Improved edge blackening for waveguide eyepieces for use with virtual reality and augmented reality display systems

Abstract

An improved stacked waveguide assembly and method for making the same. The stacked waveguide assembly includes multiple waveguides stacked together and configured to transmit image information to a user's eye. Each waveguide is bonded to an adjacent waveguide using a stack adhesive applied between adjacent waveguides proximate the edge of each waveguide. A thin blackened edge layer is applied around the edge of each waveguide and configured to absorb substantially all visible light that bounces off the edge of each individual waveguide. This design improves image contrast without affecting image sharpness.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims the benefit of priority to U.S. Provisional Patent Application No. 63 / 382,362, entitled "IMPROVED EDGE BLACKENING FOR WAVEGUIDE EYEPIECES FOR USE WITH VIRTUAL AND AUGMENTED REALITY DISPLAY SYSTEMS," filed November 4, 2022. The contents of the foregoing application are expressly incorporated herein by reference for all purposes.

[0002] The present disclosure relates to virtual reality and augmented reality imaging and visualization systems, and more particularly to improved edge blackening for waveguide eyepieces used in display systems for virtual reality and / or augmented reality systems. [Background technology]

[0003] Modern computing and display technologies have facilitated the development of systems for so-called “virtual reality” (VR) or “augmented reality” (AR) and / or “mixed reality” (MR) experiences in which digitally reproduced images or portions thereof are presented to a user in a manner that makes them appear or be perceived as real. Virtual reality, or “VR,” scenarios typically involve the presentation of digital or virtual image information without transparency to actual real-world visual input. Augmented reality, or “AR,” scenarios typically involve the presentation of digital or virtual image information as an extension to the visualization of the real world around the user. Mixed reality scenarios are a version of the AR scenario, except that they are a more comprehensive blend of the real and virtual worlds, in which physical and virtual objects in the real world coexist and can interact in real time. As used herein, the terms “extended reality” and “XR” are used collectively to refer to any of VR, AR, and / or MR. Additionally, the term “AR” refers to one or both of AR and MR.

[0004] For example, referring to Figure 1, an augmented reality scene (4) is depicted in which a user of the AR technology sees a real-world, park-like setting (6) featuring people, trees, buildings, and a concrete platform (1112) in the background. In addition to these items, the user of the AR technology also perceives that he "sees" a robotic figure (1110) standing on the real-world platform (1112) and a flying, cartoonish avatar character (2) that appears to be an anthropomorphic bumblebee, although these elements (2, 1110) do not exist in the real world. Ultimately, the human visual perception system is highly complex, making it difficult to produce VR or AR technology that facilitates the comfortable, natural-feeling, and rich presentation of virtual image elements among other virtual or real-world image elements.

[0005] Numerous challenges exist when it comes to presenting 3D virtual content to a user of an XR system. A key premise of presenting 3D content to a user involves creating the perception of multiple depths. In other words, it may be desirable for some virtual content to appear closer to the user, while other virtual content appears to occur farther away. Therefore, to achieve a 3D perception, the XR system should be configured to deliver virtual content at different focal planes to the user.

[0006] For a 3D display to provide a true sense of depth, or more specifically, a simulated sense of surface depth, it is desirable for each point in the display's field of view to generate an accommodative response that corresponds to its virtual depth. If the accommodative response to a display point does not correspond to that point's virtual depth as determined by convergence and stereoscopic binocular depth cues, the human visual system will experience accommodative conflict, which can result in unstable imaging, adverse eye strain, headaches, and, in the absence of accommodative information, a near-complete lack of surface depth.

[0007] Thus, there is a need for improved techniques for implementing 3D displays that solve these and other problems of conventional approaches. The devices, systems, and techniques described herein are configured to work with the typical human visual configuration and to address these challenges. Summary of the Invention [Means for solving the problem]

[0008] Embodiments of the present invention are directed to designs for and methods of making improved stacked waveguide assemblies for eyepieces for use with XR display systems. More specifically, disclosed herein is a new eyepiece design with improved edge blackening for use in XR display systems that has improved performance over previous waveguide and eyepiece designs. The disclosed eyepiece design includes innovative edge blackening and stack architecture for the eyepiece waveguide stack that improves functional performance of the eyepiece, such as improving virtual image contrast by maximizing absorption of light that bounces off the edges of the waveguide rather than being propagated through total internal reflection (TIR).

[0009] Thus, one embodiment disclosed herein is directed to a stacked waveguide assembly for an eyepiece for use with an XR display system. The stacked waveguide assembly includes multiple waveguides stacked together and configured to transmit image information to a user's eye. Each waveguide is bonded to an adjacent waveguide using a stacking adhesive applied between adjacent waveguides proximate the edge of each waveguide. The waveguide assembly includes a thin blackened edge layer applied over and / or around the edge of each waveguide and configured to absorb substantially all visible light that bounces off the edge of each individual waveguide.

[0010] In another aspect, the stacked waveguide assembly may further include a perimeter adhesive applied over the blackened edge layer. In yet another aspect, the perimeter adhesive adheres the stacked waveguide assembly to a frame of an eyepiece for use with an XR display system. In yet another aspect, the perimeter adhesive includes a color-absorbing adhesive.

[0011] In another aspect, the blackening edge layer includes a carbon black pigment. The pigment may be 30 nm or less in diameter. In other aspects, the blackening edge layer may be applied using a fast-drying surfactant, such as methanol, ethanol, isopropanol, or the like. In additional aspects, the blackening pigment may also be comprised of a mixture of various pigments or dyes capable of blocking various wavelengths of light, with the sum of all color blocking agents blocking light wavelengths between 400 nm and 800 nm. For example, dyes and pigments may include carbon black (size range 5 nm to 500 nm), rhodamine B, tartrazine, chemical dyes from Yamada Chemical Co., Ltd., and SUNFAST pigments from SunChemical (e.g., Green 36, Blue, Violet 23, etc.).

[0012] In another aspect, the stack adhesive includes a color-absorbing adhesive. In an additional aspect, the stack adhesive and / or perimeter bonding agent may include a prepolymer material. In another aspect, the prepolymer may include a resin material such as an epoxy vinyl ester. In yet another aspect, the prepolymer material is dispensable using an inkjet, a syringe pump, or a spray atomization. In an additional aspect, the prepolymer material may include a dye or pigment configured to absorb all or a selected portion of visible light. In another aspect, the dye or pigment may be black so as to absorb light at all visible wavelengths.

[0013] In another aspect, at least a portion of the edge of the waveguide to which the blackened edge layer is applied has a roughened surface. Up to the entire surface of the edge surface to which the blackened edge layer is applied, including the outer edge surface, top surface, and bottom surface of each waveguide (e.g., outer portions of the top and bottom surfaces extending proximate to the outer edge surface), may have a roughened surface.

[0014] Another embodiment disclosed herein is directed to a method of making any of the stacked waveguide assemblies disclosed herein. Multiple waveguides are stacked together such that the stacked waveguides are configured to transmit image information to a user's eye. Each waveguide is bonded to an adjacent waveguide using a stack adhesive applied between adjacent waveguides proximate the edges of the waveguides. A thin blackened edge layer is applied over and / or around the edge of each waveguide such that the blackened edge layer absorbs substantially all visible light that bounces off the edge of each individual waveguide.

[0015] In another aspect, the method of making the stacked waveguide assembly may further include applying a perimeter adhesive applied over the blackened edge layer. In yet another aspect, the perimeter adhesive adheres the stacked waveguide assembly to a frame of an eyepiece for use with an XR display system. In yet another aspect, the perimeter adhesive includes a color-absorbing adhesive.

[0016] In additional aspects, the method may include any combination of one or more of the additional aspects and features of the stacked waveguide assembly embodiments as described herein.

[0017] Another embodiment disclosed herein is directed to an eyepiece for an XR display system for delivering XR content to a user. The eyepiece comprises any of the stacked waveguide assemblies disclosed herein for receiving light associated with one or more frames of image data and directing the light to a user's eye. The eyepiece is configured to receive light associated with one or more frames of image data from an image generating source, such as a fiber scanning device (FSD), a high-resolution liquid crystal display ("LCD") system, a back-illuminated ferroelectric panel display, a high-frequency DLP system, or the like, and direct the light to the user's eye.

