Dummy Imprint Area

Abstract

In some implementations, the method includes imprinting an optical diffractive structure and imprinting an optical sub-diffractive structure adjacent to the optical diffractive structure. For example, the structures can be gratings having different properties. The imprinted structure can be included in optical devices and display systems. Some aspects of the present disclosure describe optical devices including a waveguide, an imprinted grating arranged to direct light into or out of the waveguide, and an imprinted sub-diffractive structure arranged adjacent to the grating.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Patent Application No. 63 / 429,434, filed December 1, 2022, which is incorporated herein by reference in its entirety.

[0002] Field of Disclosure The present disclosure relates to imprint processes and structures, such as for optical devices. [Background technology]

[0003] background Modern computing and display technologies have facilitated the development of systems for so-called "virtual reality" or "augmented reality" experiences, in which digitally rendered images or portions thereof are presented to users in such a way that they appear or can be perceived as real. Virtual reality, or "VR," scenarios typically involve presenting digital or virtual image information without transparency to other actual, real-world visual input, while augmented reality, or "AR," scenarios typically involve presenting digital or virtual image information as an augmentation to the user's visualization of the real world around them. Mixed reality, or "MR," scenarios are a type of AR scenario and typically involve virtual objects integrated into and responsive to the natural world. For example, in MR scenarios, AR image content can be occluded by interacting with real-world objects or otherwise perceived as interacting with real-world objects.

[0004] Referring to FIG. 1 , an augmented reality scene 10 is illustrated in which a user of the AR technology sees a real-world park-like setting 20 featuring people, trees, buildings, and a concrete platform 30 in the background. In addition to these items, the user of the AR technology also perceives that they "see" "virtual content," such as a robotic figure 40 standing on the real-world platform 30 and a cartoonish avatar character 50 that appears to be an anthropomorphic bumblebee flying nearby, yet these elements 40, 50 do not even exist in the real world. Due to the complexity of the human visual system, it can be challenging to create AR technology that facilitates a pleasant, natural-feeling, rich presentation of virtual image elements, among other virtual or real-world image elements.

[0005] The systems and methods disclosed herein address various challenges associated with AR and VR technologies. Imprint processes, such as nanoimprint lithography (NIL), can be used to form optical structures, such as diffraction gratings and other diffractive optical elements. The imprinted optical structures can be used in AR, VR, and other technologies. Summary of the Invention [Means for solving the problem]

[0006] overview Some aspects of the present disclosure describe methods that include imprinting an optical diffractive structure and imprinting an optical sub-diffractive structure adjacent to the optical diffractive structure.

[0007] These and other methods discussed herein may have at least one or more of the following features.

[0008] In some implementations, the optical diffractive structure includes a first grating and the optical sub-diffractive structure includes a second grating, wherein at least one geometric characteristic differs between the first grating and the second grating.

[0009] In some implementations, the at least one geometric characteristic includes at least one of a grating orientation, pitch, width, height, or duty cycle.

[0010] In some implementations, the second grating includes features that extend parallel to the separation direction of the imprints.

[0011] In some implementations, the optical sub-diffractive structure includes a plurality of different structures in each zone of the plurality of zones of the optical sub-diffractive structure.

[0012] In some implementations, the different structures differ in at least one of feature density or feature orientation.

[0013] In some implementations, the multiple zones are arranged along the imprint direction.

[0014] In some implementations, the optical sub-diffractive structure surrounds the optical diffractive structure.

[0015] In some implementations, the optical sub-diffractive structure includes features with a graded dimension, which increases or decreases in a direction toward the optical diffractive structure.

[0016] In some implementations, the features include grating walls that have heights that increase in a direction toward the light-diffracting structure.

[0017] In some implementations, the optical sub-diffractive structures include features with graded dimensions, which increase or decrease in the imprint direction.

[0018] In some implementations, imprinting the optical diffractive structures and imprinting the optical sub-diffractive structures are performed in a common imprint process using a common template.

[0019] In some implementations, the optical diffractive structure includes a diffractive input coupler to the waveguide or a diffractive output coupler from the waveguide.

[0020] In some implementations, the optical sub-diffractive structure includes features that extend circumferentially around the optical diffractive structure.

[0021] In some implementations, the optical diffractive structures have a pitch between 200 nm and 1 μm, and the optical sub-diffractive structures have a pitch between 20 nm and 200 nm.

[0022] In some implementations, the optical diffractive structure has a pitch that causes the optical diffractive structure to diffractively interact with visible light, and the optical sub-diffractive structure has a pitch that does not cause the optical sub-diffractive structure to diffractively interact with visible light.

[0023] In some implementations, imprinting the optical diffractive structures and optical sub-diffractive structures is performed in a roll-to-roll, roll-to-plate, plate-to-roll, or plate-to-plate process.

[0024] In some implementations, the optical sub-diffractive structure comprises a one-dimensional grating, a two-dimensional nanostructure array, or a three-dimensional nanostructure array.

[0025] Some aspects of the present disclosure describe optical devices that include a waveguide, an imprinted grating arranged to direct light into or out of the waveguide, and an imprinted sub-diffraction structure arranged adjacent to the grating. For example, the imprinted grating can be an optical diffractive structure in any of the methods described above or any of the methods and structures discussed herein, and the imprinted sub-diffraction structure can be an optical sub-diffraction structure in any of the methods described above or any of the methods and structures discussed herein.

[0026] Some aspects of the present disclosure describe a display system including a waveguide, a light-coupling element including the waveguide and an imprinted grating, and an imprinted sub-diffraction structure arranged adjacent to the grating. For example, the imprinted grating in the light-coupling element can be an optical diffraction structure in any of the methods described above or any of the methods and structures discussed herein, and the imprinted sub-diffraction structure can be an optical sub-diffraction structure in any of the methods described above or any of the methods and structures discussed herein.

[0027] Some aspects of the present disclosure describe an imprint template. The imprint template includes a first set of surface relief structures configured to imprint optical diffractive structures in a moldable material and a second set of surface relief structures configured to imprint optical sub-diffractive structures in the moldable material. The second set of surface relief structures is adjacent to the first set of surface relief structures. For example, the set of surface relief structures can be configured to imprint any of the adjacent active and non-active structures discussed herein. For example, the imprint template can be used to perform any of the methods described above or any of the imprint methods discussed herein.

[0028] The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other aspects, features, and advantages will become apparent from the description and drawings, and from the claims. [Brief explanation of the drawings]

[0029] [Figure 1] FIG. 1 illustrates an example of a user's view of an augmented reality (AR) device.

[0030] [Figure 2] FIG. 2 illustrates a conventional display system for simulating a three-dimensional image to a user.

[0031] [Figure 3A] FIG. 3A illustrates the relationship between the radius of curvature and the radius of focus. [Figure 3B] FIG. 3B illustrates the relationship between the radius of curvature and the focal radius. [Figure 3C] FIG. 3C illustrates the relationship between the radius of curvature and the radius of focus.

[0032] [Figure 4A] FIG. 4A illustrates a representation of the accommodation-vergence motor response of the human visual system.

[0033] [Figure 4B] FIG. 4B illustrates examples of different accommodation and convergence states of a user's eye pair.

[0034] [Figure 4C] FIG. 4C illustrates an example of a representation of a top-down view of a user viewing content through a display system.

[0035] [Figure 4D] 1 illustrates another example of a representation of a top view of a user viewing content through a display system.

[0036] [Figure 5] FIG. 5 illustrates an embodiment of a technique for simulating a three-dimensional image by correcting for wavefront divergence.

[0037] [Figure 6] FIG. 6 illustrates an example of a waveguide stack for outputting image information to a user.

[0038] [Figure 7] FIG. 7 illustrates an example of an output beam output by a waveguide.

[0039] [Figure 8]FIG. 8 illustrates an example of a stacked waveguide assembly in which each depth plane contains an image formed using multiple different component colors.

[0040] [Figure 9A] FIG. 9A illustrates a cross-sectional side view of an example set of stacked waveguides each including an input coupling optical element.

[0041] [Figure 9B] FIG. 9B illustrates a perspective view of an example of multiple stacked waveguides of FIG. 9A.

[0042] [Figure 9C] FIG. 9C illustrates a top view of an example of multiple stacked waveguides of FIGS. 9A and 9B.

[0043] [Figure 9D] FIG. 9D illustrates an example of a wearable display system.

[0044] [Figure 10] FIG. 10 illustrates a side view of an example projector assembly.

[0045] [Figure 11A] FIG. 11A illustrates a side view of an example augmented reality display system.

[0046] [Figure 11B] FIG. 11B illustrates a top view of the augmented reality display system of FIG. 11A.

[0047] [Figure 11C] FIG. 11C illustrates a side view of the augmented reality display system of FIG. 11A.

[0048] [Figure 12A] FIG. 12A illustrates a side view of an augmented reality display system.

[0049] [Figure 12B] FIG. 12B illustrates a side view of the augmented reality display system of FIG. 12A.

[0050] [Figure 12C] FIG. 12C illustrates a top view of the augmented reality display system of FIG. 12B.

[0051] [Figure 13] FIG. 13 illustrates an example of an imprint process.

[0052] [Figure 14] FIG. 14 illustrates an example of an imprint defect.

[0053] [Figure 15] FIG. 15 illustrates an example of an imprint defect.

[0054] [Figure 16] FIG. 16 illustrates an example of an imprint structure that includes active and non-active areas.

[0055] [Figure 17] FIG. 17 illustrates an example of an imprint structure that includes active and non-active areas.

[0056] [Figure 18] FIG. 18 illustrates an example of an imprint structure that includes a non-active area having multiple zones.

[0057] [Figure 19] FIG. 19 illustrates an example of a process for imprinting optical structures.

[0058] [Figure 20] FIG. 20 illustrates an example of a template and imprint pattern. DETAILED DESCRIPTION OF THE INVENTION

[0059] Detailed Description Augmented and Virtual Reality Systems The AR system can display virtual content to a user, i.e., a viewer, while the user can still see the world around the user. Preferably, this content is displayed on a head-mounted display, e.g., as part of eyewear, that projects image information to the user's eyes. In addition, the display can also transmit light from the surrounding environment to the user's eyes to allow the surrounding environment to be seen. As used herein, a "head-mounted" or "head-mountable" display is understood to be a display that can be worn on the viewer's or user's head.

[0060] Various AR systems disclosed herein include virtual / augmented / composite displays, which may further include one or more optical elements formed on or as part of a waveguide. The optical elements may include, for example, input-coupling optical elements that can be employed to couple light into the waveguide and / or output-coupling optical elements that can be employed to couple light from the waveguide to a user's eye. To achieve high efficiency in coupling light into and / or out of the waveguide, the optical elements may include a diffraction grating. In some display systems, the relatively high diffraction efficiency of the optical elements may be achieved in part by including a tilted grating, which is a type of diffraction grating that can provide high diffraction efficiency for input-coupled / output-coupled light. A tilted grating refers to a grating having an array of surface-relief trenches, where the sidewalls of the trenches in the tiling direction of the array have a substantially uniform non-normal tilt angle with respect to the surface on which the trenches are formed, such as the substrate surface. Slanted gratings can be fabricated by imprinting a slanted grating pattern onto a device substrate, e.g., a waveguide, using a device master template.

[0061] Reference is now 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.

[0062] FIG. 2 illustrates a conventional display system for simulating three-dimensional images for a user. It will be appreciated that when a user's eyes are spaced apart and viewing a real object in space, each eye may have a slightly different view of the object, forming an image of the object at a different location on each eye's retina. This may be referred to as binocular disparity and may be utilized by the human visual system to provide the perception of depth. Conventional display systems simulate binocular disparity by presenting two separate images 190, 200, one to each eye, with slightly different views of the same virtual object that correspond to the views of the virtual object as would be seen by each eye 210, 220 if the virtual object were a real object at the desired depth. These images provide binocular cues that the user's visual system may interpret to derive the perception of depth.

[0063] Continuing with reference to FIG. 2 , the images 190, 200 are spaced a distance 230 along the z-axis from the eyes 210, 220. The z-axis is parallel to the viewer's optical axis when the eyes are fixated on an object at optical infinity directly in front of the viewer. The images 190, 200 are flat and are at a fixed distance from the eyes 210, 220. Based on the slightly different appearance of the virtual object in the images presented to each eye 210, 220, the eyes naturally rotate to focus the object's image at a corresponding point on each eye's retina, maintaining single binocular vision. This rotation can cause the line of sight of each eye 210, 220 to converge on a point in space where the virtual object is perceived to reside. As a result, providing three-dimensional images traditionally involves manipulating the convergence and divergence of the user's eyes 210, 220 and providing binocular cues that the human visual system interprets to provide the perception of depth.

