and the SLM 1140. The retarder (e.g., a quarter-wave plate) can be used for skew ray management. For example, the retarder (e.g., a quarter-wave plate) can compensate for variations caused by differences in wavelength and angle of incidence on the SLM 1140.As described above, a compensator may be included to provide more consistent polarization rotation (e.g., 90°) of the SLM 1140 for different angles of incidence and different wavelengths. The compensator may be used to increase the contrast of the display by providing more consistent orthogonal rotation. The compensator may be attached or secured to the SLM 1140 as described above. For example, glue, cement, or another adhesive may be used. The compensator may also be attached to the SLM 1140 using a mechanical fastener. An air gap may or may not be included between the compensator or the SLM 1140. Other light-conditioning optical elements may additionally or alternatively be included and attached to the SLM 1140 as described above with respect to the analyzer 1150 and / or the compensator.

[0123]

[0202] In some embodiments, a large angular spread (e.g., −70 degrees) can be used. The angular spread can refer, for example, to the angle of light entering the optical element 1130 from the light sources 1110, 1112, 1114 and / or the angle of light exiting the optical element 1130 to the incoupling optics 1360, 1362, 1364. In these embodiments, a thinner SLM 1140 can be used. For example, if the SLM 1140 is a liquid crystal (LC) SLM (e.g., a liquid crystal on silicon (LCoS) SLM), the LC layer can be thinned to accommodate the large angular spread.

[0124]

[0203] The double-pass phase difference through the polarizer and analyzer 1150 may need to be half-wave. The polarizer may be between the optical element 1130 and the analyzer 1150. The double-pass phase difference may be a function of the ratio of the refractive index of the LCoS SLM 1140 to the thickness of the LCoS SLM 1140. For a given refractive index of the LCoS SLM 1140 and a given thickness of the LCoS SLM 1140, entering and exiting the LCoS SLM 1140 at a large angle results in a longer path length for light than entering and exiting the LCoS SLM 1140 at a small angle. The path length is related to the thickness of the LCoS SLM 1140. In one example, the LCoS SLM may have a first refractive index and a first thickness. For small angles, the double-pass phase difference of an LCoS SLM with a first refractive index and a first thickness may be half-wave. For large angles, the double-pass retardation of an LCoS SLM having a first refractive index and a first thickness does not have to be half-wave (e.g., it may be greater than half-wave). The thickness of the LCoS SLM can change from a first thickness to a second thickness, the second thickness being thinner than the first thickness. For small angles, the double-pass retardation of an LCoS SLM having a first refractive index and a second thickness does not have to be half-wave (e.g., it may be less than half-wave). For large angles, the double-pass retardation of an LCoS SLM having a first refractive index and a second thickness may be half-wave.

[0125]

[0204] Also, while FIGS. 20A and 20B illustrate the use of a polarization-based SLM 1140, other types of SLMs may be utilized. FIG. 20C illustrates the use of a deflection-based SLM 1140, such as a movable micromirror-based SLM. As discussed above, such an SLM 1140 may include digital light processing (DLP™) and digital micromirror device (DMD) technology. As discussed above, the deflection-based SLM 1140 can couple light from one of the light sources 1110, 1112, and 1114 into the respective incoupling optics 1360, 1362, and 1364 depending on the state of the pixels of the SLM 1140. In one state, light from the light sources 1110, 1112, and 1114 is directed to the respective incoupling optics 1360, 1362, and 1364, as shown in FIG. 20D. In another state, light from the light sources 1110, 1112, 1114 is directed away from the incoupling optics 1360, 1362, 1364, as shown in FIG. 20E. In some implementations, while in the off state, a black absorbing mask between the color filters 2040, 2042, 2044 in the color filter array 2030 can function as a light dump. As described above, the color filters 2040, 2042, 2044 may be surrounded and / or separated by a mask, such as an absorbing mask (e.g., a black mask). The mask may include an absorbing material such that incident light is absorbed rather than reflected therefrom. The mask may be opaque.

[0126]

[0205] Other variations are possible. While the light sources are shown as emitters 1110, 1112, 1114 (e.g., LEDs, laser diodes) coupled to coupling optics 1105, such as a non-imaging optical coupling element (e.g., a compound parabolic concentrator (CPC) or cone), other configurations are possible. For example, the coupling optics 1105 (e.g., a CPC) may be tilted relative to the waveguide stack. In some cases, the projector (i.e., the optical element 1130 and the SLM 1140) may be tilted relative to the eyepiece (e.g., the waveguide stack). In some implementations, the lens optical element 1130 is tilted relative to the SLM 1140 to reduce distortions such as keystone distortion. A Scheimpflug configuration can be employed to reduce such distortions. Components can be tilted as needed (e.g., the optical element 1130 and / or the spatial light modulator 1140), for example, to fit more conformally around the head and / or face. As mentioned above, the light emitter(s) and / or the coupling optics 1105 may be tilted. In some configurations, the assembly including the waveguide may be tilted, with the side closer to the side of the eye 210 (e.g., temporal) closer to the eye 210 to increase the perceived field of view of the entire binocular system (at the expense of overlap of the eyes).

[0127]

[0206] As noted above, the components and their positions and arrangements may vary. For example, FIG. 20F is a side view of system 2000F including a cover glass 2050 disposed between stack 2005 and optical element 1130. In some designs, light sources 1110, 1112, 1114 may be disposed on the front side of cover glass 2050 and configured to propagate light through cover glass 2050 to optical element 1130 and SLM 1140. As shown, cover glass 2050 may extend laterally (e.g., parallel to the x-axis) beyond stack 2005 so that light emitted by light sources 1110, 1112, 1114 enters optical element 1130 without passing through a waveguide within stack 2005. While system 2000F shows a deflection-based SLM 1140, similar configurations of light sources may also be used with non-deflection-based SLMs, or with or in any other configurations or features disclosed herein.

[0128]

[0207] FIG. 20G is a side view of system 2000G including a cover glass 2060 disposed on the front side of stack 2005 (i.e., opposite the side of stack 2005 proximate optical element 1130). In some designs, light sources 1110, 1112, 1114 may be disposed on the front side of cover glass 2050 and configured to propagate light through cover glass 2050 to optical element 1130 and SLM 1140. As shown, cover glass 2060 may extend laterally (e.g., parallel to the x-axis) beyond stack 2005 so that light emitted by light sources 1110, 1112, 1114 enters optical element 1130 without passing through a waveguide within stack 2005. While system 2000G shows a deflection-based SLM 1140, similar configurations of light sources may also be used with non-deflection-based SLMs, or in or with any other configurations or features disclosed herein.

[0129]

[0208] Also, as described above, configurations that facilitate light recycling may be employed. FIG. 21 illustrates, for example, a partial side view of a system 2100 with a configuration that provides light recycling of light from a light source 1110. The light source 1110 may be positioned relative to a polarizer 1115 configured to recycle light having an undesired polarization. The polarizer 1115 may include, for example, a wire grid polarizer that transmits light of a first polarization and retroreflects light of a second, opposite polarization. Thus, light 2110 can be emitted from the light source 1110 and impinge on the polarizer 1115. The polarizer 1115 can transmit light of a first polarization configured for use by a projector (not shown). For example, an SLM can operate appropriately with light of this first polarization. Light 2120 of a second polarization can be reflected back toward the light source 1110 and recycled. The polarization of light 2120 may be altered due to polarization rotation after reflecting off portions (e.g., sidewalls) of a coupling optic (not shown), such as a non-imaging optical element like a compound parabolic concentrator (CPC) at various angles. Some light may be generated with the appropriate polarization (e.g., polarization orientation) that can be passed through the polarizer 1115. Multiple reflections can change the polarization of the light, allowing light to exit with the desired polarization. This recycled light 2130 is then emitted back toward the polarizer 1115. Such a configuration can improve efficiency, e.g., energy efficiency, as more of the desired polarization is produced. Additionally or alternatively, a retarder can be used to change the reflected polarization state and recycle the light.

[0130]

[0209] FIG. 22 shows another configuration including light sources 1110, 1112, 1114 and corresponding collection optics 2210, 2212, 2214. The collection optics 2210, 2212, 2214 may include lenses or other optical elements for collecting light from the light sources 1110, 1112, 1114. The light sources 1110, 1112, 1114 may be laser diodes or other emitters that emit light over a wide range of angles. The collection optics 2210, 2212, 2214 may be used to collect most of that light. The light sources 1110, 1112, 1114 may emit light asymmetrically. For example, light may be emitted over a wider range of angles in one direction (e.g., the x or z direction) than in an orthogonal direction (e.g., the z or x direction). Thus, the collection optics 2210, 2212, 2214 may be asymmetric. For example, the focusing optics 2210, 2212, and 2214 may have different optical powers in different possible orthogonal directions. The focusing optics 2210, 2212, and 2214 may include lenses, such as anamorphic lenses. The focusing optics 2210, 2212, and 2214 may also include non-imaging optics in some cases. Apertures 2220, 2222, and 2224 may also be included. For example, in the case of lasers such as laser diodes, the light sources 1110, 1112, and 1114 may include a diffuser 2230 proximate the apertures 2220, 2222, and 2224. The proximity of the diffuser to the apertures 2220, 2222, and 2224 may cause the apertures to appear as laterally displaced light sources. The apertures 2220, 2222, and 2224 may be aligned with incoupling optics on one or more waveguides via optical elements and an SLM, as described above. For example, each aperture 2220, 2222, 2224 may coincide with a respective incoupling optical element. Similarly, in certain implementations such as that shown in Figure 16A, each aperture 2220, 2222, 2224 may coincide with a respective group of (e.g., color-selective) incoupling optical elements.

[0131]

[0210] A wide range of system variations and configurations are possible. For example, although linearly polarized light has been described as propagating through optical element 1130 to SLM 1140 and back through the optical element to the waveguide stack, in some designs, circularly polarized light may be used instead. For example, circularly polarized light may be directed toward optical element 1130. A retarder, such as a quarter-wave plate, may be positioned so that this light passes through the retarder before entering the SLM. The retarder (e.g., a quarter-wave plate) may be positioned between optical element 1130 and SLM 1140. In some cases, as described above, the retarder (e.g., a quarter-wave plate) may be affixed to SLM 1140, for example, using an adhesive or mechanical fasteners. The retarder (e.g., a quarter-wave plate) can convert linearly polarized light to circularly polarized light after reflection from SLM 1140. Thus, in some implementations, the circularly polarized light can pass through optical element 1130 again toward the stack. For example, another retarder (e.g., a quarter-wave plate) proximal to the analyzer 1150 may convert circularly polarized light to linearly polarized light that may or may not pass through the analyzer depending on the linear polarization (e.g., orientation). The pixels of the SLM 1140 may have states that can be changed to rotate or not rotate the polarization. Still other configurations are possible.

[0132]

[0211] 23A is a side view of an augmented reality display system 2300 including a light source 2305, a polarization rotator 2307, an optical element (e.g., a lens) 2320 having optical power, polarizers 2312, 2335 such as linear polarizers (e.g., horizontal or vertical polarizers), retarders 2315, 2330, 2340 such as quarter-wave retarders (e.g., quarter-wave plates), and at least one waveguide 2348 for outputting image information to a user. Such a configuration may be used to illuminate a reflective spatial light modulator (not shown) such that light emitted from the light source 2305 is reflected from the spatial light modulator and coupled into the at least one waveguide 2348 for being directed toward the user's eye. The configuration and arrangement of these elements, particularly the polarizer and retarder, can reduce or eliminate reflections from optical surfaces in the system, such as surfaces from the optical element 2320, which may otherwise result in ghost images visible to the user. For example, polarization-selective and / or retarder optical elements (e.g., polarizers 2312, 2335 and retarders 2315, 2330, 2340) can be positioned and configured to convert linearly polarized light into circularly polarized light that changes from left-handed to right-handed or right-handed to left-handed upon reflection from an optical surface. Similarly, polarization-selective and / or retarder optical elements (e.g., polarizers 2312, 2335 and retarders 2315, 2330, 2340) can be positioned and configured to convert circularly polarized light into linearly polarized light that can be attenuated or filtered out by a polarizer (e.g., a linear polarizer). Circular polarizers that convert linearly polarized light into circularly polarized light, and vice versa, can be fabricated using polarization-selective and retarder optical elements (e.g., polarizers 2312, 2335 and retarders 2315, 2330, 2340). For example, a circular polarizer may include a linear polarizer and a quarter-wave retarder. A circular polarizer can be used to convert linearly polarized light to circularly polarized light having a first state (e.g., handedness) and filter out circularly polarized light having a second state (e.g., handedness) that is different from the first state. For example, a circular polarizer can be used to convert linearly polarized light of one orientation to left-handed circularly polarized light and filter out right-handed circularly polarized light.Circular polarizers can be used to convert linearly polarized light of a certain orientation into right-handed circularly polarized light and filter out left-handed circularly polarized light. Circular polarizers, or other configurations of optical elements that include retarders that can be used to convert linearly polarized light back into circularly polarized light and selectively filter linearly polarized light, can be used to reduce back reflections from optical surfaces, as described below in connection with Figures 23A and 23B.

[0133]

[0212] Note that in Figures 23A and 23B, left and right circular polarizations are indicated by clockwise and counterclockwise arrows, respectively. Additionally, horizontal and vertical linear polarizations are indicated using horizontal arrows and circular dots, respectively.