[0018] Another embodiment disclosed herein is directed to an XR display system for delivering extended reality content to a user, the XR display system comprising: an image generation source for providing one or more frames of image data; a light modulator for transmitting light associated with the one or more frames of image data; and an eyepiece comprising any of the stacked waveguide assemblies disclosed herein for receiving the light associated with the one or more frames of image data and directing the light to a user's eye.

[0019] In additional aspects, an XR display system may include any combination of one or more of the additional aspects and features of the stacked waveguide assembly embodiments as described herein.

[0020] Another embodiment disclosed herein is directed to an XR system for generating and displaying XR content to a user. The XR system comprises a computer having a computer processor, a memory, a storage device, and a software application stored on the storage device and executable to program the computer to perform operations that enable the augmented reality system. The XR system includes an XR display system. The XR display system may be any suitable display system, such as an XR headset having a display for displaying 3D virtual images (i.e., XR images). For example, the XR headset may include a frame structure configured to be worn on a user's head. The frame structure holds an image generation source for providing one or more frames of image data, a light modulator for transmitting light associated with the one or more frames of image data, and an eyepiece comprising any of the stacked waveguide assemblies disclosed herein for receiving the light associated with the one or more frames of image data and directing the light to the user's eye.

[0021] In additional aspects, an XR display system may include any combination of one or more of the additional aspects and features of the stacked waveguide assembly embodiments as described herein.

[0022] Additional and other objects, features, and advantages of the present invention are set forth in the detailed description, drawings, and claims. [Brief explanation of the drawings]

[0023] The drawings illustrate the design and utility of various embodiments of the present disclosure. It should be noted that the drawings are not drawn to scale, and that elements of similar structure or function are represented by like reference numerals throughout the drawings. To better understand how the above-listed and other advantages and objects of the various embodiments of the present disclosure are obtained, a more particular description of the present disclosure, briefly described above, will be made with reference to specific embodiments thereof, which are illustrated in the accompanying drawings. With the understanding that these drawings depict only exemplary embodiments of the present disclosure and therefore should not be considered limiting of its scope, the present disclosure will be described and explained with additional specificity and detail through the use of the accompanying drawings.

[0024] [Figure 1] FIG. 1 illustrates a user's view of augmented reality (AR) through a wearable AR user device in one illustrated embodiment.

[0025] [Figure 2] FIG. 2 illustrates a conventional stereoscopic 3D simulation display system for an XR system.

[0026] [Figure 3] FIG. 3 illustrates an improved approach for implementing a stereoscopic 3D simulation display system for an XR system, according to some embodiments disclosed herein.

[0027] [Figure 4A] 4A-4D illustrate various systems, subsystems, and components to address the objective of providing a high-quality, comfortably perceived display system for human XR. [Figure 4B] 4A-4D illustrate various systems, subsystems, and components to address the objective of providing a high-quality, comfortably perceived display system for human XR. [Figure 4C] 4A-4D illustrate various systems, subsystems, and components to address the objective of providing a high-quality, comfortably perceived display system for human XR. [Figure 4D] 4A-4D illustrate various systems, subsystems, and components to address the objective of providing a high-quality, comfortably perceived display system for human XR.

[0028] [Figure 5] FIG. 5 illustrates a plan view of an example configuration of an XR system utilizing an improved diffractive structure according to some embodiments disclosed herein.

[0029] [Figure 6] FIG. 6 illustrates a stacked waveguide assembly for use in an XR display system.

[0030] [Figure 7] FIG. 7 illustrates a DOE (diffractive optical element) for use in a display system according to some embodiments disclosed herein.

[0031] [Figure 8] 8 and 9 illustrate example diffraction patterns for a DOE that result in different exit beams being directed towards the eye, according to some embodiments. [Figure 9]8 and 9 illustrate example diffraction patterns for a DOE that result in different exit beams being directed towards the eye, according to some embodiments.

[0032] [Figure 10] 10 and 11 illustrate two stacked waveguides into which a beam is launched. [Figure 11] 10 and 11 illustrate two stacked waveguides into which a beam is launched.

[0033] [Figure 12] FIG. 12 illustrates a stack of waveguides.

[0034] [Figure 13A] FIG. 13A is a schematic illustration of an embodiment of a previously disclosed stacked waveguide assembly.

[0035] [Figure 13B] FIG. 13B is a schematic illustration of a stacked waveguide assembly according to one embodiment disclosed herein.

[0036] [Figure 14] FIG. 14 is a table showing a comparison of image ANSI contrast from an RGB (red, green, blue) stack per R, G, B color waveguide for various stack architectures.

[0037] [Figure 15] FIG. 15 is a graph showing examples of transmission curves in the visible spectrum at 0 degrees incidence for four different types of adhesives used for the stack adhesive material and perimeter bond.

[0038] [Figure 16] FIG. 16 is a schematic illustration of a stacked waveguide assembly having roughened edge surfaces according to another embodiment disclosed herein.

[0039] [Figure 17A] FIG. 17A is a schematic illustration of one of the waveguides of the stacked waveguide assembly of FIG. 16 showing the roughened edge surface prior to the application of edge blackening.

[0040] [Figure 17B] FIG. 17B is a schematic illustration of one of the waveguides of the stacked waveguide assembly of FIG. 16 showing the roughened edge surface after application of edge blackening.

[0041] [Figure 18A] FIG. 18A is a schematic illustration of one of the waveguides of the stacked waveguide assembly of FIG. 16 showing roughened edge surfaces on the top and / or bottom edge gaps prior to application of edge blackening.

[0042] [Figure 18B] FIG. 18B is a schematic illustration of one of the waveguides of the stacked waveguide assembly of FIG. 16 showing roughened surfaces on the top and / or bottom edge gap surfaces after application of edge blackening.

[0043] [Figure 19] FIG. 19 is an enlarged view of a portion of the roughened edge surface of the waveguide of FIGS. 16-18B. DETAILED DESCRIPTION OF THE INVENTION

[0044] Detailed Description The following describes various embodiments of an extended reality (XR) display system for delivering extended reality content to a user and an improved waveguide assembly for an eyepiece used for the XR system. The stacked waveguide assembly incorporates an innovative edge-blackening and stack architecture that improves the functional performance of the eyepiece, including improving virtual image contrast by maximizing absorption of light that bounces off the edges of the waveguide rather than being propagated through the waveguide via TIR. Display Systems According to Some Embodiments

[0045] This section of the disclosure describes exemplary display systems that may be used in conjunction with the improved stacked waveguide assemblies disclosed herein.

[0046] 2 illustrates a conventional stereoscopic 3D simulation display system for an XR system. The display system typically has separate displays 74 and 76 for each eye (4 and 6), each at a fixed radial focal distance (10) from the eye. This conventional approach fails to consider many of the useful cues utilized by the human eye and brain, including accommodation cues, and is unable to detect and interpret depth in three dimensions.

[0047] In fact, a typical human eye can interpret multiple layers of depth based on radial distance; for example, the human eye can interpret approximately 12 layers of depth. A near-field limit of approximately 0.25 meters is approximately the closest depth of focus, and a far-field limit of approximately 3 meters means that any item farther than approximately 3 meters from the human eye will experience infinity focus. The layers of focus become thinner and thinner closer to the eye; in other words, the eye can perceive very small differences in focal length relatively close to the eye, and this effect dissipates as the object becomes farther away from the eye. At an infinite object location, the depth of focus / dioptric separation value is approximately 1 / 3 diopter.

[0048] FIG. 3 illustrates an improved approach for implementing a stereoscopic 3D simulation display system for use in an AR system, according to some embodiments of the present invention. In this approach, two composite images are displayed, one for each eye (4 and 6), and different radial focal depths (12) for different sides (14) of each image are utilized to provide the perception of three-dimensional depth layering within the image perceived by each eye. Because multiple focal planes (e.g., 12 focal planes) exist between the user's eyes and infinity, data within these focal planes and the depicted relationships can be utilized to position virtual elements within the augmented reality scenario for the user's viewing, as human eyes constantly move around, utilizing focal planes and perceiving depth. While this figure shows a specific number of focal planes at various depths, it should be noted that implementations of the present invention may use any number of focal planes as needed for a desired specific application, and the present invention is therefore not limited to devices having only the specific number of focal planes shown in any of the figures and / or described in this disclosure.

