Dummy imprint region

Abstract

In some embodiments, a method includes imprinting an optical diffractive structure, and imprinting an optical sub-diffractive structure adjacent to the optical diffractive structure. For example, these structures may be gratings with different characteristics. Imprint structures may be included in optical devices and display systems.

Description

[0001] Cross - reference to related applications

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 429,434, filed on December 1, 2022, the entire content of which is incorporated herein by reference. Technical Field

[0003] The present disclosure relates to imprinting processes and structures, such as imprinting processes and structures for optical devices. Background Art

[0004] Modern computing and display technologies have facilitated the development of so - called "virtual reality" or "augmented reality" experience systems, in which digitally reproduced images or portions thereof are presented to a user in a manner that appears real or may 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 inputs; augmented reality or "AR" scenarios typically involve presenting digital or virtual image information as an enhancement to the visualization of the actual world around the user. 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 an MR scenario, AR image content may be occluded by objects in the real world or otherwise perceived as interacting with objects in the real world.

[0005] Reference Figure 1 , which depicts an augmented reality scenario 10, in which a user of AR technology sees a real - world park - like environment 20 featuring people, trees, buildings in the background, and a concrete platform 30. In addition to these items, the user of AR technology also senses that he "sees" "virtual content", such as a robotic statue 40 standing on the real - world platform 30 and a flying cartoon avatar character 50, which appears to be an avatar of a bumblebee, although these elements 40, 50 do not exist in the real world. Due to the complexity of the human visual perception system, it can be challenging to produce an AR technology that promotes a comfortable, natural feeling and richly presents virtual image elements as well as other virtual or real - world image elements.

[0006] The systems and methods disclosed herein address various challenges associated with AR and VR technologies. Imprinting processes, such as nano - imprint 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

[0007] Some aspects of the present disclosure describe a method that includes imprinting an optical diffractive structure and imprinting an optical sub - diffractive structure adjacent to the optical diffractive structure.

[0008] The method discussed in this document and other methods can have at least one or more of the following characteristics.

[0009] In some embodiments, the optical diffraction structure includes a first grating, and the optical sub-diffraction structure includes a second grating. At least one geometric feature is different between the first grating and the second grating.

[0010] In some embodiments, the at least one geometric feature includes at least one of the following: grating orientation, pitch, width, height, or duty cycle.

[0011] In some embodiments, the second grating includes features that extend parallel to the separation direction of the imprint.

[0012] In some implementations, the optical sub-diffraction structure includes a plurality of different structures in respective zones of a plurality of zones of the optical sub-diffraction structure.

[0013] In some embodiments, the plurality of different structures differ in at least one of feature density or feature orientation.

[0014] In some embodiments, the plurality of zones are arranged along the imprint direction.

[0015] In some embodiments, the optical sub-diffraction structure surrounds the optical diffraction structure.

[0016] In some embodiments, the optical sub-diffraction structure includes features having a graded size that increases or decreases in a direction towards the optical diffraction structure.

[0017] In some embodiments, the features include grating walls, and the height of the grating walls increases in a direction towards the optical diffraction structure.

[0018] In some embodiments, the optical sub-diffraction structure includes features having a graded size that increases or decreases in the imprint direction.

[0019] In some embodiments, imprinting the optical diffraction structure and imprinting the optical sub-diffraction structure are performed in a common imprinting process using a common template.

[0020] In some embodiments, the optical diffraction structure includes a diffractive in-coupler to a waveguide or a diffractive out-coupler from the waveguide.

[0021] In some embodiments, the optical sub-diffraction structure includes features that extend circumferentially around the optical diffraction structure.

[0022] In some embodiments, the pitch of the optical diffraction structure is between 200 nm and 1 μm, and the pitch of the optical sub-diffraction structure is between 20 nm and 200 nm.

[0023] In some embodiments, the optical diffraction structure has a pitch such that the optical diffraction structure diffracts with visible light, and the optical sub-diffraction structure has a pitch such that the optical sub-diffraction structure does not diffract with visible light.

[0024] In some embodiments, imprinting the optical diffraction structure and the optical sub-diffraction structure is performed in a roll-to-roll, roll-to-plate, plate-to-roll, or plate-to-plate process.

[0025] In some embodiments, the optical sub-diffraction structure includes a one-dimensional grating, a two-dimensional nanostructure array, or a three-dimensional nanostructure array.

[0026] Certain aspects of the present disclosure describe an optical device including: a waveguide; an imprinted grating arranged to direct light into or out of the waveguide; and an imprinted sub-diffraction structure arranged near the grating. For example, the imprinted grating can be the optical diffraction structure in any of the above methods or any methods and structures discussed herein, and the imprinted sub-diffraction structure can be the optical sub-diffraction structure in any of the above methods or any methods and structures discussed herein.

[0027] Certain aspects of the present disclosure describe a display system including: a waveguide; an optical coupling element including an imprinted grating; and an imprinted sub-diffraction structure arranged adjacent to the grating. For example, the imprinted grating in the optical coupling element can be the optical diffraction structure in any of the above methods or any methods and structures discussed herein, and the imprinted sub-diffraction structure can be the optical sub-diffraction structure in any of the above methods or any methods and structures discussed herein.

[0028] Certain aspects of the present disclosure describe an imprinting template. The imprinting template includes: a first set of surface relief structures configured to imprint an optical diffraction structure in a formable material; and a second set of surface relief structures configured to imprint an optical sub-diffraction structure in the formable material. The second set of surface relief structures is adjacent to the first set of surface relief structures. For example, these sets of surface relief structures can be configured to imprint any adjacent active and non-active structures described herein. For example, the imprinting template can be used to perform any of the foregoing methods or any imprinting method described herein.

[0029] Details of one or more embodiments will be set forth in the accompanying drawings and the following description. Other aspects, features, and advantages will be apparent from the specification, the drawings, and the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Shows a view of AR by a user through an augmented reality (AR) device.

[0031] Figure 2 Shows a conventional display system for simulating three-dimensional images for a user.

[0032] Figures 3A - 3C Shows the relationship between the radius of curvature and the radius of focus.

[0033] Figure 4A Shows a representation of the accommodation-vergence response of the human visual system.

[0034] Figure 4B Shows an example of different accommodation states and vergence states of a user's pair of eyes.

[0035] Figure 4C Shows an example of a representation of a top view of a user viewing content via a display system.

[0036] Figure 4D Shows another example of a representation of a top view of a user viewing content via a display system.

[0037] Figure 5 Shows aspects of a method for simulating three-dimensional images by modifying wavefront divergence.

[0038] Figure 6 Shows an example of a waveguide stack for outputting image information to a user.

[0039] Figure 7 Shows an example of an output beam emitted by a waveguide.

[0040] Figure 8 Shows an example of a stacked waveguide assembly, where each depth plane includes an image formed using multiple different component colors.

[0041] Figure 9A Shows a cross-sectional side view of an example of a set of stacked waveguides, where each waveguide includes an optically coupled-in element.

[0042] Figure 9B Shows Figure 9A A perspective view of an example of multiple stacked waveguides.

[0043] Figure 9C Shows Figure 9A And9B Top plan view of an example of multiple stacked waveguides.

[0044] Figure 9D Illustration of an example of a wearable display system.

[0045] Figure 10 Side view of an example of a projector assembly.

[0046] Figure 11A Side view of an example of an augmented reality display system.

[0047] Figure 11B Illustration of Figure 11A Top view of an augmented reality display system.

[0048] Figure 11C Illustration of Figure 11A Side view of an augmented reality display system.

[0049] Figure 12A Side view of an augmented reality display system.

[0050] Figure 12B Illustration of Figure 12A Side view of an augmented reality display system.

[0051] Figure 12C Illustration of Figure 12B Top view of an augmented reality display system.

[0052] Figure 13 Illustration of an example of an imprinting process.

[0053] Figure 14 Illustration of an example of an imprinting defect.

[0054] Figure 15 Illustration of an example of an imprinting defect.

[0055] Figure 16 Illustration of an example of an imprinted structure including an active region and a non-active region.

[0056] Figure 17 Illustration of an example of an imprinted structure including an active region and a non-active region.

[0057] Figure 18 Illustration of an example of an imprinted structure including a non-active region having multiple zones.

[0058] Figure 19 Illustration of an example of a process for imprinting an optical structure.

[0059] Figure 20 Illustration of an example of a template and an imprint pattern. DETAILED DESCRIPTION

[0060] Augmented Reality and Virtual Reality Systems

[0061] An AR system can display virtual content to a user or viewer while still allowing the user to view the world around them. Preferably, the content is displayed on a head-mounted display, such as as part of glasses, which projects image information onto the user's eyes. Additionally, the display can also transmit light from the surrounding environment to the user's eyes, thus allowing the user to observe the surrounding environment. As used herein, a "head-mounted" or "head-mountable" display refers to a display that can be mounted on the head of a viewer or user.

[0062] The various AR systems disclosed herein include a virtual / augmented / mixed display, which in turn can include one or more optical elements formed on or as part of a waveguide. These optical elements can include, for example, an input optical element for coupling light into the waveguide, and / or an output optical element for coupling light from the waveguide into the user's eyes. To achieve efficient light coupling into and / or out of the waveguide, the optical elements can include diffraction gratings. In some display systems, a relatively high diffraction efficiency of the optical elements can be partially achieved by including tilted gratings, which are a type of diffraction grating that can provide a high diffraction efficiency for input / output light. A tilted grating refers to a grating having an array of surface relief grooves, where the sidewalls of the grooves have a substantially uniform non-vertical tilt angle with respect to the surface (e.g., the substrate surface) forming the grooves in the tiling direction of the array. The tilted diffraction grating can be fabricated by imprinting a tilted diffraction grating pattern on a device substrate (e.g., a waveguide) using a device master template.

[0063] Reference will now be made to the accompanying drawings, in which like reference numerals always refer to like parts. Unless otherwise noted, the drawings are schematic and not necessarily drawn to scale.

[0064] Figure 2 A conventional display system for simulating three-dimensional images for a user is shown. It will be understood that the user's eyes are separated, and when viewing a real object in space, each eye will have a slightly different view of the object, and an image of the object can be formed at different positions on the retina of each eye. This can be referred to as binocular parallax, and can be utilized by the human visual system to provide depth perception. The conventional display system simulates binocular parallax by presenting two different images 190, 200 with slightly different views of the same virtual object (one for each eye 210, 220), the different views corresponding to the views of the virtual object that each eye would see, where the virtual object is a virtual object of a real object located at a desired depth. These images provide binocular cues, where the user's visual system can interpret the binocular cues to obtain depth perception.

[0065] Continue to refer to Figure 2 , images 190, 200 are separated from eyes 210, 220 by a distance 230 along the z-axis. In the case where their eyes are fixed on an object at optical infinity directly in front of the viewer, the z-axis is parallel to the viewer's optical axis. Images 190, 200 are flat and at a fixed distance from eyes 210, 220. Based on slightly different views of a virtual object in the images presented to eyes 210, 220 respectively, the eyes can rotate naturally so that the images of the object fall on corresponding points on the retina of each eye to maintain single binocular vision. This rotation can cause the lines of sight of each of eyes 210, 220 to converge on a point in the space where the virtual object is perceived to exist. As a result, providing a three-dimensional image generally involves providing binocular cues that can manipulate the convergence of the user's eyes 210, 220, and the human visual system interprets these binocular cues to provide depth perception.

[0066] However, generating a realistic and comfortable depth perception is challenging. It will be appreciated that light from objects at different distances from the eyes has wavefronts with different amounts of divergence. Figures 3A - 3C Illustrates the relationship between distance and the divergence of light rays. The distances between the objects and eye 210 are represented by R1, R2, and R3 in decreasing order of distance. As shown in Figures 3A - 3C it can be seen that as the distance to the object decreases, the light rays become more divergent. Conversely, as the distance increases, the light rays become more collimated. In other words, it can be said that the light field generated by a point (object or part of an object) has a spherical wavefront curvature that is a function of the distance of that point from the user's eyes. The curvature increases as the distance between the object and eye 210 decreases. Although for clarity of illustration only a single eye 210 is shown in Figures 3A - 3C and other figures in this document, the discussion regarding eye 210 can be applied to both eyes 210 and 220 of the viewer.

[0067] Continue to refer to Figures 3A - 3C, light from an object gazed upon by a viewer's eyes can have different degrees of wavefront divergence. Due to the different amounts of wavefront divergence, the light can be focused differently by the eye's lens, which in turn may require the lens to assume different shapes to form a focused image on the retina of the eye. In the case where a focused image is not formed on the retina, the resulting retinal blur serves as an accommodation cue that causes a change in the shape of the eye's lens until a focused image is formed on the retina. For example, the accommodation cue can trigger the relaxation or contraction of the ciliary muscle surrounding the eye lens, thereby regulating the force applied to the zonular ligaments that hold the lens, whereby the shape of the eye lens is changed until the retinal blur of the gazed object is eliminated or minimized, thereby forming a focused image of the gazed object on the retina (e.g., fovea) of the eye. The process by which the shape of the eye lens changes can be referred to as accommodation, and the shape of the eye lens required to form a focused image of the gazed object on the retina (e.g., fovea) of the eye can be referred to as the accommodative state.

[0068] Now referring to Figure 4A , a representation of the accommodation-vergence response of the human visual system is shown. Eye movements are made to gaze at an object such that the eyes receive light from the object, where the light forms an image on each retina of the eyes. The presence of retinal blur in the images formed on the retinas can provide an accommodation cue, and the relative positions of the images on the retinas can provide a vergence cue. The accommodation cue causes accommodation to occur, resulting in the eye lenses each assuming a specific accommodative state that forms a focused image of the object on the retina (e.g., fovea) of the eye. On the other hand, the vergence cue causes vergence movements (rotation of the eyes) to occur such that the images formed on each retina of each eye are at corresponding retinal points that maintain single binocular vision. At these positions, the eyes can be said to be in a specific vergence state. Continuing to refer to Figure 4A , accommodation can be understood as the process by which the eyes achieve a specific accommodative state, and vergence can be understood as the process by which the eyes achieve a specific vergence state. As Figure 4A shown, if the user gazes at another object, the accommodation and vergence states of the eyes can change. For example, if the user gazes at a new object at a different depth on the z-axis, the accommodative state can change.

[0069] Without being limited by theory, it is believed that a viewer of an object can perceive the object as "three-dimensional" due to a combination of convergence and accommodation. As described above, the convergence movement of the two eyes relative to each other (e.g., the rotation of the eyes such that the pupils move towards or away from each other to converge the lines of sight of the eyes to fixate on an object) is closely related to the accommodation of the lenses of the eyes. Under normal circumstances, changing the shape of the lens of the eye to change the focus from one object to another object located at a different distance will automatically cause a matching change in convergence to the same distance in a relationship known as the "accommodation-convergence reflex". Similarly, under normal circumstances, a change in convergence will trigger a matching change in the shape of the lens.