[0064] However, creating a realistic and comfortable depth perception is challenging. 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, light rays become more collimated. In other words, the light field produced by a point (an object or portion of an object) can be said to have a spherical wavefront curvature that 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 illustrate only a single eye 210 for clarity of illustration, the discussion of the eye 210 may also apply to both eyes 210 and 220 of a viewer.

[0065] Continuing with reference to Figures 3A-3C, light from an object at which a viewer's eye is fixating may have different wavefront divergences. Due to the different amounts of wavefront divergence, the light may be focused differently by the eye's lens, which may then need 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 blurring of the retinal image acts as an accommodative cue, causing the shape of the eye's lens to change until a focused image is formed on the retina. For example, the accommodative cue may relax or contract the ciliary muscles surrounding the eye's lens, thereby adjusting the force applied to the supporting ligaments that hold the lens in place, thus changing the shape of the eye's lens until blurring of the retinal image of the fixated object is eliminated or minimized, thereby forming a focused image of the fixated object on the eye's retina (e.g., the fovea). The process by which the eye's lens changes shape can be called accommodation, and the shape of the eye's lens required to form a focused image of a gazed object on the eye's retina (e.g., the fovea) can be called the state of accommodation.

[0066] Referring now to FIG. 4A, a representation of the accommodation-vergence response of the human visual system is illustrated. Eye movements to gaze at an object cause the eye to receive light from the object, which forms an image on each of the eye's retinas. The presence of retinal blur in the image formed on the retina can provide a cue for accommodation, and the relative location of the image on the retina can provide a cue for vergence. The accommodation cue generates accommodation, resulting in each eye's lens adopting a specific accommodation state that forms a focused image of the object on the eye's retina (e.g., the fovea). Meanwhile, the vergence cue generates a vergence movement (eye rotation) so that the image formed on each retina of each eye is at a corresponding retinal point, maintaining single binocular vision. In these positions, the eyes can be said to be adopting a specific vergence state. Continuing to refer to FIG. 4A, accommodation can be understood as a process by which the eyes achieve a specific accommodation state, and convergence can be understood as a process by which the eyes achieve a specific convergence state. As indicated in FIG. 4A, when a user gazes at a different object, the accommodation state and convergence state of the eyes may change. For example, the accommodation state may change when the user gazes at a new object at a different depth on the z-axis.

[0067] 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 vergence movement of the two eyes relative to one another (e.g., the rotation of the eyes so that the pupils move toward or away from one another to converge the lines of sight of the eyes to fixate on an object) is closely linked to the accommodation of the eye's lens. Under normal conditions, changing the shape of the eye's lens to change focus from one object to another at a different distance automatically produces a corresponding change in vergence for the same distance, under a relationship known as the "accommodation-divergence reflex." Similarly, changes in vergence cause a corresponding change in lens shape under normal conditions.

[0068] 4B, examples of different accommodation and convergence states of the eyes are illustrated. Eye pair 222a is fixating on an object at optical infinity, while eye pair 222b is fixating on object 221 at less than optical infinity. In particular, the convergence states of each eye pair are different, with eye pair 222a looking straight ahead and eye pair 222 converging on object 221. The accommodation states of the eyes forming each eye pair 222a and 222b are also different, as represented by the different shapes of lenses 210a, 220a.

[0069] Unfortunately, many users of conventional "3D" display systems find such systems uncomfortable or fail to perceive depth at all due to a mismatch between accommodation and convergence states in these displays. As noted above, many stereoscopic or "3D" display systems display a scene by providing slightly different images to each eye. Such systems are uncomfortable for many viewers, particularly because they simply provide different presentations of the scene, causing changes in the eyes' convergence states without a corresponding change in the eyes' accommodation states. Rather, images are presented by displays at a fixed distance from the eyes so that the eyes view all image information in a single accommodation state. Such an arrangement adversely affects the "accommodation-divergence reflex" by causing changes in convergence states without a corresponding change in accommodation states. This mismatch is believed to cause discomfort to the viewer. Display systems that provide better matching between accommodation and convergence may produce more realistic and comfortable simulations of three-dimensional images.

[0070] Without being limited by theory, it is believed that the human eye can typically interpret a finite number of depth planes to provide depth perception. As a result, a highly realistic simulation of perceived depth can be achieved by providing the eye with different presentations of images corresponding to each of these limited number of depth planes. In some embodiments, the different presentations can provide both convergence cues and matching cues to accommodation, thereby providing physiologically correct accommodation-vergence matching.

[0071] 4B , two depth planes 240 are illustrated that correspond to different distances in space from the eyes 210, 220. For a given depth plane 240, vergence cues may be provided by displaying appropriately different viewpoint images for each eye 210, 220. Additionally, for a given depth plane 240, the light forming the image provided to each eye 210, 220 may have a wavefront divergence that corresponds to the light field produced by points at that depth plane 240.

[0072] In the illustrated embodiment, the distance along the z-axis of depth plane 240 containing point 221 is 1 meter. As used herein, distance or depth along the z-axis may be measured at a zero point located at the exit pupil of a user's eye. Thus, depth plane 240 located at a depth of 1 meter corresponds to a distance of 1 meter away from the exit pupil of a user's eye on the optical axis of those eyes when the eyes are pointed at optical infinity. As an approximation, depth or distance along the z-axis may 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 may be referred to as eye relief and corresponds to the distance between the exit pupil of the user's eye and the display worn by the user in front of the eye. In practice, the eye relief value may be a normalized value commonly used for all viewers. For example, the eye relief may be assumed to be 20 mm, and a depth plane located at a depth of 1 meter may be at a distance of 980 mm in front of the display.

[0073] 4C and 4D, examples of matched and mismatched accommodation-vergence distances are illustrated, respectively. As illustrated in FIG. 4C, the display system may provide an image of a virtual object to each eye 210, 220. The image may cause the eyes 210, 220 to assume a convergence state in which the eyes converge to point 15 on the depth plane 240. In addition, the image may be formed by light having a wavefront curvature corresponding to the real object on the depth plane 240. As a result, the eyes 210, 220 assume an accommodation state in which the image is focused on the retinas of these eyes. Therefore, the user may perceive the virtual object as being at point 15 on the depth plane 240.

[0074] It will be appreciated that each of the accommodation states and convergence states of the eyes 210, 220 is associated with a particular distance on the z-axis. For example, an object at a particular distance from the eyes 210, 220 will cause those eyes to assume a particular accommodation state based on the distance of the object. The distance associated with a particular accommodation state is referred to as the accommodation distance A. d Similarly, a particular convergence distance V associated with the eyes in a particular convergence state or position relative to one another may be referred to as d When the accommodation distance and the convergence distance are consistent, the relationship between accommodation and convergence can be said to be physiologically correct. This is considered to be the most comfortable scenario for the viewer.

[0075] However, in a stereoscopic display, the accommodation distance and the vergence distance may not necessarily match. For example, as illustrated in FIG. 4D , the images displayed to the eyes 210, 220 may be displayed with a wavefront divergence corresponding to the depth plane 240, and the eyes 210, 220 may assume a particular accommodation state focused on points 15a, 15b on that depth plane. However, the images displayed to the eyes 210, 220 may provide a convergence cue that causes the eyes 210, 220 to converge on a point 15 that is 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 210, 220 to the depth plane 240, while the vergence distance corresponds to a larger distance from the exit pupils of the eyes 210, 220 to point 15. The accommodation distance is different from the vergence distance. As a result, there is an accommodation-vergence mismatch. Such misalignment is considered undesirable and may cause discomfort to the user. d -A d ) and can be characterized in terms of diopters.

[0076] It will be appreciated that in some embodiments, a reference point other than the exit pupil of the eye 210, 220 can be used to determine the distance for determining accommodation-vergence mismatch, 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.

[0077] Without being limited by theory, it is believed that a user may still 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, FIG. 6 ) presents 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.

[0078] 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 may output light 650 with a prescribed amount of wavefront divergence corresponding to the wavefront divergence of a light field produced 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. Additionally, it is illustrated that image information may be provided to the user's other eye from a similar waveguide.

[0079] In some embodiments, a single waveguide may be configured to output light with 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, multiple waveguides or stacks of waveguides may be utilized to provide different amounts of wavefront divergence for different depth planes and / or to output light in different wavelength ranges. As used herein, it will be understood that a depth plane may be planar or may follow the contours of a curved surface.

[0080] 6 illustrates an example of a waveguide stack for outputting image information to a user. Display system 250 includes a stack of waveguides or stacked waveguide assembly 260 that can be utilized to provide three-dimensional perception to the eye / brain using multiple waveguides 270, 280, 290, 300, 310. It will be appreciated that in some embodiments, display system 250 can be considered a light field display. Additionally, waveguide assembly 260 may also be referred to as an eyepiece.

[0081] In some embodiments, display system 250 may be configured to provide substantially continuous vergence cues and multiple distinct accommodation cues. Vergence cues may be provided by displaying different images to each of the user's eyes, and accommodation cues may be provided by outputting light forming images with selectable distinct 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 distinct level of wavefront divergence corresponds to a particular depth plane and may be provided by a particular one of waveguides 270, 280, 290, 300, 310.

[0082] 6 , the waveguide assembly 260 may also include multiple features 320, 330, 340, 350 between the waveguides. In some embodiments, the features 320, 330, 340, 350 may be one or more lenses. The waveguides 270, 280, 290, 300, 310 and / or multiple lenses 320, 330, 340, 350 may be configured to deliver image information to the eye with various levels of wavefront curvature or ray divergence. Each waveguide level may be associated with a particular depth plane and configured to output image information corresponding to that depth plane. The image injection devices 360, 370, 380, 390, 400 may act as light sources for the waveguides and may be utilized to inject image information into the waveguides 270, 280, 290, 300, 310, each of which may be configured as described herein to distribute incident light across each respective waveguide for output toward the eye 210. The light exits output faces 410, 420, 430, 440, 450 of the image injection devices 360, 370, 380, 390, 400 and is injected into corresponding input faces 460, 470, 480, 490, 500 of the 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 a portion of a major surface of the corresponding waveguide (i.e., one of the waveguide surfaces that directly faces the world 510 or the viewer's eye 210). In some embodiments, a single light beam (e.g., a collimated beam) may be injected into each waveguide to output an entire field of cloned collimated beams that are 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 injection devices 360, 370, 380, 390, 400 may be associated with and inject light into multiple (e.g., three) waveguides 270, 280, 290, 300, 310.

[0083] In some embodiments, image injection devices 360, 370, 380, 390, 400 are individual displays that each produce image information for injection into corresponding waveguides 270, 280, 290, 300, 310, respectively. In some other embodiments, image injection devices 360, 370, 380, 390, 400 are the output of a single multiplexed display that may, for example, send image information via one or more optical conduits (such as fiber optic cables) to each of image injection devices 360, 370, 380, 390, 400. It will be understood that the image information provided by image injection devices 360, 370, 380, 390, 400 may include light of different wavelengths, i.e., colors (e.g., different component colors as discussed herein).

[0084] 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 is directed through a beam splitter 550 to a light modulator 540, such as a spatial light modulator, where it may be modified by the light modulator 540. 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 illustrated schematically, and in some embodiments, these image injection devices may represent different light paths and locations 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 may function as ideal lenses, relaying light injected into the waveguides to the user's eyes. In this concept, the object may be spatial light modulator 540, and the image may be an image on a depth plane.

[0085] In some embodiments, the 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 to the viewer's eye 210. In some embodiments, the example 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 the waveguides 270, 280, 290, 300, 310. In some other embodiments, the example image injection devices 360, 370, 380, 390, 400 may generally represent multiple scanning fibers or multiple bundles of scanning fibers, each configured to inject light into an associated one of the waveguides 270, 280, 290, 300, 310. It will be appreciated that one or more optical fibers may be configured to transmit light from the optical module 530 to one or more waveguides 270, 280, 290, 300, 310. For example, it will be appreciated that one or more intervening optical structures may be provided between the scanning fiber or fibers and one or more waveguides 270, 280, 290, 300, 310 to redirect light exiting the scanning fiber into one or more waveguides 270, 280, 290, 300, 310.

[0086] 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, controller 560 can be a single integrated device or a distributed system connected by wired or wireless communication channels. Controller 560 can also be part of processing module 140 or 150 (FIG. 9D).

