Virtual and augmented reality systems and methods

Abstract

A head-mounted display system includes an emissive micro-display including an array of light emitters corresponding to pixels, where the array of light emitters is configured to output image light that defines images. The system also includes an aspheric lens configured to receive the image light from the emissive micro-display and correct the image light. The system also includes a first surface mirror configured to redirect the image light from the aspheric lens from a first direction to a second direction substantially orthogonal to the first direction. Moreover, the system includes a collimating optic configured to receive the image light from the first surface mirror and collimate the image light. In addition, the system includes an eyepiece configured to receive the image light from the collimating optic and to direct the image light to an eye of a user.

Description

Attorney Docket No. ML-5018WOVIRTUAL AND AUGMENTED REALITY SYSTEMS AND METHODSCross-Reference to Related Application(s)

[0001] The present application claims the benefit of U.S. Provisional Patent Application Serial No. 63 / 759,796, filed on February 18, 2025 under attorney docket number ML-5018USPRV and entitled “VIRTUAL AND AUGMENTED REALITY SYSTEMS AND METHODS”. This application describes embodiments similar to those described in U.S. Patent Application Serial No. 14 / 726,424 filed on May 29, 2015 under attorney docket number ML.20016.00 and entitled “METHODS AND SYSTEMS FOR GENERATING VIRTUAL CONTENT DISPLAY WITH A VIRTUAL OR AUGMENTED REALITY APPARATUS” and issued as U.S. Patent No. 10,175,478 on January 8, 2019; U.S. Patent Application Serial No. 15 / 007,117 filed on January 26, 2016 under attorney docket number ML.20022.00 and entitled “VIRTUAL AND AUGMENTED REALITY SYSTEMS AND METHODS HAVING IMPROVED DIFFRACTIVE GRATING STRUCTURES” and issued as U.S. Patent No. 9,915,826 on March 13, 2018; U.S. Patent Application Serial Number 15 / 146,296 filed under on May 4, 2016 under attorney docket number ML.20058.00 and entitled “SEPARATED PUPIL OPTICAL SYSTEMS FOR VIRTUAL AND AUGMENTED REALITY AND METHODS FOR DISPLAYING IMAGES USING SAME” and issued as U.S. Patent Number 11,402,629 on August 2, 2022; and U.S. Patent Application Serial No. 15 / 443,002, filed on February 27, 2017 under attorney docket number ML.20059.00 and entitled “VIRTUAL AND AUGMENTED REALITY SYSTEMS AND METHODS” and issued as U.S. Patent Number 10,739,593 on AugustAttorney Docket No. ML-5018WO11 , 2020. The contents of the aforementioned patent applications and patents are hereby expressly and fully incorporated by reference in their entirety, as though set forth in full.Copyright Notice

[0002] A portion of the disclosure of this patent document contains material, which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever.BackgroundField

[0003] The present disclosure relates to display systems and, more particularly, to augmented and virtual reality display systems.Description of the Related Art

[0004] Modem computing and display technologies have facilitated the development of systems for so called “virtual reality” or “augmented reality” experiences, in which digitally reproduced images or portions thereof are presented to a user in a manner wherein they seem to be, or may be perceived as, real. A virtual reality, or “VR”, scenario typically involves the presentation of digital or virtual image information without transparency to other actual real-world visual input; an augmented reality, or “AR”, scenario typically involves presentation of digital or virtual image information as an augmentation to visualization of the actual world around the user. A mixed reality, or “MR”, scenario is a type of AR scenario and typically involves virtual objects that areAttorney Docket No. ML-5018WO integrated into, and responsive to, the natural world. For example, an MR scenario may include AR image content that appears to be blocked by or is otherwise perceived to interact with objects in the real world.