[0049] 4A-4D, several general component options for an XR system 50 are illustrated, according to some embodiments of the present invention. In the portion of the detailed description that follows the discussion of FIGS. 4A-4D, various systems, subsystems, and components are presented to address the objective of providing a high-quality, comfortably perceived display system for a human XR experience.

[0050] As shown in Figure 4A, an XR system user (60) is depicted wearing a frame (64) structure coupled to a display system (62) positioned directly in front of the user's eyes. Speakers (66), in the depicted configuration, are coupled to the frame (64) and positioned adjacent to the user's ear canals (in one embodiment, another speaker, not shown, is positioned adjacent to the user's other ear canal to provide stereo / shapeable sound control). The display (62) is operatively coupled via a communications link (68), such as by wired or wireless connection, to a local processing and data module (70), which may be mounted in a variety of configurations, such as fixedly attached to the frame (64), fixedly attached to a helmet or hat (80) as shown in the embodiment of FIG. 4B, embedded within headphones, removably attached to the torso (82) of the user (60) in a backpack-style configuration as shown in the embodiment of FIG. 4C, or removably attached to the waist (84) of the user (60) in a belt-coupled configuration as shown in the embodiment of FIG. 4D.

[0051] The local processing and data module (70) may include a power-saving processor or controller and digital memory, such as flash memory, both of which may be utilized to assist in processing, caching, and storing data, including a) captured from sensors, such as image capture devices (such as cameras), microphones, inertial measurement units, accelerometers, compasses, GPS units, wireless devices, and / or gyroscopes, that may be operatively coupled to the frame (64), and / or b) data so obtained and / or processed using the remote processing module (72) and / or remote data repository (74), possibly for processing or retrieval and subsequent passage to the display (62). The local processing and data module (70) may be operatively coupled to the remote processing module (72) and the remote data repository (74) via communications links (76, 78), such as wired or wireless communications links, such that the remote modules (72, 74) are operatively coupled to each other and available as resources to the local processing and data module (70).

[0052] In one embodiment, the remote processing module (72) may comprise one or more relatively powerful processors or controllers configured to analyze and process the data and / or image information. In one embodiment, the remote data repository (74) may comprise a relatively large digital data storage facility that may be available over the Internet or other networking configuration in a "cloud" resource configuration. In one embodiment, all data is stored and all calculations are performed in the local processing and data module, allowing for fully autonomous use from any remote module.

[0053] The perception of Z-axis difference (i.e., linear distance from the eye along the optical axis) can be enhanced by using a waveguide in conjunction with a variable-focus optics configuration. Image information from a display can be collimated, injected into a waveguide, and distributed in a large-exit-pupil fashion using any suitable substrate-guided optics method known to those skilled in the art. Variable-focus optics capabilities can then be utilized to change the focus of the wavefront of the light emerging from the waveguide, providing the eye with the perception that the light emanating from the waveguide is from a specific focal distance. In other words, because the incident light is collimated to avoid issues with total internal reflection waveguide configurations, it exits in a collimated manner, requiring the viewer's eye to accommodate to a far point and focus it on the retina, which is naturally interpreted as being from optical infinity unless some other intervention refocuses the light and causes it to be perceived as being from a different viewing distance; one suitable such intervention is a variable-focus lens.

[0054] In some embodiments, collimated image information is launched into a piece of glass or other material at an angle such that it undergoes total internal reflection and is passed into an adjacent waveguide. The waveguide may be configured so that collimated light from the display is distributed to exit approximately uniformly across a distribution of reflectors or diffractive features along the length of the waveguide. Depending on the exit light directed toward the eye, the exiting light is passed through a variable-focus lens element, and depending on the controlled focus of the variable-focus lens element, the light exiting the variable-focus lens element and entering the eye will have different levels of focus (a collimated, flat wavefront represents optical infinity, while greater beam divergence / wavefront curvature represents closer viewing distances to the eye (58)) (see Figures 5-12).

[0055] In a "frame sequential" configuration, a stack of sequential two-dimensional images can be sequentially fed to a display, similar to how a computed tomography system uses stacked image slices to represent three-dimensional structures over time, creating a three-dimensional perception. A series of two-dimensional image slices can be presented to the eye, each at a different focal distance relative to the eye, and the eye / brain will integrate such stacks into the perception of a coherent three-dimensional volume. Depending on the display type, line-by-line or even pixel-by-pixel sequential processing can be performed to create the perception of three-dimensional viewing. For example, in a scanning optical display (such as a scanning fiber display or a scanning mirror display), the display presents a waveguide one line or one pixel at a time in a sequential manner.

[0056] 6, a stacked waveguide assembly (178) may be utilized to provide three-dimensional perception to the eye / brain by having multiple waveguides (182, 184, 186, 188, 190) and multiple weak lenses (198, 196, 194, 192) that are together configured to transmit image information to the eye with various levels of wavefront curvature per waveguide level that indicate the focal length to be perceived for that waveguide level. Multiple displays (200, 202, 204, 206, 208), or in another embodiment, a single multiplexed display, may be utilized to inject collimated image information into the waveguides (182, 184, 186, 188, 190), each of which may be configured to distribute incident light substantially equally across its length for emission to the eye, as described above.

[0057] The waveguide 182 closest to the eye 58 is configured to deliver collimated light to the eye 58 as it is injected into the waveguide 182, which may represent an optical infinity focal plane. The next upper waveguide 184 is configured to send collimated light that passes through a first weak lens 192 (e.g., a weak negative lens) before it can reach the eye 58. The first weak lens 192 may be configured to create a slight convex wavefront curvature so that the eye / brain interprets the light emerging from the next upper waveguide 184 as originating from a first focal plane closer to the eye 58, inward from optical infinity. Similarly, the third upper waveguide 186 passes its output light through both the first lens 192 and the second lens 194 before reaching the eye 58. The combined refractive power of the first lens (192) and the second lens (194) may be configured to create another incremental amount of wavefront divergence such that the eye / brain interprets light emerging from that third upper waveguide (186) as originating from a second focal plane that is even closer inward from optical infinity towards the person than light from the next upper waveguide (184).

[0058] The other waveguide layers (188, 190) and weak lenses (196, 198) are similarly configured, with the highest waveguide (190) in the stack transmitting its output through all of the weak lenses between it and the eye for a collective focal power representing the focal plane closest to the person. To compensate for the stack of lenses (198, 196, 194, 192) when viewing / interpreting light originating from the world (144) on the other side of the stacked waveguide assembly (178), a compensatory lens layer (180) is positioned on top of the stack to compensate for the collective refractive power of the lower lens stacks (198, 196, 194, 192). Such a configuration, as described above, again provides a relatively large exit pupil configuration for as many perceived focal planes as there are available waveguide / lens pairings. Both the reflective side of the waveguide and the focusing side of the lens may be static (i.e., not dynamic or electro-active). In an alternative embodiment, they may be dynamic using electro-active features as described above, allowing a small number of waveguides to be multiplexed in a time-sequential manner to produce a larger number of effective focal planes.

[0059] Various diffractive configurations can be employed to focus and / or redirect a collimated beam. For example, passing a collimated beam through a linear diffractive pattern, such as a Bragg grating, will deflect, or "steer," the beam. Passing a collimated beam through a radially symmetric diffractive pattern, i.e., a "Fresnel zone plate," will change the focus of the beam. Combination diffractive patterns can be employed that have both linear and radial elements and result in both deflection and focusing of a collimated input beam. These deflection and focusing effects can be produced in reflective as well as transmissive modes.

[0060] These principles may also be applied in conjunction with waveguide configurations to enable additional optical system control. As shown in Figure 7, a diffraction pattern (220), i.e., a "diffractive optical element" (or "DOE"), is embedded within a planar waveguide (216) so that as a collimated beam is totally internally reflected along the planar waveguide (216), it intersects the diffraction pattern (220) at multiple locations. The structure may also include another waveguide (218) into which a beam may be launched (e.g., by a projector or display), with a DOE (221) embedded within this other waveguide (218).