[0087] Continuing with reference to FIG. 6 , the waveguides 270, 280, 290, 300, and 310 can be configured to propagate light within each respective waveguide 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 the top and bottom major surfaces. In an exemplary configuration, the waveguides 270, 280, 290, 300, and 310 can each include output coupling optics 570, 580, 590, 600, and 610 configured to extract light from the waveguide by redirecting light propagating within the respective waveguide out of the waveguide to output image information to the eye 210. The extracted light may be referred to as output coupled light, and the output coupling optics light may be referred to as light extraction optics. The extracted light beam may be output by the waveguide where light propagating within the waveguide strikes a light extraction optical element. The output coupling optical elements 570, 580, 590, 600, 610 may be, for example, gratings including diffractive optical features (e.g., gratings within active / diffractive regions with adjacent non-active / sub-diffractive regions), as discussed further herein. For ease of explanation and clarity of the drawings, the output coupling optical elements 570, 580, 590, 600, 610 are illustrated as being located on the bottom major surfaces of the waveguides 270, 280, 290, 300, 310, but in some embodiments, they may be located on the top and / or bottom major surfaces and / or directly within the volume of the waveguides 270, 280, 290, 300, 310, as discussed further herein. In some embodiments, the output coupling 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 output coupling optical elements 570, 580, 590, 600, 610 may be formed on and / or within that piece of material.

[0088] Continuing with reference to FIG. 6 , as discussed 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-up 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, and such first lens 350 may be configured to create a slightly convex wavefront curvature so that the eye / brain interprets the light coming from the next-up waveguide 280 as coming from a first focal plane closer inward from optical infinity toward the eye 210. Similarly, the third upper waveguide 290 may have its output light pass through both the first lens 350 and the second lens 340 before reaching the eye 210, and the combined refractive power of the first lens 350 and the second lens 340 may be configured to create another 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 closer inward from optical infinity towards the person than the light from the next upper waveguide 280.

[0089] The other waveguide layers 300, 310 and lenses 330, 320 are similarly configured, with the highest waveguide 310 in the stack sending its output through all lenses between the waveguide 310 and the eye for an aggregate 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 world 510 on the other side of the stacked waveguide assembly 260, a compensatory lens layer 620 may be placed on top of the stack to compensate for the aggregate refractive 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 pairings. Both the output coupling 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 electro-active features.

[0090] In some embodiments, two or more of the waveguides 270, 280, 290, 300, 310 may have the same associated depth plane. For example, multiple waveguides 270, 280, 290, 300, 310 may be configured to output images set in the same depth plane, or multiple subsets of waveguides 270, 280, 290, 300, 310 may be configured to output images set in the same multiple depth planes, one set in each depth plane. This may provide advantages for forming tiled images to provide an extended field of view in those depth planes.

[0091] Continuing with reference to FIG. 6 , output-coupling optics 570, 580, 590, 600, 610 can be configured to redirect light out of their respective waveguides and output this light with an 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 output-coupling optics 570, 580, 590, 600, 610 that output light with different amounts of divergence depending on the associated depth plane. In some embodiments, 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, light-extraction optics 570, 580, 590, 600, 610 can be volume holograms, surface holograms, and / or diffraction gratings. In some embodiments, the features 320, 330, 340, 350 may not be lenses; rather, they may simply be spacers (eg, cladding layers and / or structures to form air gaps).

[0092] In some embodiments, the output coupling optical elements 570, 580, 590, 600, 610 are diffractive features, or "diffractive optical elements" (also referred to herein as "DOEs"), that form a diffraction pattern. Preferably, the DOEs have a sufficiently low diffraction efficiency so that only a portion of the light in the beam is deflected toward the eye 210 at each intersection of the DOE, while the remainder continues traveling through the waveguide via TIR. 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 output radiation toward the eye 210 for this particular collimated beam bouncing within the waveguide.

[0093] In some embodiments, one or more DOEs may be switchable between an actively diffracting "on" state and a non-significantly diffracting "off" state. For example, a switchable DOE may include a layer of polymer-dispersed liquid crystal in which microdroplets contain 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).

[0094] In some embodiments, a camera assembly 630 (e.g., a digital camera including a visible light camera and an infrared light camera) may be provided to capture images of the eye 210 and / or tissue surrounding the eye 210, for example, to detect user input and / or monitor the user's physiological condition. As used herein, a camera may be any image capture device. In some embodiments, the camera assembly 630 may include an image capture device and a light source for projecting light (e.g., infrared light) onto the eye, which may then be reflected by the eye and detected by the image capture device. In some embodiments, the camera assembly 630 may be mounted on the frame 80 (FIG. 9D) and may be in electrical communication with processing modules 140 and / or 150, which may process image information from the camera assembly 630. In some embodiments, one camera assembly 630 may be utilized for each eye to monitor each eye separately.

[0095] 7, an example of an output beam output by a waveguide is shown. While one waveguide is illustrated, 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 illustrated 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 discussed herein. It will be appreciated that a substantially parallel output beam may be directed down a waveguide with output coupling optics that output couples light to form an image that appears to be set on a depth plane at a large distance (e.g., optical infinity) from the eye 210. Other waveguides or other sets of output coupling optics may output a more divergent output beam pattern, which requires the eye 210 to accommodate 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.

[0096] In some embodiments, a full-color image can be formed in each depth plane by overlapping images of each of the component colors, for example, three or more component colors. 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, but 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. Different depth planes are indicated in the diagram by different numbers of diopters (dpt) following the letters G, R, and B. By way of example only, the number following each of these letters indicates the diopter (1 / m), i.e., the inverse distance of the depth plane from the viewer, and each box in the diagram represents an individual component color image. In some embodiments, the exact placement of the depth planes for the different component colors can 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 arranged on depth planes corresponding to different distances from the user. Such an arrangement may increase visual acuity and user comfort and / or reduce chromatic aberration.

[0097] 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, resulting in 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.

[0098] 8, in some embodiments, G is green, R is red, and B is blue. In some other embodiments, other colors associated with other wavelengths of light, including magenta and cyan, may be used in addition to or may replace one or more of red, green, or blue.

[0099] It will be understood that references throughout this disclosure to a given color of light are understood to encompass light of one or more wavelengths within the wavelength range of light perceived by a viewer as being of that given color. For example, red light may include one or more wavelengths of light in the range of about 620-780 nm, green light may include one or more wavelengths of light in the range of about 492-577 nm, and blue light may include one or more wavelengths of light in the range of about 435-493 nm.

[0100] In some embodiments, light source 530 (FIG. 6) may be configured to emit light at one or more wavelengths outside the viewer's visual range, e.g., infrared and / or ultraviolet wavelengths. Additionally, the waveguide input coupling, output coupling, and other light redirecting structures of display system 250 may be configured to direct and emit this light from the display toward the user's eye 210, e.g., for imaging and / or user stimulation applications.

[0101] Referring now to FIG. 9A , in some embodiments, light impinging on a waveguide may need to be redirected to couple the light into the waveguide. Input coupling optics may be used to redirect and couple the light into its corresponding waveguide. FIG. 9A illustrates a cross-sectional side view of an example of a plurality or set 660 of stacked waveguides, each including an input coupling optic. The waveguides may each be configured to output light of one or more different wavelengths or one or more different wavelength ranges. It will be understood that the stack 660 may correspond to the stacked waveguide assembly 260 ( FIG. 6 ), and the example waveguides of the stack 660 may correspond to portions of the plurality of waveguides 270, 280, 290, 300, 310, except that light from one or more of the image injection devices 360, 370, 380, 390, 400 is injected into the waveguide from a location where the light requires redirection for coupling.

[0102] The example set 660 of stacked waveguides includes waveguides 670, 680, and 690. Each waveguide includes an associated input coupling optical element (which may also be referred to as a light input region on the waveguide), having, for example, an input coupling optical element 700 located on a major surface (e.g., the top major surface) of waveguide 670, an input coupling optical element 710 located on a major surface (e.g., the top major surface) of waveguide 680, and an input coupling optical element 720 located on a major surface (e.g., the top major surface) of waveguide 690. In some embodiments, one or more of the input coupling optical elements 700, 710, 720 may be located on the bottom major surface of the respective waveguide 670, 680, 690 (particularly when one or more of the input coupling optical elements is a reflective, polarizing optical element). As illustrated, the input coupling optical elements 700, 710, 720 may be located on the upper major surfaces of their respective waveguides 670, 680, 690 (or on top of the next lower waveguide), particularly if the input coupling optical elements are transmissive deflecting optical elements. In some embodiments, the input coupling optical elements 700, 710, 720 may be located within the body of the respective waveguides 670, 680, 690. In some embodiments, as discussed herein, the input coupling optical elements 700, 710, 720 are wavelength selective so as to selectively redirect one or more wavelengths of light while transmitting other wavelengths of light. While illustrated on one side or corner of their respective waveguides 670, 680, 690, it will be understood that in some embodiments, the input coupling optical elements 700, 710, 720 may be located within other regions of their respective waveguides 670, 680, 690.

[0103] As illustrated, the input coupling optical elements 700, 710, 720 may be laterally offset from one another. In some embodiments, each input coupling optical element may be offset to receive light without the light passing through another input coupling optical element. For example, each input coupling optical element 700, 710, 720 may be configured to receive light from a different image injection device 360, 370, 380, 390, and 400, as shown in FIG. 6 , and may be separated (e.g., laterally spaced) from the other input coupling optical elements 700, 710, 720 so as to not receive substantially light from another one of the other input coupling optical elements 700, 710, 720.

[0104] Each waveguide also includes an associated light distribution element, having, 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, the light distribution elements 730, 740, 750 may be disposed on both the top and bottom major surfaces of the associated waveguides 670, 680, 690, respectively, or the light distribution elements 730, 740, 750 may be disposed on different ones of the top and bottom major surfaces of different associated waveguides 670, 680, 690, respectively.

[0105]

[0084] The waveguides 670, 680, 690 may be spaced apart and separated by, for example, gas, liquid, and / or solid material layers. For example, as illustrated, layer 760a may separate waveguides 670 and 680, and layer 760b may separate waveguides 680 and 690. In some embodiments, layers 760a and 760b are formed from a low refractive index material (i.e., a material having a lower refractive index than the material forming the immediately adjacent ones of the waveguides 670, 680, 690). Preferably, the refractive index of the material forming layers 760a and 760b is 0.05 or more or 0.10 or less lower than the refractive index of the material forming waveguides 670, 680, 690. Advantageously, the low refractive index layers 760a, 760b may 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 illustrated, it will be understood that the top and bottom of the exemplary set of waveguides 660 may include immediately adjacent cladding layers.

[0106] Preferably, for ease of manufacturing and other considerations, the materials forming waveguides 670, 680, 690 are similar or the same, and the materials forming layers 760a, 760b are similar or the same. In some embodiments, the materials forming waveguides 670, 680, 690 may vary between one or more waveguides, and / or the materials forming layers 760a, 760b may vary while still maintaining the various refractive index relationships described above.

[0107] 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 injection devices 360, 370, 380, 390, 400 (FIG. 6).

[0108] 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. The input coupling optical elements 700, 710, 720 each deflect the incident light such that the light propagates through each of the waveguides 670, 680, 690 by TIR. In some embodiments, the input coupling optical elements 700, 710, 720 each selectively deflect one or more particular wavelengths of light while transmitting other wavelengths to the underlying waveguides and associated input coupling optical elements.

[0109] For example, input coupling optical element 700 may be configured to deflect light beam 770 having a first wavelength or wavelength range while 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 input coupling optical element 710, which is configured to deflect light of the second wavelength or wavelength range. Light beam 790 is deflected by input coupling optical element 720, which is configured to selectively deflect light of the third wavelength or wavelength range.

[0110] 9A , the deflected light rays 770, 780, 790 are deflected such that they propagate through their corresponding waveguides 670, 680, 690; i.e., the input coupling optical elements 700, 710, 720 of each waveguide deflect the light into its corresponding waveguide 670, 680, 690 to input couple 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.

[0111] 9B, a perspective view of one example of the multiple stacked waveguides of FIG. 9A is illustrated. As described above, the input coupled light rays 770, 780, and 790 are deflected by the input coupling optical elements 700, 710, and 720, respectively, and then propagate by TIR within the waveguides 670, 680, and 690, respectively. The light rays 770, 780, and 790 then impinge on the light distribution elements 730, 740, and 750, respectively. The light distribution elements 730, 740, and 750 deflect the light rays 770, 780, and 790 to propagate toward the output coupling optical elements 800, 810, and 820, respectively.

[0112] In some embodiments, the light distribution elements 730, 740, 750 are orthogonal pupil expanders (OPEs). In some embodiments, the OPEs deflect or distribute light to the output coupling optics 800, 810, 820, and in some embodiments, may increase the beam or spot size of the light as it propagates to the output coupling optics. In some embodiments, the light distribution elements 730, 740, 750 may be omitted, and the input coupling optics 700, 710, 720 may be configured to deflect light directly to the output coupling optics 800, 810, 820. For example, with reference to FIG. 9A , the light distribution elements 730, 740, 750 may be replaced with the output coupling optics 800, 810, 820, respectively. In some embodiments, the output coupling optical elements 800, 810, 820 are exit pupils (EPs) or exit pupil expanders (EPEs) that direct light toward the viewer's eye 210 ( FIG. 7 ). It will be appreciated that an OPE may be configured to increase the size of the eyebox in at least one axis, and that an EPE may increase the size of the eyebox in an axis that intersects the axis of the OPE, e.g., orthogonal to the axis of the OPE. For example, each OPE may be configured to redirect a portion of the light striking the OPE to the EPE of the same waveguide while allowing the remaining portion of the light to continue propagating through the waveguide. Upon striking the OPE again, another portion of the remaining light is redirected to the EPE, which continues to propagate further through the waveguide, and so on. Similarly, upon striking the EPE, a portion of the striking light is directed out of the waveguide toward the user, and the remaining portion of that light continues to propagate through the waveguide until it again strikes the EP, at which point another portion of the striking light is directed out of the waveguide, and so on. As a result, a single in-coupled light beam may be "replicated" each time a portion of its light is redirected by an OPE or EPE, thereby forming a field of cloned light beams, as shown in Figure 6. In some embodiments, the OPE and / or EPE may be configured to modify the size of the light beam.