[0134]

[0213] As mentioned above, Figure 23A shows a configuration of an augmented reality display system 2300 in which polarizers 2312, 2335, such as linear polarizers (e.g., horizontal polarizers), and retarders 2315, 2330, 2340, such as quarter-wave retarders (e.g., quarter-wave plates), are arranged to reduce back reflections from optical surfaces, such as the surface of an optical element 2320, in the path of light illuminating and reflecting from a spatial light modulator (not shown). The first polarizer 2312 and the first retarder 2315 are arranged between the light source 2305 and the optical element 2320. The first polarizer 2312 is arranged between the light source 2305 and the first retarder 2315. Similarly, the first retarder 2315 is arranged between the first polarizer 2312 and the optical element 2320.

[0135]

[0214] As shown, light source 2305 emits light represented by light ray 2310. In some implementations, light ray 2310 can pass through polarization rotator 2307. Rotator 2307 is optional and can be used to rotate the polarization of light from light source 2305, e.g., light ray 2310. In various implementations, rotator 2307 can rotate the angle of polarization (e.g., of linear polarization). For example, rotator 2307 can rotate the linear polarization of light ray 2310 to an orientation aligned with first polarizer 2312 for transmission through first polarizer 2312. In some implementations, polarization rotator 2307 can include a retarder, e.g., a half-wave retarder in some cases. The optical axis of the half-wave retarder can be oriented to rotate the polarization of light from light source 2305 from vertical to horizontal or vice versa. Alternatively, polarization rotator 2307 may be configured to rotate the polarization angle of linearly polarized light emitted from light source 2305 by a different amount. Polarization rotator 2307 does not have to be included in the system. For example, in implementations in which light source 2305 emits light having the same polarization as first polarizer 2312, polarization rotator 2307 may be omitted. As shown, light, e.g., light ray 2310, passes through polarizer 2312, shown here as a horizontal polarizer. If the light from light source 2305 is unpolarized, light transmitted through horizontal polarizer 2312, shown as light ray 2310, will be linearly polarized (e.g., horizontally polarized) after passing through polarizer 2312. While a horizontal linear polarizer is used in this example, it will be understood that the principles taught can also be applied using a vertical linear polarizer. Alternatively, linear polarizers with different orientations other than vertical, linear, may also be used.

[0136]

[0215] Horizontally polarized light beam 2310 travels through retarder 2315, shown here as a quarter-wave retarder. This retarder 2315 can contain a phase difference sufficient to convert linearly polarized light to circularly polarized light. For example, horizontally polarized light may be converted to left-handed circularly polarized light, as indicated by the curved (e.g., clockwise) arrow. In this example, the combination of polarizer 2312 and retarder 2315 (e.g., quarter-wave) forms a circular polarizer, referred to herein as a first circular polarizer, that can convert light of a particular linear polarization (e.g., horizontally or vertically polarized) to a particular circular polarization (e.g., left-handed or right-handed circularly polarized, or vice versa). The circular polarizer may also block light of a particular circular polarization (e.g., right-handed or left-handed circularly polarized) depending on the configuration.

[0137]

[0216] In some implementations, the various optical elements have birefringence. In certain such cases, the retarder 2315 can include a sufficient amount of retardation to convert linearly polarized light to circularly polarized light and need not be a quarter-wave plate. Retardation longer or shorter than a quarter wavelength may be included in the retarder 2315, as retardation may be contributed by other optical elements. Similarly, retardation may be distributed among several optical elements. As another example, multiple retarders may be employed to provide the appropriate amount of retardation.

[0138]

[0217] Circularly polarized light ray 2310 (here, left-handed circularly polarized light) then passes through optical element 2320. Unwanted reflections can occur at any interface in the system with media having different refractive indices, such as an air-material interface. These reflections can be problematic if allowed to enter at least one waveguide 2348 because this reflected light can be directed toward the user's eye and form a "ghost" image visible to the user. For example, if a display uses at least one waveguide 2348 to project a first image toward the observer's eye, the user may also see a second, faint replica image that is displaced (e.g., laterally displaced) relative to the first image. Such "ghost" images formed by reflections from optical surfaces directed toward the user's eye can disrupt or otherwise degrade the viewing experience. For example, as shown in FIG. 23A, light such as reflected light ray 2325 can be reflected from a lens in optical element 2320. This light may be directed to at least one waveguide 2348 configured to direct the light to the user's eye to present an image. However, in this case, the circularly polarized light reverses its handedness. For example, upon reflection from a lens, the direction of the circularly polarized light changes (e.g., from left-handed to right-handed). The right-handed reflected light ray 2325 then travels through the retarder 2315 and is converted to linearly polarized light having a different (e.g., orthogonal) linear polarization than that transmitted by the polarizer 2312. In this case, for example, light reflected from the optical surface of the lens is converted by the retarder 2315 to vertically linearly polarized light, orthogonal to the polarization transmitted by the horizontal linear polarizer 2312. The horizontal linear polarizer 2312 selectively passes horizontally polarized light and filters out vertically polarized light. Thus, reflected light ray 2325 is attenuated and / or not transmitted by horizontal linear polarizer 2312 and prevented from reaching at least one waveguide 2348, or at least a reduced amount of such reflected light reaches at least one waveguide 2348 or is coupled into it, for example via an incoupling optical element (e.g., one or more incoupling gratings). The result is similar for left-handed circularly polarized light reflected from a different optical surface of optical element 2320 or from other optical surfaces on different optical elements.

[0139]

[0218] As shown, the display system 2300 further includes a second retarder 2330 (e.g., a quarter-wave retarder or a quarter-wave plate) and a second polarizer 2335 (e.g., a linear polarizer) disposed between the optical element 2320 and a spatial light modulator (not shown). The second retarder 2330 and the second linear polarizer 2335 may form a second circular polarizer in certain implementations. The second retarder 2330 is disposed between the optical element 2320 and the second polarizer 2335. Similarly, the second polarizer 2335 is disposed between the second retarder 2330 and the spatial light modulator. Thus, after passing through the optical element 2320, the light ray 2310 can pass through the second retarder 2330 (e.g., a quarter-wave retarder). The second retarder 2330 is configured (e.g., with its optic axis appropriately oriented) so that the light beam 2310 is converted from left-handed circularly polarized light to horizontally linearly polarized light. Similarly, the second retarder 2330 converts the circularly polarized light back to the original linear polarization state output by the first polarizer 2312. As described below, this second retarder 2330 and second polarizer 2312 can be useful to reduce "ghost" images caused by light reflected from a spatial light modulator passing through an optical surface (e.g., on a powered optical element or lens 2320) as the light travels through the at least one light guide 2348.

[0140]

[0219] A third retarder 2340 (e.g., a quarter-wave retarder or quarter-wave plate) is disposed between the second polarizer 2335 and the spatial light modulator. Thus, the third retarder 2340 is disposed between the second retarder 2330 and the spatial light modulator. Also, in various implementations as shown, the second polarizer 2335 is between the second retarder 2330 and the third retarder 2340. As shown, the light beam 2310 becomes linearly polarized upon passing through the second polarizer 2335, and in some implementations, the second retarder 2330 / second polarizer 2335 may convert the light back to the original linear polarization (e.g., horizontal polarization) of the first polarizer 2312. This linear polarization is incident on the third retarder 2340. The third retarder 2340 is configured to convert the light back into circular polarization, which in some implementations is the same polarization as that output by the first retarder 2315 (e.g., left-handed circular polarization in this example). In particular implementations, the spatial light modulator is configured to operate with circularly polarized light. In some implementations, the spatial light modulator is a reflective spatial light modulator that reflects incident circularly polarized light back as circularly polarized light. In some embodiments, the circularly polarized light reflected from the spatial light modulator can have the same handedness as that incident (e.g., left-handed circular polarization) depending on whether the spatial light modulator pixels are in an "on" state or an "off" state. In some embodiments, the spatial light modulator can have circularly polarized light of a different handedness than that incident (e.g., right-handed circular polarization) depending on whether the spatial light modulator pixels are in an "on" state or an "off" state. However, other types of spatial light modulators may be used.

[0141]

[0220] FIG. 23A shows light, shown as ray 2342, reflected from the spatial light modulator and traveling toward waveguide 2385. The reflected ray 2342 is shown as left-handed circularly polarized light. Ray 2342 passes through a third retarder 2340, which converts the circularly polarized light to linearly polarized light. In this example, the left-handed circularly polarized light is converted to horizontally polarized light. The linearly polarized light is transmitted through a second polarizer 2335. In this example, the horizontally polarized light passes through the second polarizer 2335. The linearly polarized light enters the second retarder 2330 and is converted to circularly polarized light. In this example, the horizontally polarized light is converted to left-handed polarization and transmitted to the optical element 2320. Again, reflections from optical surfaces, such as the surface of the optical element 2320 having optical power, may create ghost images by reflecting back from the spatial light modulator to at least one waveguide 2348 and the user's eye. As mentioned above, unwanted reflections can occur at any interface between media with different refractive indices, such as an air-material interface. As mentioned above, the inclusion of a second retarder and polarizer 2330, 2335 can attenuate these reflections and reduce the likelihood of ghost reflections. FIG. 23A shows, for example, light reflected from the optical surface of optical element 2320, shown as ray 2346. The act of reflection from the surface results in reflected ray 2346, which becomes circularly polarized and switches handedness—in this example, from left-handed to right-handed. The switched circular polarization is attenuated by the second circular polarizer formed by the second retarder and polarizer 2330, 2335. As shown in FIG. 23A, for example, the reflected circularly polarized light 2346 enters the second retarder 2330 and is converted by the second retarder to linearly polarized light having a different, e.g., orthogonal, linear polarization to the linear polarization selectively transmitted by the second linear polarizer 2335. In this case, for example, right-handed circularly polarized light reflected from the optical surface of optical element 2320 is converted by retarder 2330 to vertically linearly polarized light, orthogonal to the polarization selectively transmitted by polarizer 2335. Second polarizer 2335 attenuates or prevents transmission of this linearly polarized light. In this example, light 2346 is vertically polarized, but second polarizer 2335 is a horizontal polarizer that selectively passes horizontally polarized light and filters out vertically polarized light.

[0142]

[0221] In contrast, light 2342 passing through optical element 2320 and incident on first retarder 2315 is circularly polarized and has a different handedness than light reflected from the optical surfaces of optical element 2320. This light 2342 directed into at least one waveguide 2348 has a polarization (e.g., left-handed polarization) that is converted by first retarder 2315 to linear polarization (e.g., horizontal linear polarization) that is selectively transmitted by first polarizer 2312. In this way, light 2342 reaches at least one waveguide 2348 and can be coupled therein and directed toward the user's eye.

[0143]

[0222] In the example shown in Figure 23A, a first circular polarizer formed by a first polarizer 2312 and a first retarder 2315, and a second circular polarizer formed by a second retarder 2330 and a second polarizer 2335, on either side of the optical element 2320, one closer to the light source 2305 and the other closer to the spatial light modulator, are used to reduce reflections that can result in "ghost images." An additional retarder 2340 is included between the second circular polarizer (e.g., second polarizer 2335) and the spatial light modulator to convert the light to circularly polarized light. However, a wide range of variations are possible. For example, there could be only one circular polarizer. Alternatively, additional circular polarizers or other types of polarizing optical elements could be included.

[0144]

[0223]

[00110] Figure 23B illustrates a third circular polarizer that can be added to an augmented reality system 2300 such as that shown in Figure 23A. In particular, Figure 23B illustrates a second circular polarizer including the second polarizer 2335 and second retarder 2330 introduced above, as well as a third retarder 2340, and further illustrates a spatial light modulator 2375. This spatial light modulator (SLM) 2375 can include a liquid crystal spatial light modulator (e.g., reflective liquid crystal or LCoS). In some implementations, the SLM 2375 can be covered with a cover glass 2370.

[0145]

[0224] 23B also shows a third circular polarizer including a fourth retarder 2345, such as a quarter-wave retarder (e.g., a quarter-wave plate), and a third polarizer 2355, such as a linear polarizer, disposed between the second circular polarizer including the second polarizer 2335 and the second retarder 2330 and the spatial light modulator 2375. The third polarizer 2355 is between the fourth retarder 2345 and the spatial light modulator 2375. An additional fifth retarder 2360, such as a quarter-wave retarder (e.g., a quarter-wave plate), and a compensator 2365 are disposed between the third circular polarizer including the fourth retarder 2345 and the third polarizer 2355 and the spatial light modulator 2375, more specifically, the cover glass 2370 shown in FIG. The fifth retarder 2360 is between the third polarizer 2355 and the compensator 2365. The compensator 2365 is between the fifth retarder 2360 and the spatial light modulator 2375, or specifically the cover glass 2370.