[0061] Preferably, the DOE (220) has a relatively low diffraction efficiency so that only a portion of the beam's light is deflected toward the eye (58) at each intersection of the DOE (220), while the remainder continues traveling through the planar waveguide (216) via total internal reflection. The light carrying the image information is thus split into several related light beams that exit the waveguide at multiple locations, resulting in a fairly uniform pattern of output emission toward the eye (58) for this particular collimated beam bouncing around within the planar waveguide (216), as shown in FIG. 8. The output beam directed toward the eye (58) is shown in FIG. 8 as being approximately parallel, because in this case the DOE (220) has only a linear diffraction pattern. However, variations to this linear diffraction pattern pitch may be utilized to controllably deflect the output parallel beam, thereby creating scanning or tiling functionality.

[0062] Referring to Figure 9, with the change in radially symmetric diffraction pattern components of the embedded DOE (220), the output beam pattern becomes more divergent, which requires the eye to accommodate to closer distances and focus it on the retina, and will be interpreted by the brain as light from a viewing distance closer to the eye than optical infinity.

[0063] Referring to FIG. 10, with the addition of another waveguide (218) into which a beam may be launched (e.g., by a projector or display), a DOE (221) embedded within this other waveguide (218), such as a linear diffraction pattern, may function to spread the light across the entire larger planar waveguide (216), which functions to provide the eye (58) with a very large incident field of incident light, e.g., a large eyebox, exiting the larger planar waveguide (216) according to the particular DOE configuration in operation.

[0064] Although the DOEs (220, 221) are depicted as bisecting the associated waveguides (216, 218), this is not necessarily the case; the DOEs (220, 221) can be located closer to or on either side of the waveguides (216, 218) with identical functionality. Thus, as shown in FIG. 11 , with the injection of a single collimated beam, the entire field of cloned collimated beams can be directed toward the eye (58). Additionally, in combined linear / radially symmetric diffraction pattern scenarios such as those discussed above, beam distribution waveguide optics with Z-axis focusing capability (due to functionality such as the expanded exit pupil, with configurations such as that of FIG. 11 , the exit pupil can be as large as the optical element itself, which can be a very significant advantage for user comfort and ergonomics) are presented, with the divergence angle of the cloned beams and the wavefront curvature of each beam both representing light originating from a point closer than optical infinity.

[0065] In one embodiment, one or more DOEs are switchable between an "on" state in which they actively diffract and an "off" state in which they do not significantly diffract. For example, a switchable DOE may comprise a layer of polymer-dispersed liquid crystal in which the microdroplets comprise a diffractive pattern within a host medium and can be switched so that the refractive index of the microdroplets substantially matches that of the host material (in which case the pattern does not significantly diffract incident light), or the microdroplets can be switched to a refractive index that does not match that of the host medium (in which case the pattern actively diffracts incident light). Furthermore, with dynamic changes to the diffraction term, beam scanning or tiling functionality can be achieved. As described above, it is desirable to have a relatively low diffraction grating efficiency in each of the DOEs (220, 221) because this facilitates light distribution and because light originating through a waveguide that is desirably transmitted (e.g., in an augmented reality configuration, light originating from the world 144 towards the eye 58) is less affected when the diffraction efficiency of the DOE (220) it intersects is lower, resulting in a better view of the real world through such a configuration.

[0066] Configurations such as those illustrated herein are preferably driven by the introduction of image information in a time-sequential approach, with frame-sequential operation being the simplest to implement. For example, an image of the sky at optical infinity can be introduced at time 1, and a diffraction grating can be utilized to keep the light collimated. An image of a closer tree branch can then be introduced at time 2, while the DOE controllably applies a focus change, e.g., one diopter or one meter away, providing the eye / brain with the perception that the branch's optical information originates from a closer focal distance. This type of paradigm can be repeated in a rapid time-sequential manner, such that the eye / brain perceives the input as all part of the same image. This is only an example of two focal planes; preferably, the system would include more focal planes, providing smoother transitions between objects and their focal distances. This type of configuration generally assumes that the DOE is switched relatively slowly (i.e., synchronized with the frame rate of the display introducing the image, within the range of tens to hundreds of cycles per second).

[0067] At the other extreme may be a configuration in which the DOE elements can shift focus over tens to hundreds of MHz or even over hundreds of MHz, facilitating switching of the focus state of the DOE elements on a pixel-by-pixel basis as the pixels are scanned into the eye 58 using a scanning light display type approach. This is desirable because it means that the overall display frame rate can be kept very low (low enough to ensure that "flicker" is not an issue (in the range of about 60-120 frames per second)).

[0068] Between these ranges, if the DOE can be switched at a kHz rate, the focus on each scan line may be adjusted on a line-by-line basis, which may provide a visual advantage to the user in terms of temporal artifacts, for example, during eye movement relative to the display. For example, different focal planes within a scene may be interleaved in this way to minimize visual artifacts in response to head movement (as discussed in more detail later in this disclosure). The line-by-line focus modulator may be operably coupled to a line-scanning display, such as a grating light valve display, in which a linear array of pixels is swept to form an image, or to a scanning light display, such as a fiber scanning display and a mirror scanning light display.

[0069] Stacked configurations similar to that of FIG. 6 may use dynamic DOEs to provide simultaneous multi-plane focusing. For example, with three simultaneous focal planes, a primary focal plane (e.g., based on measured ocular accommodation) may be presented to the user, and + and - boundaries (i.e., one focal plane closer and one focal plane farther away) may be utilized to provide a large focal distance to which the user can accommodate before a plane update is required. This increased focal distance may provide a time advantage in that if the user switches to a closer or farther focus (i.e., as determined by accommodation measurements), the new plane of focus may be at the mid-focus depth, and the + and - boundaries may again be ready for a fast switch to either one while the system catches up.

[0070] Referring to Figure 12, a stack (222) of planar waveguides (244, 246, 248, 250, 252) is shown, each with a reflector (254, 256, 258, 260, 262) at its end, configured so that collimated image information launched into one end by a display (224, 226, 228, 230, 232) bounces back by total internal reflection up to the reflector, at which point some or all of the light is reflected out toward the eye or other target. Each reflector may have a slightly different angle so that they all reflect the exiting light toward a common destination, such as the pupil. Lenses (234, 236, 238, 240, 242) may be interposed between the display and the waveguide for beam steering and / or focusing.

[0071] As discussed above, an object at optical infinity produces a nearly plane wavefront, while an object closer, say 1 m away from the eye, produces a curved wavefront (with a convex radius of curvature of about 1 m). The optical system of the eye needs to have sufficient refractive power to bend incoming rays of light so that they are ultimately focused onto the retina (the convex wavefront is turned concave and then brought to a focal point on the retina). These are the basic functions of the eye.

[0072] In many of the embodiments described above, the light directed to the eye is treated as a portion of a single continuous wavefront, with a subset of that portion impinging on the pupil of a particular eye. In another approach, the light directed to the eye may be effectively discretized or split into multiple beamlets or individual rays, each with a diameter of less than about 0.5 mm and a unique propagation path as part of a larger aggregate wavefront that can be functionally created with the aggregation of the beamlets or rays. For example, a curved wavefront may be approximated by aggregating multiple discrete, nearby collimated beams, each of which approaches the eye from an appropriate angle and represents an origin that coincides with the center of the radius of curvature of the desired aggregate wavefront.

[0073] When the beamlets have a diameter of about 0.5 mm or less, it is as if they are occurring through a pinhole lens configuration, meaning that each individual beamlet is always in a relative focus on the retina, independent of the eye's state of accommodation; however, the trajectory of each beamlet will be affected by the state of accommodation. For example, if the beamlets approach the eye parallel and represent a discrete, collimated aggregate wavefront, an eye correctly accommodating to infinity will deflect the beamlets, causing them all to converge onto the same shared spot on the retina, and appear focused. When the eye accommodates, for example, to 1 m, the beams will appear blurred, as they converge to a spot directly in front of the retina, cross paths, and fall on multiple nearby or partially overlapping spots on the retina.

[0074] If beamlets approach the eye in a divergent configuration with a shared origin 1 meter from the viewer, accommodation at 1 meter will steer the beam to a single spot on the retina, appearing focused; if the viewer accommodates to infinity, the beamlets will converge to a spot behind the retina, resulting in multiple nearby or partially overlapping spots on the retina and a blurred image. More generally, the eye's accommodation determines the degree of overlap of the spots on the retina; a given pixel is "in focus" when all of the spots are directed to the same spot on the retina, and "defocused" when the spots are offset from each other. This concept, that beamlets with a diameter of 0.5 mm or less are all always focused and can be perceived by the eye / brain as if they were aggregated and substantially identical coherent wavefronts, can be utilized in creating configurations for comfortable three-dimensional virtual or augmented reality perception.