[0113] 9A and 9B, in some embodiments, a waveguide set 660 includes waveguides 670, 680, 690, input coupling optical elements 700, 710, 720, light distribution elements (e.g., OPEs) 730, 740, 750, and output coupling optical elements (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 input coupling optical elements 700, 710, 720 redirect or deflect incident light into their respective waveguides (with different input coupling optical elements receiving light of different wavelengths). 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 input coupling optical element 700 and then continues to bounce down the waveguide, interacting with the light distribution element (e.g., OPE) 730 and then the output coupling optical element (e.g., EP) 800, as previously described. Light rays 780 and 790 (e.g., green and red light, respectively) pass through the waveguide 670, where light ray 780 strikes the input coupling optical element 710 and is deflected by the input coupling optical element 710. Light ray 780 then bounces down the waveguide 680 via TIR and travels to its light distribution element (e.g., OPE) 740 and then to the output coupling optical element (e.g., EP) 810. Finally, light ray 790 (e.g., red light) passes through the waveguide 690 and strikes the input coupling optical element 720 of the waveguide 690. The input coupling optics 720 deflects the light ray 790 so that it propagates by TIR to the light distribution element (e.g., OPE) 750 and then by TIR to the output coupling optics (e.g., EP) 820. Finally, the output coupling optics 820 then output couples the light ray 790 to the viewer, who also receives the output coupled light from the other waveguides 670, 680.

[0114] FIG. 9C illustrates a top-down view of one example of the multiple stacked waveguides of FIGS. 9A and 9B. As illustrated, the waveguides 670, 680, 690, along with each waveguide's associated light distribution elements 730, 740, 750 and associated output coupling optical elements 800, 810, 820, may be vertically aligned. However, as discussed herein, the input coupling optical elements 700, 710, 720 are not vertically aligned; rather, the input coupling optical elements preferably do not overlap (e.g., are laterally spaced apart as seen in the top-down view). As discussed further herein, this non-overlapping spatial arrangement facilitates one-to-one injection of light from different sources into different waveguides, thereby allowing a particular light source to be uniquely coupled to a particular waveguide. In some embodiments, arrangements including non-overlapping, spatially separated input coupling optical elements may be referred to as shifted pupil systems, and the input coupling optical elements in these arrangements may correspond to sub-pupils.

[0115] 9D illustrates one example of a wearable display system 60 into which the various waveguides and associated systems disclosed herein may be incorporated. In some embodiments, the display system 60 is the display 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.

[0116] 9D , display system 60 includes display 70 and various mechanical and electronic modules and systems to support the functionality of display 70. Display 70 may be coupled to a frame 80 that is wearable by a user or viewer 90 of the display system and configured to position display 70 in front of the user's 90 eyes. Display 70 may 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, another speaker, not shown, may be positioned adjacent the user's other ear canal, if desired, to provide stereo / shapeable sound control). Display system 60 may also include one or more microphones 110 or other devices for detecting sound. In some embodiments, the microphones may 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 may also include ambient sensors 120a that are separate from the frame 80 and may be attached to the body of the user 90 (e.g., to the head, torso, limbs, etc. of the user 90). The ambient sensors 120a, in some embodiments, may be configured to obtain data characterizing a physiological state of the user 90. For example, the sensors 120a may be electrodes.

[0117] 9D , the display 70 is operably coupled to a local data processing module 140 by a communication link 130, such as a wired lead or a wireless connection, which may be mounted in a variety of configurations, such as fixedly attached to the frame 80, fixedly attached to a helmet or hat worn by the user, incorporated into headphones, or otherwise removably attached to the user 90 (e.g., in a backpack-type configuration, a belt-type configuration). Similarly, the sensor 120a may be operably coupled to the local processor and data module 140 by a communication link 120b, such as a wired lead or a wireless connection. The local processing and data module 140 may include 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. If desired, the 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) data captured from sensors (e.g., which may be operatively coupled to frame 80 or otherwise attached to user 90), such as image capture devices (e.g., cameras), microphones, inertial measurement units, accelerometers, compasses, GPS units, wireless devices, gyros, and / or other sensors disclosed herein, and / or b) data obtained and / or processed using remote processing module 150 and / or remote data repository 160 (including data related to virtual content), possibly for passing to display 70 after such processing or retrieval. Local processing and data module 140 may be operatively coupled to remote processing module 150, 160 by communication links 170, 180, e.g., via wired or wireless communication links, such that remote processing module 150 and remote data repository 160 are operatively coupled to each other and available as a resource to 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 on 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.

[0118] 9D , in some embodiments, remote processing module 150 may include 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 may include 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 may 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 within 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. may perform at least a portion of the processing (e.g., generating image information, processing data) and may provide and receive information to and from modules 140, 150, 160, e.g., via a wireless or wired connection.

[0119] 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 to an eyepiece (not shown) via projection optics 1040. 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 may emit polarized light, unpolarized light, or partially polarized light. In an exemplary design, the illumination source 1010 may 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).

[0120] 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 configured to transmit light of a first polarization (e.g., p-polarized light). The light then travels to and enters the spatial light modulator 1030. Illustratively, 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 can 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) such that a bright state (e.g., a white pixel) is indicated. 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, thus indicating 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.

[0121] After reflecting from the SLM 1030, a portion of the light (e.g., modulated light) 1014 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 input coupling grating (ICG) 1050 in an eyepiece (not shown).

[0122] 11A illustrates a system (e.g., an augmented reality display system) 1100A for presenting an image to a user's eye 210 and viewing a world 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 arranged such that light from the light source 1110 illuminates the SLM 1140 and light reflected from the SLM 1140 is coupled into the waveguide 1120 and directed toward the eye 210. The system 1100A includes an optical system 1130 positioned to illuminate the SLM 1140 and project an image of the SLM 1140. Light from the light source 1110 propagates in a first direction, for example, through the optical system 1130 onto the SLM 1140, thereby illuminating the SLM 1140. Light reflected from SLM 1140 propagates again through optics 1130 in a second direction opposite to the first direction and is directed into and coupled into waveguide 1120 .

[0123] The light source 1110 may include a light-emitting diode (LED), a laser (e.g., a laser diode), or other types of light sources. The light source 1110 may be a polarized light source, but the light source 1110 need not be so limited. In some implementations, a polarizer 1115 may be positioned between the light source 1110 and the SLM 1140. As illustrated, the polarizer 1115 is between the light source 1110 and the waveguide 1120. This polarizer 1115 may 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 may be, for example, a wire grid polarizer. A coupling optic 1105, such as a non-imaging optic (e.g., a cone, a compound parabolic concentrator (CPC, lens)), may be positioned relative to the light source 1110 to receive the light output from the light source 1110. The coupling optics 1105 may 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 optics 1105 may, for example, collimate the light output from the light source 1110. The coupling optics 1105 may collect light that matches the angular spectral field of the system 1100A. As such, the coupling optics 1105 may match the angular spectrum of the light output by the light source 1110 with the field of the system 1100A. The coupling optics 1105 may have an asymmetric profile to operate asymmetrically with respect to the light emitted from the light source 1110. For example, the coupling optics 1105 may reduce divergence by different amounts in orthogonal directions (e.g., x-direction and z-direction). Such asymmetry in the coupling optics 1105 may 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) than in the orthogonal direction (e.g., z or x, respectively).

[0124] As discussed above, system 1100A includes optical system 1130 configured to illuminate SLM 1140 and positioned in the optical path between light source 1110 and SLM 1140. Optical system 1130 may include transmission optics that transmit light from light source 1110 to SLM 1140. Optical system 1130 may also be configured to project an image of SLM 1140 or formed by SLM 1140 onto waveguide 1120. The image may be projected onto eye 210. In some designs, optical system 1130 may include one or more lenses or optical elements having refractive power. Optical system 1130 may have, for example, positive refractive power. Optical system 1130 may include one or more refractive optical elements, such as a refractive lens. Other types of optical elements may also be used in some cases.

[0125] The SLM 1140 may reflect, modulate, and reflect light therefrom. The SLM 1140 may be a polarization-based SLM configured to modulate polarization. The SLM 1140 may include, for example, a liquid crystal (LC) SLM (e.g., a liquid crystal on silicon (LCOS) SLM). The LC SLM may include, for example, a twisted nematic (TN) liquid crystal. The SLM 1140 may be substantially similar to the SLM 1030 with respect to FIG. 10. The SLM 1140 may include, for example, 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 may 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).

[0126] As discussed 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), the pixel has a bright state, and when the pixel is on (e.g., a voltage above the threshold turn-on voltage), the pixel has a dark state. In this crossed polarizer configuration, leakage is minimized when the pixel is on and has a dark state.

[0127] In the parallel polarizer configuration, the LCOS SLM 1140 is nominally black. When the pixel is off (e.g., 0 voltage), the pixel has a dark state, and when the pixel is on (e.g., voltage above the threshold turn-on voltage), the pixel has a bright state. In this parallel polarizer configuration, leakage is minimized when the pixel is off and has a dark state. The dark state can be (re)optimized using the rubbing direction and compensator angle. The compensator angle may refer to the angle of a compensator that may be between the optical system 1130 and the SLM 1140.

[0128] The dynamic range and throughput of the parallel polarizer configuration may be different from the dynamic range and throughput of the crossed polarizer configuration. Furthermore, the parallel polarizer configuration may be optimized for contrast differently than the crossed polarizer configuration.

[0129] 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 discussed above. The waveguide 1120 may include a substantially transparent material having a refractive index sufficient to guide light therethrough. Illustratively, the waveguide 1120 may include a first side 1121, a second side 1123 opposite the first side 1121, corresponding upper and lower major surfaces and surrounding edges. The first and second major surfaces 1121 and 1123 may be sufficiently flat so that image information can be preserved during propagation of 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 system 1130 and the SLM 1140 may be positioned on a first side 1121 of the waveguide 1120. The light source 1110 may be mounted on a 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 system 1130 and reaching the SLM 1140. As such, the waveguide 1120 may be mounted between the light source 1110 and the optical system 1130. Furthermore, at least a portion of the waveguide 1120 may extend between the light source 1110 and the optical system 1130, thereby allowing light to travel through a portion of the waveguide 1120 to the optical system 1130. Thus, light emitted from the light source 1110 can be directed through the waveguide 1120 into the optical system 1130, pass through the optical element, and enter the SLM 1140. The SLM 1140 reflects the light back through the optical system 1130 to the waveguide 1120.

[0130] The system 1100A also includes an input coupling optical element 1160 for coupling light from the optical system 1130 into the waveguide 1120. The input coupling optical element 1160 may be located on a major surface (e.g., the upper major surface 1123) of the waveguide 1120. In some designs, the input coupling optical element 1160 may be located on the lower major surface 1121 of the waveguide 1120. In some designs, the input coupling optical element 1160 may be located within the body of the waveguide 1120. Although illustrated on one side or comer of the waveguide 1120, the input coupling optical element 1160 may be located in / on other regions of the waveguide 1120. The input coupling optical element 1160 may be substantially similar to the input coupling optical elements 700, 710, 720 described above with reference to FIGS. 9A, 9B, and 9C. The input coupling optical element 1160 may be a diffractive optical element or a reflector. Other structures may be used as the input coupling optical element 1160. The input coupling optical element 1160 may be configured to direct light incident thereon into the waveguide 1120 at a grazing angle sufficiently large (e.g., greater than the critical angle) relative to the upper major surface 1123 and the lower major surface 1121 of the waveguide 1120 to be guided therein by total internal reflection. Furthermore, the input coupling optical element 1160 may operate over a wide wavelength range and thus may be configured to couple multiple colors of light into the waveguide 1120. For example, the input coupling 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.

[0131] 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 reference to FIG. 9B. For example, the light distribution element 1170 may be an orthogonal pupil expander (OPE). The light distribution element 1170 may be configured to diffuse light within the waveguide 1120 by redirecting light propagating in the x-direction, for example, toward the z-direction as illustrated 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 enters the diffractive optical element and redirect the light, for example, in a substantially orthogonal direction. Other configurations are possible.