[0146]

[0225] Figure 23B shows how light from light source 2305 (shown in Figure 23A), for example, light ray 2310, can propagate through a second circular polarizer including retarder 2330 and second polarizer 2335, and third retarder 2340, to a third circular polarizer including fourth retarder 2345 and third polarizer 2355. After passing through the second circular polarizer including second retarder 2330 and second polarizer 2335, light ray 2310 from light source 2305 is incident on a third circular polarizer, specifically fourth retarder 2345. Fourth retarder 2345 can convert the circularly polarized light of light ray 2310 to linearly polarized light. In the example shown in FIG. 23B , light ray 2310 is circularly polarized (e.g., left-handed circularly polarized) and converted to linearly polarized (e.g., horizontally polarized) light by fourth retarder 2345. This linearly polarized light passes through third polarizer 2355, which in FIG. 23B includes a horizontal polarizer that selectively transmits horizontally polarized light. This linearly polarized light propagates through fifth retarder 2360, which may include a quarter-wave retarder that converts linearly polarized light to circularly polarized light. In the example shown in FIG. 23B , horizontally linearly polarized light ray 2310 incident on fifth retarder 2360 is converted to left-handed circularly polarized light. This circularly polarized light then enters and passes through compensator 2365, which may include a polarizing element that adjusts the polarization to a desired polarization. Compensator 2365 may be used to offset the birefringence of various optical elements in the system. For example, the light may be slightly elliptically polarized due to the retardation contribution of one or more optical elements. In various implementations, the light output from the compensator 2365 is circularly polarized. In the example shown in FIG. 23B , the light output from the compensator 2365 is left-handed circularly polarized. In various implementations, the compensator 2365 can be used to offset residual retardation in an SLM, which may include, for example, a liquid crystal (e.g., LCoS) SLM cell. The compensator can introduce in-plane retardation and / or out-of-plane retardation. In some implementations, the compensator 2365 can include a combination of optical retarders that, when combined, generate a retardation that can potentially offset residual retardation from the SLM (e.g., an LCoS panel).

[0147]

[0226] In Figure 23B, after passing through compensator 2365, the light is incident on cover glass 2370 and SLM 2375. This light incident on cover glass 2370 and SLM 2375 is shown as left-handed circularly polarized light. Depending on the type and state of the spatial modulator, SLM 2375 may reflect circularly polarized light of the same handedness. For example, when the pixels of SLM 2375 are in the "on" state (which may be an undriven state in some implementations), SLM 2375 can introduce a quarter-wave phase difference for each pass through SLM 2375. Thus, upon reflection, incident circularly polarized light may remain circularly polarized upon reflection. In various configurations, the handedness may also remain the same. For example, as shown in Figure 23B, incident left-handed circularly polarized light may remain left-handed upon reflection. This circularly polarized light reflected from SLM 2375, represented by ray 2342, may pass through cover glass 2370 and compensator 2365 and be incident on fifth retarder 2360, which converts the circularly polarized light to linearly polarized light. In the example shown in FIG. 23B, the circularly polarized light incident on fifth retarder 2360 is left-handed, and fifth retarder 2360 converts the circularly polarized light to horizontally polarized light. Third polarizer 2355 may be configured to selectively transmit the polarization of the light output by fifth retarder 2360. Thus, in the example shown in FIG. 23B where the light output from fifth retarder 2360 is horizontally polarized, third polarizer 2355 selectively transmits horizontally polarized light. This linearly polarized light transmitted by polarizer 2355 is incident on fourth retarder 2345 and converted to circularly polarized light. In the example shown in FIG. 23B, the circularly polarized light is left-handed. This light can pass through a second circular polarizer including a second retarder 2330 and a second polarizer 2335, optical element 2320, and a first circular polarizer including a first polarizer 2312 and a first retarder 2315, as described above in connection with Figure 23A, onto at least one waveguide 2348 and into the user's eye.

[0148]

[0227] However, light reflected from the optical surface may be attenuated by the third circular polarizer, thereby reducing the likelihood that such reflection will reach at least one waveguide 2348 and be directed toward the user's eye, creating a ghost image. For illustrative purposes, FIG. 23B shows an example of a light ray 2343 reflected from the optical surface of the third retarder 2340, e.g., from the interface between air and the third retarder 2340. As discussed above, reflection can occur at any interface between media with different refractive indices, such as a material interface between different dielectric layers or an air-to-optic interface. However, circularly polarized light reverses its handedness upon reflection. For example, reflecting from the surface of the third retarder 2340 changes the direction of the circular polarization (e.g., from left-handed to right-handed). The right-handed reflected light ray 2343 then travels through the fourth retarder 2345 and is converted to linearly polarized light having a different, e.g., orthogonal, linear polarization from the linear polarization selectively transmitted by the third polarizer 2355. In this case, for example, light reflected from the optical surface of the third retarder 2340 is converted by the fourth retarder 2345 to vertically linearly polarized light, orthogonal to the polarization selectively transmitted by the third polarizer 2355. The third polarizer 2355 selectively passes horizontally polarized light and filters out vertically polarized light. Thus, the reflected light rays 2343 are attenuated and / or not transmitted by the third polarizer 2355 and are prevented from reaching the at least one waveguide 2348 (e.g., by reflecting off another surface), or at least a reduced amount of such reflected light reaches or is coupled into the at least one waveguide 2348.

[0149]

[0228] The results may be similar for circularly polarized light reflected from different optical surfaces. Figure 23B, for example, shows the reflection of incident light ray 2310 from the optical surface of fourth retarder 2345. Reflection 2350 from fourth retarder 2345 switches the handedness of the polarization. For example, incident light ray 2310, shown as left-handed circularly polarized light, is converted to light ray 2350, shown as having right-handed circular polarization upon reflection. Reflected light ray 2350 passes through third retarder 2340 and is converted to vertically polarized light. This vertically polarized light is selectively attenuated or filtered out by second polarizer 2335.

[0150]

[0229] As described above, a pixel of SLM2375 may be in an “on” state (although in some implementations it may be undriven) in which light incident on that pixel of SLM2375 is reflected therefrom and coupled into at least one waveguide 2348 and directed toward a user's eye. However, a pixel of SLM2375 may be in an “off” state (which may be driven in some implementations) in which light incident on the pixel of SLM2375 is not coupled into at least one waveguide 2348 and directed toward a user's eye. In this “off” state, for example, various implementations of SLM2375 may not introduce a phase difference upon reflection therefrom. Thus, in the example shown in FIG. 23B , circularly polarized light incident on SLM2375 may remain circularly polarized upon reflection from SLM2375. However, the handedness of this circularly polarized light may change upon reflection from SLM2375. For example, light ray 2310 shown in FIG. 23B , which is left-handed circularly polarized light incident on SLM 2375, may be converted to right-handed circularly polarized light upon reflection from SLM 2375. However, this reflected light may be selectively attenuated by third polarizer 2355. For example, right-handed circularly polarized light reflected from SLM 2375 may pass through cover glass 2370, compensator 2365, and fifth retarder 2360. Fifth retarder 2360 may convert right-handed circularly polarized light to vertically polarized light, which is selectively attenuated by third polarizer 2355, which may include a horizontal polarizer. Thus, in various implementations, fifth retarder 2360 may convert light reflected from pixels of SLM 2375 when the pixels of the SLM are in the “off” state to linearly polarized light that is orthogonal to the linearly polarized light selectively transmitted by third polarizer 2355. This third polarizer 2355 can therefore selectively attenuate this linearly polarized light, thereby reducing or blocking light from that pixel of the SLM 2375 from reaching the at least one waveguide 2348 and being directed into the eye.

[0151]

[0230] Variations in the configuration are possible, such as variations in the polarizing optics. For example, more or fewer circular polarizers may be included.

[0152]

[0231] In various implementations, the third circular polarizer, including the fourth retarder 2345 and the third polarizer 2355, is omitted, as shown in FIG. 23C . In this particular implementation, the fourth retarder 2345, the third polarizer 2355, and the fifth retarder 2360 are not included in the system. FIG. 23C illustrates a design of an augmented reality system 2300 including the components shown in FIGS. 23A and 23B , except for the fourth retarder 2345, the third polarizer 2355, and the fifth retarder 2360. Nevertheless, despite the omission of the third circular polarizer, the augmented reality display system is still configured to reduce ghost images. The second circular polarizer, for example, reduces reflections that would otherwise contribute to ghost images. For illustrative purposes, FIG. 23C illustrates light reflected from the third retarder 2340, shown as ray 2380. Upon reflection from the surface of third retarder 2340, reflected ray 2380, which is circularly polarized light, switches handedness. In this example, the polarization is switched from left-handed to right-handed. Switched circularly polarized light 2380 then passes through compensator 2365 and is incident on cover glass 2370 and SLM 2375. As described above, SLM 2375 can reflect circularly polarized light of the same handedness. Thus, the incident circularly polarized light may remain right-handed upon reflection. This circularly polarized light reflected from SLM 2375, represented by ray 2382, may pass through cover glass 2370 and compensator 2365 and be incident on third retarder 2340. Switched circularly polarized light 2382 is attenuated by the second circular polarizer, specifically third retarder 2340 and polarizer 2335. 23C , for example, circularly polarized light 2382 reflected from SLM 2375 is incident on third retarder 2340 and converted by third retarder 2340 into linearly polarized light having a different, e.g., orthogonal, linear polarization than the linear polarization selectively transmitted by second linear polarizer 2335. In this case, for example, right-handed circularly polarized light 2382 is converted by third retarder 2340 into vertically linearly polarized light that is orthogonal to the polarization selectively transmitted by second retarder 2335. Second polarizer 2335 attenuates or prevents transmission of this linearly polarized light.

[0153]

[0232] Reflections that can contribute to ghost reflections can also potentially be reduced by tilting optical surfaces within the system. FIG. 24 shows an example configuration with tilted optical surfaces to reduce reflections that can cause ghost reflections. FIG. 24 shows an augmented reality display system 2400 including a light source 2305 that emits light represented by light rays 2310 that pass through any number of polarizers, retarders, lenses, and / or other optical components as the light travels toward a spatial light modulator (SLM) 2375. A first polarizer 2312 and a first retarder 2315, possibly forming a first circular polarizer, and a lens 2320 are shown in FIG. 24 for illustrative purposes. However, additional components may be included, or components may be omitted, positioned, or configured differently. In the example shown, the SLM 2375 includes a cover glass 2370. The cover glass 2370 can contribute to reflections that create ghost images. Thus, in some implementations, the cover glass 2370 can be shaped to direct reflections that can cause ghost images away from the user's eyes. As shown, the cover glass 2370 has surfaces that can be tilted so that the surfaces are not parallel to other components or optical surfaces of the system (e.g., the SLM 2375, the first retarder 2315, the first polarizer 2312, the at least one waveguide 2348, etc., or their optical surfaces). The major surfaces of the cover glass 2370 can have normals that are tilted so that they are not aligned with or parallel to the optical axis of the augmented reality display system 2400 or the optical components therein, such as the optical element 2320. By being tilted, reflections from the optical surfaces of the cover glass 2370 can be directed away from the at least one waveguide 2348 or an incoupling optical element (e.g., an incoupling grating or diffractive optical element) to incouple light into the at least one waveguide 2348, reducing the likelihood that reflections from the cover glass 2370 will enter the at least one waveguide 2348. As shown, reflected light 2405 returns towards the light source 2305 and is directed away from the at least one waveguide 2348 where such light may ultimately reach the user's eye.In some implementations, the reflected light 2405 may be returned to the light source and at least partially recycled back to the light source 2305 .

[0154]

[0233] While FIG. 24 shows the cover glass 2370 with a sloped surface, any component in the system capable of unwanted reflections can include a sloped optical surface to deflect reflections and prevent them from being coupled into the at least one waveguide 2348. Accordingly, optical surfaces on other components, such as polarizers, retarders, etc., may be sloped to reduce reflections from being coupled into the at least one waveguide 2348 and the user's eye. Variations in the shape and size of the cover glass 2370 or other optical component are possible. The cover glass 2370 or another optical component may, for example, be thinner. Similarly, the cover glass 2370 or other optical component may have an aspect ratio (length to thickness) different from that shown in FIG. 24. In some implementations, the cover glass 2370 or other optical component is wedge-shaped. However, other shapes are possible.

[0155]

[0234] Still other arrangements are possible. FIG. 25 illustrates, for example, an implementation of an augmented reality display system 2500 similar to system 2400 shown in FIG. 24 , but further including a light dump 2505 to absorb light directed thereto. System 2500 includes a tilted cover glass 2370 to direct reflection 2510 toward the light dump 2505 instead of back from the cover glass 2370 toward the light source 2305. The light dump 2505 may include an absorbing material or structure configured to absorb light. The location of the light dump 2505 may vary depending on the implementation, for example, depending on the angle of the tilted cover glass 2370. As discussed above, this approach can be applied to other optical surfaces in the system. Also, the optical elements may have different shapes and sizes.

[0156]

[0235] A wide range of variations in augmented reality displays are possible. Variations in polarization optics are possible. For example, while horizontal polarizers are used, in some implementations, vertical polarizers or a combination of horizontal and vertical polarizers are employed. Furthermore, polarizers featuring polarizations other than vertical or horizontal may be used. Similarly, light shown in the figures need not be horizontally polarized, but may be vertically polarized. Similarly, light shown as vertically polarized may be horizontally polarized in different implementations, or vice versa. Also, linearly polarized light with polarizations other than vertical or horizontal may be used.

[0157]

[0236] Additionally, retarders may be configured differently. For example, the polarization in the figures need not be left-handed circular polarization but may be right-handed, and / or right-handed circular polarization may be left-handed. Still other variations are possible. Different retarder configurations can be employed to generate different left-handed and / or right-handed polarization combinations than those shown. Also, in some implementations, elliptically polarized light may alternatively be used instead of circularly polarized light. For example, retarders may be employed to convert elliptically polarized light to linearly polarized light, or vice versa. Linear polarizers can be used to filter light and to reduce ghost reflections, as described herein.