[0070] Now referring to Figure 4B , an example of different accommodation and convergence states of the eyes is shown. The pair of eyes 222a is fixated on an object at optical infinity, while the pair of eyes 222b is fixated on an object 221 that is less than optically infinite. It is noted that the convergence states of each pair of eyes are different, where the pair of eyes 222a is pointed straight ahead, while the pair of eyes 222 is converged on the object 221. The accommodation states of the eyes forming each pair of eyes 222a and 222b are also different, as indicated by the different shapes of the lenses 210a, 220a.

[0071] Unfortunately, many users of traditional "3-D" display systems find these traditional systems uncomfortable or do not perceive a sense of depth at all due to the mismatch between the accommodation and convergence states in these displays. As described above, many stereoscopic or "3-D" display systems display a scene by providing slightly different images to each eye. Such systems are uncomfortable for many viewers because they merely provide different presentations of the scene among other things and cause a change in the convergence state of the eyes, but without a corresponding change in the accommodation state of those eyes. Instead, the images are presented by a display at a fixed distance from the eyes such that the eyes view all the image information in a single accommodation state. This arrangement violates the "accommodation-convergence reflex" by causing a change in the convergence state without a matching change in the accommodation state. This mismatch is thought to cause discomfort to the viewer. A display system that provides a better match between accommodation and convergence can form a more realistic and comfortable three-dimensional image simulation.

[0072] Without being limited by theory, it is believed that the human eye can generally interpret a limited number of depth planes to provide depth perception. Therefore, by providing different presentations of images corresponding to each of these limited number of depth planes to the eyes, a highly believable simulation of perceived depth can be achieved. In some embodiments, the different presentations can provide convergence cues and matching accommodation cues, thereby providing a physiologically correct accommodation-convergence match.

[0073] Continuing to refer to Figure 4B, shows two depth planes 240, which correspond to different distances from the eyes 210, 220 in space. For a given depth plane 240, a vergence cue can be provided by displaying appropriately different perspectives of an image for each eye 210, 220. Additionally, for a given depth plane 240, the light forming the images provided to each eye 210, 220 can have a wavefront divergence corresponding to the light field generated by points at the distance of that depth plane 240.

[0074] In the illustrated embodiment, the depth plane 240 containing the point 221 is at a distance of 1 m along the z-axis. As used herein, the distance or depth along the z-axis can be measured by a zero point located at the exit pupil of the user's eye. Thus, the depth plane 240 at a depth of 1 m corresponds to a distance of 1 m from the exit pupil of the user's eye on the optical axis of those eyes that are directed optically infinitely far. As an approximation, the depth or distance along the z-axis can be measured from a display in front of the user's eyes (e.g., from the surface of a waveguide), plus the value of the distance between the device and the exit pupil of the user's eye. This value can be referred to as the 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 eyes. In practice, the value of the eye relief can be a standardized value commonly used for all viewers. For example, it can be assumed that the eye relief is 20 mm, and the depth plane at a depth of 1 m can be at a distance of 980 mm in front of the display.

[0075] Now refer to Figure 4C and 4D , which show examples of a matched accommodation-vergence distance and a mismatched accommodation-vergence distance, respectively. As Figure 4C shown, the display system can provide images of virtual objects to each eye 210, 220. The images can cause the eyes 210, 220 to exhibit a vergence state where the eyes converge on a point 15 on the depth plane 240. Additionally, the images can be formed by light having a wavefront curvature corresponding to a real object at that depth plane 240. As a result, the eyes 210, 220 exhibit an accommodation state where the images are in focus on the retinas of those eyes. Thus, the user can perceive the virtual object at the point 15 on the depth plane 240.

[0076] It will be understood that each of the accommodation and vergence states of eyes 210, 220 is associated with a specific distance on the z-axis. For example, an object at a specific distance from eyes 210, 220 causes those eyes to assume a specific accommodation state based on the distance of the object. The distance associated with a specific accommodation state may be referred to as the accommodation distance Ad. Similarly, there is a specific vergence distance Vd associated with the eyes or their positions relative to each other in a specific vergence state. When the accommodation distance and the vergence distance match, it can be said that the relationship between accommodation and vergence is physiologically correct. This is considered the most comfortable scenario for the viewer.

[0077] However, in a stereoscopic display, the accommodation distance and the vergence distance may not always match. For example, as Figure 4D shown, the images presented to eyes 210, 220 may be presented with a wavefront divergence corresponding to depth plane 240, and eyes 210, 220 may assume a specific accommodation state in which points 15a, 15b on that depth plane are in focus. However, the images presented to eyes 210, 220 may provide vergence cues that cause eyes 210, 220 to converge at a point 15 that does not lie on depth plane 240. As a result, in some embodiments, the accommodation distance corresponds to the distance from the exit pupils of eyes 210, 220 to depth plane 240, while the vergence distance corresponds to a greater distance from the exit pupils of eyes 210, 220 to point 15. The accommodation distance is different from the vergence distance. Thus, there is an accommodation-vergence mismatch. This mismatch is considered undesirable and may cause discomfort to the user. It will be understood that this mismatch corresponds to a distance (e.g., V d -A d ) and can be characterized using diopters.

[0078] In some embodiments, it will be understood that a reference point other than the exit pupils of eyes 210, 220 can be used to determine the distance for determining the accommodation-vergence mismatch, provided that the same reference point is used for both the accommodation distance and the vergence distance. For example, the distance from the cornea to the depth plane, from the retina to the depth plane, from the eyepiece (e.g., the waveguide of the display device) to the depth plane, etc. can be measured.

[0079] Without being bound by theory, it is believed that a user can still perceive an accommodation-vergence mismatch of up to approximately 0.25 diopters, up to approximately 0.33 diopters, and up to approximately 0.5 diopters as being physiologically correct without significant discomfort caused by the mismatch itself. In some embodiments, the display systems disclosed herein (e.g., Figure 6The display system 250 presents an image to a viewer with an accommodation-convergence mismatch of about 0.5 diopters or less. In some other embodiments, the accommodation-convergence mismatch of the image provided by the display system is about 0.33 diopters or less. In still some other embodiments, the accommodation-convergence mismatch of the image provided by the display system is about 0.25 diopters or less, including about 0.1 diopters or less.

[0080] Figure 5 Aspects of a method for simulating a three-dimensional image by modifying wavefront divergence are shown. 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 having a limited amount of wavefront divergence corresponding to the wavefront divergence of the light field generated by points on a desired depth plane 240. In some embodiments, the same amount of wavefront divergence is provided for all objects presented on the depth plane. Additionally, it will be described that image information from a similar waveguide may be provided to the user's other eye.

[0081] In some embodiments, a single waveguide may be configured to output light having a set amount of wavefront divergence corresponding to a single or a limited number of depth planes and / or the waveguide may be configured to output light within a limited wavelength range. Thus, in some embodiments, multiple waveguides or a stack of waveguides may be utilized to provide different amounts of wavefront divergence for different depth planes and / or output light having different wavelength ranges. As used herein, it will be understood that a depth plane may be flat or follow the contour of a curved surface.

[0082] Figure 6 An example of a stack of waveguides for outputting image information to a user is shown. The display system 250 includes a stack of waveguides or a stacked waveguide assembly 260 that may be used to provide a three-dimensional perception to the eye / brain using multiple waveguides 270, 280, 290, 300, 310. It will be understood that in some embodiments, the display system 250 may be considered a light field display. Additionally, the waveguide assembly 260 may also be referred to as an eyepiece.

[0083] In some embodiments, the display system 250 may be configured to provide substantially continuous convergence cues and multiple discrete accommodation cues. The convergence cues may be provided by displaying different images to each eye of the user, and the accommodation cues may be provided by outputting light forming an image with a selectable discrete amount of wavefront divergence. In other words, the display system 250 may be configured to output light having a variable level of wavefront divergence. In some embodiments, each discrete level of wavefront divergence corresponds to a specific depth plane and may be provided by a specific one of the waveguides 270, 280, 290, 300, 310.

[0084] Continuing to refer Figure 6 , the waveguide assembly 260 can also include a plurality of features 320, 330, 340, 350 between the waveguides. In some embodiments, the features 320, 330, 340, 350 can be one or more lenses. The waveguides 270, 280, 290, 300, 310 and / or the plurality of lenses 320, 330, 340, 350 can be configured to send image information to the eye with various levels of wavefront curvature or light divergence. Each waveguide level can be associated with a particular depth plane and can be configured to output image information corresponding to that depth plane. The image injection devices 360, 370, 380, 390, 400 can act as light sources for the waveguides and can be used to inject image information into the waveguides 270, 280, 290, 300, 310. As described herein, each waveguide can be configured to distribute incident light across each corresponding waveguide for output toward the eye 210. Light leaves the output surfaces 410, 420, 430, 440, 450 of the image injection devices 360, 370, 380, 390, 400 and is injected into the corresponding input surfaces 460, 470, 480, 490, 500 of the waveguides 270, 280, 290, 300, 310. In some embodiments, each of the input surfaces 460, 470, 480, 490, 500 can be an edge of the corresponding waveguide or can be a part of the major surface of the corresponding waveguide (i.e., a surface of the waveguide that directly faces the world 510 or the viewer's eye 210). In some embodiments, a single light beam (e.g., a collimated beam) can 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 can be associated with a plurality (e.g., three) of the waveguides 270, 280, 290, 300, 310 and inject light into the plurality (e.g., three) of the waveguides 270, 280, 290, 300, 310.

[0085] In some embodiments, the image injection devices 360, 370, 380, 390, 400 are discrete displays, each of which generates image information for injection into the corresponding waveguides 270, 280, 290, 300, 310, respectively. In some other embodiments, the image injection devices 360, 370, 380, 390, 400 are the output terminals of a single multiplexed display, and the output terminals of the single multiplexed display can deliver image information to each of the image injection devices 360, 370, 380, 390, 400 via, for example, one or more optical conduits (such as fiber optic cables). It will be understood that the image information provided by the image injection devices 360, 370, 380, 390, 400 can include light of different wavelengths or colors (e.g., different component colors as discussed herein).

[0086] In some embodiments, the light injected into the waveguides 270, 280, 290, 300, 310 is provided by a light projector system 520, which includes a light module 530 that can include a light emitter, such as a light emitting diode (LED). The light from the light module 530 can be guided to a light modulator 540 (e.g., a spatial light modulator) via a beam splitter 550 and modified by the light modulator 540. The light modulator 540 can 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) that include liquid crystal on silicon (LCOS) displays. It will be understood that the image injection devices 360, 370, 380, 390, 400 are schematically shown, and in some embodiments, these image injection devices can represent different optical paths and positions in a common projection system that is configured to output light into the associated waveguides among the waveguides 270, 280, 290, 300, 310. In some embodiments, the waveguides of the waveguide assembly 260 can act as ideal lenses while relaying the light injected into the waveguides out to the user's eyes. In this concept, the object can be the spatial light modulator 540, and the image can be an image on a depth plane.

[0087] In some embodiments, the display system 250 can be a scanned fiber optic display that includes one or more scanned optical fibers configured to project light into one or more waveguides 270, 280, 290, 300, 310 and ultimately to the viewer's eye 310 in various patterns (e.g., raster scan, helical scan, Lissajous pattern, etc.). In some embodiments, the illustrated image injection devices 360, 370, 380, 390, 400 can schematically represent a single scanned optical fiber or a bundle of scanned optical fibers configured to inject light into one or more of the waveguides 270, 280, 290, 300, 310. In some other embodiments, the illustrated image injection devices 360, 370, 380, 390, 400 can schematically represent multiple scanned optical fibers or multiple bundles of scanned optical fibers, each of which is 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 can be configured to transmit light from the optical module 530 to one or more of the waveguides 270, 280, 290, 300, 310. It will be appreciated that one or more intermediate optical structures can be provided between the scanned optical fiber or fibers and one or more of the waveguides 270, 280, 290, 300, 310 to, for example, redirect the light exiting the scanned optical fiber into one or more of the waveguides 270, 280, 290, 300, 310.

[0088] The controller 560 controls the operation of one or more of the stacked waveguide assemblies 260, including the operation of the image injection devices 360, 370, 380, 390, 400, the light source 530, and the light modulator 540. In some embodiments, the controller 560 is part of the local data processing module 140. The controller 560 includes programming (e.g., instructions in a non-transitory medium) that regulates the timing and provision of image information to the waveguides 270, 280, 290, 300, 310 according to any of the various schemes disclosed herein, for example. In some embodiments, the controller can be a single integrated device or a distributed system connected by wired or wireless communication channels. In some embodiments, the controller 560 can be part of the processing module 140 or 150 ( Figure 9D ).

[0089] Continuing to refer Figure 6, waveguides 270, 280, 290, 300, 310 can be configured to enable light to propagate within each respective waveguide by total internal reflection (TIR). Waveguides 270, 280, 290, 300, 310 can each be planar or have an alternative shape (e.g., curved), having a major top surface and a major bottom surface and edges extending between those major top and bottom surfaces. In the illustrated configuration, waveguides 270, 280, 290, 300, 310 can each include outcoupling optical elements 570, 580, 590, 600, 610, which are configured to extract light out of the waveguide by redirecting the light propagating within each respective waveguide out of the waveguide for outputting image information to the eye 210. The extracted light can also be referred to as outcoupled light, and the outcoupling optical elements can also be referred to as light extraction optical elements. The extracted light beam can be output by the waveguide at the location where the light propagating in the waveguide impinges on the light extraction optical element. The outcoupling optical elements 570, 580, 590, 600, 610 can be, for example, gratings including diffractive optical features (e.g., gratings located in an active / diffractive region and having adjacent non-active / sub-diffractive regions), as further discussed herein. Although illustrated as being disposed at the bottom major surface of waveguides 270, 280, 290, 300, 310 for ease of description and clarity of the drawings, in some embodiments, the outcoupling optical elements 570, 580, 590, 600, 610 can be disposed at the top and / or bottom major surfaces, and / or can be disposed directly within the volume of waveguides 270, 280, 290, 300, 310, as further discussed herein. In some embodiments, the outcoupling optical elements 570, 580, 590, 600, 610 can be formed in a material layer attached to a transparent substrate to form waveguides 270, 280, 290, 300, 310. In some other embodiments, waveguides 270, 280, 290, 300, 310 can be a single piece of material, and the outcoupling optical elements 570, 580, 590, 600, 610 can be formed on and / or within the surface of the piece of material.

[0090] Continue to refer to Figure 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 can be configured to deliver collimated light (which is injected into such waveguide 270) to the eye 210. The collimated light can represent an optically infinite focal plane. The next upper waveguide 280 can be configured to send out collimated light that passes through a first lens 350 (e.g., a negative lens) before it can reach the eye 210; such a first lens 350 can be configured to produce a slightly convex wavefront curvature such that the eye / brain interprets the light from the next upper waveguide 280 as coming from a first focal plane that is closer inward from the optically infinite towards the eye 210. Similarly, the third upper waveguide 290 has its output light pass through the first lens 350 and the second lens 340 before reaching the eye 210; the combined optical power of the first lens 350 and the second lens 340 can be configured to produce another increment of wavefront curvature such that the eye / brain interprets the light from the third waveguide 290 as coming from a second focal plane that is closer inward from the optically infinite towards the person than the light from the next upper waveguide 280.