[0132] 11B, system 1100A may also include output coupling optics 1180 for coupling light from waveguide 1120 to eye 210. Output coupling optics 1180 may be configured to redirect light propagating within waveguide 1120 by total internal reflection (TIR) ​​at an angle more perpendicular to the upper major surface 1123 and / or lower major surface 1121 of waveguide 1120 so that the light is not guided within waveguide 1120. Instead, the light is redirected from waveguide 1120, for example, through the lower major surface 1121. Output coupling optics 1180 may include, for example, one or more diffractive optical elements configured to diffract light propagating within waveguide 1120 that is incident on the diffractive optical element to redirect the light, for example, from waveguide 1120. Other configurations are possible.

[0133] 11B also shows the location of the input coupling optics 1160, which is located laterally relative to the light distribution optics (e.g., orthogonal pupil expander) 1170 and the output coupling optics 1180. FIG. 11B also shows the location of the light source 1110, which is located laterally relative to the input coupling optics 1160, the light distribution optics (e.g., orthogonal pupil expander) 1170, and the output coupling optics 1180.

[0134] During operation, the light source 1110 of the system 1100A emits light into the coupling optics 1105 through the polarizer 1115. This light is therefore 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 optics 1130 to the SLM 1140. The optics 1130 quasi-collimates and / or selects the light from the light source 1110, thereby illuminating 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 pixel by pixel 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 optics 1105 and the optics 1130 may illuminate the SLM 1140 fairly uniformly. After entering the SLM 1140, the light is reflected through the optics 1130. The optics 1130 may 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 optically conjugate to the SLM 1140 and / or the image formed by and / or on the SLM 1140. The output of the optics 1130 may facilitate the projection of the image on the SLM 1140 into and onto the retina of the eye 210. In some implementations, for example, optical power provided by the output coupling optics 1180 may assist and / or influence the image ultimately formed in the eye 210. Optical system 1130 acts as a projection lens as light reflected from SLM 1140 travels through the system toward waveguide 1120. The optical system may roughly function as a Fourier transform of the image on SLM 1140 onto a plane within waveguide 1120 near input coupling optics 1160. Together, both paths through optical system 1130 (the first path from light source 1110 to SLM 1140 and the second path from SLM 1140 to waveguide 1120) may act to roughly image the pupil of coupling optics 1105.The alignment and orientation of the light source 1110 (and possibly also the coupling optics 1105 and / or polarizer 1115), the optics 1130, and the SLM 1140 are such that light from the light source 1110 reflected from the SLM 1140 is directed onto the input coupling optics 1160. A pupil associated with the coupling optics 1105 may be aligned with the input coupling optics 1160. The light may 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 , the analyzer (e.g., a polarizer) 1150 may be placed in the optical path between the optics 1130 and the input coupling optics 1160. The analyzer 1150 may be, for example, a linear polarizer oriented to transmit light of a first polarization (p-polarization) and block light of a second polarization (s-polarization), or vice versa. The analyzer 1150 may be a clean-up polarizer and 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 back toward the SLM 1140 from the waveguide 1120, specifically the input coupling optics 1160. The analyzer 1150 may include a wire grid polarizer, such as an absorptive wire grid polarizer, as any of the polarizers disclosed herein. Such polarizers 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 multilayer film. 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. Compensators may be used to improve the contrast of a display by improving the circular polarization of incident light rays over 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 produce 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 the first polarization to produce a dark pixel state when the light is attenuated or blocked by the analyzer 1150. In such a configuration, the polarizer 1115 closer along the optical path to the light source 1110 may be oriented differently (e.g., orthogonal) with respect to the analyzer 1150 further along the optical path from the light source 1110. Other, e.g., opposite, configurations are also possible. The light is then deflected to be guided within the waveguide 1120, where it propagates by TIR, and is redirected, for example, by the input coupling optical element 1160. The light then strikes the light distribution element 1170, which redirects 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. The light is thus deflected toward the output coupling optics 1180, which directs the light from the waveguide 1120 toward the eye 210 (e.g., the user's eye, as shown). The light being output by different portions of the output coupling optics 1180 along the z-direction 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 system 1130 is used both to illuminate the SLM 1140 and to project an image onto the input coupling optics 1160. As such, optical system 1130 can act as a projection optical system that distributes (e.g., uniformly) light from light source 1110, as well as an imaging optical system that provides an image of SLM 1140 and / or an image formed by SLM 1140 to the eye.

[0135] As mentioned above, alternative configurations are possible. Referring to FIG. 11C , for example, in some designs, system 1100C can 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 illustrated in FIG. 11C , a single shared analyzer / polarizer 1155 is utilized. This analyzer 1155 may transmit light of a first polarization (e.g., s-polarized) and attenuate or reduce transmission of a second polarization (e.g., p-polarized). Thus, light incident on the first pixel in a first state that does not rotate the polarization direction (e.g., s-polarized light) is reflected from 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 direction (e.g., s-polarized light) is reflected from the SLM 1140 and is attenuated, reduced, or does not pass through the analyzer 1155 to the waveguide 1120. This configuration may potentially simplify the system 1100 of FIGS. 11A / B by allowing the polarizer 1115 and analyzer 1150 shown in FIG. 11A to be incorporated into a shared optical element, the analyzer 1155 shown in FIG. 11C, reducing the number of optical components. The analyzer 1155 may be located between the waveguide 1120 and the optical system 1130. In other implementations, separate analyzer / polarizers and analyzer / polarizers may be used, as shown in system 1100 of Figures 11A / B, which illustrate a polarizer 1115 between the light source 1110 and the waveguide 1120, and an analyzer 1140 between the optical system 1130 and the waveguide 1120.

[0136] A wide variety of other configurations may be employed that utilize the optical system 1130 for both illuminating the SLM 1140 and focusing the image formed by the SLM 1140. For example, while FIGS. 12A-12C show a single waveguide 1120, one or more waveguides, such as a stack of waveguides (possibly different waveguides for different colors of light), may be used. For example, FIG. 12A illustrates a cross-sectional side view of an exemplary system 1200A that includes a stack 1205 that includes waveguides 1120, 1122, and 1124, each of which includes input coupling optical elements 1260, 1262, and 1264. The waveguides 1120, 1122, and 1124 may each be configured to output light of one or more different wavelengths or one or more different wavelength ranges. Stack 1205 may be substantially similar to stacks 260 and 660 (FIGS. 6 and 9A), and the illustrated waveguides 1120, 1122, 1124 of stack 1205 may correspond to portions of waveguides 670, 680, 690, although stack 1205 and waveguides 1120, 1122, 1124 need not be so limited. As illustrated in FIG. 12A, input coupling optical elements 1260, 1262, 1264 may, for example, be associated with, included in, or on waveguides 1120, 1122, 1124, respectively. Input coupling optical elements 1260, 1262, 1264 may be color-selective and may primarily deflect or redirect particular wavelengths into the corresponding waveguides 1120, 1122, 1124 to be guided. As illustrated, because the input coupling optical elements 1260, 1262, 1264 are color-selective, the input coupling optical elements 1260, 1262, 1264 need not be laterally displaced but may be stacked on top of one another. Wavelength multiplexing may be employed to couple specific colors into corresponding waveguides. For example, a red input coupling optical element may couple red light into a waveguide designated to propagate red light, but not blue or green light, which are instead coupled into other waveguides by other blue-selective and green-selective waveguides, respectively.

[0137] 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, 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 can be repeated, and the SLM 1140 can be adjusted to produce 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. The different waveguides 1120, 1122, 1124 of the stack 1205 can each be configured to output light of a different respective color. For example, as illustrated in FIG. 12A , the waveguides 1120, 1122, 1124 can be configured to output blue light, green light, and red light, respectively. Of course, other colors are possible; for example, the light source 1110 may emit other colors, and the color-selective input-coupling optics 1260, 1262, 1264, output-coupling optics, etc., may be configured for such other colors. Furthermore, individual red, green, and blue emitters may be positioned close enough to effectively function as a single-pupil light source. The red, green, and blue emitters may 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 may also be used in combination with multiple display pupils to increase the number of layers that can be addressed.

[0138] The different input coupling optical elements 1260, 1262, 1264 in the different waveguides 1120, 1122, 1124 may be located above and / or below each other and aligned laterally with respect to each other (e.g., in the x and z directions shown in FIG. 12A ), as opposed to being laterally displaced and unaligned from each other. Thus, in some implementations, for example, the different input coupling optical elements 1260, 1262, 1264 may be configured such that light of a first color can be coupled by the input coupling optical element 1260 into the waveguide 1120 to be guided, and light of a second color different from the first color can pass through the input coupling optical element 1260 to the next input coupling optical element 1262 and be coupled by the input coupling optical element 1262 into the waveguide 1122 to be guided. Light of a third color, different from the first and second colors, can pass through input coupling optical elements 1260 and 1262 to input coupling optical element 1264 and can be coupled into waveguide 1124 to be guided. Furthermore, input coupling optical elements 1260, 1262, 1264 may be polarization-selective. For example, different input coupling optical elements 1260, 1262, 1264 can be configured such that light of a particular polarization is coupled into the waveguide by the corresponding polarization-selective input coupling optical element 1260, 1262, 1264 or passes through input coupling optical element 1260, 1262, 1264.

[0139] 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). Various aspects of such systems employing polarization-based SLMs are discussed above, and any of such features may be employed in combination with any other features described herein. However, other designs are still possible.

[0140] For example, a deflection-based SLM 1140 may be employed. For example, the SLM 1140 may 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 may include one or more pixels that include such optical elements, such as micromirrors or reflectors. The SLM 1140 may 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 may include an absorptive material or structure configured to absorb light. The deflection-based SLM 1140 may 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 input coupling optics 1260, 1262, 1264 when a given pixel is in a bright state. As discussed above, this light is then coupled by one of the input coupling 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, light from the light source 1110 may be deflected to the light dump 1250, and the light is not coupled by one of the input coupling optics 1260, 1262, 1264 into one of the respective waveguides 1120, 1122, 1124 and directed toward the eye 210. Instead, the light may be absorbed by an absorbing material comprising the light dump 1250. In some implementations, the analyzer 1150 can be a polarizer (e.g., a “clean-up” polarizer) used to eliminate unwanted reflections from the input coupling optics 1260, 1262, 1264. This polarizer can be useful because the optical system 1130 can include plastic optical elements that have birefringence and can change polarization.The "clean-up" polarizer may attenuate or eliminate light having undesired polarizations (e.g., reflections) from being directed onto the waveguides 1120, 1122, 1124. Other types of light-conditioning elements may be placed between the SLM 1140 and the waveguides 1120, 1122, 1124, such as between the optical system 1130 and the waveguides 1120, 1122, 1124. For example, such light-conditioning elements may also include circular polarizers (i.e., linear polarizers and retarders such as quarter-wave plates). The circular polarizers may reduce the amount of reflections from the waveguides 1120, 1122, 1124 or the input coupling optical elements 1260, 1262, 1264 that re-enter and are coupled into the waveguides 1120, 1122, 1124. The reflected light may be circularly polarized and 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). The retarder in the circular polarizer may convert the circularly polarized light to linear polarization, such as the polarizer's orthogonal polarization, which is attenuated, e.g., absorbed, by the circular polarizer's linear polarizer. Clean-up polarizers may be used with polarization-independent modulators, such as DMDs. As mentioned above, clean-up polarizers may be useful to suppress reflections and / or improve the coupling of light into the input coupling optics 1260, 1262, 1264 with optimal polarization states.

[0141] 12B illustrates a side or cross-sectional view of such a system 1200B, while FIG. 12C shows a top view of the lateral arrangement of the input coupling optical element 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 lateral location of the input coupling optical element 1264 (as well as the other input coupling optical elements 1260, 1262) or to the light dump 1250, depending on the state of a particular pixel. Optical system with dummy area

[0142] Imprint processes such as nanoimprint lithography (NIL) can be used to form optical structures such as diffraction gratings and other diffractive optical elements. These optical structures can be included in VR systems, AR systems, and other types of display and / or projection systems, such as those discussed above with reference to Figures 1-12C.

[0143] Defects in the imprinted structures can impair the performance of the optical system (e.g., light input / output coupling efficiency). For example, in some cases, grating peeling and / or other damage can be observed at the edges (e.g., leading / trailing edges) of imprinted patterns such as gratings. Such defects can be exacerbated if the grating extends perpendicular to the separation direction during the imprint process.