[0158]

[0237] In some implementations, other types of polarizing elements and their configurations are employed. For example, the retarders are not limited to quarter-wave retarders or quarter-wave plates. For example, in some implementations, various optical elements have birefringence. In certain such cases, the retarders 2315, 2330, and 2340 can include a sufficient amount of retardation to convert linearly polarized light to circularly polarized light and need not be quarter-wave retarders. Retardation longer or shorter than a quarter wavelength may be included in one or more of the retarders 2315, 2330, and 2340, as retardation may be contributed by other optical elements. Similarly, retardation may be distributed among several optical elements. As another example, multiple retarders may be employed to provide the appropriate amount of retardation. Also, as described above, in some implementations, elliptically polarized light may alternatively be used instead of circularly polarized light. For example, a retarder may be employed to convert elliptically polarized light to linearly polarized light, or vice versa. Linear polarizers can be used to filter light and to reduce ghost reflections, as described herein.

[0159]

[0238] Additionally, the optical components may be in the form of optical layers, sheets, and / or films, as well as stacks or one or more layers, sheets, and / or films. Thus, different amounts, positions, and arrangements of different polarizing elements may be used. For example, one or more of the retarders and / or polarizers may include a film.

[0160]

[0239] In some implementations, the spatial light modulator may operate differently, for example, the spatial light modulator may operate with and / or output light other than circularly polarized light.

[0161]

[0240] Embodiments of the present invention relate to manufacturable architectures in which eyepiece stack architectures can benefit from using a split ICG pupil design or a combination of in-line and split ICG pupil designs, expanding applications beyond the exclusive use of in-line ICG. A split ICG pupil, as described herein, is an ICG pupil in which light from a projection system is incoupled into two or more diffractive ICG pupils in a stack that do not overlap when viewed through an ICG plane that forms a surface toward the projection system input. An in-line ICG pupil, as described herein, is an ICG pupil that partially or completely overlaps in this same plan view. The inventors have determined that there are several advantages achieved by using a split pupil with an LCOS-based projection system that can project, for example, blue and green projection images (e.g., images generated using light-emitting diode (LED) light sources) into a single pupil or two separate pupils in a single eyepiece waveguide layer.

[0162]

[0241] 26A shows a plan view of an eyepiece waveguide using a two active layer architecture according to one embodiment of the present invention. As will be described more fully below, embodiments of the present invention utilize a two active layer architecture for an eyepiece waveguide 2600 in which two eyepiece waveguide layers are utilized, in which light of a first wavelength (e.g., a red projected image generated using a red light source such as a red light emitting diode (LED)) passes through an aperture on the first eyepiece waveguide layer and is incoupled into the second eyepiece waveguide layer using an incoupling diffractive structure. After incoupling into the second eyepiece waveguide layer, the first wavelength is guided towards an outcoupling diffractive structure optically coupled to the second eyepiece waveguide layer.

[0163]

[0242] In the examples described herein, the first wavelength is a red wavelength, the second wavelength is a green wavelength, and the third wavelength is a blue wavelength. Therefore, the terms "first wavelength / red wavelength(s)," "second wavelength / green wavelength(s)," and "third wavelength / blue wavelength(s)" are used interchangeably. Furthermore, in the examples described herein, the incoupling diffractive structure is an incoupling grating (ICG) (i.e., the first ICG2612), and the outcoupling diffractive structure is a combined OPE / EPE pupil dilator (CPE). Although these references are used in the description, it will be understood that other implementations are within the scope of the present invention.

[0164]

[0243] Light of the second and third wavelengths (e.g., a green projection image generated using a green light source such as a green LED and a blue projection image generated using a blue light source such as a blue LED) is incoupled into the first eyepiece waveguide layer using an incoupling diffractive structure, which in some embodiments is implemented as a first ICG2612. After incoupling into the first eyepiece waveguide layer, the second and third wavelengths are guided toward an outcoupling diffractive structure optically coupled to the first eyepiece waveguide layer. Similar to the exemplary use of the red wavelength as the first wavelength, the green and blue wavelengths are used as exemplary second and third wavelengths, respectively.

[0165]

[0244] Figure 26B shows an exploded view of the eyepiece waveguide shown in Figure 26A. In this exploded view of the eyepiece waveguide 2600, a first eyepiece waveguide layer 2610 is positioned on the user side of the eyepiece waveguide 2600, and a second eyepiece waveguide layer 2620 is positioned on the front side of the eyepiece waveguide 2600. The first eyepiece waveguide layer 2610 includes a first ICG 2612 used to incouple blue and green wavelengths. The second eyepiece waveguide layer 2620 includes a second ICG 2622 used to incouple red wavelengths. A first CPE 2614 outcouples light from the first eyepiece waveguide layer 2610, and a second CPE 2624 outcouples light from the second eyepiece waveguide layer 2620.

[0166]

[0245] Figure 26C shows a cross-sectional view of the eyepiece waveguide shown in Figure 26A. As shown in Figure 26C, the red projected image can be separately incoupled into the second eyepiece waveguide layer 2620 after passing through the first eyepiece waveguide layer 2610 (i.e., the blank area 2605 of the first eyepiece waveguide layer) and impinging on the second ICG 2622 of the second eyepiece waveguide layer 2620. After guiding in the second eyepiece waveguide layer 2620, the light is outcoupled by the second CPE 2624. The blank area 2605 of the first eyepiece waveguide layer 2610, through which the red light passes through the first eyepiece waveguide layer 2610, can have an anti-reflection coating or nanopattern with a sub-diffraction pitch (e.g., <160 nm) to reduce reflection of these red wavelengths. As an example, the first eyepiece waveguide layer 2610 may be TADF55W with a refractive index of n=2.01, and the first eyepiece waveguide layer 2610 may have an ICG grating pattern pitch of approximately 330 nm for blue (455 nm) and green (530 nm) light.

[0167]

[0246] 26C , the green and blue projected images may be incoupled by the first ICG 2612 into the first eyepiece waveguide layer 2610. After guiding in the first eyepiece waveguide layer 2610, the light is outcoupled by the first CPE 2614.

[0168]

[0247] As an example, the substrates used to fabricate the first eyepiece waveguide layer 2610 and the second eyepiece waveguide layer 2620 may be TADF55W with a refractive index of n=2.01, the first ICG 2612 may have a grating pattern pitch of approximately 330 nm effective for incoupling both blue light (i.e., 455 nm) and green light (i.e., 530 nm), and the second ICG 2622 may have a grating pitch of approximately 420 nm effective for incoupling red light (i.e., 630 nm). The two active layer architecture of the eyepiece waveguide 2600 may be suitable for supporting a high diagonal field of view of 60° or more.

[0169]

[0248] The eyepiece waveguide is implemented as a double-sided eyepiece waveguide with diffractive structures on both sides of the eyepiece waveguide layer, although this is not required by the present invention and single-sided designs can also be utilized. Additionally, although a two-pupil design is shown in Figure 26A, this is not required, as will be explained more fully below, and three-pupil designs are also within the scope of the present invention.

[0170]

[0249] Figure 27A shows a plan view of an eyepiece waveguide using a two active layer architecture according to another embodiment of the present invention, Figure 27B shows an exploded view of the eyepiece waveguide shown in Figure 27A, and Figure 27C shows a cross-sectional view of the eyepiece waveguide shown in Figure 27A.

[0171]

[0250] The two active layer architecture used in eyepiece waveguide 2700 shown in Figures 27A-27C shares common features with the two active layer architecture used in eyepiece waveguide 2600 shown in Figures 26A-26C, and the description provided in relation to Figures 26A-26C is applicable, as appropriate, to eyepiece waveguide 2700. In particular, the three-pupil design shown in Figure 27A is well suited for use in LCOS-based projector systems.

[0172]

[0251] Referring to Figure 27A, the eyepiece waveguide 2700 includes an architecture in which the third ICG 2722, the second ICG 2713, and the first ICG 2712 are spatially separated within the plane of the eyepiece waveguide. As shown in the exploded view of Figure 27B, the first eyepiece waveguide layer 2710 is positioned on the user side of the eyepiece waveguide 2700, and the second eyepiece waveguide layer 2720 is positioned on the front side of the eyepiece waveguide 2700. The first eyepiece waveguide layer 2710 includes the first ICG 2712 used to incouple blue wavelengths and the second ICG 2713 used to incouple green wavelengths. The second eyepiece waveguide layer 2720 includes the third ICG 2722 used to incouple red wavelengths. The first CPE 2714 outcouples light from the first eyepiece waveguide layer 2710 and the second CPE 2724 outcouples light from the second eyepiece waveguide layer 2720.

[0173]

[0252] 27C , the red projected image passes through the first eyepiece waveguide layer 2710 and impinges on the third ICG 2722 of the second eyepiece waveguide layer 2720, and is then separately incoupled into the second eyepiece waveguide layer 2720. After guiding in the second eyepiece waveguide layer 2720, the light is outcoupled by the second CPE 2724. The blue projected image is incoupled into the first eyepiece waveguide layer 2710 by the first ICG 2712, and the green projected image is incoupled into the first eyepiece waveguide layer 2710 by the second ICG 2713. After guiding in the first eyepiece waveguide layer 2710, the light is outcoupled by the first CPE 2714.

[0174]

[0253] As shown in Figure 27C, another differentiating aspect of the two active layer architectures discussed herein is the use of a thicker waveguide substrate that is very flat (e.g., total thickness variation (TTV) < 100 nm), or the use of an eyepiece waveguide layer with a tapered thickness, e.g., the ICG side is thicker than the CPE side and the thickness gradually decreases across the eyepiece waveguide layer (e.g., TTV across the eyepiece waveguide layer ranges from 300 nm to 800 nm). In the implementation shown in Figure 27C, blue and green light are incoupled and guided in the thicker first eyepiece waveguide layer 2710, and red light is guided in the thinner second eyepiece waveguide layer 2720. This architecture also improves the uniformity of the projected RGB image due to the design maintaining the eyepiece waveguide stack at a specific (e.g., minimum) thickness to achieve mechanical rigidity, but within a specific total stack thickness suitable for wearable devices. As shown in Figure 27C, red light has the longest bounce interval and may therefore replicate the pupil, creating a virtual image gap that widens as it exits, thus creating a screen-door image artifact. Conversely, incoupling and propagation of blue light in the thinnest waveguide may result in loss of blue light, potentially resulting in reduced image clarity due to the fact that blue light has the shortest bounce interval. When red light is incoupling into a thinner waveguide, the uniformity artifact is improved compared to a thicker waveguide, and when blue and green light are incoupling into a thicker waveguide, the overall clarity of the image increases and, to some extent, the light outcoupling efficiency for the two colors is improved.

[0175]

[0254] Figures 28A-28C show cross-sectional views of two active layer eyepiece waveguides according to various embodiments of the present invention. These figures show two pupil designs with waveguide layers of different thicknesses and with waveguide layers whose thickness varies across the waveguide layer (i.e., same or varying TTV). These embodiments are suitable for incoupling and outcoupling of different colors.

[0176]

[0255] In Figure 28A, the first eyeguide layer 2810 is thicker than the second eyeguide layer 2820. Red light is incoupled at the second ICG 2822, and blue and green light are incoupled at the first ICG 2812. The first ICG 2812 and the second ICG 2822 are spatially separated laterally (i.e., in the x-y plane) in this split-pupil configuration. Thus, in some embodiments, the second eyeguide layer 2820 has a thickness t2 that is thicker than the thickness t1 of the first eyeguide layer 2810. This thickness difference can be designed taking into account the wavelengths propagating in the eyeguide, e.g., a thinner eyeguide to support red wavelengths and a thicker eyeguide to support blue and green wavelengths, as shown in Figure 28A.

[0177]

[0256] In Figure 28B, similar to the implementation shown in Figure 28A, the first eyeguide layer 2810 is thicker than the second eyeguide layer 2830. Red light is incoupled at the second ICG 2822, and blue and green light are incoupled at the first ICG 2812. The first ICG 2812 and the second ICG 2822 are spatially separated in this split-pupil configuration. In contrast to the embodiment shown in Figure 28A, the thickness of the second eyeguide layer 2830 varies, being thicker near the second ICG 2822 than near the CPE 2832. Thus, the thickness of one or more of the eyeguide layers may vary in the lateral plane, i.e., the xy plane.

[0178]

[0257] In Figure 28C, the first eyeguide layer 2840 is thicker than the second eyeguide layer 2830. Red light is incoupled at the second ICG 2822, and blue and green light are incoupled at the first ICG 2812. In contrast to the embodiment shown in Figures 28A and 28B, the thickness of the first eyeguide layer 2840 also varies, being thicker near the first ICG 2812 than near the CPE 2842.

[0179]

[0258] As shown herein, a single ICG pupil can be utilized, i.e., a single-position ICG pupil for in-line ICG, or multiple ICG pupils can be utilized, i.e., a split-pupillary configuration. In the embodiment shown in Figures 28A-28C, a split-pupillary configuration is utilized, with the second ICG spatially offset in the lateral plane (i.e., the x-y plane) relative to the first ICG. These split-pupillary designs can also include a three-pupillary design, as described in connection with Figure 27A. Furthermore, the ICGs can operate in a reflective mode, as described above, or in a transmissive mode, as described more fully below. In some embodiments, at least one ICG is transmissive so that undiffracted light can pass through the transmissive ICG to the ICG pupil of the next active layer, thereby allowing this transmitted light to be incoupled and guided to the next active layer.

[0180]

[0259] Figure 29A shows a plan view of an eyepiece waveguide using a two active layer architecture with both split and in-line ICG according to one embodiment of the present invention. The eyepiece waveguide 2900 shown in Figure 29A shares common elements with the eyepiece waveguide 2600 shown in Figure 26A, and the description provided in relation to Figure 26A is also applicable to Figure 29A, as appropriate.