[0091] The other waveguide layers 300, 310 and lenses 330, 320 are configured similarly, where the highest waveguide 310 in the stack sends its output through all the lenses between it and the eye, for representing the total optical power of the focal plane closest to the person. To compensate for the stack of lenses 320, 330, 340, 350 when viewing / interpreting light from the world 510 on the other side of the stacked waveguide assembly 260, a compensating lens layer 620 can be provided on top of the stack to compensate for the total optical power of the underlying lens stack 320, 330, 340, 350. Such a configuration provides as many focal planes as there are available waveguide / lens pairings. Both the outcoupling optical elements of the waveguides and the focusing aspects of the lenses can be static (i.e., non-dynamic or electroactive). In some alternative embodiments, one or both of them can be dynamic using electroactive features.

[0092] In some embodiments, two or more of the waveguides 270, 280, 290, 300, 310 can have the same associated depth plane. For example, multiple waveguides 270, 280, 290, 300, 310 can be configured to output a set of images to the same depth plane, or multiple subsets of the waveguides 270, 280, 290, 300, 310 can be configured to output a set of images to the same multiple depth planes, where there is one set of images for each depth plane. This can provide the advantage of forming a stitched image to provide an extended field of view at those depth planes.

[0093] Continuing to refer to Figure 6, the output optical elements 570, 580, 590, 600, 610 can be configured to redirect light out of their respective waveguides and output the light with an appropriate amount of divergence or collimation for a particular depth plane associated with the waveguide. Thus, waveguides having different associated depth planes can have different configurations of the output optical elements 570, 580, 590, 600, 610, which depend on the associated depth plane to output light with different amounts of divergence. In some embodiments, the light extraction optical elements 570, 580, 590, 600, 610 can be volume or surface features that can be configured to output light at a particular angle. For example, the light extraction optical elements 570, 580, 590, 600, 610 can be volume holograms, surface holograms, and / or diffraction gratings. In some embodiments, the features 320, 330, 340, 350 can not be lenses; instead, they can simply be spacers (e.g., cladding and / or structures for forming voids).

[0094] In some embodiments, the output optical elements 570, 580, 590, 600, 610 are diffraction features that form a diffraction pattern, or "diffractive optical elements" (also referred to herein as "DOEs"). Preferably, the DOE has a low enough diffraction efficiency such that only a portion of the light beam is deflected away from the eye 210 through each intersection of the DOE, while the remaining portion continues to travel through the waveguide via TIR. The light carrying the image information is thus split into a number of associated outgoing beams that exit the waveguide at many locations, and the result is a fairly uniform pattern of outgoing emission towards the eye 210 for that particular collimated beam that bounces around within the waveguide.

[0095] In some embodiments, one or more DOEs can be switched between an "on" state in which they actively diffract and an "off" state in which they do not significantly diffract. For example, a switchable DOE can include a polymer dispersed liquid crystal layer, where the droplets include a diffraction pattern in a host medium, and the refractive index of the droplets can be switched to substantially match the refractive index of the host material (in which case the pattern does not significantly diffract the incident light) or the droplets can be switched to a refractive index that does not match the refractive index of the host medium (in which case the pattern actively diffracts the incident light).

[0096] In some embodiments, a camera component 630 (e.g., a digital camera, including visible light and infrared cameras) can be provided to capture images of the eye 210 and / or tissue surrounding the eye 210 to, for example, detect user input and / or monitor the user's physiological state. As used herein, a camera can be any image capture device. In some embodiments, the camera component 630 can include an image capture device and a light source that projects light (e.g., infrared light) toward the eye, which can then be reflected by the eye and detected by the image capture device. In some embodiments, the camera component 630 can be attached to the frame 80( Figure 9D ) and can be in electrical communication with the processing module 140 and / or 150, which can process image information from the camera component 630. In some embodiments, one camera component 630 can be utilized for each eye to separately monitor each eye.

[0097] Now referring to Figure 7 , an example of an output beam exiting a waveguide is shown. One waveguide is shown, but it will be understood that in cases where the waveguide assembly 260 includes multiple waveguides, the other waveguides in the waveguide assembly 260( Figure 6 ) can operate similarly. Light 640 is injected into the waveguide 270 at the input surface 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 an output beam 650. The output beam 650 is illustrated as being substantially parallel, but as discussed herein, it can also be redirected to propagate at an angle to the eye 210 (e.g., form a diverging output beam), depending on the depth plane associated with the waveguide 270. It will be understood that a substantially parallel output beam can indicate that the waveguide has such an outcoupling optical element that outcouples light to form an image that appears to be disposed on a depth plane at a large distance (e.g., optically infinite) from the eye 210. Other waveguides or other sets of outcoupling optical elements can output a more diverging output beam pattern, which will require the eye 210 to accommodate to a closer distance to focus on the retina and will be interpreted by the brain as light from a distance closer to the eye 210 than optically infinite.

[0098] In some embodiments, a full-color image can be formed at each depth plane by overlapping images of each of the component colors (e.g., three or more component colors). Figure 8An example of a stacked waveguide assembly is shown, where each depth plane includes an image formed using a plurality of different component colors. The illustrated embodiment shows depth planes 240a–240f, although more or fewer depths are also contemplated. Each depth plane may have three or more component color images associated therewith, 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 figures by different numbers for diopters (dpt) following the letters G, R, and B. By way of example only, the numbers following each of these letters indicate the diopter (1 / m), or the inverse distance of the depth plane from the viewer, and each box in the figures represents a single component color image. In some embodiments, to account for differences in the focusing of light of different wavelengths by the eye, the precise placement of the depth planes for different component colors may vary. For example, the different component color images for a given depth plane may be placed on depth planes corresponding to different distances from the user. Such an arrangement may increase visual sensitivity and user comfort and / or may reduce chromatic aberration.

[0099] In some embodiments, light of each component color may be output by a single dedicated waveguide, and thus, each depth plane may have a plurality of waveguides associated therewith. In such embodiments, each box in the figures including the letters G, R, or B may be understood to represent a separate waveguide, and three waveguides may be provided per depth plane, where three component color images are provided per depth plane. While the waveguides associated with each depth plane are shown in the figure as being adjacent to each other, it will be understood that in a physical device, the waveguides may all be arranged in a stack, where each layer has one waveguide. In some other embodiments, a plurality of component colors may be output by the same waveguide, such that, for example, only a single waveguide may be provided per depth plane.

[0100] Continuing to refer to Figure 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 additionally be used or may replace one or more of red, green, or blue.

[0101] It will be understood that references throughout this disclosure to a given light color will be understood to encompass light of one or more wavelengths within the range of wavelengths of light that are perceived by a viewer as having that given color. For example, red light may include light of one or more wavelengths in the range of approximately 620–780 nm, green light may include light of one or more wavelengths in the range of approximately 492–577 nm, and blue light may include light of one or more wavelengths in the range of approximately 435–493 nm.

[0102] In some embodiments, light source 530 (Figure 6 ) can be configured to emit light of one or more wavelengths outside the viewer's visual perception range, e.g., infrared and / or ultraviolet wavelengths. Additionally, the input, output, and other light redirecting structures of the waveguide of the display system 250 can be configured to direct and emit such light towards the user's eye 210 and outside the display, e.g., for imaging and / or user stimulation applications.

[0103] Now referring to Figure 9A , in some embodiments, light incident on the waveguide may need to be redirected to couple the light into the waveguide. Input optical elements can be used to redirect and couple light into its corresponding waveguide. Figure 9A A cross-sectional side view showing an example of a plurality of waveguides 660 or a stack of waveguides 660, where each waveguide includes an input optical element. The waveguides can 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 can correspond to the stacked waveguide assembly 260 ( Figure 6 ), and the waveguides of the illustrated stack 660 can correspond to a portion 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 position where the desired light redirection for coupling is to occur.

[0104] The illustrated set of stacked waveguides 660 includes waveguides 670, 680, and 690. Each waveguide includes an associated optical coupling element (which may also be referred to as an optical input region on the waveguide), e.g., an optical coupling element 700 disposed on the main surface (e.g., the upper main surface) of waveguide 670, an optical coupling element 710 disposed on the main surface (e.g., the upper main surface) of waveguide 680, and an optical coupling element 720 disposed on the main surface (e.g., the upper main surface) of waveguide 690. In some embodiments, one or more of the optical coupling elements 700, 710, 720 may be disposed on the bottom main surface of the respective waveguides 670, 680, 690 (particularly, where one or more of the optical coupling elements are reflective deflecting optical elements). As illustrated, the optical coupling elements 700, 710, 720 may be disposed on the upper main surface of their respective waveguides 670, 680, 690 (or on top of the next lower waveguide), particularly where those optical coupling elements are transmissive deflecting optical elements. In some embodiments, the optical coupling elements 700, 710, 720 may be disposed within the body of the respective waveguides 670, 680, 690. In some embodiments, as discussed herein, the optical coupling elements 700, 710, 720 are wavelength selective such that they selectively redirect one or more wavelengths of light while transmitting other wavelengths of light. Although illustrated at one edge or corner of their respective waveguides 670, 680, 690, it will be understood that in some embodiments, the optical coupling elements 700, 710, 720 may be disposed in other regions of their respective waveguides 670, 680, 690.

[0105] As illustrated, the optical coupling elements 700, 710, 720 may be laterally offset from each other. In some embodiments, each optical coupling element may be offset such that it receives light without the light passing through another optical coupling element. For example, each of the optical coupling elements 700, 710, 720 may be configured to receive light from different image injection devices 360, 370, 380, 390, and 400 as shown in Figure 6 and may be separated (e.g., laterally spaced apart) from the other optical coupling elements 700, 710, 720 such that it substantially does not receive light from the other optical coupling elements among the optical coupling elements 700, 710, 720.

[0106] Each waveguide also includes an associated optical distribution element, e.g., an optical distribution element 730 disposed on the main surface (e.g., the top main surface) of waveguide 670, an optical distribution element 740 disposed on the main surface (e.g., the top main surface) of waveguide 680, and an optical distribution element 750 disposed on the main surface (e.g., the top main surface) of waveguide 690. In some other embodiments, the optical distribution elements 730, 740, 750 may be disposed on the bottom main surfaces of the associated waveguides 670, 680, 690, respectively. In some other embodiments, the optical distribution elements 730, 740, 750 may be disposed on the top and bottom main surfaces of the associated waveguides 670, 680, 690, respectively; or the optical distribution elements 730, 740, 750 may be disposed on different main surfaces of the top and bottom main surfaces in different associated waveguides 670, 680, 690.

[0107] Waveguides 670, 680, 690 may be separated and isolated by, e.g., 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 of a low refractive index material (i.e., a material having a lower refractive index than the material of the directly adjacent waveguides among waveguides 670, 680, 690). Preferably, the refractive index of the material forming layers 760a, 760b is less than the refractive index of the material forming waveguides 670, 680, 690 by 0.05 or more, or 0.10 or less. Advantageously, the lower refractive index layers 760a, 760b can be used as claddings that facilitate total internal reflection (TIR) of light through waveguides 670, 680, 690 (e.g., TIR between the top and bottom main surfaces of each waveguide). In some embodiments, layers 760a, 760b are formed of air. Although not illustrated, it will be understood that the top and bottom of the illustrated waveguide group 660 may include directly adjacent claddings.

[0108] 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 be different between one or more waveguides, and / or the materials forming layers 760a, 760b may be different, while still maintaining the various refractive index relationships noted above.

[0109] Continuing reference Figure 9A, light rays 770, 780, 790 are incident on waveguide group 660. It will be understood that light rays 770, 780, 790 can be injected into waveguides 670, 680, 690 by one or more image injection devices 360, 370, 380, 390, 400( Figure 6 ).

[0110] In some embodiments, light rays 770, 780, 790 have different characteristics, e.g., different wavelengths or different wavelength ranges corresponding to different colors. Coupling optical elements 700, 710, 720 each deflect the incident light such that the light propagates through the respective waveguides in waveguides 670, 680, 690 by TIR. In some embodiments, coupling optical elements 700, 710, 720 each selectively deflect one or more specific wavelengths of light while transmitting other wavelengths to the underlying waveguide and associated coupling optical element.

[0111] For example, coupling optical element 700 can be configured to deflect light ray 770 having a first wavelength or wavelength range while transmitting light rays 780 and 790 having different second and third wavelengths or wavelength ranges, respectively. The transmitted light ray 780 is incident on coupling optical element 710 and is deflected by coupling optical element 710, which is configured to deflect light of the second wavelength or wavelength range. Light ray 790 is deflected by coupling optical element 720, which is configured to selectively deflect light of the third wavelength or wavelength range.

[0112] Continuing to refer to Figure 9A , the deflected light rays 770, 780, 790 are deflected such that they propagate through the corresponding waveguides 670, 680, 690; that is, the coupling optical elements 700, 710, 720 of each waveguide deflect the light into the corresponding waveguide 670, 680, 690 to couple the light into the corresponding waveguide. Light rays 770, 780, 790 are deflected at an angle such that the light propagates through the respective waveguides 670, 680, 690 by TIR. Light rays 770, 780, 790 propagate through the respective waveguides 670, 680, 690 by TIR until incident on the corresponding light distribution elements 730, 740, 750 of the waveguide.

[0113] Now referring to Figure 9B , there is shown Figure 9APerspective view of an example of multiple stacked waveguides. As described above, the coupled-in light rays 770, 780, 790 are deflected by the coupled-in optical elements 700, 710, 720 respectively, and then propagate through the waveguides 670, 680, 690 by TIR respectively. The light rays 770, 780, 790 then impinge on the light distribution elements 730, 740, 750 respectively. The light distribution elements 730, 740, 750 deflect the light rays 770, 780, 790 such that they propagate towards the coupled-out optical elements 800, 810, 820 respectively.

[0114] In some embodiments, the light distribution elements 730, 740, 750 are orthogonal pupil expanders (OPEs). In some embodiments, the OPE deflects or distributes light to the coupled-out optical elements 800, 810, 820, and in some embodiments, the beam size or spot size of the light can also be increased as the light propagates to the coupled-out optical elements. In some embodiments, the light distribution elements 730, 740, 750 can be omitted and the coupled-in optical elements 700, 710, 720 can be configured to deflect light directly to the coupled-out optical elements 800, 810, 820. For example, referring to Figure 9A , the light distribution elements 730, 740, 750 can be replaced by the coupled-out optical elements 800, 810, 820 respectively. In some embodiments, the coupled-out optical elements 800, 810, 820 are exit pupils (EPs) or exit pupil expanders (EPEs) that direct light to the viewer's eye 210 of the viewer ( Figure 7 ). It will be appreciated that the OPE can be configured to increase the size of the eyebox on at least one axis, and the EPE can increase the eyebox on an axis that intersects (e.g., is orthogonal to) the axis of the OPE. For example, each OPE can be configured to redirect a portion of the light impinging on the OPE to the EPE of the same waveguide while allowing the remaining portion of the light to continue propagating down the waveguide. When the remaining light impinges on the OPE again, another portion of the remaining light is redirected to the EPE, and the remaining portion of that portion continues to propagate further down the waveguide, and so on. Similarly, when impinging on the EPE, a portion of the incident light is directed towards the user out of the waveguide, and the remaining portion of the light continues to propagate through the waveguide until it impinges on the EP again, at which time another portion of the incident light is directed out of the waveguide, and so on. Thus, a single beam of coupled-in light can be "copied" each time a portion of the light is redirected by the OPE or EPE, thereby forming a field of cloned beams, as shown in Figure 6 . In some embodiments, the OPE and / or EPE can be configured to modify the size of the light beam.