[0144] For example, FIG. 13 illustrates an imprinting process using a soft mold 1302 on a substrate 1304 (e.g., a semiconductor wafer or dielectric substrate) having a coating 1306 (e.g., a UV-curable polymer). A pattern in the surface of the mold 1302 forms a corresponding pattern 1308 (in this example, a grating) in the coating 1306. When imprinting occurs in the rolling direction (imprint direction) 1310, separation occurs approximately at location 1312, and the separation is associated with a separation force (sometimes referred to as a demolding force), e.g., a shear force. Solid-mold (“hard-to-hard”) imprinting processes (e.g., solid-mold NIL processes) can sometimes exhibit even higher shear forces than those observed using soft molds. The separation force can lead to defects, particularly at the edges of gratings and other imprinted patterns. For example, at the boundary between the pattern-rich and blank regions, a spike in the demolding force (e.g., a sudden tug) can occur, which can shear the pattern and lead to imprint defects.

[0145] 14, for example, shows an imprint optical structure 1400, 1410 exhibiting a delamination grating 1402 (observed as dark lines) at the edge of the grating region 1404. In this case, delamination is observed at the leading edge (where separation first begins during the nanoimprint lithography imprint process), although delamination and other defects can occur at other edges, such as the trailing edge.

[0146] In some cases, defects are more likely to occur when the grating extends perpendicular to the separation / demolition direction. Additionally, defects can be exacerbated in tilted grating situations, where the grating is tilted from the normal to the surface. Tilted gratings can significantly increase shear forces when the grating is not aligned with the separation direction (e.g., in a pinwheel arrangement, as discussed below with reference to FIG. 17).

[0147] As another example, when performing an imprint process (e.g., particularly a high-speed imprint process), bubble formation can occur at the edges of patterned areas, such as grating regions. During the imprint process, air can become trapped at the edges, resulting in bubbles. For example, FIG. 15 shows imprinted optical structures 1500, 1510 exhibiting air bubbles 1502 at the edges of the active region 1504. The bubbles can cause degradation of the optical performance of waveguides, gratings, and other active optical structures.

[0148] According to some implementations of the present disclosure, dummy imprint regions, such as non-active grating zones, are added adjacent to one or more active patterns, such as active gratings, to mitigate grating peeling and / or other defects. The dummy imprint regions are formed in a common imprint process with the active regions, e.g., using a common mold. As a result, fabrication-related defects associated with pattern edges are kept spatially separated from the active patterns, resulting in a defect-free or relatively defect-free active pattern. For example, the separation edge where the imprint mold first separates from the imprint material (e.g., polymer) during the imprint process can be located at the edge of a dummy imprint region, such as a non-active grating region, thereby reducing or preventing damage to the active grating region adjacent to the dummy imprint region.

[0149] As another example, because air bubbles have been observed to form at the boundary between the grating and blank (e.g., non-imprinted) regions, non-active dummy imprint regions can be provided adjacent to the grating such that the patterned / blank interface is spatially separated from the grating. As a result, air bubbles (if formed during imprinting) are more likely to occur in the non-active dummy imprint regions, thus mitigating the effect of the air bubbles on the optical performance of the grating.

[0150] Additionally, in some implementations, the non-active dummy imprint region may include one or more non-active structures that reduce and / or diffuse the separation force, for example, based on the orientation and / or feature height of the non-active structures. Thus, in some implementations, separation-induced damage may not only be kept away from the active structures, but may also be reduced.

[0151] In some implementations, the non-active regions discussed herein can function as a barrier to prevent residual film thickness (RLT) deficiencies / defects due to resist overflow at grating edges. For example, in some cases, a volume of resist in a pattern-rich region (e.g., which may require a large resist volume) flows toward a blank region (e.g., with a smaller resist volume) due to normal capillary action, which can "starve" the pattern-rich region of resist, leaving the pattern-rich region with insufficient resist volume for pre-hardening, thus leading to unfilled defects, clogging, and / or peeling, for example, because a residual interconnect layer may form between structures and cause adhesion to the template. In some implementations, the presence of dummy imprint regions can reduce this flow (e.g., because the flow from the pattern-rich region to the dummy imprint region with non-diffractive or sub-diffractive structures may be less than the flow from the pattern-rich region to the blank region).

[0152] In some implementations according to the present disclosure, an “active” region is a diffractive region having one or more diffractive optical structures, and a “non-active region” is an optically non-diffractive or optically sub-diffractive region. For example, in some implementations, a non-active region can (but need not) include one or more structures that may perform one or more optical functions, such as anti-reflection, but that do not perform a diffractive optical function (e.g., input / output coupling of light using a grating) for the wavelength(s) of light diffracted by the active region. Whether an optical structure / nanostructure performs a diffractive or non-diffractive / sub-diffractive function can be based at least on the critical dimensions (e.g., depth, width, and / or spacing) of the structure, such as the grating dimensions. Thus, references throughout this disclosure to “active” regions and / or structures can, in some implementations, refer to “diffractive” regions and / or structures, and references to “non-active,” “dummy,” etc. regions and / or structures can refer to “non-diffractive” or “sub-diffractive” regions and / or structures.

[0153] In some implementations, the non-active dummy regions are non-active grating regions having imprinted gratings. The non-active gratings may have a significantly different geometry (grating orientation, pitch, critical dimensions such as width and / or height, duty cycle, and / or another parameter) than the active gratings, for example, such that the non-active gratings do not diffractively interact with light having wavelengths that diffractively interact with the diffractive structures in the active grating regions.

[0154] For example, in some implementations, an optically diffractive structure, such as a grating, is configured to in-couple light into a waveguide (e.g., from air to a substrate) and / or out-couple light from a waveguide (e.g., from a substrate to air), such that the light is directed by total internal reflection (TIR). Light having the same wavelength does not diffractively interact with non-active gratings adjacent to the optically diffractive structure, such that the non-active gratings do not actively change the optical performance of the active region substantially or at all.

[0155] For example, in some implementations, the pitch of the grating(s) in the non-active region can be much larger or smaller than the pitch of the grating(s) in the active region, and the different pitches can result in different optical interactions with the gratings (e.g., sub-diffractive for the non-active region and diffractive for the active region).

[0156] For example, in some implementations, the diffractive structures have a pitch (periodicity on one or two axes) of 200 nm to 1 μm or 200 nm to 2 μm, and the sub-diffractive structures have a pitch of 100 nm or less, 200 nm or less, 300 nm or less, or 400 nm or less, and a pitch of, for example, greater than 20 nm or greater than 50 nm, dimensions that can impart diffractive and sub-diffractive behavior to visible light, respectively. In some implementations, the diffractive structures have a pitch of 200 nm to 1 μm or 200 nm to 2 μm, and the non-active structures have a pitch of 1 μm or more, 2 μm or more, or 3 μm or more. In some implementations, the active structures have parameter (e.g., pitch) values ​​that cause the diffractive structures to diffractively interact with one or more types of light, and the non-active structures have parameter values ​​that do not cause the non-active structures to diffractively interact with one or more types of light, where the one or more types of light can include visible light, infrared light, and / or ultraviolet light. In some implementations, the active structures have parameter (e.g., pitch) values ​​that cause the diffractive structures to couple light in and / or out of the underlying substrate via the diffractive structures, and the non-active structures have parameter values ​​that do not cause the non-diffractive structures to couple light in and / or out of the underlying substrate via the non-diffractive structures.

[0157] The "pitch" and other characteristics of patterned structures, as used herein, can refer not only to strict periodicity but also to quasi-periodicity, e.g., tiling / arrangement of structures with varying height or varying orientation.

[0158] The use of a grating or other structure with a defined pattern as an inactive / dummy structure can, in some implementations, provide advantages over the use of another type of structure, such as a random structure. For example, the grating can be oriented to provide a relatively low release force (e.g., by having a grating structure that extends in the direction of peeling) and / or to gradually direct the release force, for example, by having multiple zones with different heights and / or grating orientations. In contrast, a random structure can result in unpredictable and potentially high release forces depending on the random structure.

[0159] As described above, in some implementations, the non-active structures (e.g., non-active gratings) perform one or more optical functions non-diffractively or sub-diffractively. For example, in some implementations, the non-active gratings are configured to be anti-reflective and / or the non-active region can include an anti-reflective coating. For example, the geometry of the gratings in the non-active region can be such that the gratings interact with light sub-diffractively or non-diffractively, e.g., by having one or more dimensions that are larger and / or smaller than corresponding dimensions of the gratings in the active region.

[0160] The distance between a non-active structure and an adjacent active structure is small enough to reduce or prevent imprint-related defects that would otherwise occur on or at the edges of the active structure. For example, in various implementations, the distance between a non-active structure and an adjacent active structure can be less than 10 nm, less than 25 nm, less than 50 nm, less than 100 nm, less than 250 nm, less than 500 nm, less than 1 μm, less than 5 μm, less than 20 μm, less than 50 μm, or another value. In some implementations, this distance is very small, for example, within the minimum resolution of electron beam lithography or another process used to fabricate the template.

[0161] 16 illustrates several examples of inactive regions adjacent to active regions, in this case including an inactive grating. In this example, for simplicity, all regions are located on a common substrate 1600, but in general, inactive and active regions need not be located on a substrate with other inactive and active regions. The structures of the inactive and active regions are formed in an imprint process with an imprint direction 1601 parallel to the separation direction.

[0162] As shown in FIG. 16 , the active region 1602 is adjacent to non-active regions 1604a, 1604b, 1604c, and 1604d, collectively referred to as the non-active region 1604. The non-active regions 1604 can have the same or different types of structures (e.g., sub-diffractive structures and / or non-diffractive structures). In this example, the non-active region 1604a includes a graded non-active grating 1606. The non-active grating 1606 includes parallel-extending walls 1608 separated by trenches. In any of the implementations described herein, the walls of the grating (e.g., sub-diffractive grating) in the non-active region can, but need not, extend parallel to the walls of the grating in the adjacent active region; for example, the walls 1608 can extend parallel to the walls of the grating in the active region 1602 (not shown). 16, the wall 1608 extends parallel to the boundary 1610 between the non-active area 1604a and the active area 1602. In some implementations, the wall 1608 extends perpendicular to the imprint direction 1601, as shown in this example.

[0163] The non-active lattice 1606 "tapers" in the sense that the height of the wall 1608 increases in the direction of the adjacent active region 1602. For example, the wall 1608 closer to the active region 1602 is higher than the wall 1608 farther from the active region 1602. The taper can be applied to all the walls 1608 (e.g., such that the non-active lattice 1606 has walls 1608 with a monotonically increasing height towards the active region 1602), or can be applied to a subset of the walls 1608. For example, a plurality of adjacent walls 1608 within the non-active lattice 1606 (e.g., in various implementations, two or more adjacent walls 1608, three or more adjacent walls 1608, four or more adjacent walls 1608, or another number of adjacent walls 1608) can have a height that increases towards the adjacent active region 1602.

[0164] In some implementations, the taper can help to guide the direction of the imprint force and the direction of the release force so as to prevent a "sudden" spatially concentrated release force at the edge / boundary between the active diffraction region and the sub-diffraction non-active region.

[0165] In some implementations, the tapered height (or other tapered dimension) of the non-active structure approaches the corresponding height (or other dimension) of the adjacent active structure. For example, a lattice adjacent to the non-active lattice 1606 within the active region 1602 can have a height h, and the features of the non-active lattice 1606, such as the height of the lattice walls, can be h1 < h2 < … < h n where h n is less than or equal to h, and in some implementations, can be near h, for example, within 10% or 20% of h, or match h. For example, the height of the features within the non-active region 1604 can be gradually increased until reaching the active region 1602. Thus, the release force can be gradually induced / reduced so as to potentially reduce generation separation defects.

[0166] In some implementations, one or more parameters are graded instead of or in addition to height. The parameter(s) can include, for example, feature height or depth, feature spacing, feature width, feature length, feature density, orientation (e.g., array angle relative to a given direction), and / or array pitch and / or duty cycle in one or more dimensions. In some implementations, the gradation occurs in the imprint direction, which need not be the same as the direction toward adjacent active areas.

[0167] Another of the non-active regions 1604 adjacent to the active region 1602, non-active region 1604c, includes a grating 1612 made up of parallel walls 1614. In this example, the walls 1614 extend parallel to the separation direction of the imprint process. In some implementations, this orientation of non-active structures, such as grating walls, features extending parallel to the separation direction can reduce the occurrence of imprint defects, for example, by reducing shear forces during imprinting.

[0168] Other non-active regions 1604b, 1604d adjacent to the active region 1602 can include respective non-active gratings that can have characteristics as described for non-active grating 1606 (e.g., having walls that extend parallel to the boundary with the active region 1602 and / or having a gradation in feature height) and / or characteristics as described for non-active grating 1612 (e.g., having walls that extend perpendicular to the boundary with the active region 1602, having walls that extend parallel to the separation direction, and / or having no gradation in feature height). Other feature shapes can also be used instead or additionally.