[0181]

[0260] 29A-29C , light of a first wavelength (e.g., red wavelength) is incoupled at the second ICG 2922, propagates through the second eyepiece waveguide layer 2920, and is outcoupled at the second CPE 2924. Light of a second and third wavelengths (green wavelength and blue wavelength) is incoupled into the first eyepiece waveguide layer 2910 using the first ICG 2912. After incoupling into the first eyepiece waveguide layer 2910, the second and third wavelengths (e.g., green light and blue light) are guided towards the first CPE 2914. Furthermore, light of the first wavelength (e.g., red light) is incoupled at the transmissive ICG 2913 coupled to the second eyepiece waveguide layer 2920.

[0182]

[0261] Figure 29B shows an exploded view of the eyepiece waveguide shown in Figure 29A. In this exploded view of the eyepiece waveguide 2900, a first eyepiece waveguide layer 2910 is positioned on the user side of the eyepiece waveguide 2900, and a second eyepiece waveguide layer 2920 is positioned on the front side of the eyepiece waveguide 2900. The first eyepiece waveguide layer 2910 includes a first ICG 2912 used to incouple blue and green wavelengths. The second eyepiece waveguide layer 2920 includes a second ICG 2922 used to incouple red wavelengths. A first CPE 2914 outcouples light from the first eyepiece waveguide layer 2910, and a second CPE 2924 outcouples light from the second eyepiece waveguide layer 2920.

[0183]

[0262] Figure 29C shows a cross-sectional view of the eyepiece waveguide shown in Figure 29A. As shown in Figure 29C, the red projected image can be separately incoupled into the first eyepiece waveguide layer 2910 by the transmission ICG 2913 and into the second eyepiece waveguide layer 2920 by the second ICG 2922. Thus, in contrast to the blank area of ​​the first eyepiece waveguide layer as shown in Figure 26C, the transmission ICG 2913 incouples red wavelengths in a transmission mode into the first eyepiece waveguide layer 2910. The red wavelengths that are not incoupled by the transmission ICG 2913 propagate through the first eyepiece waveguide layer 2910 and impinge on the second ICG 2922 of the second eyepiece waveguide layer 2920. After guiding in the first eyepiece waveguide layer 2910 and the second eyepiece waveguide layer 2920, the red wavelengths are outcoupled by the second CPE 2924 and the first CPE 2914, respectively.

[0184]

[0263] 29C , the green and blue projected images may be incoupled by the first ICG 2912 into the first eyepiece waveguide layer 2910. After guiding in the first eyepiece waveguide layer 2910, the light is outcoupled by the first CPE 2914.

[0185]

[0264] While a reflective ICG implemented as the second ICG 2922 is coupled to the second eyeguide layer 2920, in other embodiments, an additional reflective ICG is implemented as a third ICG on the opposite side of the transmissive ICG 2913 to incouple additional red light into the first eyeguide layer 2910. This additional reflective ICG may be implemented instead of or in addition to the second ICG 2922. Furthermore, an additional transmissive ICG may be implemented on the second eyeguide layer 2920 opposite the second ICG 2922. Furthermore, a transmissive ICG may be implemented on the first eyeguide layer 2910 opposite the first ICG 2912. Thus, both reflective and transmissive ICGs may be used in combination in both split-pupil and single-pupil designs in two active layer architectures. Those skilled in the art will recognize many variations, modifications, and alternatives.

[0186]

[0265] Figure 30A shows a plan view of an eyepiece waveguide 3000 using a two active layer architecture according to one embodiment of the present invention. In this two active layer architecture, a split pupil is used in combination with an in-line ICG, which can include an ICG operating in reflection and / or transmission mode. Figure 30B shows an exploded view of the eyepiece waveguide shown in Figure 30A. Figure 30C shows a cross-sectional view of the eyepiece waveguide shown in Figure 30A.

[0187]

[0266] 30A to 30C , light of a first wavelength (e.g., red wavelength) is incoupled by the second ICG 3022, propagates through the second eyepiece waveguide layer 3020, and is outcoupled by the second CPE 3024. Light of a second wavelength (e.g., green wavelength) is incoupled into the second eyepiece waveguide layer 3020 using the third ICG 3023. After incoupling into the second eyepiece waveguide layer 3020, the light of the second wavelength (i.e., green wavelength) is guided towards the second CPE 3024.

[0188]

[0267] Considering the first eyepiece waveguide layer, a transmissive ICG 3013 is used to incouple light of a second wavelength into the first eyepiece waveguide layer 3010. After incoupling into the first eyepiece waveguide layer 3010, the light of the second wavelength is guided towards the CPE 3014. Also, light of a third wavelength (e.g., a blue wavelength) is incoupled by the first ICG 3012 and propagates within the first eyepiece waveguide layer 3010.

[0189]

[0268] This causes light of green wavelengths to be supported in both the eyepiece waveguide layer that supports red wavelengths (i.e., the second eyepiece waveguide layer in this example) and the eyepiece waveguide layer that supports blue wavelengths (i.e., the first eyepiece waveguide layer in this example). Because green wavelengths may appear darker at the nose in an eyepiece waveguide layer designed to support blue wavelengths and darker at the temples in an eyepiece waveguide layer designed to support red wavelengths, propagation of light of green wavelengths in both the first eyepiece waveguide layer 3010 and the second eyepiece waveguide layer 3020 improves image uniformity.

[0190]

[0269] In some embodiments, an optional transmissive ICG 3015 is utilized to enable light to be incoupled into the first eye-waveguide layer 3010 via both a transmissive ICG (e.g., the transmissive ICG 3015) and a reflective ICG (e.g., the first ICG 3012). Thus, for each color incoupled into one active layer, light can enter through a transmissive ICG on the projector light input side, propagate through the eye-waveguide layer, and then be incoupled by a reflective ICG as well, thereby directing the same type of projector light into the eye-waveguide layer via both transmissive and reflective incoupling. Thus, embodiments of pi can use two ICGs to split light into two different directions within a plane perpendicular to the cross-section shown in FIG. 30C . Additionally, thicker substrates can utilize one or more ICGs on either side of the eye-waveguide to increase pupil replication and reduce screen-door artifacts. Although optional transmission ICG 3015 is shown with the first eye guide layer 3010, a similar transmission ICG can be utilized with the second eye guide layer 3020. Thus, as shown in Figure 30C, embodiments of the present invention can utilize both transmission and reflection ICGs positioned at one or more pupil locations and on one or both sides of the corresponding eye guide layer. Those skilled in the art will recognize many variations, modifications, and alternatives.

[0191]

[0270] Figure 31A shows a plan view of an eyepiece waveguide 3100 using a two active layer architecture according to another embodiment of the present invention. Figure 31B shows an exploded view of the eyepiece waveguide shown in Figure 31A. Figure 31C shows a cross-sectional view of the eyepiece waveguide shown in Figure 31A.

[0192]

[0271] 31A to 31C , light of red wavelengths is incoupled by the first ICG 3113, propagates in the first eyepiece waveguide layer 3110, and is outcoupled by the CPE 3114. Light of green wavelengths is incoupled into the first eyepiece waveguide layer 3110 by the transmissive ICG 3115, and light of green wavelengths is also incoupled into the second eyepiece waveguide layer 3120 by the second ICG 3122. After incoupling into the first eyepiece waveguide layer 3110 and the second eyepiece waveguide layer 3120, the light of green wavelengths is guided towards the CPE 3114 and CPE 3124, respectively. Light of blue wavelengths is incoupled by the third ICG 3123 and propagates in the second eyepiece waveguide layer 3120 before being outcoupled by the CPE 3124.

[0193]

[0272] This means that green wavelengths are supported by both the eyepiece waveguide layer that supports red wavelengths (i.e., the first eyepiece waveguide layer in this example) and the eyepiece waveguide layer that supports blue wavelengths (i.e., the second eyepiece waveguide layer in this example).

[0194]

[0273] Similar to optional transmissive ICG 3015 shown in FIG. 30C , optional transmissive ICG 3125 and optional transmissive ICG 3127 can be utilized such that light can be incoupled into the second eye guide layer 3120 via both transmissive ICGs (e.g., transmissive ICG 3125 and / or transmissive ICG 3127) and reflective ICGs (e.g., second ICG 2133 and / or third ICG 3123). Thus, as shown in FIG. 31C , embodiments of the present invention can utilize both transmissive and reflective ICGs positioned at one or more pupil positions and on one or both sides of the corresponding eye guide layer. Those skilled in the art will recognize many variations, modifications, and alternatives.

[0195]

[0274] Thus, two active layer architectures with split pupil designs combined with in-line ICG, with or without ICG operating in reflective and / or transmissive modes, are within the scope of the present invention. Those skilled in the art will recognize many variations, modifications, and alternatives.

[0196]

[0275] In addition to the two-active-layer architecture using a split pupil with or without an in-line ICG shown in the examples above, embodiments of the present invention allow for the ICG pupil size to be specified as a function of the proximity of the ICG to the projector and the thickness of the eyepiece waveguide layer to which it is coupled. This arises from the fact that light generated by a projector (e.g., an LCOS projector) spreads outward in a conical shape. When light incouples through the diffractive structure of the ICG, light that undergoes total internal reflection can bounce off the opposite surface and bounce back toward the ICG grating, resulting in outcoupling due to diffraction by the ICG pupil. This bounced light is lost and does not reach the CPE, thereby reducing the brightness of the virtual image projected outward from the eyepiece waveguide toward the user. As an example, for an eyepiece waveguide layer with a thickness of approximately 350 μm, the ICG size with minimal bounce loss is less than 0.9 mm in the direction of the optical axis toward the combiner element due to diffusion and outcoupling. Similarly, when the thickness of the waveguide substrate is 500 μm, the ICG size increases slightly.

[0197]

[0276] Figure 32A shows a cross-sectional view of an eyepiece waveguide according to one embodiment of the present invention. In Figure 32A, light from a projector 3205 is incident on a first eyepiece waveguide layer 3210, which includes a first ICG 3212 operating in a transmission mode to incouple light into the first eyepiece waveguide layer 3210. Light from the projector 3205 is also incident on a second eyepiece waveguide layer 3220, which includes a second ICG 3222 operating in a transmission mode to incouple light into the second eyepiece waveguide layer 3220, and a third ICG 3224 operating in a reflection mode to incouple light into the second eyepiece waveguide layer 3220. As shown in Figure 32A, the diameter D of each ICG increases as a function of distance to the projector 3205.

[0198]

[0277] Figure 32B shows a plan view of the ICGs of the eyepiece waveguide shown in Figure 32A. In this layout, the first ICG 3212, second ICG 3222, and third ICG 3224 are concentric, with the diameter of each ICG increasing as shown in Figure 32A.

[0199]

[0278] Figure 32C shows a plan view of an alternative ICG that can be utilized in the eyepiece waveguide shown in Figure 32A. In this non-concentric layout, the first ICG 3212', second ICG 3222', and third ICG 3224' are aligned to a common y-position but are offset along the x-axis in addition to being truncated along their bases.

[0200]

[0279] Figure 32D shows a cross-sectional view of an eyepiece waveguide according to an alternative embodiment of the present invention. In Figure 32D, the projector 3235 is tilted relative to the z-axis, so light from the projector 3205 enters the eyepiece waveguide layer at an angle. As a result, the ICG is offset to accommodate this angled injection of light. As shown in Figure 32D, light from the projector 3235 enters the first eyepiece waveguide layer 3240, which includes a first ICG 3242 operating in a transmission mode to incouple light into the first eyepiece waveguide layer 3240. Light from the projector 3235 is also incident on the second eyepiece waveguide layer 3250, which includes a second ICG 3252 operating in a transmission mode to incouple light into the second eyepiece waveguide layer 3250, and a third ICG 3254 operating in a reflection mode to incouple light into the second eyepiece waveguide layer 3250. As shown in Figure 32D, the diameter D of each ICG increases as a function of the distance to the projector 3235. Furthermore, as the distance from the projector 3235 increases, the ICGs are displaced to a more negative position along the x-axis.

[0201]

[0280] Figure 32E shows a plan view of the ICGs of the eyepiece waveguide shown in Figure 32D. In this layout, the first ICG 3242, the second ICG 3252, and the third ICG 3254 are displaced along the x-axis, and the diameter of each ICG increases as shown in Figure 32D.

[0202]

[0281] Figure 32F shows a plan view of an alternative ICG that can be utilized in the eyepiece waveguide shown in Figure 32D. In this layout, the first ICG 3242', second ICG 3252', and third ICG 3254' are aligned to a common y-position but are offset along the x-axis in addition to being truncated along their bases.

[0203]

[0282] Thus, embodiments of the present invention can utilize a design in which the dependence of ICG size and pupil positioning in the overlapping in-line ICG region can be varied to account for the thickness of the waveguide substrate and the tilt of the projector plane relative to the ICG waveguide surface plane.

[0204]

[0283] Figure 33A shows a plan view of an eyepiece waveguide with a three-pupil layout according to one embodiment of the present invention. In this two-active layer architecture, three pupils are utilized in combination with an LCOS projector, with individual ICGs operating in reflective mode for red and blue wavelengths and in both reflective and transmissive modes for green wavelengths. As described below, green wavelengths are incoupled into an eyepiece waveguide layer designed for red wavelengths, although in other embodiments, green wavelengths can be incoupled into an eyepiece waveguide layer designed for blue wavelengths in combination with or instead of incoupling into the red eyepiece waveguide layer.