[0115] Thus, referring to Figure 9A and 9B, in some embodiments, the set of waveguides 660 includes waveguides 670, 680, 690 for each component color; input optical elements 700, 710, 720; light distribution elements (e.g., OPE) 730, 740, 750; and output optical elements (e.g., EPE) 800, 810, 820. The waveguides 670, 680, 690 may be stacked with a gap / cladding between each one. The input optical elements 700, 710, 720 redirect or deflect the incident light (wherein different input optical elements receive light of different wavelengths) into their respective waveguides. The light then propagates at an angle that will result in TIR within the respective waveguides 670, 680, 690. In the example shown, the light ray 770 (e.g., blue light) is deflected by the first input optical element 700 in the previously described manner and then continues to bounce downward along the waveguide, interacting with the light distribution element (e.g., OPE) 730 and then the output optical element (e.g., EP) 800. The light rays 780 and 790 (e.g., green light and red light, respectively) will pass through the waveguide 670, wherein the light ray 780 impinges on the input optical element 710 and is deflected by the input optical element 710. The light ray 780 then bounces downward along the waveguide 680 via TIR, continues to its light distribution element (e.g., OPE) 740 and then to the output optical element (e.g., EP) 810. Finally, the light ray 790 (e.g., red light) passes through the waveguide 690 to impinge on the light input optical element 720 of the waveguide 690. The light input optical element 720 deflects the light ray 790 such that the light ray propagates to the light distribution element (e.g., OPE) 750 via TIR and then propagates to the output optical element (e.g., EP) 820 via TIR. Then, the output optical element 820 finally couples out the light ray 790 to the viewer, who also receives the coupled-out light from the other waveguides 670, 680.

[0116] Figure 9C Shown Figure 9A And Figure 9B A top plan view of an example of a plurality of stacked waveguides. As illustrated, the waveguides 670, 680, 690 together with the associated light distribution elements 730, 740, 750 and the associated output optical elements 800, 810, 820 of each waveguide may be vertically aligned. However, as discussed herein, the input optical elements 700, 710, 720 are not vertically aligned; rather, the input optical elements are preferably non-overlapping (e.g., laterally separated as seen in the top view). As further discussed herein, this non-overlapping spatial arrangement facilitates injecting light from different sources into different waveguides on a one-to-one basis, thereby allowing a particular light source to be uniquely coupled to a particular waveguide. In some embodiments, an arrangement including non-overlapping spatially separated input optical elements may be referred to as an offset pupil system, and the input optical elements within these arrangements may correspond to sub-pupils.

[0117] Figure 9D An example of a wearable display system 60 is shown, into which various waveguides and related systems disclosed herein can be integrated. In some embodiments, the display system 60 is Figure 6 display system 250, wherein Figure 6 some components of the system 60 are schematically shown in more detail. For example, Figure 6 the waveguide assembly 260 can be part of the display 70.

[0118] Continuing to refer to Figure 9D , the display system 60 includes a display 70 and various mechanical and electronic modules and systems that support the functions of the display 70. The display 70 can be coupled to a frame 80 that can be worn by a user or viewer 90 of the display system and is configured to position the display 70 in front of the eyes of the user 90. In some embodiments, the display 70 can be considered glasses. In some embodiments, a speaker 100 is coupled to the frame 80 and is configured to be located near the ear canal of the user 90 (in some embodiments, another speaker, not shown, can optionally be located near the other ear canal of the user to provide stereo / plastic sound control). The display system 60 can also include one or more microphones 110 or other devices to detect sound. In some embodiments, the microphone is configured to allow the user to provide input or commands to the system 60 (e.g., selection of voice menu commands, natural language questions, etc.) and / or can allow audio communication with other people (e.g., other users of a similar display system). The microphone can also be configured as a peripheral sensor to collect audio data (e.g., sounds from the user and / or the environment). In some embodiments, the display system can also include a peripheral sensor 120a that can be separated from the frame 80 and attached to the body of the user 90 (e.g., on the head, torso, limb, etc. of the user 90). In some embodiments, the peripheral sensor 120a can be configured to capture data representative of the physiological state of the user 90. For example, the sensor 120a can be an electrode.

[0119] Continuing to refer to Figure 9D, the display 70 is operatively coupled to the local data processing module 140 via a communication link 130 (such as via a wired lead or a wireless connection). The local data processing module 140 can be installed in various configurations, such as fixedly attached to the frame 80, fixedly attached to a helmet or hat worn by the user, embedded within a headset, or removably attached to the user 90 (e.g., in a backpack configuration, in a belt-coupled configuration). Similarly, the sensor 120a can be operatively coupled to the local processor and data module 140 via a communication link 120b (e.g., a wired lead or a wireless connection). The local processing and data module 140 can include a hardware processor and a digital memory such as a non-volatile memory (e.g., flash memory or hard disk drive), both of which can be used to assist in processing, caching, and storing data. Optionally, the local processor and data module 140 can include one or more central processing units (CPUs), graphics processing units (GPUs), dedicated processing hardware, etc. The data can include: a) data captured from sensors (e.g., the sensor can be operatively coupled to the frame 80 or otherwise attached to the user 90), such as an image capture device (such as a camera), a microphone, an inertial measurement unit, an accelerometer, a compass, a GPS unit, a radio device, a gyroscope, and / or other sensors disclosed herein; and / or b) data obtained and / or processed using the remote processing module 150 and / or the remote data repository 160 (including data related to virtual content), which can be transmitted to the display 70 after such processing or retrieval. The local processing and data module 140 can be operatively coupled to the remote processing module 150 and the remote data repository 160 via communication links 170, 180 (such as via a wired or wireless communication link), such that these remote modules 150, 160 are operatively coupled to each other and can be used as resources for the local processing and data module 140. In some embodiments, the local processing and data module 140 can include one or more of an image capture device, a microphone, an inertial measurement unit, an accelerometer, a compass, a GPS unit, a radio device, and / or a gyroscope. In some other embodiments, one or more of these sensors can be attached to the frame 80, or can be a separate structure that communicates with the local processing and data module 140 via a wired or wireless communication path.

[0120] Continuing reference Figure 9D, in some embodiments, the remote processing module 150 may include one or more processors configured to analyze and process data and / or image information, such as one or more central processing units (CPUs), graphics processing units (GPUs), dedicated processing hardware, etc. In some embodiments, the remote data repository 160 may include a digital data storage facility that may be available via the Internet or other network configurations in a "cloud" resource configuration. In some embodiments, the remote data repository 160 may include one or more remote servers that provide information to the local processing and data module 140 and / or the remote processing module 150, such as information for generating augmented reality content. In some embodiments, all data is stored and all computations are performed in the local processing and data module, allowing for fully autonomous use from the remote module. Alternatively, an external system including a CPU, GPU, etc. (e.g., a system with one or more processors, one or more computers) may perform at least a portion of the processing (e.g., generating image information, processing data) and provide information to and receive information from modules 140, 150, 160, e.g., via a wireless or wired connection.

[0121] Figure 10 is a schematic diagram showing the projector assembly 1000 that uses a polarization beam splitter (PBS) 1020 to illuminate a spatial light modulator (SLM) 1030 and redirect the light from the SLM 1030 through projection optics 1040 to an eyepiece (not shown). The projector assembly 1000 includes an illumination source 1010, which may include, for example, a light emitting diode (LED), a laser (e.g., a laser diode), or other types of light sources. The light may be collimated by collimation optics. The illumination source 1010 may emit polarized, unpolarized, or partially polarized light. In the illustrated design, the illumination source 1010 may emit polarized light 1012 having p-polarization. The first optical element 1015 (e.g., a pre-polarizer) is aligned to allow light having a first polarization (e.g., p-polarization) to pass through.

[0122] The light is directed to a polarization beam splitter 1020. Initially, the light passes through an interface 1022 (e.g., a polarization interface) of the PBS 1020, which is configured to transmit light of a first polarization (e.g., p-polarization). Thus, the light advances to and impinges on a spatial light modulator 1030. As illustrated, the SLM 1030 is a reflective SLM, which is configured to retroreflect the incident light and selectively modulate the light. For example, the SLM 1030 includes one or more pixels that can have different states. The light impinging on the respective pixels can be modulated based on the state of the pixels. Thus, the SLM 1030 can be driven to modulate the light to provide an image. In this example, the SLM 1030 can be a polarization-based SLM, which modulates the polarization of the light impinging on it. For example, in the on state, the pixels of the SLM 1030 change the input light from a first polarization state (e.g., p-polarization state) to a second polarization state (e.g., s-polarization state), such that a bright state (e.g., a white pixel) is displayed. The second polarization state can be the first polarization state modulated (e.g., rotated) by 90 ° The first polarization state modulated (e.g., rotated) by 90 degrees. In the on state, the light having the second polarization state is reflected by the interface 1022 and propagates downstream to the projector optics 1040. In the off state, the SLM 1030 does not change the polarization state of the light impinging on it, e.g., does not rotate the input light from the first polarization state, and thus a dark state (e.g., a black pixel) is displayed. In the off state, the light having the first polarization state is transmitted through the interface 1022 and propagates upstream back to the illumination source 1010 instead of the user's eye.

[0123] After reflection from the SLM 1030, a portion of the light 1014 (e.g., the modulated light) is reflected from the interface 1022 and exits the PBS 1020 to be directed to the user's eye. The emitted light passes through the projector optics 1040 and is imaged onto an input coupling grating (ICG) 1050 of an eyepiece (not shown).

[0124] Figure 11A A system (e.g., an augmented reality display system) 1100A is shown for presenting an image to a user's eye 210 and for viewing the world 510, which has an Figure 10Configurations different from those shown in. System 1100 includes a light source 1110, a spatial light modulator (SLM) 1140, and a waveguide 1120, which are arranged such that light from the light source 1110 irradiates the SLM 1140, and the light reflected from the SLM 1140 is coupled into the waveguide 1120 to be guided to the eye 210. System 1100A includes an optical device 1130, which is configured to both irradiate the SLM 1140 and project an image of the SLM 1140. Light from the light source 1110 propagates through the optical device 1130 in a first direction, for example, to irradiate the SLM 1140. The light reflected from the SLM 1140 again propagates through the optical device 1130 in a second direction opposite to the first direction and is guided to and coupled into the waveguide 1120.

[0125] 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, although the light source 1110 need not be so limited. In some embodiments, a polarizer 1115 may be positioned between the light source 1110 and the SLM 1140. As illustrated, the polarizer 1115 is located between the light source 1110 and the waveguide 1120. This polarizer 1115 may also be a light recycler, transmitting light of a first polarization and reflecting 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 optical device 1105 (such as a non-imaging optical element (e.g., a cone, a compound parabolic concentrator (CPC), a lens)) may be disposed relative to the light source 1110 to receive the light output from the light source 1110. The coupling optical device 1105 may collect the light from the light source 1110 and, in some cases, reduce the divergence of the light emitted from the light source 1110. The coupling optical device 1105 may, for example, collimate the light output from the light source 1110. The coupling optical device 1105 may collect light that matches the angular spectral field of view of the system 1100A. Thus, the coupling optical device 1105 may match the angular spectrum of the light output by the light source 1110 to the field of view of the system 1100A. The coupling optical device 1105 may have an asymmetric profile to operate on the light emitted from the light source 1110 asymmetrically. For example, the coupling optical device 1105 may reduce the divergence to different amounts in orthogonal directions (e.g., the x and z directions). Such an asymmetry in the coupling optical device 1105 may address the asymmetry of the light emitted from the light source 1110, which may include, for example, a laser diode that emits a wider range of light angles in one direction (e.g., x or z) than in the orthogonal direction (e.g., z or x, respectively).

[0126] As discussed above, system 1100A includes optics 1130 configured to illuminate SLM 1140, which is disposed in the optical path between light source 1110 and SLM 1140. Optics 1130 may include transmissive optics that transmit light from light source 1110 to SLM 1140. Optics 1130 may also be configured to project an image of SLM 1140 or an image formed by SLM 1140 into waveguide 1120. The image may be projected into the eye of eye 210. In some designs, optics 1130 may include one or more lenses or optical elements having a focal power. Optics 1130 may have, for example, a positive focal power. Optics 1130 may include one or more refractive optical elements, such as refractive lenses. Other types of optical elements may also be used.

[0127] SLM 1140 may be reflective, modulate, and reflect light therefrom. SLM 1140 may be a polarization-based SLM configured to modulate polarization. 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. SLM 1140 may be substantially similar to SLM 1030 of the reference Figure 10 SLM 1140 may include, for example, one or more pixels configured to selectively modulate light incident on the pixel depending on the state of the pixel. For some types of SLM 1140, the pixel may modulate the light beam incident thereon, for example, by changing the polarization state (such as rotating the polarization (e.g., rotating the orientation of linearly polarized light)).

[0128] As discussed above, SLM 1140 may be an LCoS SLM 1140. In a cross-polarizer configuration, the LCoS SLM 1140 may be nominally white. When the pixel is off (e.g., 0 volts), it has a bright state, and when the pixel is on (e.g., a voltage higher than the threshold turn-on voltage), it has a dark state. In this cross-polarization configuration, leakage is minimized when the pixel is on and has a dark state.

[0129] In a parallel-polarizer configuration, the LCoS SLM 1140 is nominally black. When the pixel is off (e.g., 0 volts), it has a dark state, and when the pixel is on (e.g., a voltage higher than the threshold turn-on voltage), it has a bright state. In this parallel-polarizer configuration, leakage is minimized when the pixel is off and has a dark state. The rubbing direction and compensator angle may be used to (re)optimize the dark state. The compensator angle may refer to the angle of a compensator that may be located between optics 1130 and SLM 1140.

[0130] The dynamic range and throughput of a parallel polarizer configuration can be different from that of a crossed polarizer configuration. Additionally, the parallel polarizer configuration can be optimized differently for contrast than the crossed polarizer configuration.