[0169] Additional non-active regions 1620a, 1620b, and 1620c (collectively referred to as non-active regions 1620) are adjacent to and surround active regions 1618a, 1618b, and 1618c (collectively referred to as active regions 1618), respectively. The non-active regions 1620 include respective non-active lattices having walls extending parallel to the local interface between the non-active region 1620 and the active region 1618. For example, circular active region 1618b has a circular interface 1622 with non-active region 1620b, and walls 1626 of non-active lattice 1624 in non-active region 1620b extend circumferentially parallel to the circular interface 1622. In some implementations, this orientation can help maintain smooth release and / or imprint forces and space delamination and / or unfilled zones from the active structures, as discussed above.

[0170] The non-active gratings in each of the non-active regions 1620a, 1620c (not shown) can have properties as described for the grating 1624. For example, the walls of the non-active grating in the non-active region 1620c can be elliptical in shape to surround and be locally parallel to the elliptical boundary between the non-active region 1620c and the elliptical active region 1618c, and the walls of the non-active grating can be radially tiled relative to the center of the active region 1618c. As another example, the active region 1618a can be rectangular, and the non-active region 1620a can include four non-active gratings on each of the four sides of the active region 1618a, with the walls of each non-active grating extending parallel to the nearest side of the active region 1618a and tiled / periodic in the direction perpendicular to the nearest side.

[0171] Although the non-active grating 1624 is shown as being non-graded, consisting of walls with uniform height, in some implementations, a non-active grating having a circumferential configuration (e.g., circular or elliptical) can be graded in height, for example, as described with respect to the non-active grating 1606.

[0172] The non-active structures of the non-active area 1620, and other non-active structures in the examples discussed herein, can include 1D lines and spaces / grids, 2D meshes of holes, pillars, and / or discontinuous lines / spaces, and / or 2D pillars / checkerboards (e.g., grids composed of a 2D array of pillars and / or columns), to name a few non-limiting examples. Various geometries, patterns, and arrangements of the structure(s) within the non-active area are within the scope of this disclosure. The orientation of the non-active grid can be parallel, perpendicular, and / or tilted relative to the grid in the active area, and can be parallel, perpendicular, and / or tiled relative to the imprint and / or separation directions. In some implementations, the non-active structure can include several sections around the active area, each section having a different grid geometry, such as a different non-active grid orientation and / or structure, in some combination combined with grading. The non-active grating not only helps to mitigate shear-induced delamination / damage to the grating, but in some implementations can also help maintain sufficient resist in the residual layer below the grating to reduce / prevent unfilled defects in the active area. For example, the non-active grating 1606 can act as a barrier to fluid flowing out of the active area 1602 due to capillary forces, helping to reduce or eliminate defects in the active area 1602. The non-active area structure may alternatively or additionally pin, balance, diffuse, and / or reduce imprint forces.

[0173] In some implementations where the active region includes a tilted grating, the shear forces associated with imprinting are greater when the grating is tilted relative to the imprint direction, such as when the tilted grating region is in the pinwheel position and the orientation of the tilted grating is tilted relative to the imprint direction. Inactive regions adjacent to and / or surrounding the active region with the tilted grating can be added to move the separation edge into the active region, thus helping to mitigate grating damage that would otherwise be initiated at the edge of the tilted grating.

[0174] For example, Figure 17 shows a substrate 1700 having imprint active areas 1702a-1702f (collectively referred to as active areas 1702) thereon. The imprint structures on the substrate 1700 are formed in an imprint process with an imprint direction 1701 parallel to the separation direction. Each active area 1702 includes a tilted grating having a different orientation and tilt direction corresponding to the pinwheel arrangement of the tilted grating. For example, the tilted grating can be tiled outward from a center position 1704 of the pinwheel, and the walls of the grating can extend perpendicular to the tiling direction or can be tilted along the tiling direction (e.g., tilted toward or away from the center position 1704). For example, the tilted grating 1706 in the active region 1702b has walls 1708 that extend parallel to the imprint direction 1701 (and separation direction), with the walls 1708 tilted orthogonal to the imprint direction 1701 (towards the central position 1704 along the central direction 1714) and not tilted along the imprint direction 1701 (or separation direction). This can result in relatively low shear forces for imprinting the tilted grating 1706. As discussed for the walls 1614 of the grating 1612, the features of the tilted grating 1706 extend parallel to the imprint direction 1701, and the same advantages as discussed for the grating 1612 can be obtained from this orientation.

[0175] However, the tilted grating 1710 in the active region 1702d includes walls 1712 that are tilted (towards the central location 1704) along a central direction 1716 that is non-orthogonal to the imprint direction 1701. Thus, the imprint of the tilted grating 1710 may be associated with relatively high shear forces.

[0176] To mitigate this shear force, at least one of the active regions 1702 (in this example, all of the active regions 1702) can be adjacent to and / or surrounded by a corresponding non-active region 1718 having a non-active lattice. The non-active lattice can have a configuration and orientation as described for non-active regions 1620b, 1620c with reference to FIG. 16, for example. The presence of non-active lattice regions (shown in green) surrounding each of the tilted lattice regions (shown in yellow) can move the separation edge into the non-active region, thus helping to mitigate lattice damage initiated at the edges of the tilted lattice. In some implementations, the non-active lattice can be non-tilted to reduce shear forces at the boundaries of the non-active lattice.

[0177] The imprinted structures in the non-active regions in each example described herein can, but need not, comprise nanostructures, and the nanostructures can be comprised of nanostructure arrays such as 1D lattices (e.g., lines / walls and spaces / trenches), 2D nanostructure arrays (e.g., pillars / holes / columns within an array), and / or 3D nanostructure arrays (e.g., periodic or quasi-periodic multi-tiered pillars / holes with lines and spaces, etc.), and are not limited to the specific structures described in each example. The imprinted structures need not be periodic or quasi-periodic (e.g., periodic except for gradations in feature height or another dimension) but rather, in some cases, can comprise aperiodic and / or random structures. For example, the imprinted structures in the non-active regions can comprise 1D, 2D, and / or 3D nanostructures without necessarily having periodicity. As noted above, in some implementations, the imprinted non-active structures have a pitch of 20 nm to 200 nm or 50 nm to 200 nm. Additionally, in some implementations, the imprint non-active structures have linewidths of 10 nm to 150 nm and / or heights of 10 nm to 300 nm. These dimensions have been found to provide advantages in structural integrity, reliability / ease of imprinting, and desired optical properties. However, in some implementations, the imprint non-active structures have dimensions that differ from these.

[0178] 18 illustrates another example of an imprint structure. The structure is imprinted on a substrate 1800 and, unless otherwise specified, has the characteristics as described with reference to the imprint structure in FIG. 16. For example, an active area 1802 can have the characteristics as described for the corresponding active areas 1602 and 1618a, 1618b, and 1618c, and an adjacent inactive area 1804 can have the characteristics as described for the inactive areas 1604b, 1604c, 1604d, 1620a, 1620b, and 1620c. The imprint pattern is formed with an imprint direction 1801 parallel to the separation direction.

[0179] The non-active region 1806 includes multiple zones 1808a, 1808b, 1808c, and 1808d (collectively referred to as zones 1808) having different respective non-active optical structures. Zone 1808d is adjacent to an active optical structure (e.g., a grating) 1810 in the active region 1802. The non-active structures within zone 1808 and / or the zones 1808 themselves (e.g., the relative positions of zones 1808) can be oriented such that the imprint structure varies in a direction parallel to the imprint direction and / or the demolding / separation direction. For example, the imprint structure can vary across zone 1808 in proximity to the active optical structure 1810, such as a diffraction pattern on a waveguide, in a direction parallel to the imprint direction 1801. For example, as shown in Figure 18, the zones 1808 can be oriented such that the imprint direction 1801 passes through the multiple zones 1808 in succession, and correspondingly, during several imprint processes to form the structures shown in Figure 18, the structures in the multiple zones 1808 are formed in succession by the template, which successively separates from each zone 1808. The different zones 1808 can have different structure densities, geometric shapes, types, arrangements, and / or other properties.

[0180] For example, in some implementations, the non-active optical structures of zone 1808 have one or more dimensions in the imprint direction 1801 that vary from zone to zone. For example, one or more alignment parameters (e.g., feature height or depth, feature spacing, feature width, feature length, feature density, orientation (e.g., array angle relative to a given direction), and / or array pitch and / or duty cycle in one or more dimensions) can be different for each non-active (e.g., sub-diffractive) array in zones 1808a, 1808b, 1808c, 1808d; for example, the alignment parameter can increase or decrease from zone 1808a to 1808b, 1808c, 1808d, or from one or more of those zones to one or more adjacent zones (e.g., from zone 1808b to zone 1808c). In some implementations, the one or more alignment parameters vary from zone to zone to approach the value of the same alignment parameter(s) in the active optical structures 1810. For example, if an alignment parameter in active optical structure 1810 has a value x5 and the same alignment parameter in zones 1808a-1808d has values ​​x1-x4, respectively, then in some implementations the structures are configured such that x1≦x2≦x3≦x4≦x5, or x1≧x2≧x3≧x4≧x5.

[0181] For example, in some implementations, the orientation of the gratings in each of the zones 1808 varies from zone to zone to approximate the orientation of the active optical structure 1810. For example, the active optical structure 1810 can include a grating with walls oriented perpendicular to the imprint direction 1801, which can lead to defects at the edges of the grating due to, for example, high separation forces. Zone 1808d can have a non-active grating that is close to the orientation of the grating in the active optical structure 1810 but possibly oriented at least somewhat closer to parallel to the imprint direction 1801; the non-active grating in zone 1808c can be even more parallel to the imprint direction 1801; and so on until zone 1808a includes a non-active grating that is parallel or substantially parallel to the imprint direction 1801. Thus, the imprint and / or separation forces are gradually modulated / redirected to / from the active optical structure 1810, avoiding spatially concentrated forces that can increase the incidence of defects.

[0182] As another example, in some implementations, the pattern fill factor (the ratio of structure to empty space within a region) varies from zone to zone, which can (i) reduce fluid spreading and help keep the fluid in the active region, and / or (ii) facilitate a gradual demolding force from the active optical structures 1810, through zones 1808d, 1808c, 1808b, and 1808a, toward regions (e.g., blank regions) outside of the non-active region 1806. For example, the fill factor can increase from zone 1808a to zone 1808b to zone 1808c to zone 1808d.

[0183] 18 illustrates four zones 1808, in some implementations a different number of zones can be provided, such as two, three, or more than four. Additionally, in some implementations, the inactive area includes a single zone, as in the case of inactive area 1604c, for example.

[0184] Optical elements including an active region and an adjacent non-active region may be utilized in AR, VR, XR, and other head-worn devices, headsets, such as those described with reference to FIGS. 1-12. For example, the optical elements described with reference to FIGS. 1-12 can be formed by imprinting an optical structure in the active region and imprinting a non-active region (e.g., adjacent to the active region) to reduce imprint-related defects, as described above. For example, the optical structures formed by imprinting the described active regions (e.g., including gratings) can include output coupling optical elements 570, 580, 590, 600, 610, input coupling optical elements 1260, 1262, 1264, and / or another optical element, e.g., any suitable type of diffractive optical element (DOE), such as a beam splitter, beam shaper, lens, and / or diffuser. For example, the active optical structure can include a diffractive optical element located above or otherwise proximate to the waveguide for coupling light to / from the waveguide, and the non-active structure can be a non-diffractive or sub-diffractive structure adjacent to the active optical structure. Gratings described herein can include, for example, binary phase gratings, blazed gratings, and / or tilted gratings.

[0185] FIG. 19 illustrates an example of a process 1900 that can be performed according to some aspects of the present disclosure. Process 1900 includes imprinting an optical diffractive structure (1902) and imprinting an optical sub-diffractive structure adjacent to the optical diffractive structure (1904). For example, imprinting the two structures can be performed in a common imprint process, e.g., using a common template including both the optical diffractive structure and a surface relief structure corresponding to the optical diffractive structure. The optical diffractive structure can be any of the active optical structures discussed herein (e.g., with reference to FIGS. 13-18), and the optical sub-diffractive structure can include any of the non-active structures in an area adjacent to the active optical area discussed herein.

[0186] As discussed above, by including optical sub-diffractive structures in the imprint process(es) of process 1900, imprint defects affecting the optical diffractive structures, such as delamination and / or bubble formation, can be reduced or eliminated, thereby improving the performance of the optical device.

[0187] Imprint processes within the scope of the present disclosure include at least nanoimprint lithography processes such as thermoplastic nanoimprint lithography, photo nanoimprint lithography, and direct thermal nanoimprint lithography. Further examples of imprint processes within the scope of the present disclosure include microimprint processes. Imprint structures, such as active optical structures and non-active (e.g., sub-diffractive) structures, can be formed in the imprint resist by mechanical deformation of the resist and subsequent treatments such as thermal and / or UV curing. The template mold comprises a surface relief pattern that forms a corresponding pattern in the imprint resist. Imprint processes within the scope of the present disclosure include at least hard mold, soft mold, roll-to-roll, roll-to-plate, plate-to-roll, plate-to-plate, and hybrid nanoimprint processes.