[0205]

[0284] Figure 33B shows light incoupling and propagation using the cross-section of the eyepiece waveguide shown in Figure 33A. Referring to Figures 33A and 33B, a three-pupil layout for an LCOS projector is utilized with two active layer architectures. For clarity, the cross-section shown in Figure 33B shows each eyepiece waveguide layer twice, with blue light interaction shown at the top of the figure, green light interaction shown in the middle of the figure, and red light interaction shown at the bottom of the figure. To incoupling red light into the first eyepiece waveguide layer 3310 (see bottom of figure), the red ICG 3321 coupled to the first eyepiece waveguide layer 3310 operates in a reflective mode. Similarly, to incoupling blue light into the second eyepiece waveguide layer 3320 (see top of figure), the blue ICG 3324 coupled to the second eyepiece waveguide layer 3320 also operates in a reflective mode.

[0206]

[0285] The green light (see the central part of the figure) is first incoupled by the transmissive ICG 3323 operating in a transmission mode into the first eye waveguide layer 3310, which in some embodiments is optimized for red wavelengths. The green light not incoupled by the transmissive ICG 3323 is transmitted through the first eye waveguide layer 3310 by the green ICG 3322 operating in a reflection mode and incoupled into the second eye waveguide layer 3320, which in some embodiments is optimized for blue wavelengths. In addition to incoupling the green light, the green ICG 3322 diffracts the zeroth order light (i.e., the zeroth order diffracted light) back towards the first eye waveguide layer 3310, such that the transmissive ICG 3323 coupled to the first eye waveguide layer 3310 operating in a reflection mode incouples the zeroth order diffracted light. This recycling of light, as illustrated by light rays 3315 through multiple eyepiece waveguide layers, can improve the light efficiency provided by the eyepiece waveguides because the air gap between the eyepiece waveguides can be well controlled, for example in the range of less than 3 μm / cm. Various embodiments of the present invention provide air gap control by using spacer elements such as glass beads, imprinted posts, dispensed and cured dots on certain portions of the waveguides, using well-cured edge bonding adhesives, and increasing the thickness of at least one eyepiece waveguide layer.

[0207]

[0286] Figures 33C-33E are field of view images produced by the eyepiece waveguide shown in Figure 33A. In these figures, the field of view is 70°. As shown in Figures 33C-33E, the desired uniformity is provided by the two active layer architecture described herein.

[0208]

[0287] The choice of diffractive pitch used for the two active eyepiece waveguide layers may vary depending on the color combination propagating in the eyepiece waveguide layer(s).

[0209]

[0288] Figure 34A is a spectral plot showing the diffraction pitch used in two active layer architectures according to one embodiment of the present invention, and Figures 34B and 34C are simplified cross-sectional views of two active layer architectures according to one embodiment of the present invention.

[0210]

[0289] As shown in Figure 34A, in a three-active layer architecture, the blue ICG has a grating pitch corresponding to the blue wavelength λ1 and the red ICG has a grating pitch corresponding to the red wavelength λ4, while the two-active layer architecture shown in Figure 34C can set grating pitches corresponding to colors between the blue and red wavelengths, e.g., the cyan wavelength λ2 of the first ICG and the orange wavelength λ3 of the second ICG. Alternatively, to achieve RGB virtual image waveguiding and projection, blue-orange or cyan-red combinations, as well as blue-red combinations, can be utilized as shown in Figure 34B.

[0211]

[0290] Therefore, some embodiments project RGB virtual images using combinations of waveguides individually designed for more specific wavelength ranges. For example, using a combination of two active layers, the ICG diffraction pitches for a >60° FoV with a substrate refractive index of n = 2.0 are: a) a 330 nm pitch optimized for blue and a 420 nm pitch optimized for red; or b) a 340 nm pitch optimized for blue-green and a 390-410 nm pitch optimized for green-red. Therefore, some embodiments use gratings corresponding to wavelengths (e.g., λ2 and λ3) between the wavelengths output by the projector (e.g., λ1 and λ4). The advantage of using an eyepiece waveguide stack with gratings corresponding to cyan (λ2) and orange (λ3) compared to an eyepiece waveguide stack with gratings corresponding to blue (λ1) and red (λ4) is that the red-optimized pitch interacts with world light in a way that can generate a replica of a real-world image in the user's FoV (e.g., rainbow artifacts). Furthermore, as the pitch increases, the transmission of the blue wavelength spectrum decreases, making the visible stack appear less "white" and slightly "yellow." This can undesirably alter the color spectrum of the world image seen by a user through such a waveguide stack. Therefore, as shown in Figures 34B and 34C, two active layer architectures can be considered for RGB virtual image waveguiding and projection using optimized diffractive pitches that satisfy blue-red, blue-orange, cyan-orange, or cyan-red color combinations.

[0212]

[0291] Figure 35A shows a cross-sectional view of an eyepiece waveguide using a two active layer architecture according to one embodiment of the present invention. Figures 35B-35C show plan views of the eyepiece waveguide layer on the user side of the eyepiece waveguide shown in Figure 35A. Figures 35D-35E show plan views of the eyepiece waveguide layer on the front side of the eyepiece waveguide shown in Figure 35A.

[0213]

[0292] As shown in FIG. 35A , the first eyepiece waveguide layer 3510 (i.e., the blue eyepiece waveguide layer) includes a transmissive ICG 3512 operating in a transmissive mode to diffract green wavelengths into the first eyepiece waveguide layer 3510. The transmissive ICG 3512 can be a tilted grating structure utilizing a double-layer structure (e.g., a TiO layer capped by a SiO layer). In some embodiments, the corners of the tilted grating may be sharp or rounded. Additionally, the first eyepiece waveguide layer 3510 includes a first reflective ICG 3514 coupled to the front side of the first eyepiece waveguide layer 3510 and operating in a reflective mode to diffract blue wavelengths into the first eyepiece waveguide layer 3510.

[0214]

[0293] The second eyepiece waveguide layer 3520 (i.e., the red eyepiece waveguide layer) includes two ICGs operating in reflective mode: a second reflective ICG 3522 coupled to the front side of the second eyepiece waveguide layer 3520 and operating in reflective mode to diffract green wavelengths into the second eyepiece waveguide layer 3520; and a third reflective ICG 3524 coupled to the front side of the second eyepiece waveguide layer 3520 and operating in reflective mode to diffract red wavelengths into the second eyepiece waveguide layer 3520.

[0215]

[0294] Longer wavelength light launched into an eyepiece waveguide designed to propagate light at shorter wavelengths (e.g., launching 530 nm green light into an eyepiece waveguide with a grating corresponding to 450 nm blue light) can result in stronger outcoupling at the nasal side, and shorter wavelength light launched into an eyepiece waveguide designed to propagate light at longer wavelengths (e.g., launching 530 nm green light into an eyepiece waveguide with a grating corresponding to 660 nm red light) can result in stronger outcoupling at the temporal side. Therefore, the combination of a transmissive ICG 3512 on the first eyepiece waveguide layer 3510 (i.e., the blue eyepiece waveguide layer) and a second reflective ICG 3522 on the second eyepiece waveguide layer 3520 (i.e., the red eyepiece waveguide layer) can result in uniform outcoupling, as light incoupled by the transmissive ICG 3512 outcouples more strongly on the nose side and light incoupled by the second reflective ICG 3522 outcouples more strongly on the temple side.

[0216]

[0295] As shown in Figures 35B-35E, the ICG super pupil 3530 includes six segments: a first segment 3531, a second segment 3532, a third segment 3533, a fourth segment 3534, a fifth segment 3535, and a sixth segment 3536. As shown in Figures 35B and 35C, the transmissive ICG 3512 is positioned in the sixth segment 3536 of the ICG super pupil 3530, and the first reflective ICG 3514 is positioned in the first segment 3531 of the ICG super pupil 3530. As shown in Figures 35D and 35E, the second reflective ICG 3522 is positioned in the sixth segment 3536 of the ICG super pupil 3530, and the third reflective ICG 3524 is positioned in the fifth segment 3535 of the ICG super pupil 3530. 35B-35E are merely representative, and the placement of the ICGs can be changed to place ICGs in other sections of the super-pupillary as needed. As an example, the positions of the first reflective ICG 3514 and the third reflective ICG 3524 can be swapped, with the first reflective ICG 3514 positioned in the fifth section 3535 and the third reflective ICG 3524 positioned in the first section 3531. Also, the positions of the eye guide layers can be swapped, with the first eye guide layer 3510 positioned on the user side (i.e., the projector side) of the eye guide and the second eye guide layer 3520 positioned on the front side. Furthermore, in some embodiments, the transmissive ICG 3512 is optional, resulting in an eye guide that utilizes only three reflective ICGs. In other embodiments, the transmissive ICG 3512 is replaced with a reflective ICG in the eyepiece waveguide, utilizing four reflective ICGs coupled to the front side of the eyepiece waveguide layer. One or more of the ICGs may include a coating to enhance their transparency. Those skilled in the art will recognize many variations, modifications, and alternatives.

[0217]

[0296] Referring again to FIG. 35A , a cover layer 3542 is integrated with the eyepiece waveguide stack. The cover layer 3542 can include a reflective surface (e.g., at visible wavelengths) that reflects incident light that has passed through the eyepiece waveguide layer. In this embodiment, the cover layer 3542 reflects light, effectively recycling the light and improving the efficiency of the eyepiece waveguide stack. In other embodiments, the cover layer 3542 can include an absorbing surface (e.g., at visible wavelengths) that absorbs light that has passed through the eyepiece waveguide layer. The absorbing surface avoids undesirable bounces and the generation of ghost images that would otherwise be generated by the eyepiece waveguide stack. In the embodiment shown in FIG. 35A , the cover layer 3542 includes a dual-layer coating implemented with a reflective surface 3544 (e.g., a partially reflective surface) and a light-absorbing surface 3546 opposite the reflective surface 3544. In other embodiments, the positions of the reflective surface 3544 and the light-absorbing surface 3546 are swapped.

[0218]

[0297] Figures 36A-36F illustrate various diffraction grating structures that can be utilized in an incoupling grating, an orthogonal pupil dilator grating, an exit pupil dilator grating, or a compound pupil dilator grating according to an embodiment of the present invention. The diffraction element, e.g., grating, utilized in the eyepiece waveguide may be, but is not limited to, a slope (as shown in Figure 36A), a slope with a coating (as shown in Figure 36B), a sawtooth or sharkfin (as shown in Figure 36C), or a reflective coating on a slope (as shown in Figure 36D), a slope (as shown in Figure 36E), or a sawtooth (as shown in Figure 36F in the context of a multilayer reflective coating). The coating can be a high-index and / or low-index dielectric material that can bond to the underlying structure and improve efficiency compared to an uncoated grating. To achieve directional launch of diffracted light, either non-conformal or directional coatings can be utilized. These coatings can be formed using PVD processes such as sputtering and evaporation, and the nanogeometry supporting the coating can be a slope, sharkfin, sawtooth, etc., as shown. Furthermore, the gratings can be binary, multi-step, metageometric, 1D, 2D, 3D structures, morphed hybrid gratings, etc. Thus, the example grating architecture shown can be part of a surface relief grating with an eyepiece waveguide structure. Transmissive and / or reflective ICGs can be defined by imprinting a polymer or etching into a substrate or coating. Subsequent dielectric or metal coatings can be formed over the pattern in a multi-step process, using directional or conformal coating processes as needed.

[0219]

[0298] The pattern of the ICG can be defined by a patterned diffractive structure made of a UV / thermosetting polymer material with an index ranging from 1.5 to 2.0. Transmissive ICGs can utilize patterned polymer structures with high and low refractive index dielectric coatings, such as TiO2, ZrO2, SiC, MgF2, and SiO2. Reflective ICGs can have dielectric and metallic coatings, such as Al, Ag, and metal alloys. Metal coatings can be formed to produce opaque or translucent surfaces. For example, Al coatings can be opaque with thicknesses greater than 70 nm. Furthermore, transmissive ICGs operating in a reflective mode using Al in the coating architecture can utilize Al coatings ranging in thickness from 5 nm to 50 nm. Those skilled in the art will recognize many variations, modifications, and alternatives.

[0220]

[0299] The grating structure can be present on either one side of the waveguide or both sides of the waveguide. Such gratings can be directly imprinted with low- to high-index nanoimprinted polymers (1.5-2.0), inorganic patterns etched directly into high-index substrates (e.g., LiNbO3, LiTaO3, SiC, etc.), or high-index films (e.g., TiO2, ZrO2, SiC, Si3N4, etc.) on high-index substrates, or high-index (with or without low-index) film coatings on the imprinted polymer or etched inorganic patterns. The coating can consist of multiple films of different refractive indices, and the final etched geometry can be composed of materials with more than one refractive index within at least one grating or CPE section. These diffractive elements can be fabricated by etching processes or high / low-index deposition processes.

[0221]

[0300] Because some grating designs diffract more light into the second order than others, a grating design that balances first and second order diffraction can be utilized to balance the light not supported by the eyepiece waveguide after first order diffraction (e.g., first portion 803) with the light supported by the eyepiece waveguide after second order diffraction (e.g., complementary portion 805) to provide a uniformly illuminated field of view. For example, the inventors have determined that an etched blazed grating etched into a lithium niobate (LiNbO) substrate with a dual dielectric / metal coating, e.g., a multilayer stack of TiO and SiO coated with aluminum, enhances second order diffraction, thereby providing a higher launch efficiency, also referred to as diffraction efficiency, in second order diffraction than that achieved by first order diffraction. Thus, the amount of light coupled into the first and second orders can be adjusted using the appropriate grating / coating design. Those skilled in the art will recognize many variations, modifications, and alternatives.