[0131] System 1100A includes a waveguide 1120 for outputting image information to an eye 210. Waveguide 1120 can be substantially similar to waveguides 270, 280, 290, 300, 310, 670, 680, and 690 discussed above. Waveguide 1120 can include a substantially transparent material having a refractive index sufficient to guide light therein. As illustrated, waveguide 1120 can include a first side 1121 and a second side 1123 opposite the first side 1121, as well as corresponding upper and lower major surfaces and surrounding edges. The first major surface 1121 and the second major surface 1123 can be flat enough such that image information can be retained as light propagates from the SLM 1140 to the eye 210, such that an image formed by the SLM 1140 can be injected into the eye. Optical device 1130 and SLM 1140 can be positioned on the first side 1121 of the waveguide 1120. Light source 1110 can be disposed on the second side 1123 such that light from the light source 1110 is incident on the second side 1123 before passing through the waveguide 1120 and through the optical device 1130 to reach the SLM 1140. Thus, waveguide 1120 can be disposed between the light source 1110 and the optical device 1130. Additionally, at least a portion of the waveguide 1120 can extend between the light source 1110 and the optical device 1130 such that light passes through this portion of the waveguide 1120 to reach the optical device 1130. Thus, light emitted from the light source 1110 can be guided through the waveguide 1120, into the optical device 1130 and through the optical device 1130, and incident on the SLM 1140. The SLM 1140 reflects the light back through the optical device 1130 and to the waveguide 1120.

[0132] System 1100A further includes a light-coupling optical element 1160 for coupling light from the optical device 1130 into the waveguide 1120. The light-coupling optical element 1160 can be disposed on a major surface (e.g., the upper major surface 1123) of the waveguide 1120. In some designs, the light-coupling optical element 1160 can be disposed on the lower major surface 1121 of the waveguide 1120. In some designs, the light-coupling optical element 1160 can be disposed within the body of the waveguide 1120. Although the light-coupling optical element 1160 is shown on one side or a corner of the waveguide 1120, the light-coupling optical element 1160 can be disposed in / on other regions of the waveguide 1120. The light-coupling optical element 1160 can be similar to that referenced above Figure 9A 、 9BThe coupling optical elements 700, 710, and 720 described in 9C are substantially similar. The coupling optical element 1160 can be a diffractive optical element or a reflector. Other structures can be used as the coupling optical element 1160. The coupling optical element 1160 can be configured to guide light incident thereon into the waveguide 1120 at a grazing angle (e.g., greater than the critical angle) relative to the upper major surface 1123 and the lower major surface 1121 of the waveguide 1120 large enough to be guided in the waveguide 1120 by total internal reflection. In addition, the coupling optical element 1160 can operate over a wide wavelength range and can thus be configured to couple light of multiple colors into the waveguide 1120. For example, the coupling optical element 1160 can be configured to couple red, green, and blue light into the waveguide 1120. The light source 1110 can emit red, green, and blue light at different times.

[0133] The system 1100A includes a light distribution element 1170 disposed on or in the waveguide 1120. The light distribution element 1170 can be substantially similar to the light distribution elements 730, 740, and 750 described above with respect to Figure 9B . For example, the light distribution element 1170 can be an orthogonal pupil expander (OPE). The light distribution element 1170 can be configured to spread light within the waveguide 1120 by steering light propagating in the x direction, for example, toward the z direction as shown in the top view Figure 11B . Thus, the light distribution element 1170 can be configured to increase the size of the eye box along the z axis; see Figure 11B . For example, the light distribution element 1170 can include one or more diffractive optical elements configured to diffract light incident on the diffractive optical element propagating within the waveguide 1120 so as to redirect the light in a direction, for example, substantially orthogonal. Other configurations are possible.

[0134] As Figure 11B shown, the system 1100A can also include a coupling-out optical element 1180 for coupling light from the waveguide 1120 to the eye 210. The coupling-out optical element 1180 can be configured to redirect light propagating within the waveguide 1120 by total internal reflection (TIR) to an angle more perpendicular to the upper major surface 1123 and / or the lower major surface 1121 of the waveguide 1120 such that the light is not guided within the waveguide 1120. Instead, the light is guided out of the waveguide 1120 through, for example, the lower major surface 1121. The coupling-out optical element 1180 can include, for example, one or more diffractive optical elements configured to diffract light incident on the diffractive optical element propagating within the waveguide 1120 so as to, for example, redirect the light out of the waveguide 1120. Other configurations are possible.

[0135] Figure 11BThe position of the light-incoupling optical element 1160, which is disposed laterally with respect to the light distribution optical element (e.g., an orthogonal pupil expander) 1170 and the light-extracting optical element 1180, is also shown. Figure 11B The position of the light source 1110, which is disposed laterally with respect to the light-incoupling optical element 1160, the light distribution optical element (e.g., an orthogonal pupil expander) 1170, and the light-extracting optical element 1180, is also shown.

[0136] In operation, the light source 1110 of system 1100A emits light into the coupling optics 1105 and through the polarizer 1115. Thus, the light can be polarized, e.g., linearly polarized in a first direction. The polarized light can pass through the waveguide 1120, enter the second major surface of the waveguide 1120, and exit from the first major surface of the waveguide 1120. The light can propagate through the optics 1130 to reach the SLM 1140. The optics 1130 collimates and / or selects the light from the light source 1110 so as to illuminate the SLM 1140, which may include a polarization-based modulator that modulates the polarization of the light incident thereon, such as by selectively rotating the orientation of the modulator 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 but not rotate the polarization. The light between the coupling optics 1105 and the optics 1130 can illuminate the SLM 1140 rather uniformly. After being incident on the SLM 1140, the light is reflected back through the optics 1130. The optics 1130 can be configured to project the image from the SLM 1140 into the waveguide 1120 and ultimately into the eye 210 such that the image is visible to the eye 210. In some designs, the retina of the eye 210 is the optical conjugate of the SLM 1140 and / or the image formed by and / or on the SLM 1140. The dioptric power of the optics 1130 can facilitate projecting the image on the SLM 1140 into the eye 210 and onto the retina of the eye 210. In some embodiments, the dioptric power provided, e.g., by the decoupling optical element 1180, can contribute to and / or affect the image ultimately formed in the eye 210. As the light reflected from the SLM 1140 travels through the optics towards the waveguide 1120, the optics 1130 acts as a projection lens. The optics can roughly function as a Fourier transform of the image on the SLM 1140 to a plane in the waveguide 1120 near the coupling optical element 1160. The total of two passes through the optics 1130 (first from the light source 1110 to the SLM 1140 and second from the SLM 1140 to the waveguide 1120) can together roughly image the pupil of the coupling optics 1105. The alignment and orientation of the light source 1110 (and possibly also the coupling optics 1105 and / or the polarizer 1115), the optics 1130, and the SLM 1140 are such that the light from the light source 1110 reflected from the SLM 1140 is directed onto the coupling optical element 1160. The pupil associated with the coupling optics 1105 can be aligned with the coupling optical element 1160. The light can pass through an analyzer 1150 (e.g., a polarizer) in the optical path between the SLM 1140 and the eye 210. As Figure 11AAs shown, an analyzer (e.g., a polarizer) 1150 can be disposed in the optical path between the optical device 1130 and the optical coupling element 1160. The analyzer 1150 can be, for example, a linear polarizer having an orientation that transmits light of a first polarization (p-polarization) and blocks light of a second polarization (s-polarization), and vice versa. The analyzer 1150 can be a clean polarizer and further blocks polarized light blocked by another polarizer between the SLM 1140 and the analyzer 1150 or within the SLM 1140. The analyzer 1150 can be, for example, a circular polarizer that acts as an isolator to reduce reflections that bounce back from the waveguide 1120 (specifically, the optical coupling element 1160) to the SLM 1140. Like any polarizer disclosed herein, the analyzer 1150 can include a wire grid polarizer, such as an absorptive wire grid polarizer. Such polarizers can significantly absorb unwanted light and thus increase contrast. Some such polarizers can be made to include one or more dielectric layers on top of the wires and / or multi-layer films. In some embodiments, the SLM 1140 can be a liquid crystal on silicon (LCOS) SLM and can include LC cells and retarders (e.g., compensators). In some embodiments, the analyzer 1150 can be a compensator that is designed to provide more consistent polarization rotation (e.g., 90°) of the SLM 1140 for different angles of incidence and different wavelengths. The compensator can be used to improve the contrast of the display by improving the rotation of polarized light incident across an angular and wavelength range. The SLM 1140 can include, for example, a TN LCOS that is configured to rotate incident light of a first polarization (e.g., s-polarization) to a second polarization (e.g., p-polarization) for a first pixel to create a bright pixel state when the light will pass through the analyzer 1150. Conversely, the SLM 1140 can be configured not to rotate incident light of the first polarization (e.g., s-polarization) to the second polarization (e.g., p-polarization) for a second pixel such that the reflected light remains the first polarization to create a dark pixel state when the light will be attenuated or blocked by the analyzer 1150. In such a configuration, the polarizer 1115 closer to the light source 1110 along the optical path can be oriented differently (e.g., orthogonally) from the analyzer 1150 farther from the light source 1110 along the optical path. Other (e.g., opposite) configurations are possible.

[0137] Then, the light is deflected, e.g., redirected by the optical coupling element 1160, so as to be guided in the waveguide 1120, where the light propagates by TIR. Then, the light impinges on the light distribution element 1170, redirecting the light in another direction (e.g., more towards the z-direction), resulting in an increase in the size of the eye box along the z-axis direction, as Figure 11B shown. Thus, the light is redirected towards the optical coupling-out element 1180, which causes the light to be directed out of the waveguide 1120 towards the eye 210 (e.g., the user's eye as shown). The light is coupled out along the z-direction by different portions of the optical coupling-out element 1180, resulting in an eye box size along at least theFigure 11B increases in a direction parallel to the z-axis defined therein. It should be noted that in this configuration, the optical device 1130 is used both to illuminate the SLM 1140 and to project an image onto the coupled-in optical element 1160. Thus, the optical device 1130 can act as a projection optical device to distribute (e.g., uniformly) light from the light source 1110, and act as an imaging optical device to provide the image of the SLM 1140 and / or the image formed by the SLM 1140 into the eye.

[0138] As described above, alternative configurations are possible. Referring to Figure 11C , for example, in some designs, the system 1100C can be configured to allow light with a polarization that is not rotated by the SLM 1140 to pass through. In one embodiment, for example, the SLM 1140 is a liquid crystal (LC)-based SLM and can include vertically aligned (VA) liquid crystal on silicon (LCoS). The SLM 1140 can have a first pixel in a first state that does not rotate polarization and a second pixel in a second state that rotates polarization. In the configuration shown in FIG. 11C, a single shared analyzer / polarizer 1155 is utilized. This analyzer 1155 can transmit light of a first polarization (e.g., s-polarization) and attenuate or reduce the transmission of a second polarization (e.g., p-polarization). Thus, light (e.g., s-polarized light) incident on the first pixel in the first state that does not rotate the polarization orientation is reflected from the SLM 1140 and passes through the analyzer 1155 to reach the waveguide 1120. In contrast, light (e.g., s-polarized light) incident on the second pixel in the second state that rotates the polarization orientation is reflected from the SLM 1140 and is attenuated, reduced, or does not pass through the analyzer 1155 to reach the waveguide 1120. This configuration can thus allow Figure 11A the polarizer 1115 and the analyzer 1150 shown in Figure 11C to be combined into a shared optical element ( Figure 11A the analyzer 1155 shown in Figure 11A ), thus potentially simplifying the Figure 11A / B system 1100 by reducing the number of optical components. The analyzer 1155 can be disposed between the waveguide 1120 and the optical device 1130. In other embodiments, separate analyzer / polarizers and analyzer / polarizers can be used, such as Figure 11A shown in the system 1100 of Figure 11A and 11B shows a polarizer 1115 located between the light source 1110 and the waveguide 1120, and an analyzer 1140 located between the optical device 1130 and the waveguide 1120.

[0139] Various other configurations can be employed that utilize the optical device 1130 to illuminate the SLM 1140 and image the image formed by the SLM 1140. For example, although Figures 12A - 12CA single waveguide 1120 is shown, but one or more waveguides may be used, such as a waveguide stack (possibly using different waveguides for different colors of light). For example, Figure 12A FIG. 12 shows a cross-sectional side view of an exemplary system 1200A that includes a stack 1205. The stack 1205 includes waveguides 1120, 1122, 1124, and each waveguide includes an optical coupling element 1260, 1262, 1264. The waveguides 1120, 1122, 1124 may each be configured to output one or more different wavelengths of light, or one or more different wavelength ranges of light. The stack 1205 may be substantially similar to stacks 260 and 660 ( Figure 6 and 9A ), and the shown waveguides 1120, 1122, 1124 of the stack 1205 may correspond to a portion of the waveguides 670, 680, 690. However, the stack 1205 and the waveguides 1120, 1122, 1124 are not necessarily so limited. As shown in Figure 12A , the optical coupling elements 1260, 1262, 1264 may be, for example, associated with, included in, or on the waveguides 1120, 1122, 1124, respectively. The optical coupling elements 1260, 1262, 1264 may be color selective and may primarily transfer or redirect certain wavelengths into the corresponding waveguides 1120, 1122, 1124 for guiding therein. As shown, since the optical coupling elements 1260, 1262, 1264 are color selective, the optical coupling elements 1260, 1262, 1264 do not need to be laterally shifted and may be stacked on top of each other. Wavelength multiplexing may be employed to couple a specific color into the corresponding waveguide. For example, a red optical coupling element may couple red light into a waveguide designated for propagating red light without coupling blue or green light, which is coupled into other waveguides by other blue and green selective waveguides, respectively.

[0140] In some embodiments, the light source 1110 may be a multicolor light source capable of emitting different colors of light at different times. For example, the light source 1110 may emit red, green, and blue (RGB) light and may be configured to emit red light and no more than a negligible amount of green and blue light in a first time period, green light and no more than a negligible amount of red and blue light in a second time period, and blue light and no more than a negligible amount of red and green light in a third time period. These cycles may repeat, and the SLM 1140 may be coordinated to generate a suitable pixel state pattern for a specific color (red, green, or blue) to provide an appropriate image color component for a given image frame. The different waveguides 1120, 1122, 1124 of the stack 1205 may each be configured to output light having a different corresponding color. For example, as shown in Figure 12AAs shown, waveguides 1120, 1122, 1124 can be configured to output blue, green, and red light, respectively. Of course, other colors are possible. For example, light source 1110 can emit other colors, and color-selective coupling-in optical elements 1260, 1262, 1264, coupling-out optical elements, etc. can be configured for such other colors. In addition, separate red, green, and blue emitters can be positioned close enough to effectively serve as a single-pupil light source. The red, green, and blue emitters can be combined with lenses and dichroic beam splitters to form single red, green, and blue pupil sources. The multiplexing of a single pupil can extend beyond or be supplementary to color selectivity and can include the use of polarization-sensitive gratings and polarization switches. These color or polarization gratings can also be used in combination with multiple display pupils to increase the number of addressable layers.