[0075] In other words, a set of multiple narrow beams may be used to mimic the situation when using a larger diameter variable focus beam, and if the beamlet diameter is kept at a maximum of about 0.5 mm, they will maintain a relatively static focus level, resulting in a defocused perception, when the desired beamlet angular trajectory can be selected to create an effect similar to a larger defocused beam (such defocusing may not be identical to Gaussian blurring as for larger beams, but will create a multimodal point spread function that can be interpreted in a manner similar to Gaussian blurring).

[0076] In some embodiments, the beamlets are not mechanically deflected to create this aggregate focus effect; rather, the eye receives a superset of many beamlets that includes both multiple angles of incidence and multiple locations where the beamlets intersect the pupil, and to represent a given pixel from a particular viewing distance, a subset of beamlets from the superset with appropriate angles of incidence and intersection points with the pupil are turned on with a matching color and intensity to represent that aggregate wavefront (as if such beamlets were emitted from the same shared origin in space), while beamlets in the superset that do not match the shared origin are not turned on with that color and intensity (although some of such beamlets may be turned on with some other color and intensity level, e.g., to represent a different pixel).

[0077] Referring now to FIG. 5 , an exemplary embodiment of an XR system (800) using an improved eyepiece with an improved diffractive structure will now be described. The XR system (800) generally includes an image generation processor (812), at least one FSD (fiber scanning device) (808), FSD circuitry (810), coupling optics (832), and a pair of eyepieces 804 (one for each eye (58)). Each eyepiece (804) includes an optical system assembly (802) (also referred to as a “DOE assembly (802)”). The DOE assembly (802) includes multiple stacked DOEs (1300) having a diffractive structure, including a waveguide with an improved diffractive structure, as described herein. The system (800) may also include an eye tracking subsystem (806). As shown in FIG. 5, the FSD circuitry (810) may include circuitry (810) having a Maxim chip CPU (818), a temperature sensor (820), a piezoelectric driver / transducer (822), a red laser (826), a blue laser (828), a green laser (830), and a fiber combiner that combines all three lasers (826, 828, and 830). The FSD circuitry (810) is in communication with an image generation processor (812). It should be noted that other types of imaging technologies may also be used in place of the FSD device. For example, high-resolution liquid crystal display ("LCD") systems, back-illuminated ferroelectric panel displays, and / or high-frequency DLP systems may all be used in some embodiments of the present invention.

[0078] The image generation processor (812) is responsible for generating the virtual content that is ultimately displayed to the user. The image generation processor (812) may convert images or videos associated with the virtual content into a format that can be projected to the user in 3D. For example, when generating 3D content, the virtual content may need to be formatted so that one portion of a particular image is displayed on a particular depth plane, while another portion is displayed on another depth plane. Alternatively, all images may be generated at a particular depth plane. Alternatively, the image generation processor (812) may be programmed to feed slightly different images to the right and left eyes so that, when viewed together, the virtual content appears coherent and comfortable to the user's eyes. In one or more embodiments, the image generation processor (812) delivers the virtual content to the optical system assembly (802) in a time-sequential manner. A first portion of the virtual scene may be delivered first, such that the optical system assembly (802) projects the first portion into the first depth plane. The image generation processor (812) may then deliver another portion of the same virtual scene such that the optical system assembly (802) projects a second portion into a second depth plane, and so on, where the Alvarez lens assembly may be translated laterally sufficiently rapidly to produce multiple lateral translations (corresponding to multiple depth planes) on a frame-by-frame basis.

[0079] The image generation processor (812) may further include memory (814), a CPU (818), a GPU (816), and other circuitry for image generation and processing. The image generation processor (812) may be programmed with desired virtual content to be presented to a user of the XR system (800). It should be understood that in some embodiments, the image generation processor may be stored within the wearable XR system. In other embodiments, the image generation processor (812) and other circuitry may be stored within a belt pack coupled to the wearable optics.

[0080] The XR system 800 also includes coupling optics 832 for directing light from the FSD 808 to the optical system assembly 802. The coupling optics 832 may refer to one or more conventional lenses used to direct light into the DOE assembly 802. The XR system 800 also includes an eye tracking subsystem 806 configured to track the user's eyes and determine the user's focus.

[0081] In one or more embodiments, software blur may be used to induce blur as part of the virtual scene. The blur module may, in one or more embodiments, be part of the processing circuitry. The blur module may blur a portion of one or more frames of image data being fed into the DOE. In such an embodiment, the blur module may completely blur portions of the frames that are not intended to be rendered at a particular depth frame. An exemplary approach that may be used to implement the above-described image display system and components therein is described in U.S. Utility Patent Application No. 14 / 555,585, filed November 27, 2014, which is incorporated herein by reference in its entirety. (New stacked waveguide assembly design with improved edge blackening)

[0082] As described above, the eyepiece (EP) (e.g., the optical system assembly (802)) of the XR display system (800) includes a stacked waveguide assembly (1300) comprising a stack of multiple waveguides. As described herein, one or more of the waveguides may have a diffraction pattern formed thereon such that as a collimated beam is totally internally reflected along the waveguide, the beam intersects the diffraction pattern at multiple locations. This stacked waveguide arrangement can provide image objects at multiple focal planes in a stereoscopic 3D simulation display system according to some embodiments of the present invention.

[0083] Generally, eyepiece stacks having an active waveguide layer and a cover layer require edge blackening and good stack mechanical stability to ensure high-contrast virtual images are produced from the EP stack. Existing waveguide stacks use at least one blackening adhesive to bond the waveguides together in the waveguide stack, which can be difficult to cure and typically does not adequately absorb light to provide the best possible contrast. Disclosed herein is a new design and method for making a waveguide stack with an improved edge blackening combination for the active layer, including a thin layer of carbon black pigment applied on and around the edges of the waveguide layer, with and without additional color-absorbing pigments / dyes, and using an optional filler-based adhesive in the adhesive on the exterior of the edge blackening to bond the active layer to other active layers and / or the cover layer. The improved edge-blackened waveguide stack improves optical virtual image contrast by ensuring that light bouncing off the edges of the eyepiece waveguide is absorbed as much as possible, as opposed to being propagated through total internal reflection (TIR). The architecture disclosed herein may use a fast-drying pigmented carbon black ink that is applied to the edges of singulated waveguides cut to a shape, either before or after stack lamination, using either a clear or color-absorbing adhesive. The new edge-blackened stack can then be perimeter-bonded to a frame using a clear or color-absorbing adhesive.

[0084] 13A and 13B illustrate a comparison between an existing waveguide stack bonding architecture 300 (see FIG. 13A ) and an improved edge-blackening and stack bonding architecture 400 (see FIG. 13B ) disclosed herein. As shown in FIG. 13A , the existing waveguide stack bonding architecture 300 includes a stack adhesive (304 a, 304 b) between each waveguide (306 a, 306 b, 306 c), forming a stack gap 312 between adjacent waveguides (306) and an edge gap surface (308) between the stack adhesive (304) and the edge of the waveguide 306. The opposing edge gap surfaces (308) of each waveguide (306) form an edge gap (309) (i.e., a gap between the opposing edge gap surfaces (308) that extends from the inner edge of the waveguide (306) to the edge of the stack adhesive (304)). The edge gap (309) may extend an average length (316) of approximately 0.21 mm from the edge of the waveguide 306. The stack adhesive (304) may have an average length (318) of approximately 0.91 mm along the stack gap (312). The stack gap (312) may have a thickness (312) of approximately 30-50 μm. The waveguide stack 300 is bonded to a frame (e.g., a frame the same as or similar to the frame (64) shown in FIG. 4A or other metal frame) of an XR headset or XR eyeglasses (also referred to as eyepieces) using a perimeter adhesive. The perimeter adhesive (310) may have a thickness (314) of approximately 800 μm. As shown in FIG. 13A, the perimeter adhesive (310) tends to penetrate into the edge gap (312) between adjacent waveguides (306).