[0188] Imprinting, such as the imprinting in process 1900, can be performed using a template (e.g., a superstrate, mold, stamp, etc.), a substrate, and a formable material (sometimes referred to as a coating or imprint resist) disposed on the template and / or substrate. For example, the formable material can be provided to the template, the substrate, or both prior to imprinting. The formable material can include, for example, a polymer, an epoxy, a resin, a photoresist, a spin-on glass, or another material that can be structured in the imprint process. In some implementations, the formable material is curable, for example, by application of thermal energy, light (e.g., UV), and / or another stimulus. For example, the formable material can be hardened after forming structures in the formable material, and the hardening can occur while the template is in contact with the formable material, after removing the template from the formable material, or both.

[0189] 20 illustrates an example of a template 2000 and corresponding imprint structures. The template 2000 has a first set of surface relief structures 2020 in a first region 2004 and a second set of surface relief structures 2018 in a second region 2002, the two sets of surface relief structures 2018, 2020 being adjacent to each other. The template 2000 can be composed of, for example, an organic polymer and / or an inorganic material such as a dielectric, metal, alloy, etc. The template 2000 can be rigid and / or flexible.

[0190] Template 2000 is used to imprint a formable material 2006 disposed on a substrate 2008. Moldable material 2006 can include any of the types of formable materials discussed above, such as a polymer, epoxy, resin, photoresist, spin-on glass, or another material that can be structured in an imprinting process.

[0191] Various types of substrate 2008 are within the scope of this disclosure, including semiconductor, dielectric, organic (e.g., polymer or plastic), metal, etc. The substrate 2008 can be rigid and / or flexible. In some implementations, the substrate 2008 has a refractive index (e.g., for a waveguide within the substrate 2008) in the range of 1.45 to 2.7 (e.g., SiC) (e.g., corresponding to fused silica or quartz). As noted above, imprinting can be roll-to-roll, roll-to-plate, plate-to-roll, plate-to-plate, or another suitable imprinting process.

[0192] As a result of the imprinting, optical diffractive structures 2024 are formed in the active region 2012 of the moldable material 2006, and optical sub-diffractive structures 2022 (in some implementations, non-diffractive structures) are formed adjacent to the optical diffractive structures 2024 in the non-active region 2010 of the moldable material 2006. The imprint structures 2022, 2024 are formed by and directly correspond to, for example, sets of surface relief structures 2018, 2020 of the template 2000 having matching or inverse shapes and topographies. For example, the pitch 2014 of the optical sub-diffractive structures 2022 can be smaller than the pitch 2016 of the optical diffractive structures 2024 based on the pitch (not shown) of the second set of surface relief structures 2018 being smaller than the pitch (not shown) of the first set of surface relief structures 2020. For example, in some implementations, the pitch 2014 is equal to the pitch of the second surface relief structures 2018 and the pitch 2016 is equal to the pitch of the first surface relief structures 2020.

[0193] The set of surface relief structures 2018, 2020 can be configured (e.g., based on their topology) to imprint any of the combinations of adjacent active and non-active regions, or adjacent diffractive and sub-diffractive or non-diffractive structures discussed herein. For example, the sets of surface relief structures 2018, 2020 can be adjacent to one another, such that an optical diffractive structure 2024 and an optical sub-diffractive structure 2022 are adjacent to one another. Furthermore, based on the correspondence between the template structure and the imprint structure, the set of surface relief structures 2018, 2020 can be any of the structures discussed herein for active and non-active structures, including, for example, gratings, arrays, etc., having the dimensions and patterns discussed herein for active and non-active structures with reference to FIGS. 16-18.

[0194] In some implementations, the substrate 2008 includes one or more waveguides (not shown) arranged to optically couple with the optical diffractive structure 2024, for example, for in-coupling / out-coupling of light at one or more wavelengths. Light having the same wavelength(s) may not couple into or out of the waveguide through the optical sub-diffractive structure 2022 based on the dimension(s) of the optical sub-diffractive structure 2022.

[0195] In the foregoing description, various example implementations have been described. It will be apparent, however, that various modifications and changes may 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.

[0196] 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.

[0197] 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, one or more features from the described combination may, in some cases, be deleted from the combination, and the described 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.

[0198] It will be understood that conditional language used herein, such as, among others, "can," "could," "might," "may," "e.g.," and the like, is generally intended to convey that certain embodiments include certain features, elements, and / or steps, and 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 by one or more embodiments, or that one or more embodiments necessarily include logic for determining, with or without authorial input or direction, whether or not those features, elements, and / or steps should be included or performed in any particular embodiment. 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. Also, the term "or" is used in an inclusive (rather than exclusive) sense, such as when used to connect a list of elements, so that the term "or" refers to one, some, or all of the elements in the list. Additionally, the articles "a," "an," and "the" as used in this application should be construed to mean "one or more" or "at least one," unless otherwise specified.

[0199] Furthermore, the separation of various system components in the embodiments described above should not be understood as requiring such separation in all implementations, and it should be understood that the described program components and systems may generally be integrated with one another.

[0200] Thus, the examples provided herein are not intended to be limited to the embodiments shown herein but are to be accorded the widest scope consistent with the present disclosure and the principles and novel features disclosed herein.

[0201] Example embodiments include at least the following:

[0202] Embodiment 1: A method comprising imprinting an optical diffractive structure and imprinting an optical sub-diffractive structure adjacent to the optical diffractive structure.

[0203] Embodiment 2: Embodiment 1, wherein the optical diffraction structure includes a first grating, the optical sub-diffraction structure includes a second grating, and at least one geometric characteristic is different between the first grating and the second grating.

[0204] Embodiment 3: Embodiment 2, wherein the at least one geometric characteristic includes at least one of grating orientation, pitch, width, height, or duty cycle.

[0205] Embodiment 4: Any of embodiments 2-3, wherein the second grating comprises features that extend parallel to the separation direction of the imprints.

[0206] Embodiment 5: Any of embodiments 1 to 4, wherein the optical sub-diffraction structure includes a plurality of different structures in each of the plurality of zones of the optical sub-diffraction structure.

[0207] Embodiment 6: Embodiment 5, wherein the plurality of different structures differ in at least one of feature density or feature orientation.

[0208] Embodiment 7: Any of embodiments 5 to 6, wherein the plurality of zones are arranged along the imprint direction.

[0209] Embodiment 8: Any of embodiments 1 to 7, wherein the optical sub-diffraction structure surrounds the optical diffraction structure.

[0210] Embodiment 9: Any of embodiments 1 to 8, wherein the optical sub-diffractive structure comprises features with gradation dimensions, the gradation dimensions increasing or decreasing in a direction towards the optical diffractive structure.

[0211] Embodiment 10: Embodiment 9, wherein the features include grating walls having heights that increase in a direction toward the light-diffracting structure.

[0212] Embodiment 11: Any of embodiments 1 to 10, wherein the optical sub-diffractive structure comprises features with gradation dimensions, the gradation dimensions increasing or decreasing in the imprint direction.

[0213] Embodiment 12: Any of embodiments 1 to 11, wherein imprinting the optical diffractive structure and imprinting the optical sub-diffractive structure are performed in a common imprint process using a common template.

[0214] Embodiment 13: Any of embodiments 1-12, wherein the optical diffractive structure includes a diffractive input coupler to the waveguide or a diffractive output coupler from the waveguide.

[0215] Embodiment 14: Any of embodiments 1 to 13, wherein the optical sub-diffractive structure includes features extending circumferentially around the optical diffractive structure.

[0216] Embodiment 15: Any of embodiments 1 to 14, wherein the optical diffractive structure has a pitch of 200 nm to 1 μm, and the optical sub-diffractive structure has a pitch of 20 nm to 200 nm.

[0217] Embodiment 16: Any of embodiments 1 to 15, wherein the optical diffractive structure has a pitch that causes the optical diffractive structure to diffractively interact with visible light, and the optical sub-diffractive structure has a pitch that does not cause the optical sub-diffractive structure to diffractively interact with visible light.

[0218] Embodiment 17: Any of embodiments 1 to 16, wherein imprinting the optical diffractive structures and optical sub-diffractive structures is performed in a roll-to-roll, roll-to-plate, plate-to-roll, or plate-to-plate process.

[0219] Embodiment 18: Any of embodiments 1 to 17, wherein the optical sub-diffractive structure comprises a one-dimensional grating, a two-dimensional nanostructure array, or a three-dimensional nanostructure array.

[0220] Embodiment 19: An optical device comprising a waveguide, an imprinted grating arranged to direct light into or out of the waveguide, and an imprinted sub-diffractive structure arranged adjacent to the grating.

[0221] Embodiment 20: A display system comprising a waveguide, an optical coupling element including an imprinted grating, and an imprinted sub-diffractive structure arranged adjacent to the grating.

[0222] Embodiment 21: An imprint template comprising a first set of surface relief structures configured to imprint optical diffractive structures in a moldable material and a second set of surface relief structures configured to imprint optical sub-diffractive structures in the moldable material, the second set of surface relief structures being adjacent to the first set of surface relief structures.

[0223] Embodiment 22: An optical device including an optical diffractive structure and an optical sub-diffractive structure, the optical device being formed according to any one of embodiments 1-18.

[0224] Several embodiments have been described. However, it will be understood that various modifications may be made. Elements of one or more embodiments may be combined, deleted, modified, or supplemented to form further embodiments. In yet another example, the logic flow depicted in the figures does not require the particular order shown, or sequential order, to achieve desirable results. Additionally, other steps may be provided or steps may be eliminated from the described flow, and other components may be added to or removed from the described systems. Accordingly, other embodiments are within the scope of the following claims.

Claims

1. 1. A method comprising: imprinting an optically diffractive structure; imprinting optical sub-diffractive structures adjacent to said optical diffractive structure; A method comprising:

2. the optical diffraction structure comprises a first grating; the optical sub-diffraction structure comprises a second grating; The method of claim 1 , wherein at least one geometric characteristic differs between the first and second gratings.

3. The method of claim 2 , wherein the at least one geometric characteristic comprises at least one of a grating orientation, pitch, width, height, or duty cycle.

4. The method of claim 2 , wherein the second grating includes features that extend parallel to a separation direction of the imprints.

5. The method of claim 1 , wherein the optical sub-diffractive structure comprises a plurality of different structures in each zone of a plurality of zones of the optical sub-diffractive structure.

6. The method of claim 5 , wherein the plurality of different structures differ in at least one of feature density or feature orientation.

7. The method of claim 5 , wherein the plurality of zones are arranged along an imprint direction.

8. The method of claim 1 , wherein the optical sub-diffractive structure surrounds the optical diffractive structure.

9. The method of claim 1 , wherein the optical sub-diffractive structure comprises features having a gradation dimension, the gradation dimension increasing or decreasing in a direction toward the optical diffractive structure.

10. The method of claim 9 , wherein the features comprise grating walls having heights that increase in the direction toward the light-diffracting structure.

11. The method of claim 1 , wherein the optical sub-diffractive structures comprise features with a graded dimension, the graded dimension increasing or decreasing in an imprint direction.

12. The method of claim 1 , wherein imprinting the optical diffractive structure and imprinting the optical sub-diffractive structure are performed in a common imprint process using a common template.

13. The method of claim 1 , wherein the optical diffractive structure comprises a diffractive input coupler to a waveguide or a diffractive output coupler from the waveguide.

14. The method of claim 1 , wherein the optical sub-diffractive structure comprises features extending circumferentially around the optical diffractive structure.

15. the optical diffraction structure has a pitch of 200 nm to 1 μm; The method of claim 1 , wherein the optical sub-diffractive structures have a pitch of 20 nm to 200 nm.

16. the optically diffractive structure has a pitch that causes the optically diffractive structure to diffractively interact with visible light; The method of claim 1 , wherein the optical sub-diffractive structures have a pitch that causes the optical sub-diffractive structures not to diffractively interact with visible light.

17. The method of claim 1 , wherein imprinting the optical diffractive structures and the optical sub-diffractive structures is performed in a roll-to-roll, roll-to-plate, plate-to-roll, or plate-to-plate process.

18. The method of claim 1 , wherein the optical sub-diffractive structure comprises a one-dimensional grating, a two-dimensional nanostructure array, or a three-dimensional nanostructure array.

19. 1. An optical device comprising: A waveguide; an imprinted grating, the grating arranged to direct light into or out of the waveguide; an imprint sub-diffractive structure arranged adjacent to the grating; An optical device comprising:

20. 1. A display system comprising: A waveguide; an optical coupling element comprising an imprinted grating, the optical coupling element configured to: an imprint sub-diffractive structure arranged adjacent to the grating; A display system comprising:

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