[0141] The different coupling-in optical elements 1260, 1262, 1264 in the different waveguides 1120, 1122, 1124 can be arranged above and / or below each other and laterally aligned with respect to each other (e.g., in the Figure 12A x and z directions shown), rather than being laterally shifted and misaligned with respect to each other. Thus, in some embodiments, for example, the different coupling-in optical elements 1260, 1262, 1264 can be configured such that light of a first color can be coupled into waveguide 1120 by coupling-in optical element 1260 for guiding therein, while light of a second color different from the first color can pass through coupling-in optical element 1260 to the next coupling-in optical element 1262 and can be coupled into waveguide 1122 by coupling-in optical element 1262 for guiding therein. Light of a third color different from the first and second colors can pass through coupling-in optical elements 1260 and 1262 to coupling-in optical element 1264 and can be coupled into waveguide 1124 for guiding therein. In addition, the coupling-in optical elements 1260, 1262, 1264 can be polarization-selective. For example, the different coupling-in optical elements 1260, 1262, 1264 can be configured such that light of a particular polarization is either coupled into the waveguide through the corresponding polarization-selective coupling-in optical elements 1260, 1262, 1264 or passes through the coupling-in optical elements 1260, 1262, 1264.

[0142] Depending on the configuration, SLM 1140 can include a polarization-based SLM that modulates polarization. System 1200A can include a polarizer and / or an analyzer to modulate the light injected into stack 1205 pixel by pixel, for example, depending on the state of the corresponding pixel (e.g., whether the pixel rotates the polarization orientation). Various aspects of such systems employing a polarization-based SLM have been discussed above, and any one of such features can be used in combination with any other feature described herein. However, other designs are still possible.

[0143] For example, a deflection-based SLM 1140 can be employed. For example, the SLM 1140 can include one or more movable optical elements, such as movable mirrors, which can reflect and / or deflect light in different directions depending on the state of the optical elements. The SLM 1140 can include, for example, one or more pixels that include optical elements such as micromirrors or reflectors. The SLM 1140 can be combined with, for example, digital light processing (DLP TM ) technology. Figure 12BAn example of a system 1200B using such a deflection-based SLM 1140 is shown. The system 1200B includes a deflection-based SLM 1140 and a light dump 1250. The light dump 1250 may include an absorbing 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 can be configured to deflect light from the light source 1110 incident thereon to the coupling optical elements 1260, 1262, 1264 when a given pixel is in the bright state. As discussed above, depending on the color of the light, for example, the light will thus be coupled by one of the coupling optical elements 1260, 1262, 1264 into one of the corresponding waveguides 1120, 1122, 1124 and guided to the eye 210. Conversely, when a given pixel is in the dark state, the light from the light source 1110 can be deflected to the light dump 1250, and the light will not be coupled by one of the coupling optical elements 1260, 1262, 1264 into one of the corresponding waveguides 1120, 1122, 1124 and guided to the eye 210. Instead, the light may be absorbed by the absorbing material including the light dump 1250. In some embodiments, the analyzer 1150 can be a polarizer (e.g., a "cleaning" polarizer) that is used to eliminate unwanted reflections from the coupling optical elements 1260, 1262, 1264. Since the optical device 1130 may include plastic optical elements that are birefringent and can change polarization, this polarizer may be useful. The "cleaning" polarizer can attenuate or remove light (e.g., reflections) with unwanted polarization so that it is not guided onto the waveguides 1120, 1122, 1124. Other types of light conditioning elements can be disposed between the SLM 1140 and the waveguides 1120, 1122, 1124, such as between the optical device 1130 and the waveguides 1120, 1122, 1124. For example, such light conditioning elements can also include circular polarizers (i.e., linear polarizers and retarders, such as quarter-wave plates). The circular polarizer can reduce the amount of reflection from the waveguides 1120, 1122, 1124 or the coupling optical elements 1260, 1262, 1264 that is incident again onto the waveguides 1120, 1122, 1124 and coupled therein. The reflected light can be circularly polarized and can have a circular polarization opposite to that of the incident light (e.g., right-handed circularly polarized light is converted to left-handed circularly polarized light upon reflection, and vice versa). The retarder in the circular polarizer can convert the circularly polarized light into linearly polarized light, such as linearly polarized light orthogonal to the polarization of the polarizer, which is attenuated (e.g., absorbed) by the linear polarizer in the circular polarizer. The cleaning polarizer can be used with polarization-independent modulators such as DMDs.As described above, the cleaning polarizer can be used to suppress reflection and / or improve the coupling of light into the light-coupling optical elements 1260, 1262, 1264 in an optimal polarization state.

[0144] Figure 12B A side view or a cross-sectional view of the system 1200B is shown, while Figure 12C A top view showing the lateral arrangement of the light-coupling optical element 1264, the light dump 1250, and the light source 1110 is shown. The SLM 1140 will be configured to reflect, deflect, and / or guide the light from the light source 1110 to the lateral position of the light-coupling optical element 1264 (and other light-coupling optical elements 1260, 1262) or the light dump 1250 depending on the state of a particular pixel.

[0145] Optical System with a dummy area

[0146] Imprinting 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 displays and / or projection systems, such as the systems discussed above with reference to Figures 1 to 12C the discussion.

[0147] Defects in the imprinted structure may affect the performance of the optical system (e.g., light coupling / in-coupling efficiency). For example, in some cases, grating delamination and / or other damages can be observed at the edges (e.g., leading / trailing edges) of the imprinted pattern (e.g., grating). Such defects may be more severe when the grating extends perpendicular to the separation direction during the imprinting process.

[0148] For example, Figure 13 A process of imprinting using a soft mold 1302 on a substrate 1304 (e.g., a semiconductor wafer or a dielectric substrate) having a coating 1306 (e.g., an ultraviolet curable polymer) is shown. The pattern in the face of the mold 1302 forms a corresponding pattern 1308 (a grating in this example) in the coating 1306. Since the imprinting is performed along the rolling direction (imprinting direction) 1310, separation occurs at approximately position 1312, and the separation is associated with a separation force (sometimes called a demolding force), such as a shear force. In some cases, a solid mold ("hard-on-hard") imprinting process (e.g., a solid mold NIL process) may exhibit a higher shear force than when using a soft mold. The separation force may cause defects, especially at the edges of the grating and other imprinted patterns. For example, at the boundary between a pattern-rich region and a blank region, a peak (e.g., a bump-like force) of the demolding force may occur, and this peak of the force may shear the pattern, resulting in imprinting defects.

[0149] For example, Figure 14Shown are imprint optical structures 1400 and 1410, which present a layered grating 1402 (represented by dark lines) at the edges of the grating region 1404. In this case, delamination was observed at the leading edge (the location where separation first occurs during the nanoimprint lithography process); however, delamination and other defects may also occur at other edges (such as the trailing edge).

[0150] In some cases, when the grating extends perpendicular to the separation / demolding direction, defects are more likely to occur. Additionally, in the case of an inclined grating, the defects may be more severe because the grating is inclined from the normal direction of the surface. When the grating is misaligned with the separation direction (e.g., in the pinwheel arrangement discussed below with reference to Figure 17 ), the inclined grating may cause a significant increase in shear force.

[0151] As another example, during the imprint process (e.g., especially a high-speed imprint process), bubbles may form at the edges of the patterned region (such as the grating region). During the imprint process, air may become trapped at the edges, resulting in bubbles. For example, Figure 15 Shown are imprint optical structures 1500 and 1510, which have bubbles 1502 at the edges of the active region 1504. Bubbles may cause a degradation in the optical performance of waveguides, gratings, and other active optical structures.

[0152] According to some embodiments of the present disclosure, to mitigate grating delamination and / or other defects, a dummy imprint region (such as a non-active grating partition) is added adjacent to the active pattern (such as an active grating). The dummy imprint region is formed using a common imprint process with the active region, e.g., using a common mold. Thus, manufacturing-related defects associated with the pattern edges are spatially separated from the active pattern, resulting in a defect-free or relatively low-defect active pattern. For example, during the imprint process, the separation edge where the imprint mold first separates from the imprint material (such as a polymer) can be located at the edge of the 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.

[0153] As another example, since bubbles have been observed to form at the boundary between the grating and the blank region (e.g., a non-imprinted region), a non-active dummy imprint region can be provided near the grating to spatially separate the patterning / blank interface from the grating. In this way, bubbles (regardless of what type of bubbles form during imprinting) are more likely to appear in the non-active dummy imprint region, thereby mitigating the impact of the bubbles on the optical performance of the grating.

[0154] In addition, in some embodiments, the non-active dummy imprint region may include one or more non-active structures that reduce and / or disperse the separation force, for example, based on the orientation and / or feature height of the non-active structure. Thus, in some embodiments, separation-induced damage can not only be transferred away from the active structures, but also reduced.

[0155] In some embodiments, the non-active regions discussed herein can act as a barrier to prevent residual layer thickness (RLT) deficiencies / defects due to resist overflow at the grating edges. For example, in certain cases, a certain volume of resist in a pattern-rich region (e.g., where a larger resist volume may be required) will flow due to normal capillary action towards a blank region (e.g., with a lesser resist volume), which can "starve" the resist in the pattern-rich region, resulting in under-curing of the resist volume in the pattern-rich region, and thus resulting in unfilled defects, bridging, and / or peeling, e.g., because a residual interconnect layer may form between the structures and cause adhesion to the template. In some embodiments, the presence of the dummy imprint region can reduce such flow (e.g., because the flow from a pattern-rich region to a dummy imprint region with non-diffractive or sub-diffractive structures may be less than the flow from a pattern-rich region to a blank region).

[0156] In some embodiments according to the present disclosure, an "active" region is a diffractive region having one or more diffractive optical structures, while a "non-active region" is an optically non-diffractive region or an optically sub-diffractive region. For example, in some embodiments, the non-active region may (but need not) include one or more structures that perform one or more optical functions (e.g., anti-reflection), but do not perform diffractive optical functions (e.g., light coupling in / out using a grating) for the wavelengths of light for which the active region has diffractive characteristics. Whether an optical structure / nanostructure performs a diffractive function or a non / sub-diffractive function can be based at least on the critical dimension of the structure, such as the grating size (e.g., depth, width, and / or pitch). Thus, in some embodiments, references in the present disclosure to "active" regions and / or structures may refer to "diffractive" regions and / or structures, while references to "non-active", "dummy", etc. regions and / or structures may refer to "non-diffractive" or "sub-diffractive" regions and / or structures.

[0157] In some embodiments, the non-active dummy region is a non-active grating region having an imprinted grating. The geometry of the non-active grating (grating orientation, pitch, critical dimensions (e.g., width and / or height), duty cycle, and / or other parameters) may be significantly different from that of the active grating, such that, for example, the non-active grating does not diffract light having a wavelength that diffractively interacts with the diffractive structures in the active grating region.

[0158] For example, in some embodiments, an optical diffraction structure (e.g., a grating) is configured to couple light into a waveguide (e.g., air to substrate) and / or couple light out of a waveguide (e.g., substrate to air), and the light is guided in a total internal reflection (TIR) manner. Light having the same wavelength may not undergo a diffraction interaction with a non-active grating adjacent to the optical diffraction structure, such that the non-active grating does not significantly or does not actively change the optical performance of the active region.

[0159] For example, in some embodiments, the pitch of the grating in the non-active region can be much larger or much smaller than the pitch of the grating in the active region, and the different pitches can result in different optical interactions of the grating (e.g., sub-diffraction for the non-active region and diffraction for the active region).

[0160] For example, in some embodiments, the pitch of the diffraction structure (i.e., the periodicity in one or two axes) is between 200 nm and 1 μm or between 200 nm and 2 μm; and the pitch of the sub-diffraction structure is 100 nm or less, 200 nm or less, 300 nm or less, or 400 nm or less. For example, the pitch is greater than 20 nm or greater than 50 nm, and these dimensions can provide diffraction and sub-diffraction behaviors for visible light, respectively. In some embodiments, the pitch of the diffraction structure is between 200 nm and 1 μm, or between 200 nm and 2 μm; the pitch of the non-active structure is 1 μm or greater, 2 μm or greater, or 3 μm or greater. In some embodiments, the active structure has a parameter value (e.g., pitch) that causes the diffraction structure to undergo a diffraction interaction with one or more types of light; and the non-active structure has a parameter value that causes the non-active structure not to undergo a diffraction interaction 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 embodiments, the active structure has a parameter value (e.g., pitch) that causes the diffraction structure to couple light into the underlying substrate and / or couple light out of the underlying substrate through the diffraction structure; and the non-active structure has a parameter value that does not cause the non-diffraction structure to couple light into the underlying substrate and / or couple light out of the underlying substrate through the non-diffraction structure.

[0161] As used herein, "pitch" and other features of the patterned structure can refer not only to strict periodicity but also to quasi-periodicity, such as tiling / arrays of structures having a varying height or a varying orientation.

[0162] In some embodiments, using a grating or other structure with a defined pattern as a non-active / dummy structure can provide advantages compared to using another type of structure (e.g., a random structure). For example, the grating can be oriented to provide a relatively small release force (e.g., by extending the grating structure along the peel direction), and / or gradually guide the release force (e.g., by setting multiple partitions with different heights and / or grating orientations). In contrast, a random structure may result in unpredictable and potentially higher release forces, depending on the random structure.

[0163] As described above, in some embodiments, the non-active structure (e.g., a non-active grating) performs one or more optical functions in a non-diffractive or sub-diffractive manner. For example, in some embodiments, the non-active grating is configured to perform anti-reflection, and / or the non-active region may include an anti-reflection coating. For example, the geometry of the grating in the non-active region can be such that the grating interacts with light in a sub-diffractive or non-diffractive manner, e.g., by having one or more dimensions that are larger and / or smaller than the corresponding dimensions of the diffractive grating in the active region.

[0164] The distance between the non-active structure and the adjacent active structure is small enough to reduce or prevent imprint-related defects that may occur on or at the edges of the active structure. For example, in various embodiments, the distance between the non-active structure and the adjacent active structure can be less than 10 nanometers, less than 25 nanometers, less than 50 nanometers, less than 100 nanometers, less than 250 nanometers, less than 500 nanometers, less than 1 micrometer, less than 5 micrometers, less than 20 micrometers, less than 50 micrometers, or other values. In certain embodiments, the distance is very small, e.g., within the minimum resolution of electron beam lithography or other processes used to fabricate the template.

[0165] Figure 16 Several examples of a non-active region (including a non-active grating in this example) adjacent to an active region are shown. In this example, for simplicity, all regions are disposed on a common substrate 1600; however, generally, the non-active region and the active region do not have to be disposed on the substrate together with other non-active regions and active regions. The structures of the non-active region and the active region are formed during the imprint process with an imprint direction 1601 parallel to the separation direction.

[0166] As Figure 16As shown, the active region 1602 is adjacent to non-active regions 1604a, 1604b, 1604c, 1604d, which are collectively referred to as non-active region 1604. The non-active regions 1604 can have the same or different types of structures (e.g., sub-diffraction structures and / or non-diffraction structures). In this example, non-active region 1604a includes a tapered non-active grating 1606. The non-active grating 1606 includes walls 1608 that extend parallel and are separated by trenches. In any of the embodiments described herein, the walls of the grating of the non-active region (e.g., sub-diffraction grating) can (but need not) extend parallel to the walls of the grating of the adjacent active region. For example, walls 1608 can extend parallel to the walls of the diffraction grating of active region 1602 (not shown). In certain embodiments, as Figure 16 shown, walls 1608 extend parallel to the boundary 1610 between non-active region 1604a and active region 1602. In certain embodiments, as shown in this example, walls 1608 extend perpendicular to the imprint direction 1601.