[0085] In comparison, the improved waveguide stack (400) shown in FIG. 13B includes edge blackening (402) on the outer edge (404) of each waveguide (306). The edge blackening (402) (also referred to as blackened edge layer 402) typically has a thickness of less than 1 μm. The edge blackening (402) may extend over the edge gap surface (308) of each waveguide (306), forming an edge gap 309 between adjacent waveguides (306), as shown in FIG. 13B. A perimeter bonding compound (310) is then applied over the edge blackening (402) to bond the waveguide stack (400) to the frame of an XR headset or XR glasses (e.g., a frame the same as or similar to frame (64) shown in FIG. 4A or other metal frame).

[0086] 14 is a table showing a comparison of image ANSI contrast from an RGB (red, green, blue) stack per R, G, B color waveguide for various stack architectures. The first column (502) from the left shows image ANSI contrast per R, G, B color waveguide for a waveguide stack (503) (shown diagrammatically) having only stack adhesive (304) bonding the waveguides (306) together. The second column (504) from the left shows image ANSI contrast per R, G, B color waveguide for a waveguide stack (505) (shown diagrammatically) having stack adhesive 304 bonding the waveguides (306) together and edge black ink (402) on the outer edge of each waveguide. The third column (506) from the left shows the image ANSI contrast per R, G, B color waveguide for a waveguide stack (507) (shown diagrammatically) with a stack adhesive (304) bonding the waveguides together and a perimeter adhesive on the outer edge of the waveguide stack, but without edge blackening. The fourth column (508) from the left shows the image ANSI contrast per R, G, B color waveguide for a waveguide stack (509) (shown diagrammatically) with a stack adhesive (304) bonding the waveguides (306), edge black ink (402) on the outer edge (404) of each waveguide, and perimeter adhesive (310) (with color absorbing material) applied over the edge black ink (402) on the outer edge (404) of the waveguide stack (509). The table in Figure 14 shows that the edge-blackened waveguide stack designs (505, 509) disclosed herein (second column (504) and fourth column (508) from the left) have improved image ANSI contrast (i.e., higher image ANSI contrast) relative to previous stack designs (first column (502) and third column (506) from the left) without affecting image sharpness. As shown in the fourth column (508) of the table in Figure 14, the perimeter cement (310) with color absorbing material further improves absorption of light bouncing off the edge of the eyepiece waveguide, thereby improving image ANSI contrast, compared to edge-blackening alone as shown in the second column (505).

[0087] A blackening edge (402), such as a blackening ink, applied to the edge (404) of a singulated or stacked eyepiece waveguide (400) (with or without a blank cover layer (e.g., perimeter adhesive (310)) on the outer stack surface) can be applied to the edge (404) using a roller tip, brush tip, microgravure, spray / atomization, etc. The blackening agent (402) can be a carbon black pigment as small as 30 nm in diameter, applied using a fast-drying surfactant such as methanol, ethanol, isopropanol, etc. The blackening pigment can also be composed of a mixture of various pigments or dyes capable of blocking various wavelengths of light, with the sum of all color blocking agents blocking light wavelengths between 400 nm and 800 nm. Suitable dyes and pigments include, for example, carbon black (size range 5 nm to 500 nm), rhodamine B, tartrazine, chemical dyes from Yamada Chemical Co., Ltd., and SUNFAST from SunChemical Corp. TM Powdered coating pigments such as powder coating pigments (e.g., Green 36, Blue, Violet 23, etc.).

[0088] The stack adhesive material (304) and the perimeter bonding agent (310) may be prepolymer materials that can be dispensed using ink jets, syringe pumps, sprayers / atomizers, etc. The prepolymer materials may include resin materials such as epoxy vinyl esters. The color-absorbing resins may include UV- and heat-curable crosslinkable monomers and oligomers, with or without oxygen inhibitors. To create the color-absorbing resins, the dyes or pigments are typically premixed with the solvent and resin, and a photoinitiator is added to produce a UV-curable resin. The dyes or pigments may be selected to absorb all or a portion of light in the visible range. In some embodiments, the dyes or pigments are black (i.e., absorb all visible wavelengths). In other embodiments, the dyes or pigments are blue (i.e., absorb green and red wavelengths), green (i.e., absorb blue and red wavelengths), red (i.e., absorb blue and green wavelengths), or any combination thereof. In particular, the color absorbing resin may include a combination of red, green, and blue dye or pigment polymers that are not black but absorb the full range of wavelengths of visible light incident on the waveguide.

[0089] Figure 15 shows an example of transmission curves in the visible spectrum at 0 degrees incidence for four different types of adhesives used for the stack adhesive material (304) and the perimeter bonding agent (310). Line (600) is the transmission curve for a 1 μm thick black ink layer, and lines (602, 604, and 606) are individual transmission curves for 30 μm thick layers of three different types of color-absorbing enriched dye-pigment UV / thermal crosslinkable adhesives. Figure 15 illustrates how the 1 μm thick black ink application layer blocks more light compared to the resin-crosslinked dye-pigment adhesive layer, which can be up to 30 μm thick.

[0090] The prepolymer resin can include vinyl monomers (e.g., methyl methacrylate) and / or di- or trifunctional vinyl monomers (e.g., diacrylates, triacrylates, dimethacrylates, etc.), with or without aromatic molecules in the monomer. The prepolymer material can include monomers with one or more functional groups, such as alkyl, carboxyl, carbonyl, hydroxyl, and / or alkoxy. Sulfur atoms and aromatic groups, both of which have higher polarizability, can be incorporated into these acrylate components to increase the refractive index of the formulation, generally ranging from 1.5 to 1.75. In some implementations, the prepolymer material can include a cycloaliphatic epoxy-containing resin and can be cured using ultraviolet light and / or heat. Additionally, the prepolymer material can include an ultraviolet cationic photoinitiator and a co-reactant to promote efficient ultraviolet curing under ambient conditions.

[0091] Incorporating inorganic nanoparticles (NPs) such as ZrO2 and TiO2 into such imprintable resin polymers can significantly increase the refractive index, even up to 2.1. Pure ZrO2 and TiO2 crystals can reach refractive indices of 2.2 and 2.4–2.6 at 532 nm, respectively. For the preparation of optical nanocomposites of acrylate monomers and inorganic nanoparticles, particle sizes are smaller than 10 nm to avoid excessive Rayleigh scattering. Due to their high specific surface area, high polarity, and incompatibility with crosslinked polymer matrices, ZrO2 NPs tend to aggregate in the polymer matrix. Surface modification of NPs can be used to overcome this problem. In this technique, the hydrophilic surface of ZrO2 is modified to be compatible with organics, thus allowing the NPs to be uniformly mixed with the polymer. Such modification can be carried out using silanes and carboxylic acid-containing capping agents. One end of the capping agent is attached to the ZrO2 surface, and the other end of the capping agent contains either a functional group or a non-functional organic moiety that can participate in acrylate crosslinking. Examples of surface-modified sub-10 nm ZrO2 particles are available from PIXELLIGENT TECHNOLOGIES. TM and CERION ADVANCED MATERIALS TM These functionalized nanoparticles are typically sold as homogeneous formulations, uniformly suspended in a solvent, which can be combined with other base materials to produce resist formulations with jettable viscosity and increased refractive index. Optionally, having a higher refractive index at the cured polymer interface can improve light coupling into the color-absorbing spacer material, thus eliminating any scattering-based artifacts of light replicated internally in the TIR within the waveguide.

[0092] Ultraviolet (UV) acrylate coatings and films tend to suffer from oxygen inhibition during ambient cure. During cure, oxygen will react with acrylate radicals on the surface to generate peroxide radicals, which are inactive. This effectively stops the chain reaction and results in a sticky, wet surface after UV exposure, which is undesirable. The viscosity of the material can range from about 10 cPs to about 100,000 cPs to about 500,000 cPs. Suitable dyes and pigments include, for example, carbon black (size range 5 nm to 500 nm), rhodamine B, tartrazine, chemical dyes from Yamada Chemical Co., Ltd., and SUNFAST from Sun Chemical Corp. TM Powdered coating pigments such as pigments (e.g., Green 36, Blue, Violet 23, etc.) are included.