[0222]

[0301] A variety of materials can be utilized in the eyepiece waveguides described herein. The waveguide substrates used to create the eyepieces can be fabricated using materials with a variety of refractive indices, ranging from high refractive index glasses such as 1.7 SCHOTT SF5, 1.8 SF6, 2.01 HOYA high density tantalum Flint glass TAFD55, and 2.06 TAFD65, to crystalline substrates such as lithium tantalate LiTaO3, 2.25 lithium niobate LiNbO3, and 2.65 silicon carbide.

[0223]

[0302] Inorganic and organic materials comprising film coatings on waveguide substrates, diffractive and sub-diffractive nanostructures, and / or overcoats on such nanopatterns can include, but are not limited to:

[0224]

[0303] Inorganic high refractive index materials such as ZrO2, Ta2O5, Si3N4, TiO2, SiC TiO2 (n range 2.0-2.65) and low refractive index materials such as MgF2, SiO2 (n range 1.36-1.45).

[0225]

[0304] Organic high refractive index material resist (1.6≦n≦2.11) and low refractive index material resist (1.15≦n≦1.6).

[0226]

[0305] Deposition of such inorganic and organic materials can be performed using, but is not limited to, physical vapor deposition (evaporation, sputtering), chemical vapor deposition (LP PECVD, ALD, AP PECVD, etc.) for inorganic thin films, and coating of organic materials by spin coating, slot die, microgravure, spin coating, atomization (spray), etc.

[0227]

[0306] High-refractive-index coatings can utilize SiC with refractive indices of 2.5–2.6, TiO2 with refractive indices of 2.2–2.5, ZrO2 with refractive indices of 2.1, Si3N4, and silicon oxynitride with refractive indices of 1.8–2.0, SiO2 with refractive indices of 1.45, and MgF2 with refractive indices of 1.38. Thin-film coatings can be achieved on blank or patterned surfaces using physical vapor deposition (PVD) techniques such as evaporation or sputtering, with or without ion-assisted (e.g., Ar / O2) or chemical vapor deposition (CVD) techniques such as low-pressure PECVD, atmospheric PECVD, and ALD. Fluorinated polymer films with a refractive index of 1.31 can also be coated; poly[4,5-difluoro-2,2-bis(trifluoromethyl)-1,3-dioxole-co-tetrafluoroethylene] is dissolved in Fluorinert™ FC-40 at concentrations up to 2% by weight. Low refractive index films (<1.3) can be formulated into single-layer or multi-layer colloidal film compositions with porous SiO2 polymer matrix compositions using sol-gel techniques. Such low refractive index coatings can be applied by, but not limited to, spin coating, spraying / atomization, inkjet, etc.

[0228]

[0307] The patterned imprintable prepolymer material can include a resin material such as an epoxy vinyl ester. The resin can include vinyl monomers (e.g., methyl methacrylate) and / or di- or tri-functional vinyl monomers (e.g., diacrylates, triacrylates, dimethacrylates, etc.), with or without aromatic molecules in the monomer. The prepolymer material can include monomers with one or more functional groups, such as alkyl, carboxyl, carbonyl, hydroxyl, and / or alkoxy. Sulfur atoms and aromatic groups both have higher polarizability and can be incorporated into these acrylate components to increase the refractive index of the formulation, typically in the range of 1.5 to 1.75. In some implementations, the prepolymer material can include a cycloaliphatic epoxy-containing resin that can be cured using ultraviolet light and / or heat. Additionally, the prepolymer material can include an ultraviolet cationic photoinitiator and a co-reactant to promote efficient ultraviolet curing under ambient conditions.

[0229]

[0308] Incorporating inorganic nanoparticles (NPs) such as ZrO2 and TiO2 into such imprintable resin polymers can significantly increase the refractive index, up to 2.1. Pure ZrO2 and TiO2 crystals can reach refractive indices of 2.2 and 2.4–2.6 at 532 nm, respectively. To prepare optical nanocomposites of acrylate monomers and inorganic nanoparticles, the particle size can be smaller than 10 nm to avoid excessive Rayleigh scattering. Due to their high specific surface area, high polarity, and incompatibility with crosslinked polymer matrices, ZrO2 NPs tend to aggregate in the polymer matrix. To overcome this problem, surface modification of NPs can be used. In this technique, the hydrophilic surface of ZrO2 is modified to be compatible with organics, allowing the NPs to be uniformly mixed with the polymer. Such modification can be carried out using silane- and carboxylic acid-containing capping agents. One end of the capping agent bonds to the ZrO2 surface, and the other end contains either a functional group or a non-functional organic moiety that can participate in acrylate crosslinking. Examples of surface-modified sub-10 nm ZrO2 particles are those supplied by Pixelligent Technologies™ and Cerion Advanced Materials™. These functionalized nanoparticles are typically sold homogeneously suspended in solvent as a homogeneous blend and can be combined with other substrates to yield resist formulations with jettable viscosity and increased refractive index.

[0230]

[0309] The prepolymer material can be patterned using a template (superstrate, rigid or flexible) bearing the inverse tone (diffractive and sub-diffractive) of the optically functional nanostructures in direct contact with the liquid prepolymer. The liquid prepolymer material can be dispensed onto the substrate or surface to be patterned using, but not limited to, inkjet drop or continuous jetting systems on demand, slot die coating, spin coating, doctor blade coating, microgravure coating, screen printing, spraying or atomization, etc. The template is contacted with the liquid, and as the liquid fills the template features, the prepolymer bearing the diffractive pattern contacted by the template (e.g., in the case of imprint lithography, for example, J-FIL™, where the prepolymer material is inkjet dispensed) is exposed to a wavelength of 310 nm to 410 nm and 0.1 J / cm. 2 ~100J / cm 2 The method can further include applying heat to the prepolymer to a temperature of 40°C to 120°C while exposing the prepolymer to actinic radiation.

[0231]

[0310] Crosslinking silane coupling agents can be used to promote adhesion between prepolymer materials and curing on the desired surface or substrate after patterning (template / mold demolding). These agents have an organic functional group at one end and a hydrolyzable group at the other, forming durable bonds with different types of organic and inorganic materials. An example of an organic functional group is acryloyl, which can crosslink to patternable polymeric materials to form desired optical patterns / shapes. Conversely, templates or molds can be coated with similar coatings in which the acryloyl termini are replaced with fluorinated chains that lower the surface energy and thus act as release sites rather than bonding. Vapor deposition is performed at low pressure, with or without an inert gas such as N2, in the presence of activated -O and / or -OH groups present on the surface of the material to be coated. The vapor coating process can deposit monolayer films as thin as 0.5 nm to 0.7 nm, with thicknesses that can be increased depending on the specific application.

[0232]

[0311] Considerations regarding materials for the eyepiece waveguide

[0233]

[0312] Waveguide substrates used to fabricate eyepieces can include materials with refractive indices ranging from high-index glasses such as SCHOTT SF5 (1.7), SF6 (1.8), HOYA high-density tantalum flint glass TAFD55 (2.01), and TAFD65 (2.06) to crystalline substrates such as lithium tantalate LiTaO3 (2.25), lithium niobate LiNbO3 (2.25), and silicon carbide (2.65). High-index coatings can be made of SiC (2.5-2.6), TiO2 (2.2-2.5), ZrO2 (2.1), Si3N4 (1.8-2.0), and silicon oxynitride (SiO2) (1.45m), MgF2 (1.38). Thin film coatings can be achieved on blank or patterned surfaces using physical vapor deposition (PVD), such as evaporation or sputtering, with or without ion assistance (e.g., Ar / O), or chemical vapor deposition (CVD), such as low-pressure PECVD, atmospheric PECVD, ALD, etc.

[0234]

[0313] The patterned imprintable prepolymer material can include a resin material such as an epoxy vinyl ester. The resin can include vinyl monomers (e.g., methyl methacrylate) and / or di- or tri-functional vinyl monomers (e.g., diacrylates, triacrylates, dimethacrylates, etc.), with or without aromatic molecules in the monomer. The prepolymer material can include monomers with one or more functional groups, such as alkyl, carboxyl, carbonyl, hydroxyl, and / or alkoxy. Sulfur atoms and aromatic groups both have higher polarizability and can be incorporated into these acrylate components to increase the refractive index of the formulation, typically in the range of 1.5 to 1.75. In some implementations, the prepolymer material can include a cycloaliphatic epoxy-containing resin that can be cured using ultraviolet light and / or heat. Additionally, the prepolymer material can include an ultraviolet cationic photoinitiator and a co-reactant to promote efficient ultraviolet curing under ambient conditions.

[0235]

[0314] By incorporating inorganic nanoparticles (NPs) such as ZrO2 and TiO2 into such imprintable resin polymers, the refractive index can be further significantly increased up to 2.1. Pure ZrO2 and TiO2 crystals can reach refractive indices of 2.2 and 2.4–2.6 at 532 nm, respectively. To prepare optical nanocomposites of acrylate monomers and inorganic nanoparticles, the particle size is smaller than 10 nm to avoid excessive Rayleigh scattering. Due to their high specific surface area, high polarity, and incompatibility with crosslinked polymer matrices, ZrO2 NPs tend to aggregate in the polymer matrix. To overcome this problem, surface modification of NPs can be used. In this technique, the hydrophilic surface of ZrO2 is modified to be compatible with organics, allowing the NPs to be uniformly mixed with the polymer. Such modification can be carried out using silane- and carboxylic acid-containing capping agents. One end of the capping agent bonds to the ZrO2 surface, and the other end contains either a functional group or a non-functional organic moiety that can participate in acrylate crosslinking. Examples of surface-modified sub-10 nm ZrO2 particles are those supplied by Pixelligent Technologies™ and Cerion Advanced Materials™. These functionalized nanoparticles are typically sold homogeneously suspended in solvent as a homogeneous blend and can be combined with other substrates to yield resist formulations with jettable viscosity and increased refractive index.

[0236]

[0315] To crosslink and pattern the diffraction pattern-bearing prepolymer that the template is in contact with (e.g., in the case of imprint lithography, e.g., J-FIL™, where the prepolymer material is inkjet dispensed), the light is applied at wavelengths of 310 nm to 410 nm and 0.1 J / cm. 2 ~100J / cm 2The method may further include heating the prepolymer to a temperature of 40°C to 120°C while exposing the prepolymer to actinic radiation. Such prepolymer resins prior to patterning using a template / mold with inverse color features may be dispensed onto the desired surface to be patterned using on-demand inkjet drop or continuous jetting systems, slot die coating, spin coating, doctor blade coating, microgravure coating, screen printing, spraying or atomization, etc.

[0237]

[0316] Crosslinking silane coupling agents are used to promote adhesion between prepolymer materials and the desired surface or substrate after patterning (template / mold demolding). These agents have an organic functional group at one end and a hydrolyzable group at the other, forming durable bonds with different types of organic and inorganic materials. An example of an organic functional group is acryloyl, which can crosslink to patternable polymeric materials to form desired optical patterns / shapes. Conversely, templates or molds can be coated with similar coatings in which the acryloyl termini are replaced with fluorinated chains that lower the surface energy and thus act as release sites, even though they are non-bonding. Vapor deposition is performed at low pressure, with or without an inert gas such as N2, in which the coupling agent is delivered in vapor form.

[0238]

[0317] In some embodiments, a reflective and / or absorbing surface (for the visible spectrum) can be provided on the surface of a cover layer added to the stack. This reflective and / or absorbing surface can help recycle light to improve the efficiency of the stack, or it can absorb light to avoid undesirable bounces and ghost images from the eyepiece waveguide stack. Figure 25 shows an embodiment in which a reflective surface (left) and an absorbing surface (right) are implemented. The cover layer can also have a double-coated surface with a partially reflective surface on one side and a light-absorbing surface on the other side.

[0239]

[0318] Reflective surfaces can be made using metals (e.g., Al, Ag, etc.) or high-index coatings (e.g., TiO2, SiC, etc.), which can be coated using dry physical or chemical vapor deposition processes or wet plating processes. Absorptive films can be made using appropriate dyes and pigments.

[0240]

[0319] To create thin films, suitable color-absorbing dyes and pigments can be incorporated into the UV / thermosetting prepolymer resins described above. Suitable dyes and pigments include carbon black (size range 5 nm to 500 nm), rhodamine B, tartrazine, Yamada Chemical Industry Co., Ltd. chemical dyes, and SunChemical's SUNFAST pigments (e.g., Green 36, Blue, Violet 23, etc.).

[0241]

[0320] The dye or pigment is combined with a solvent and then combined with a UV-curable resin to obtain a color-absorbing resin. The solvent can be a volatile solvent, such as alcohol (methanol, ethanol, butanol, etc.) or other low-volatility organic solvent, such as dimethyl sulfoxide (DMSO), propylene glycol monomethyl ether acetate (PGMEA), toluene, etc. The dye or pigment can be separated from the solvent or concentrated (e.g., using centrifugal evaporation) to obtain an optimal concentration in the crosslinked organic resin (e.g., a UV-curable, highly transparent material). Optimal dye or pigment concentration can provide a color-absorbing film with desirable optical properties, such as a higher concentration of color-absorbing dye or pigment, resulting in a less reflective film.