[0005] Referring to Figure 1 , an AR / MR scene 10 is depicted. The user of an AR technology sees a real-world park-like setting 20 featuring people, trees, buildings in the background, and a concrete platform 30. The user also perceives that he / she “sees” “virtual content” such as a robot statue 40 standing upon the real-world platform 30, and a flying cartoon-like avatar character 50 which seems to be a personification of a bumble bee. These elements 50, 40 are “virtual” in that they do not exist in the real world. Because the human visual perception system is complex, it is challenging to produce AR technology that facilitates a comfortable, natural-feeling, rich presentation of virtual image elements amongst other virtual or real-world imagery elements

[0006] One VR / AR / MR display approach uses a large number of optical elements (e.g., light sources, prisms, gratings, filters, scan-optics, beam splitters, mirrors, halfmirrors, shutters, eye pieces, etc.) to project images at a range of depth planes. The problem with this approach is that using a large number of components in this manner necessarily requires a larger form factor than is desirable, and limits the degree to which the system size can be reduced. The large number of optical elements in these systems also results in a longer optical path, over which the light and the information contained therein will be degraded. These design issues result in cumbersome systems, which are also power intensive and which can generate excess heat that must be dissipated. The systems and methods described herein are configured to address these challenges.Attorney Docket No. ML-5018WOSummary

[0007] Disclosed are virtual reality, augmented reality, and / or mixed reality display devices, systems and methods.

[0008] In one embodiment, a head-mounted display system includes an emissive micro-display including an array of light emitters corresponding to pixels, where the array of light emitters is configured to output image light that defines images. The system also includes an aspheric lens configured to receive the image light from the emissive microdisplay and correct the image light. The system also includes a first surface mirror configured to redirect the image light from the aspheric lens from a first direction to a second direction substantially orthogonal to the first direction. Moreover, the system includes a collimating optic configured to receive the image light from the first surface mirror and collimate the image light. In addition, the system includes an eyepiece configured to receive the image light from the collimating optic and to direct the image light to an eye of a user.

[0009] In one or more embodiments, the second direction is orthogonal to the first direction. Correcting the image light may include removing an aberration / error / distortion from the image light to shape the image light into a spherical wavefront. The an aberration / error / distortion may be selected from the group consisting of wavefront, coma, and astigmatism. The first surface mirror may maintain a wavefront of the image light when redirecting the image light.

[0010] In one or more embodiments, the collimating optic includes a first collimating lens and a second collimating lens. The first collimating lens may have a positive power, and the second collimating lens may have a negative power. The first and secondAttorney Docket No. ML-5018WO collimating lens may be spherical lenses. The system may have an optical path length and a field of view, and the first surface mirror may be configured to reduce a length of the system by approximately 45% compared to a straight head-mounted display system having the optical path length and the field of view. The system may have a field of view, and the first surface mirror may be configured to reduce a weight of the system compared to a head-mounted display system having a light redirecting prism and the field of view.

[0011] In one or more embodiments, the system also includes a power management integrated circuit (PMIC) configured to control the emissive micro-display. The first surface mirror may have a first surface facing the aspheric lens and the collimating optic, and a second surface opposite the first surface. The first surface mirror may include a coating disposed on the first surface of the first surface mirror. The coating may be selected from the group consisting of a spectral filtering coating, a polarization control coating, and an apodizing filter coating. The system may include a back wall having an inner back surface defining a back space with the second surface of the first surface mirror. The PMIC may be disposed on the inner back surface of the back wall in the back space, and the back space may be configured to dissipate heat generated by the PMIC.

[0012] In one or more embodiments, the system includes a side wall having an inner side surface defining a front space with the first surface of the first surface mirror, an inner surface of the aspheric lens, and an inner surface of the collimating optic. The system may also include a light absorbing coating disposed on the inner side surface of the side wall in the front space. The system may also include a baffle disposed adjacent the inner surface of the aspheric lens in the front space. The first surface mirror may be configuredAttorney Docket No. ML-5018WOto reduce stray light in the system compared to a head-mounted display system having a light redirecting prism.

[0013] Additional and other objects, features, and advantages of the invention are described in the detail description, figures and claims.Brief Description of the Drawings

[0014] This patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawings will be provided by the U.S. Patent and Trademark Office upon request and payment of the necessary fee.

[0015] The drawings illustrate the design and utility of various embodiments of the present invention. It should be noted that the figures are not drawn to scale and that elements of similar structures or functions are represented by like reference numerals throughout the figures. In order to better appreciate how to obtain the above-recited and other advantages and objects of various embodiments of the invention, a more detailed description of the present inventions briefly described above will be rendered by reference to specific embodiments thereof, which are illustrated in the accompanying drawings. Understanding that these drawings depict only typical embodiments of the invention and are not therefore to be considered limiting of its scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:

[0016] Figure 1 illustrates a user's view of augmented reality (AR) through an AR device.Attorney Docket No. ML-5018WO

[0017] Figure 2 illustrates a conventional display system for simulating three-dimensional imagery for a user.