[0093] The dye or pigment is combined with a solvent and then combined with a UV-curable resin to produce a color-absorbing resin. The solvent can be a volatile solvent such as alcohol (methanol, ethanol, butanol, or equivalent) or other less volatile organic solvents such as dimethyl sulfoxide (DMSO), propylene glycol monomethyl ether acetate (PGMEA), toluene, and equivalents. The dye or pigment can be separated from the solvent (e.g., using centrifugal evaporation) or concentrated to produce an optimal concentration with a cross-linked organic resin (e.g., a UV-curable, highly transparent material). The optimal concentration of dye or pigment can impart a color-absorbing film with desirable optical properties, such as a higher concentration of color-absorbing dye or pigment, resulting in a less reflective film. Note that while a color-absorbing adhesive may be preferred to absorb unwanted light in the TIR at the edge of the waveguide eyepiece, a transparent UV / thermal-curable adhesive can also be used when using black ink at the edge of the eyepiece, as shown in Figures 13A and 14.

[0094] Compared to traditional water- and solvent-based coatings, UV radiation-curable coatings and adhesives present additional challenges in balancing acceptable viscosity for specific applications, targeted gloss levels, and desired film properties (e.g., scratch resistance, hardness, adhesive strength, etc.). Due to solvent evaporation, traditional coatings begin to orient and "concentrate" the matting agent during physical drying of the film. As the volatile compounds evaporate, the applied film begins to shrink. This shrinkage can vary from 30% to as much as 60% of the wet film volume, depending on the volume solids. In comparison, a 100% UV coating shrinks only about 10% during a rapid cure cycle, which would result in much lower density packing of the matting agent. To achieve good matting performance, special care must be taken with matting agent particle size and loading selection and film thickness control. Silica-based matting agents are effective at reducing gloss by introducing surface roughness and wrinkling. Examples of silica matting agents are listed below from Evonik Corp.

[0095] ACEMATT TM HK 400 (D50 particle size of 6.3 μm)

[0096] ACEMATT TM OK 607 (D50 particle size of 4.4 μm)

[0097] ACEMATT TM OK 412 (D50 particle size of 6.3 μm)

[0098] ACEMATT TM 3600 (D50 particle size of 5.0 μm)

[0099] In addition to the surface roughening approach via inorganic particles, organic components can be added to enhance internal light scattering and further increase matte performance. One such component is EBECRYL® 898 radiation-curable resin from Allnex Company. To increase the opacity of coatings and adhesives to visible light, broadband absorbers such as carbon black pigments can be added in combination with matting agents to simultaneously achieve bulk dark color and a flat surface finish. Pigment loading percentages can range from 0.2% to 15% by weight, depending on the curing thickness requirements. To achieve ultra-dark colors at 10-20 microns, for example, 10% pigment can be added. To minimize oxygen inhibition and improve surface cure in air, oxygen scavengers and chain transfer agents such as primary, secondary, and tertiary thiols and amines can be added.

[0100] Crosslinking the prepolymer material involves exposing the prepolymer to a 310 nm to 410 nm wavelength and 0.1 J / cm 2 ~100J / cm 2 and exposing the prepolymer to actinic radiation having an intensity of from 40° C. to 120° C. The method can further include applying heat to the prepolymer during exposure of the prepolymer to actinic radiation.

[0101] Turning now to Figures 16-19, a stacked waveguide assembly (600) may include waveguides (600a, 606b, 606c) having roughened edge surfaces (608). The stacked waveguide assembly (600) shown in Figure 16 is identical to the stacked waveguide assembly (400) shown in Figure 13B, except that multiple waveguides have one or more edge surfaces that are roughened, and edge blackening is applied over the roughened edge surfaces, as described above. In the embodiment shown in Figure 16, only the outer edge surfaces (610) of the waveguides (606) are roughened, whereby edge blackening on the outer edge surfaces is applied. Figure 17A shows one of the waveguides (606) of the stacked waveguide assembly (600) of Figure 16, in which the outer edge (610) is roughened. Edge blackening (604) is then applied over the roughened outer edge (608), as shown in Figure 17B.

[0102] The top and bottom edge gap surfaces (612a, 612b) to which the edge blackening (604) is applied may also be roughened, as depicted in Figures 18A and 18B. Figures 18A and 18B illustrate that the roughened surface (608) may extend over the top edge gap surface 612a (i.e., the edge portion of the top surface) of the waveguide (606). This may be in addition to the surface roughening on the outer edge (610) of the waveguide (606). Figure 18A shows the roughening on the top edge gap surface (612a) of the waveguide (606). Figure 18B shows the edge blackening (604) applied over the outer edge surface (610) of the waveguide (606) and the roughened top edge gap surface (612a). The bottom edge gap surface (612b) and / or the outer edge surface (610) may also be roughened, to which edge blackening 604 is applied.

[0103] Roughening on the edge surfaces (610 and / or 612) of the waveguide (606) to which the edge blackening (604) is applied serves to increase the surface-to-volume ratio and therefore the ability of the color-absorbing material to absorb light at more angles. The roughened surface (608) may be formed by grinding or rubbing a surface against a rough surface to create random or symmetrically patterned (i.e., patterned) features in the surface. The roughened surface (608) may also be formed in any other suitable manner, such as by molding, stamping, forging, or etching the roughened surface into a discrete surface.

[0104] Figure 19 depicts an enlarged view of a portion of the roughened surface (608) of the waveguide of Figures 16-18B. The roughened surface (608) may be formed by grinding or rubbing a surface against a rough surface to create random or symmetrically patterned features in the surface.

[0105] In the foregoing specification, the invention has been described with reference to specific embodiments thereof. However, it will be apparent that various modifications and changes can be made to the invention without departing from the broader spirit and scope of the invention. For example, the process flows described above are described with reference to a particular order of process actions. However, the order of many of the described process actions may be changed without affecting the scope or operation of the invention. The specification and drawings are, therefore, to be regarded in an illustrative sense, and not a restrictive sense.

[0106] Various exemplary embodiments of the present invention are described herein. These examples are referred to in a non-limiting sense. They are provided to illustrate the more broadly applicable aspects of the present invention. Various changes may be made to the described invention, and equivalents may be substituted, without departing from the true spirit and scope of the invention. In addition, many modifications may be made to adapt a particular situation, material, composition of matter, process, process acts, or steps to the objective, spirit, or scope of the present invention. Moreover, as will be understood by those skilled in the art, each of the individual variations described and illustrated herein has discrete components and features that can be readily separated from or combined with the features of any of the other several embodiments without departing from the scope or spirit of the invention. All such modifications are intended to be within the scope of the claims associated with this disclosure.

[0107] The present invention includes methods that may be practiced using the subject devices. The methods may include the act of providing such a suitable device. Such provisioning may be performed by an end user. In other words, the act of "providing" merely requires the end user to obtain, access, approach, locate, configure, activate, power on, or otherwise act on the requisite device to provide the subject method. The methods recited herein may be carried out in any order of the recited events that is logically possible, as well as in the recited order of events.

[0108] Exemplary aspects of the invention have been described above, along with details regarding material selection and manufacturing. As for other details of the invention, these may be understood in connection with the above-referenced patents and publications and are generally known or may be understood by those skilled in the art. The same may be true with respect to method-based aspects of the invention in terms of additional acts as generally or logically adopted.

[0109] Additionally, while the present invention has been described with reference to several embodiments optionally incorporating various features, the present invention is not limited to those described or shown as contemplated with respect to each variation of the invention. Various modifications may be made to the described invention, and equivalents (whether recited herein or not included for a degree of brevity) may be substituted, without departing from the true spirit and scope of the invention. Additionally, when a range of values ​​is provided, it is understood that all intervening values ​​between the upper and lower limits of that range, and any other stated or intervening values ​​within the stated range, are encompassed within the invention.

[0110] It is also contemplated that any optional features of the described inventive variations may be described and claimed independently or in combination with any one or more of the features described herein. Reference to a singular item includes the possibility that plural identical items are present. More specifically, as used in this specification and the claims associated herewith, the singular forms "a," "an," "said," and "the" include plural referents unless specifically stated otherwise. In other words, the use of articles allows for "at least one" of the subject items in the above description and in the claims associated with this disclosure. It is further noted that such claims may be drafted to exclude any optional element. Accordingly, this language is intended to serve as a predicate for the use of exclusive terminology such as "solely," "only," and the like in connection with the recitation of claim elements, or for the use of a "negative" limitation.

[0111] Absent the use of such exclusive terminology, the term "comprising" in the claims associated with this disclosure shall permit the inclusion of any additional elements, regardless of whether a given number of elements are recited in such claim or whether the addition of a feature may be considered as changing the nature of the element recited in such claim. Except as specifically defined herein, all technical and scientific terms used herein shall be given the broadest possible commonly understood meaning while maintaining the validity of the claims.