[0242]

[0321] Compared to traditional water- and solvent-based coatings, UV radiation-curable coatings and adhesives present additional challenges in balancing acceptable viscosity for a particular application, target gloss levels, and desired film properties (e.g., scratch resistance, hardness, adhesive strength, etc.). Due to solvent evaporation, traditional coatings begin to orient and "concentrate" the matting agent during physical drying of the film. As the volatile compounds evaporate, the applied film begins to shrink. This shrinkage can vary from 30% to as much as 60% of the wet film volume, depending on the solids volume. In comparison, a 100% UV coating shrinks only about 10% during a rapid-cure cycle, resulting in a much lower density of matting agents. To achieve good matting performance, special attention is typically paid to selecting the particle size and loading of the matting agent and controlling the film thickness. Silica-based matting agents are effective in introducing surface roughness and wrinkles to reduce gloss. An example of a silica matting agent is shown below from Evonik. Acematt HK 400, D50 particle size 6.3μm Acematt OK 607, D50 particle size 4.4μm Acematt OK 412, D50 particle size 6.3μm Acematt 3600, D50 particle size 5.0μm

[0243]

[0322] In addition to the surface roughening technique using inorganic particles, organic components can be added to promote internal light scattering and further enhance matte performance. One such component is EBECRYL® 898 radiation-curable resin from Allnex. To increase the opacity of coatings and adhesives to visible light, broadband absorbers such as carbon black pigments can be added in combination with matting agents to simultaneously achieve overall darkness and a flat surface finish. Pigment loadings can range from 0.2% to 15% by weight, depending on the required cured thickness. For example, 10% pigment can be added to achieve ultra-darkness at thicknesses of 10 to 20 microns. Oxygen scavengers and chain transfer agents such as primary, secondary, and tertiary thiols and amines can be added to minimize oxygen inhibition and enhance surface cure in air.

[0244]

[0323] The eyepiece waveguide designs described herein can be utilized in augmented reality display systems such as those described in connection with Figures 1-25. Thus, for example, waveguide 1120 of Figure 11A, as well as other waveguides implemented as components of an augmented reality display system, can be implemented using one or more of the embodiments described herein.

[0245]

[0324] Example 1 is an eyepiece waveguide stack comprising a first eyepiece waveguide including a first incoupling diffractive optical element and a first compound pupil dilator, and a second eyepiece waveguide including a second incoupling diffractive optical element and a second compound pupil dilator, wherein the second incoupling diffractive optical element is laterally offset from the first incoupling diffractive optical element.

[0246]

[0325] Example 2 is an eyepiece waveguide stack as described in Example 1, wherein the first eyepiece waveguide is operable to incouple light in a first wavelength range and the second eyepiece waveguide is operable to incouple light in a second wavelength range.

[0247]

[0326] Example 3 is the eyepiece waveguide stack according to Examples 1-2, in which the first wavelength range includes 630 nm and the second wavelength range includes 530 nm and 455 nm.

[0248]

[0327] Example 4 is an eyepiece waveguide stack according to Examples 1 to 3, in which light incident on the first incoupling diffractive optical element passes through the second eyepiece waveguide before hitting the first incoupling diffractive optical element.

[0249]

[0328] Example 5 is the eyepiece waveguide stack according to Examples 1-4, in which the thickness of the first eyepiece waveguide is different from the thickness of the second eyepiece waveguide.

[0250]

[0329] Example 6 is the eyepiece waveguide stack of Examples 1-5, wherein the second incoupling diffractive optical element comprises two laterally offset diffractive structures.

[0251]

[0330] Example 7 is an eyepiece waveguide stack according to Examples 1 to 6, wherein the second incoupling diffractive optical element comprises a first diffractive structure operating in a reflection mode and a second diffractive structure operating in a transmission mode.

[0252]

[0331] Example 8 is the eyepiece waveguide stack of Examples 1 to 7, wherein at least one of the first eyepiece waveguide or the second eyepiece waveguide has a thickness that varies laterally.

[0253]

[0332] Example 9 is the eyepiece waveguide stack according to Examples 1 to 8, where the normal vector is orthogonal to the eyepiece waveguide stack and the lateral direction is orthogonal to the normal vector.

[0254]

[0333] Example 10 is the eyepiece waveguide stack of Examples 1-9, further comprising a cover layer including a reflective surface.

[0255]

[0334] Example 11 is the eyepiece waveguide stack of Examples 1-10, further comprising a cover layer including an absorbing surface.

[0256]

[0335] Example 12 is the eyepiece waveguide stack of Examples 1 to 11, wherein the cover layer further includes a partially reflective surface and a light absorbing surface opposite the partially reflective surface.

[0257]

[0336] Example 13 is an augmented reality headset including a projector and an eyepiece waveguide stack optically coupled to the projector, the eyepiece waveguide stack including a first eyepiece waveguide including a first incoupling diffractive optical element and a first compound pupil dilator, and a second eyepiece waveguide including a second incoupling diffractive optical element and a second compound pupil dilator, the second incoupling diffractive optical element being laterally offset from the first incoupling diffractive optical element.

[0258]

[0337] Example 14 is an augmented reality headset described in Example 13, wherein the first eyepiece waveguide is operable to incouple light in a first wavelength range and the second eyepiece waveguide is operable to incouple light in a second wavelength range.

[0259]

[0338] Example 15 is the augmented reality headset of Examples 13-14, wherein the first wavelength range includes 630 nm and the second wavelength range includes 530 nm and 455 nm.

[0260]

[0339] Example 16 is an augmented reality headset according to Examples 13 to 15, wherein light incident on the first incoupling diffractive optical element passes through the second eyepiece waveguide before hitting the first incoupling diffractive optical element.

[0261]

[0340] Example 17 is the augmented reality headset of Examples 13-16, wherein the thickness of the first eyepiece waveguide is different from the thickness of the second eyepiece waveguide.

[0262]

[0341] Example 18 is the augmented reality headset of examples 13-17, wherein the second incoupling diffractive optical element comprises two laterally offset diffractive structures.

[0263]

[0342] Example 19 is the augmented reality headset of Examples 13 to 18, wherein the second incoupling diffractive optical element includes a first diffractive structure operating in a reflective mode and a second diffractive structure operating in a transmissive mode.

[0264]

[0343] Example 20 is the augmented reality headset of Examples 13 to 19, wherein at least one of the first eyepiece waveguide or the second eyepiece waveguide has a thickness that varies laterally.

[0265]

[0344] Example 21 is the augmented reality headset of Examples 13 to 20, wherein the normal vector is orthogonal to the eyepiece waveguide stack and the lateral direction is orthogonal to the normal vector.

[0266]

[0345] In the foregoing specification, the present disclosure has been described with reference to specific embodiments thereof. It will, however, be apparent that various modifications and changes can be made thereto without departing from the broader spirit and scope of the present disclosure. The specification and drawings are, therefore, to be regarded in an illustrative rather than a restrictive sense.

[0267]

[0346] Indeed, it will 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.

[0268]

[0347] 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 particular combination and initially claimed as such, one or more features from a claimed combination may, in some cases, be deleted from the combination, and the claimed combination may be directed to a subcombination or a variation of the subcombination. No single feature or group of features is necessary or essential to every embodiment.

[0269]

[0348] In particular, it will be understood that conditional language used herein, such as "can," "could," "might," "may," and "e.g.," is generally intended to convey that certain embodiments include certain features, elements, and / or steps, while other embodiments do not, unless otherwise specified or understood otherwise within the context of use. Thus, such conditional language is not generally intended to imply that features, elements, and / or steps are somehow required for one or more embodiments, or that one or more embodiments necessarily include logic for determining whether those features, elements, and / or steps should be included in or performed in any particular embodiment, with or without authorial input or prompting. Terms such as "comprising," "including," and "having" are synonymous and are used in an inclusive, open-ended manner and do not exclude additional elements, features, acts, operations, etc. Additionally, the term "or" is used in an inclusive (rather than exclusive) sense; for example, when used to connect a list of elements, the term "or" may refer to one, some, or all of the elements in the list. Furthermore, the articles "a," "an," and "the," as used in this application and the appended claims, should be construed to mean "one or more" or "at least one" unless otherwise specified. Similarly, while operations are shown 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 any sequential order, or that all of the operations shown be performed, to achieve desirable results. Furthermore, the figures may generally illustrate one or more exemplary processes in the form of a flowchart. However, other operations not shown may be incorporated into the generally 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. Furthermore, operations may be rearranged or reordered in other embodiments.In certain circumstances, multitasking and parallel processing may be advantageous. Furthermore, the separation of various system components in the above-described embodiments should not be understood to require 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. Furthermore, other embodiments are within the scope of the following claims. In some cases, the actions recited in the claims can be performed in a different order and still achieve desirable results.

[0270]

[0349] While the present disclosure includes details of many specific embodiments, these should not be construed as limitations on the scope of the subject matter or the scope that may be claimed, but rather as descriptions of features that may be unique to particular embodiments. Certain features described in this disclosure 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 the foregoing features may be described as working in particular combinations and initially claimed as such, one or more features from a claimed combination may, in some cases, be deleted from the combination, and the claimed combination may be directed to a subcombination or a variation of the subcombination.

[0271]

[0350] Specific embodiments of the subject matter have been described. Other embodiments, modifications, and permutations of the described embodiments, as will be apparent to those skilled in the art, are within the scope of the following claims. Although operations are shown in the drawings or claims in a particular order, it should not be understood that such operations require performance in the particular order shown, or in any sequential order, or that all of the operations shown are required (although some operations may be considered optional) to achieve desirable results.

[0272]

[0351] Accordingly, the foregoing exemplary embodiments do not define or limit the present disclosure. Other changes, substitutions, and alterations are also possible without departing from the spirit and scope of the present disclosure.

[0273]

[0352] Thus, the scope of the claims is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the present disclosure and the principles and novel features disclosed herein.

[0274]

[0353] The examples and embodiments described herein are for illustrative purposes only. Various modifications or changes will be apparent to those skilled in the art in light thereof. These are to be included within the spirit and scope of this application and the following appended claims.

Claims

1. a first ocular waveguide including a first incoupling diffractive optical element and a first compound pupil dilator; a second ocular waveguide including a second incoupling diffractive optical element and a second compound pupil dilator, the second incoupling diffractive optical element being laterally offset from the first incoupling diffractive optical element; An eyepiece waveguide stack comprising:

2. the first eyepiece waveguide is operable to incouple light of a first wavelength range; the second eyepiece waveguide is operable to incouple light of a second wavelength range; The eyepiece waveguide stack of claim 1 .

3. The eyepiece waveguide stack of claim 2 , wherein the first wavelength range includes 630 nm and the second wavelength range includes 530 nm and 455 nm.

4. The eyepiece waveguide stack of claim 1 , wherein light incident on the first incoupling diffractive optical element passes through the second eyepiece waveguide before impinging on the first incoupling diffractive optical element.

5. The eyepiece waveguide stack of claim 1 , wherein a thickness of the first eyepiece waveguide is different from a thickness of the second eyepiece waveguide.

6. The eyepiece waveguide stack of claim 1 , wherein the second incoupling diffractive optical element comprises two laterally offset diffractive structures.

7. The eyepiece waveguide stack of claim 1 , wherein the second incoupling diffractive optical element comprises a first diffractive structure operating in a reflection mode and a second diffractive structure operating in a transmission mode.

8. The eyepiece waveguide stack of claim 1 , wherein at least one of the first eyepiece waveguide or the second eyepiece waveguide has a thickness that varies in the laterally direction.

9. The eyepiece waveguide stack of claim 1 , wherein a normal vector is orthogonal to the eyepiece waveguide stack and the lateral direction is orthogonal to the normal vector.

10. The eyepiece waveguide stack of claim 1 , further comprising a cover layer including a reflective surface.

11. The eyepiece waveguide stack of claim 1 further comprising a cover layer including an absorbing surface.

12. The eyepiece waveguide stack of claim 10 , wherein the cover layer further comprises a partially reflective surface and a light-absorbing surface opposite the partially reflective surface.

13. A projector and an eyepiece waveguide stack optically coupled to the projector, the eyepiece waveguide stack comprising: a first ocular waveguide including a first incoupling diffractive optical element and a first compound pupil dilator; a second ocular waveguide including a second incoupling diffractive optical element and a second compound pupil dilator, the second incoupling diffractive optical element being laterally offset from the first incoupling diffractive optical element; an eyepiece waveguide stack including: including augmented reality headsets.

14. the first eyepiece waveguide is operable to incouple light of a first wavelength range; the second eyepiece waveguide is operable to incouple light of a second wavelength range; 14. The augmented reality headset of claim 13.

15. 15. The augmented reality headset of claim 14, wherein the first wavelength range includes 630 nm and the second wavelength range includes 530 nm and 455 nm.

16. The augmented reality headset of claim 13 , wherein light incident on the first incoupling diffractive optical element passes through the second eyepiece waveguide before impinging on the first incoupling diffractive optical element.

17. The augmented reality headset of claim 13 , wherein the thickness of the first eyepiece waveguide is different from the thickness of the second eyepiece waveguide.

18. The augmented reality headset of claim 13 , wherein the second incoupling diffractive optical element comprises two laterally offset diffractive structures.

19. 14. The augmented reality headset of claim 13, wherein the second incoupling diffractive optical element comprises a first diffractive structure operating in a reflective mode and a second diffractive structure operating in a transmissive mode.

20. The augmented reality headset of claim 13 , wherein at least one of the first eyepiece waveguide or the second eyepiece waveguide has a thickness that varies in the laterally direction.

21. The augmented reality headset of claim 13 , wherein a normal vector is orthogonal to the augmented reality headset and the lateral direction is orthogonal to the normal vector.

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