[0167] The non-active grating 1606 is "tapered" because the height of walls 1608 increases along the direction of the adjacent active region 1602. For example, walls 1608 closer to active region 1602 are taller than walls 1608 farther from active region 1602. This tapering can be applied to all walls 1608 (e.g., such that non-active grating 1606 has walls 1608 with a monotonically increasing height towards active region 1602), or can be applied to a subset of walls 1608. For example, multiple adjacent walls 1608 in non-active grating 1606 (e.g., in various embodiments, two or more adjacent walls 1608, three or more adjacent walls 1608, four or more adjacent walls 1608, or other numbers of multiple adjacent walls 1608) can have a height that increases towards the adjacent active region 1602.

[0168] In some embodiments, the tapering can help direct the imprint force direction as well as the demolding force direction to prevent "abrupt", spatially concentrated demolding forces at the edges / boundaries between the active diffraction and sub-diffraction non-active regions.

[0169] In some embodiments, 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, the height of the grating adjacent to non-active grating 1606 in active region 1602 can be h, and the height of the features (e.g., grating walls) of non-active grating 1606, to approach active region 1602, can be h1 < h2 < … < h n , where h nless than or equal to h, and in some embodiments may approach h, e.g., within 10% or 20% of h, or match h. For example, the height of the features in the non-active region 1604 may gradually increase until it approaches the active region 1602. In this way, the demolding force can be gradually guided / reduced, thereby potentially reducing the occurrence of separation defects.

[0170] In some embodiments, one or more parameters are tapered, rather than height, or in addition to height. These parameters can include, for example, feature height or depth, feature pitch, feature width, feature length, feature density, orientation (e.g., the array angle relative to a given direction), and / or array pitch, and / or duty cycle in one or more dimensions. In some embodiments, the tapering occurs in the imprint direction, which does not have to be the same as the direction towards the adjacent active region.

[0171] Another non-active region 1604 adjacent to the active region 1602, namely non-active region 1604c, includes a grating 1612 composed of parallel walls 1614. In this example, the walls 1614 extend parallel to the separation direction of the imprinting process. In some embodiments, the orientation of such non-active structures (e.g., features such as grating walls that extend parallel to the separation direction) can reduce the occurrence of imprinting defects, e.g., by reducing the shear force during imprinting.

[0172] Other non-active regions 1604b and 1604d adjacent to the active region 1602 may include corresponding non-active gratings, which may have the characteristics as described for the non-active grating 1606 (e.g., having walls that extend parallel to the boundary of the active region 1602 and / or having a gradual change in feature height), and / or the characteristics as described for the non-active grating 1612 (e.g., the walls extend perpendicular to the boundary of the active region 1602, the walls extend parallel to the separation direction, and / or there is no gradual change in feature height). Other feature geometries may also be used alternatively or additionally.

[0173] Additional non-active regions 1620a, 1620b, 1620c (collectively referred to as non-active regions 1620) are respectively adjacent to and surround active regions 1618a, 1618b, 1618c (collectively referred to as active regions 1618). The non-active regions 1620 include corresponding non-active gratings, the walls of which extend parallel to the local interface between the non-active regions 1620 and the active regions 1618. For example, the circular active region 1618b has a circular interface 1622, and the walls 1626 of the non-active grating 1624 in the non-active regions 1620b and 1620b extend along the circumference, parallel to the circular interface 1622. In some embodiments, such an orientation can help maintain a smooth demolding and / or imprinting force, and as described above, help maintain spatial peeling and / or non-fill zones away from the active structures.

[0174] The non-active gratings (not shown) of the non-active regions 1620a and 1620c respectively may have the characteristics described for the grating 1624. For example, the walls of the non-active grating in the non-active region 1620c may be elliptical to surround and be locally parallel to the elliptical boundary between the non-active region 1620c and the elliptical active region 1618c; the walls of the non-active grating may be radially tiled with respect to the center of the active region 1618c. As another example, the active region 1618a is rectangular, and the non-active region 1620a may include four non-active gratings respectively on four corresponding sides of the active region 1618a. The walls of each non-active grating extend parallel to the nearest side of the active region 1618 and are tiled / periodically arranged in a direction orthogonal to the nearest side.

[0175] Although the non-active grating 1624 is shown as non-graded and consists of walls with a uniform height, in some embodiments, a non-active grating having a circumferential configuration (e.g., circular or elliptical) may be graded, for example, in height, as described for the non-active grating 1606.

[0176] The non-active structures of the non-active regions 1620 and other non-active structures in the examples discussed herein may include one-dimensional lines and spaces / gratings, two-dimensional mesh holes, columns, and / or discontinuous lines / spaces, and / or two-dimensional column / checkerboards (e.g., gratings composed of two-dimensional arrays of columns and / or bars), to name just a few non-limiting examples. The various geometries, patterns, and arrangements of the structures in the non-active regions are within the scope of the present disclosure. The orientation of the non-active gratings may be parallel, perpendicular, and / or tilted with respect to the gratings in the active region, and may be parallel, perpendicular, and / or tiled with respect to the imprinting and / or separating directions. In some embodiments, the non-active structure may include multiple portions around the active region, and each portion has a different grating geometry, such as different non-active grating orientations and / or structures, and is combined with grading in some combination. The non-active gratings not only help reduce grating delamination / damage caused by shear, but also, in some embodiments, help maintain sufficient resist in the residual layer under the grating, thereby reducing / preventing unfilled defects in the active region. For example, the non-active grating 1606 may act as a barrier to prevent fluid from flowing out of the active region 1602 due to capillary force, thereby helping to reduce or eliminate defects in the active region 1602. The non-active region structure may alternatively or additionally fix, balance, disperse, and / or reduce the imprinting force.

[0177] In some embodiments where the active regions include tilted gratings, when the gratings are tilted relative to the imprint direction, the shear forces associated with imprinting are greater, such as when the tilted grating region is in a pinwheel position and the orientation of the tilted grating is tilted relative to the imprint direction. Inactive regions may be added near and / or around the inactive regions having tilted gratings to move the separation edge to the inactive regions, thereby helping to mitigate grating damage that might otherwise occur at the edges of the tilted gratings.

[0178] For example, Figure 17 FIG. 17 shows a substrate 1700 on which active regions 1702a-1702f (collectively active regions 1702) are imprinted. The imprinted structures on the substrate 1700 are formed by an imprint process, and the imprint direction 1701 is parallel to the separation direction. Each active region 1702 includes a tilted grating having different orientations and tilt directions corresponding to a pinwheel arrangement of the tilted gratings. For example, the tilted gratings may tile outward from a central position 1704 of the pinwheel, and the walls of the gratings may extend perpendicular to the tiling direction and may be tilted along the tiling direction (e.g., tilted toward or away from the central position 1704). For example, the tilted grating 1706 of the active region 1702b has walls 1708 that extend parallel to the imprint direction 1701 (and the separation direction), and the walls 1708 are tilted perpendicular to the imprint direction 1701 (along the central direction 1714 toward the central position 1704), rather than being tilted along the imprint direction 1701 (or the separation direction). This may result in relatively low shear forces when imprinting the tilted grating 1706. The features of the tilted grating 1706 extend parallel to the imprint direction 1701, as discussed for the walls 1614 of the grating 1612, and the same benefits as discussed for the grating 1612 may be obtained from this orientation.

[0179] However, the tilted grating 1710 of the active region 1702d includes walls 1712 that are tilted along a central direction 1716 (toward the central position 1704), which is non-orthogonal to the imprint direction 1701. Thus, imprinting the tilted grating 1710 may be associated with relatively high shear forces.

[0180] To mitigate this shear force, at least one active region 1702 (in this example, all active regions 1702) may be adjacent to and / or surrounded by corresponding inactive regions 1718 having inactive gratings. The inactive gratings may have, for example, reference Figure 16The configurations and orientations described with respect to non-active regions 1620b and 1620c. The presence of non-active grating regions (shown in green) around each tilted grating region (shown in yellow) can move the separation edge into the non-active region, thereby helping to mitigate grating damage generated at the edge of the tilted grating. In some embodiments, the non-active grating can be non-tilted to reduce shear forces at the boundary of the non-active grating.

[0181] The imprinted structures of the non-active regions in each example described herein can include nanostructures, which can (but do not necessarily) consist of an array of nanostructures, such as one-dimensional gratings (e.g., lines / walls and spaces / grooves), two-dimensional nanostructure arrays (e.g., pillars / holes / columns in an array), and / or three-dimensional nanostructure arrays (e.g., multi-order pillars / holes with periodic or quasi-periodic lines and spaces, etc.), not limited to the specific structures described in each example. The imprinted structures do not have to be periodic or quasi-periodic (e.g., can be periodic except for a gradient in feature height or other dimensions), but in some cases can include aperiodic and / or random structures. For example, the imprinted structures of the non-active regions can include one-dimensional, two-dimensional, and / or three-dimensional nanostructures without having to be periodic. As described above, in some embodiments, the pitch of the imprinted non-active structures is between 20 nm and 200 nm, or between 50 nm and 200 nm. Additionally, in some embodiments, the line width of the imprinted non-active structures is between 10 nm and 150 nm, and / or the height is between 10 nm and 300 nm. These dimensions have been shown to have advantages in terms of structural integrity, reliability / ease of imprinting, and desired optical properties. However, in some embodiments, the dimensions of the imprinted non-active structures are different from these dimensions.

[0182] Figure 18 Another example of an imprinted structure is shown. This structure is imprinted on a substrate 1800, and its characteristics are all described with reference to Figure 16 the imprinted structure unless otherwise specified. For example, the active region 1802 can have the same characteristics as the corresponding active regions 1602 and 1618a, 1618b, 1618c, and the adjacent non-active regions 1804 can have the same characteristics as the non-active regions 1604b, 1604c, 1604d, 1620a, 1620b, and 1620c. The imprinted pattern is formed in an imprint direction 1801 that is parallel to the separation direction.

[0183] The non-active region 1806 includes a plurality of sub-regions 1808a, 1808b, 1808c, 1808d (collectively referred to as sub-regions 1808), each sub-region having a different corresponding non-active optical structure. Sub-region 1808d is adjacent to an active optical structure (e.g., a grating) 1810 in the active region 1802. The non-active structures in the sub-regions 1808 and / or the sub-regions 1808 themselves (e.g., the relative positions of the sub-regions 1808) may be oriented such that the imprinted structure varies in a direction parallel to the imprinting direction and / or the demolding / separation direction. For example, the imprinted structure may vary across the sub-regions 1808 and approach the active optical structure 1810 (e.g., a diffraction pattern on a waveguide) in a direction parallel to the imprinting direction 1801. For example, as Figure 18 shown, the sub-regions 1808 may be oriented such that the imprinting direction 1801 continuously passes through a plurality of sub-regions 1808; correspondingly, during certain imprinting processes for forming the Figure 18 structure shown, the structures of the plurality of sub-regions 1808 will be continuously formed by a template, and the template will be continuously separated from each sub-region 1808. The different sub-regions 1808 may have different structural densities, geometries, types, arrangements, and / or other characteristics.

[0184] For example, in some embodiments, the non-active optical structures of the sub-regions 1808 have one or more dimensions that vary from sub-region to sub-region in the imprinting direction 1801. For example, one or more array parameters (e.g., feature height or depth, feature pitch, feature width, feature length, feature density, orientation (e.g., the array angle relative to a given direction), and / or the array pitch and / or duty cycle in one or more dimensions) may be different for each non-active (e.g., sub-diffraction) array in the sub-regions 1808a, 1808b, 1808c, 1808d. For example, the array parameters may increase or decrease from sub-region 1808a to 1808b, to 1808c, to 1808d, or from one or more of these sub-regions to one or more adjacent sub-regions (e.g., from sub-region 1808b to sub-region 1808c). In some embodiments, one or more array parameters vary between the respective sub-regions to approach the value of the same array parameter in the active optical structure 1810. For example, when the value of an array parameter in the active optical structure 1810 is x5, and the values of the same array parameter in the sub-regions 1808a - 1808d are x1 - x4, in some embodiments, the structure is configured such that x1 ≤ x2 ≤ x3 ≤ x4 ≤ x5 or such that x1 ≥ x2 ≥ x3 ≥ x4 ≥ x5.

[0185] For example, in some embodiments, the orientation of each grating in partition 1808 varies with the partition to approximate the orientation of the active optical structure 1810. For example, the active optical structure 1810 may include a grating whose walls are oriented perpendicular to the imprint direction 1801, which may result in defects at the edges of the grating, e.g., due to large separation forces. Partition 1808d may have a non-active grating whose orientation approximates that of the grating in the active optical structure 1810, but in some cases, at least more parallel to the imprint direction 1801; the non-active grating in partition 1808c may be even more parallel to the imprint direction 1801; and so on until partition 1808a includes a non-active grating parallel or substantially parallel to the imprint direction 1801. In this way, the imprinting and / or separation forces are gradually adjusted / redirected to / from the active optical structure 1810, avoiding spatial concentration of forces that may lead to an increased defect rate.

[0186] As another example, in some embodiments, the pattern fill factor (the ratio of structures to blank space in a region) varies by partition, which can (i) help reduce fluid diffusion and keep the fluid within the active region; and / or (ii) facilitate a gradual demolding force from the active optical structure 1810 to partitions 1808d, 1808c, 1808b, and 1808a and then to the outer region of the non-active region 1806 (e.g., a blank region). For example, the fill factor may gradually increase from partition 1808a to partitions 1808b, 1808c, and 1808d.

[0187] Although Figure 18 four partitions 1808 are shown, in some embodiments, a different number of partitions may be provided, such as two, three, or more than four. Additionally, in some embodiments, the non-active region contains a single partition, such as in the case of non-active region 1604c.

[0188] The optical element including the active region and the adjacent non-active region can be used in a head-mounted device, such as a head-mounted device for AR, VR, XR, etc., as described, for example, with reference to Figure 1 - 1 2. For example, with reference to Figure 1 - 1The optical element described in 2 can be formed by imprinting an optical structure in the active region, and as described above, the non-active region (e.g., adjacent to the active region) is imprinted to reduce defects associated with imprinting. For example, the optical structure (e.g., including a grating) formed by imprinting in the active region can include optical output elements 570, 580, 590, 600, 610, optical input elements 1260, 1262, 1264, and / or other optical elements, such as any suitable type of diffractive optical element (DOE), such as a beam splitter, a beam shaper, a lens, and / or a diffuser. For example, the active optical structure can include a diffractive optical element disposed above or near the waveguide for optically coupling with the waveguide; the non-active structure can be a non-diffractive or sub-diffractive structure adjacent to the active optical structure. The gratings described herein can include, for example, binary phase gratings, blazed gratings, and / or tilted gratings.