[0112] The scope of the present invention is not limited to the examples and / or subject specification provided, but rather is limited only by the scope of the claim language associated with this disclosure.

[0113] The above description of illustrated embodiments is not intended to be exhaustive or to limit the embodiments to the precise form disclosed. While specific embodiments and examples are described herein for illustrative purposes, various equivalent modifications can be made, as will be recognized by those skilled in the art, without departing from the spirit and scope of the present disclosure. The teachings provided herein of various embodiments can be applied to other devices that implement virtual or AR or hybrid systems and / or employ user interfaces, not necessarily the exemplary AR systems generally described above.

[0114] For example, the foregoing detailed description describes various embodiments of devices and / or processes through the use of block diagrams, schematic diagrams, and examples. To the extent that such block diagrams, schematic diagrams, and examples contain one or more functions and / or operations, it will be understood by those skilled in the art that each function and / or operation within such block diagrams, flowcharts, or examples, individually and / or collectively, can be implemented by a wide range of hardware, software, firmware, or virtually any combination thereof.

[0115] In one embodiment, the present subject matter may be implemented via an application-specific integrated circuit (ASIC). However, those skilled in the art will recognize that the embodiments disclosed herein may equivalently be implemented, in whole or in part, within a standard integrated circuit as one or more computer programs executed by one or more computers (e.g., as one or more programs running on one or more computer systems), as one or more programs executed by one or more controllers (e.g., microcontrollers), as one or more programs executed by one or more processors (e.g., microprocessors), as firmware, or virtually any combination thereof, and that designing the circuitry and / or writing the code for the software and / or firmware would be well within the skill of one of ordinary skill in the art in light of the teachings of the present disclosure.

[0116] When logic is implemented as software and stored in memory, the logic or information can be stored on any computer-readable medium for use by or in connection with any processor-related system or method. In the context of this disclosure, memory is a computer-readable medium that is an electronic, magnetic, optical, or other physical device or means that contains or stores a computer and / or processor program. The logic and / or information can be embodied in any computer-readable medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, processor-containing system, or other system that may fetch instructions from the instruction execution system, apparatus, or device and execute the instructions associated with the logic and / or information.

[0117] In the context of this specification, a "computer-readable medium" may be any element that can store a program associated with logic and / or information for use by or in connection with an instruction execution system, apparatus, and / or device. A computer-readable medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable media would include the following: portable computer diskettes (magnetic, CompactFlash cards, Secure Digital, or equivalent), random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM, EEPROM, or flash memory), portable compact disc read-only memory (CDROM), digital tape, and other non-transitory media.

[0118] Any of the methods described herein may be practiced with variations, for example, many of the methods may include additional acts, omit some acts, and / or perform acts in a different order than illustrated or described.

[0119] The various embodiments described above can be combined to provide further embodiments. All U.S. patents, U.S. patent application publications, U.S. patent applications, foreign patents, foreign patent applications, and non-patent publications mentioned herein and / or listed in application data sheets are incorporated herein by reference in their entirety, unless they contradict the specific teachings and definitions of this specification. Aspects of the embodiments can be modified, if necessary, to employ systems, circuits, and concepts from the various patents, applications, and publications to provide still further embodiments.

[0120] These and other changes can be made to the embodiments in light of the description detailed above. Generally, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and claims, but should be construed to include all possible embodiments, along with the full range of equivalents to which such claims are entitled. Therefore, the claims are not limited by the present disclosure.

[0121] Furthermore, the various embodiments described above can be combined to provide further embodiments, and aspects of the embodiments can be modified, if necessary, to employ concepts from various patents, applications, and publications to provide still further embodiments.

[0122] These and other changes can be made to the embodiments in light of the description detailed above. Generally, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and claims, but should be construed to include all possible embodiments, along with the full range of equivalents to which such claims are entitled. Therefore, the claims are not limited by the present disclosure.

Claims

1. 1. A stacked waveguide assembly for an eyepiece for use with an XR display system, comprising: a plurality of waveguides configured to be stacked together and transmit image information to a user's eye, each of the waveguides being joined to an adjacent waveguide using a stacking adhesive applied between adjacent waveguides proximate an edge of each waveguide; a thin blackened edge layer applied over the edge of each waveguide and configured to absorb substantially all visible light that bounces off the edge of each individual waveguide; and 1. A stacked waveguide assembly comprising:

2. The stacked waveguide assembly of claim 1 further comprising a perimeter adhesive applied over said blackened border layer.

3. 3. The stacked waveguide assembly of claim 2, wherein the perimeter adhesive bonds the joint of the stacked waveguide assembly to a frame of an eyepiece for use with an XR display system.

4. 4. The stacked waveguide assembly of claim 2 or 3, wherein the perimeter bonding agent comprises a color absorbing adhesive.

5. 5. The stacked waveguide assembly of claim 1, wherein the blackened border layer comprises a carbon black pigment.

6. 6. The stacked waveguide assembly of claim 5, wherein the carbon black pigment is 30 nm or less in diameter.

7. 5. The stacked waveguide assembly of claim 1, wherein the blackened border layer comprises a dye or pigment selected from the group consisting of carbon black having a size range of 5 nm to 500 nm, rhodamine B chemical dye, tartrazine chemical dye, and powder coating pigments including green, blue, and violet pigments.

8. The stacked waveguide assembly of any of claims 1-7, wherein the stack adhesive comprises a color absorbing adhesive.

9. 10. The stacked waveguide assembly of claim 8, wherein the stack adhesive and / or perimeter bonding agent comprises a pre-polymer material dispenseable using at least one of an ink jet, a syringe pump, or a spray atomization, the pre-polymer material including a dye or pigment selected to absorb all or a selected portion of visible light.

10. 10. A stacked waveguide assembly according to any preceding claim, wherein at least a portion of the edge to which the blackened edge layer is applied has a roughened surface.

11. 1. A method of making a stacked waveguide assembly for an eyepiece for use with an XR display system, the method comprising: stacking a plurality of waveguides together such that the stacked waveguides are configured to transmit image information to an eye of a user; bonding each of the waveguides to the adjacent waveguide using a stack adhesive applied between the adjacent waveguides proximate an edge of the waveguide; applying a thin blackened edge layer around the edge of each individual waveguide such that the blackened edge layer absorbs substantially all visible light that bounces off the edge of each individual waveguide; A method comprising:

12. The method of claim 11 further comprising applying a perimeter bonding agent over the blackened edge layer.

13. The method of claim 12 , wherein the perimeter adhesive bonds the joint of the stacked waveguide assembly to a frame of an eyepiece for use with an XR display system.

14. The method of claim 12 or 13, wherein the perimeter bonding agent comprises a color absorbing adhesive.

15. The method of any of claims 11-14, wherein the blackened border layer comprises carbon black pigment.

16. 16. The method of claim 15, wherein the carbon black pigment is 30 nm or less in diameter.

17. 15. The method of any of claims 11-14, wherein the blackened border layer comprises a dye or pigment selected from the group consisting of carbon black having a size range of 5 nm to 500 nm, rhodamine B chemical dye, tartrazine chemical dye, and powder coating pigments including green, blue, and violet pigments.

18. The method of any of claims 11-17, wherein the stack adhesive comprises a color absorbing adhesive.

19. 20. The method of claim 18, wherein the stack adhesive and / or perimeter bonding agent comprises a pre-polymer material, the stack adhesive and / or perimeter bonding agent is dispensed using at least one of an inkjet, a syringe pump, or a spray atomization, and the pre-polymer material comprises a dye or pigment selected to absorb all or a selected portion of visible light.

20. A method according to any of claims 11-19, wherein at least a portion of the edge to which the blackened edge layer is applied has a roughened surface.

21. The method of any of claims 11-19, further comprising roughening at least a portion of the edge where the blackened edge layer is present.

22. An eyepiece for an XR display system comprising a stacked waveguide assembly according to any one of claims 1-10.

23. 1. An extended reality (XR) display system for delivering extended reality content to a user, comprising: an image source for providing one or more frames of image data; a light modulator for transmitting light associated with one or more frames of said image data; an eyepiece comprising a stacked waveguide assembly according to any one of claims 1 to 10; An extended reality (XR) display system comprising:

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