[0189] Figure 19 An example of a process 1900 that can be performed in accordance with certain aspects of the present disclosure is shown. 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 these two structures can be performed in a common imprinting process, such as using a common template that includes surface relief structures corresponding to the optical diffractive structure and the optical diffractive structure. The optical diffractive structure can be any active optical structure discussed herein (e.g., refer to Figures 13 - 18 ), and the optical sub-diffractive structure can include any non-active structure located in a region adjacent to the active optical region discussed herein.

[0190] As described above, since the optical sub-diffractive structure is included in the imprinting process of process 1900, imprinting defects that affect the optical diffractive structure, such as delamination and / or bubble formation, can be reduced or eliminated. Therefore, the performance of the optical device can be improved.

[0191] The imprinting processes within the scope of the present disclosure at least include nanoimprint lithography processes, such as thermoplastic nanoimprint lithography, photo-nanoimprint lithography, and direct thermal nanoimprint lithography. Other examples of the imprinting processes within the scope of the present disclosure include microimprint processes. Imprinted structures, such as active optical structures and non-active (e.g., sub-diffractive) structures, can be formed in an imprint resist by mechanical deformation of the imprint resist and subsequent processing (e.g., thermal curing and / or ultraviolet curing). The template mold is configured with a surface relief pattern that forms a corresponding pattern in the imprint resist. The imprinting processes within the scope of the present disclosure at least include hard mold, soft mold, roll-to-roll, roll-to-plate, plate-to-roll, plate-to-plate, and hybrid nanoimprint processes.

[0192] Imprinting (e.g., imprinting in process 1900) can be performed using a template (e.g., a cladding, a mold, a stamper, etc.), a substrate, and a formable material (sometimes referred to as a coating or an imprint resist) disposed on the template and / or the substrate. For example, the formable material can be disposed on the template, the substrate, or both prior to imprinting. The formable material can include, for example, polymers, epoxies, resins, photoresists, spin-on glass, or another material that can be structured during the imprinting process. In some embodiments, the formable material is curable, e.g., by applying heat energy, light (e.g., ultraviolet light), and / or other stimuli. For example, the formable material can be cured after its structure is formed, and the curing can occur while the template is in contact with the formable material, after the template is removed from the formable material, or both.

[0193] Figure 20 An example of a template 2000 and its corresponding imprinted structure is shown. 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 and 2020 are adjacent to each other. The template 2000 can be composed of, for example, an organic polymer and / or an inorganic material (e.g., a dielectric, a metal, an alloy, etc.). The template 2000 can be rigid and / or flexible.

[0194] The template 2000 is used to imprint a formable material 2006 disposed on a substrate 2008. The formable material 2006 can include any of the types of formable materials described above, such as polymers, epoxies, resins, photoresists, spin-on glass, or other materials that can be structured during the imprinting process.

[0195] Various types of substrates 2008 are within the scope of the present disclosure, including semiconductors, dielectrics, organic materials (e.g., polymers or plastics), metals, etc. The substrate 2008 can be rigid and / or flexible. In some embodiments, the refractive index of the substrate 2008 (e.g., for a waveguide in the substrate 2008) is in the range of 1.45 (e.g., corresponding to fused silica or quartz) to 2.7 (e.g., SiC). As described above, the imprinting can be a roll-to-roll, roll-to-plate, plate-to-roll, plate-to-plate, or other suitable imprinting process.

[0196] As a result of the imprinting, an optical diffraction structure 2024 is formed in the active region 2012 of the formable material 2006, and an optical sub-diffraction structure 2022 (a non-diffraction structure in some embodiments) is formed adjacent to the optical diffraction structure 2024 in the non-active region 2010 of the formable material 2006. The imprinted structures 2022, 2024 are formed by and directly correspond to the surface relief structure sets 2018, 2020 of the template 2000, for example having matching or opposite shapes and topographies. For example, based on the pitch (not shown) of the second set of surface relief structures 2018 being less than the pitch (not shown) of the first set of surface relief structures 2020, the pitch 2014 of the optical sub-diffraction structure 2022 can be less than the pitch 2016 of the optical diffraction structure 2024. For example, in some embodiments, the pitch 2014 is equal to the pitch of the second surface relief structure 2018, and the pitch 2016 is equal to the pitch of the first surface relief structure 2020.

[0197] The surface relief structure sets 2018, 2020 can be configured (e.g., based on their topologies) to imprint any combination of adjacent active and non-active regions described herein, or a combination of adjacent diffraction and sub-diffraction or non-diffraction structures. For example, the surface relief structure sets 2018, 2020 can be adjacent to each other such that the optical diffraction structure 2024 and the optical sub-diffraction structure 2022 are adjacent to each other. Additionally, based on the correspondence between the template structure and the imprinted structure, the surface relief structure sets 2018, 2020 can be any of the structures discussed herein for active and non-active structures, e.g., can include gratings, arrays, etc., having dimensions and patterns the same as those discussed herein for active and non-active structures Figures 16 - 18 identical.

[0198] In some embodiments, the substrate 2008 includes one or more waveguides (not shown) that are arranged to be optically coupled to the optical diffraction structure 2024, e.g., for in-coupling / out-coupling of light of one or more wavelengths. Depending on the size of the optical sub-diffraction structure 2022, light of the same wavelength may not be in-coupled or out-coupled through the optical sub-diffraction structure 2022 to / from the waveguide.

[0199] In the foregoing description, examples of various embodiments have been described. However, it will be apparent that various modifications and changes can be made thereto without departing from the broader spirit and scope of the present disclosure. Accordingly, the specification and drawings are to be regarded as illustrative rather than restrictive.

[0200] In fact, it will be understood that the systems and methods of the present disclosure each have several innovative aspects, none of which is the sole responsibility or requirement for the desired attributes disclosed herein. The various features and processes described above can be used independently of one another or can be combined in various ways. All possible combinations and sub-combinations are intended to fall within the scope of the present disclosure.

[0201] Certain features that are described in the context of separate embodiments in this specification can also be implemented in combination in a single embodiment. Conversely, the various features described in the context of a single embodiment can also be implemented separately in multiple embodiments or in any suitable sub-combination. Additionally, although features that act in a particular combination are described above, in some cases, one or more of the features in the combination can be removed from the combination, and the combination can be directed to a sub-combination or a variation of the sub-combination. No single feature or group of features is necessary or indispensable for each embodiment.

[0202] It will be understood that, unless otherwise expressly stated or understood in context from the use, conditional language used herein, such as “can,” “might,” “may,” “for example,” etc., generally is intended to convey that certain embodiments include certain features, elements, and / or steps, while other embodiments do not include such features, elements, and / or steps. Thus, such conditional language generally is not intended to imply that the features, elements, and / or steps are necessary in any way for one or more embodiments or that one or more embodiments necessarily include logic for determining whether these features, elements, and / or steps are included or are to be performed in any particular embodiment (whether the author inputs or implies such). The terms “comprising,” “including,” “having,” etc. are synonyms and are used inclusively in an open-ended manner and do not exclude additional elements, features, acts, operations, etc. Further, the term “or” is used in an inclusive sense (and not an exclusive sense), so that when, for example, used to connect a list of elements, the term “or” means one, some, or all of the elements in the list. Additionally, unless otherwise specified, the articles “a,” “an,” and “the” used in this application should be construed to mean “one or more” or “at least one.”

[0203] Furthermore, the separation of the various system components in the above embodiments should not be understood as requiring such separation in all embodiments, and it should be understood that the described program components and systems can generally be integrated together.

[0204] Accordingly, the examples provided herein are not intended to be limiting to the embodiments shown herein but should be accorded the widest scope consistent with the present disclosure and the principles and novel features disclosed herein.

[0205] Examples of embodiments include at least the following.

[0206] Embodiment 1: A method comprising: imprinting an optical diffraction structure; and imprinting an optical sub-diffraction structure near the optical diffraction structure.

[0207] Embodiment 2: Embodiment 1, wherein the optical diffraction structure includes a first grating, wherein the optical sub-diffraction structure includes a second grating, and wherein at least one geometric feature is different between the first grating and the second grating.

[0208] Embodiment 3: Embodiment 2, wherein the at least one geometric feature includes at least one of the following: grating orientation, pitch, width, height, or duty cycle.

[0209] Embodiment 4: Any one of Embodiments 2-3, wherein the second grating includes features extending parallel to the separation direction of the imprinting.

[0210] Embodiment 5: Any one of Embodiments 1-4, wherein the optical sub-diffraction structure includes a plurality of different structures in respective partitions of a plurality of partitions of the optical sub-diffraction structure.

[0211] Embodiment 6: Embodiment 5, wherein the plurality of different structures differ in at least one of feature density or feature orientation.

[0212] Embodiment 7: Any one of Embodiments 5-6, wherein the plurality of partitions are arranged along the imprinting direction.

[0213] Embodiment 8: Any one of Embodiments 1-7, wherein the optical sub-diffraction structure surrounds the optical diffraction structure.

[0214] Embodiment 9: Any one of Embodiments 1-8, wherein the optical sub-diffraction structure includes features having a graded size that increases or decreases in a direction toward the optical diffraction structure.

[0215] Embodiment 10: Embodiment 9, wherein the features include grating walls, and the height of the grating walls increases in a direction toward the optical diffraction structure.

[0216] Embodiment 11: Any one of Embodiments 1-10, wherein the optical sub-diffraction structure includes features having a graded size that increases or decreases in the imprinting direction.

[0217] Embodiment 12: Any one of Embodiments 1-11, wherein imprinting the optical diffraction structure and imprinting the optical sub-diffraction structure are performed in a common imprinting process using a common template.

[0218] Example 13: Any one of Examples 1-12, wherein the optical diffraction structure includes a diffractive input coupler to the waveguide or a diffractive output coupler from the waveguide.

[0219] Example 14: Any one of Examples 1-13, wherein the optical sub-diffraction structure includes features extending circumferentially around the optical diffraction structure.

[0220] Example 15: Any one of Examples 1-14, wherein the pitch of the optical diffraction structure is between 200 nm and 1 μm, and wherein the pitch of the optical sub-diffraction structure is between 20 nm and 200 nm.

[0221] Example 16: Any one of Examples 1-15, wherein the optical diffraction structure has a pitch such that the optical diffraction structure diffracts with visible light, and wherein the optical sub-diffraction structure has a pitch such that the optical sub-diffraction structure does not diffract with visible light.

[0222] Example 17: Any one of Examples 1-16, wherein imprinting the optical diffraction structure and the optical sub-diffraction structure is performed in a roll-to-roll, roll-to-plate, plate-to-roll, or plate-to-plate process.

[0223] Example 18: Any one of Examples 1-17, wherein the optical sub-diffraction structure includes a one-dimensional grating, a two-dimensional nanostructure array, or a three-dimensional nanostructure array.

[0224] Example 19: An optical device, comprising: a waveguide; an imprinted grating arranged to guide light into or out of the waveguide; and an imprinted sub-diffraction structure arranged adjacent to the grating.

[0225] Example 20: A display system, comprising: a waveguide; an optical coupling element including an imprinted grating; and an imprinted sub-diffraction structure arranged adjacent to the grating.

[0226] Example 21: An imprinting template, comprising: a first set of surface relief structures configured to imprint an optical diffraction structure in a formable material, and a second set of surface relief structures configured to imprint an optical sub-diffraction structure in the formable material, wherein the second set of surface relief structures is adjacent to the first set of surface relief structures.

[0227] Example 22: An optical device, comprising an optical diffraction structure and an optical sub-diffraction structure, the optical device being formed by any one of Examples 1-18.

[0228] Multiple embodiments have been described. However, it should be understood that various modifications can be made. Elements of one or more embodiments can be combined, deleted, modified, or supplemented to form further embodiments. In another example, the logical flow shown in the figures does not require the particular order or sequential order shown to achieve the desired result. Additionally, other steps can be provided in or removed from the described flow, and other components can be added to or removed from the described system. Accordingly, other embodiments are also within the scope of the following claims.

Claims

1. A method includes: Imprinting an optical diffraction structure; And Imprinting an optical sub-diffraction structure near the optical diffraction structure.

2. The method according to claim 1, wherein The optical diffraction structure includes a first grating, Wherein, the optical sub-diffraction structure includes a second grating, and Wherein, at least one geometric feature is different between the first grating and the second grating.

3. The method according to claim 2, wherein, The at least one geometric feature includes at least one of the following: grating orientation, pitch, width, height, or duty cycle.

4. The method according to claim 2, wherein, The second grating includes features extending parallel to the separation direction of the imprinting.

5. The method according to claim 1, wherein The optical sub-diffraction structure includes a plurality of different structures in respective partitions of a plurality of partitions of the optical sub-diffraction structure.

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

7. The method according to claim 5, wherein The plurality of partitions are arranged along the imprinting direction.

8. The method according to claim 1, wherein The optical sub-diffraction structure surrounds the optical diffraction structure.

9. The method according to claim 1, wherein The optical sub-diffraction structure includes features having a tapered size that increases or decreases in a direction towards the optical diffraction structure.

10. The method according to claim 9, wherein, The features include grating walls, and the height of the grating walls increases in a direction towards the optical diffraction structure.

11. The method according to claim 1, wherein, The optical sub-diffraction structure includes features having a tapered size that increases or decreases in the imprinting direction.

12. The method according to claim 1, wherein, Imprinting the optical diffraction structure and imprinting the optical sub-diffraction structure are performed in a common imprinting process using a common template.

13. The method according to claim 1, wherein The optical diffraction structure includes a diffractive in-coupler to a waveguide or a diffractive out-coupler from the waveguide.

14. The method according to claim 1, wherein, The optical sub-diffraction structure includes features extending circumferentially around the optical diffraction structure.

15. The method according to claim 1, wherein The pitch of the optical diffraction structure is between 200 nm and 1 μm, and Wherein, the pitch of the optical sub-diffraction structure is between 20 nm and 200 nm.

16. The method according to claim 1, wherein The optical diffraction structure has a pitch such that the optical diffraction structure undergoes diffractive interaction with visible light, and Wherein, the optical sub-diffraction structure has a pitch such that the optical sub-diffraction structure does not undergo diffractive interaction with visible light.

17. The method according to claim 1, wherein, Imprinting the optical diffraction structure and the optical sub-diffraction structure is performed in a roll-to-roll, roll-to-plate, plate-to-roll, or plate-to-plate process.

18. The method according to claim 1, wherein The optical sub-diffraction structure includes a one-dimensional grating, a two-dimensional nanostructure array, or a three-dimensional nanostructure array.

19. An optical device includes: A waveguide; An imprinted grating arranged to guide light into or out of the waveguide; And An imprinted sub-diffraction structure arranged adjacent to the grating.

20. A display system includes: A waveguide; An optical coupling element including an imprinted grating, the optical coupling element being configured to; And An imprinted sub-diffraction structure arranged adjacent to the grating.

Images