[0018] Figures 3A-3C illustrate relationships between radius of curvature and focal radius.

[0019] Figure 4A illustrates a representation of the accommodation-vergence response of the human visual system.

[0020] Figure 4B illustrates examples of different accommodative states and vergence states of a pair of eyes of the user.

[0021] Figure 4C illustrates an example of a representation of a top-down view of a user viewing content via a display system.

[0022] Figure 4D illustrates another example of a representation of a top-down view of a user viewing content via a display system.

[0023] Figure 5 illustrates aspects of an approach for simulating three-dimensional imagery by modifying wavefront divergence.

[0024] Figure 6 illustrates an example of a waveguide stack for outputting image information to a user.

[0025] Figure 7 illustrates an example of exit beams outputted by a waveguide.

[0026] Figure 8 illustrates an example of a stacked eyepiece in which each depth plane includes images formed using multiple different component colors.

[0027] Figure 9A is a cross-sectional side view of a set of stacked waveguides that each includes an in-coupling optical element according to some embodiments.

[0028] Figure 9B is a perspective view of the plurality of stacked waveguides of Figure 9A according to some embodiments.Attorney Docket No. ML-5018WO

[0029] Figure 9C is a top-down plan view of the plurality of stacked waveguides of Figures 9A and 9B according to some embodiments.

[0030] Figure 9D is a top-down plan view of a plurality of stacked waveguides according to some embodiments.

[0031] Figure 9E is a schematic view of a wearable display system according to some embodiments.

[0032] Figure 10 is a schematic view of a head-mounted display system according to some embodiments.

[0033] Figure 11 is a schematic view of a head-mounted display system without an aspheric lens according to some embodiments.

[0034] Figure 12 is a graph illustrating a relationship between aberrations and field of view in the head-mounted display system depicted in Figure 11 according to some embodiments.

[0035] Figure 13 is a graph illustrating a relationship between aberrations and field of view in the head-mounted display system depicted in Figure 10 according to some embodiments.

[0036] Figure 14 is a schematic view of a head-mounted display system according to some embodiments.

[0037] Figure 15 is a schematic view depicting the layout of head-mounted display systems according to two embodiments.

[0038] Figure 16 are schematic top and side views depicting head-mounted display systems according to two embodiments.Attorney Docket No. ML-5018WO

[0039] Figure 17 is a table summarizing various characteristics of head-mounted display systems according to two embodiments.

[0040] Figure 18 is a schematic view of a head-mounted display system according to some embodiments.

[0041] Figure 19 is a schematic view depicting a first surface mirror according to some embodiments.

[0042] Figure 20A and 20B are schematic views depicting a prism according to some embodiments.

[0043] Figure 21 is a schematic view depicting a first surface mirror according to some embodiments.

[0044] Figure 22 is a schematic view depicting a prism according to some embodiments.

[0045] Figure 23 is a cross-sectional schematic view of a head-mounted display system according to some embodiments.

[0046] Figure 24 is a detailed cross-sectional schematic view of a head-mounted display system according to some embodiments.

[0047] Figure 25 schematically depicts stray light in head-mounted display systems according to some embodiments.

[0048] Figure 26 schematically depicts a head-mounted display system having a prism according to some embodiments.

[0049] Figure 27 schematically depicts aberrations in head-mounted display systems according to some embodiments.Attorney Docket No. ML-5018WO

[0050] Figure 28 is a block diagram schematically depicting an illustrative computing system according to some embodiments.Detailed Description

[0051] Various embodiments of the invention are directed to systems, methods, and articles of manufacture for implementing optical systems in a single embodiment or in multiple embodiments. Other objects, features, and advantages of the invention are described in the detailed description, figures, and claims.

[0052] In the following description, certain specific details are set forth in order to provide a thorough understanding of various disclosed embodiments. However, one skilled in the relevant art will recognize that embodiments may be practiced without one or more of these specific details, or with other methods, components, materials, etc. In other instances, well-known structures associated with computer systems, server computers, and / or communications networks have not been shown or described in detail to avoid unnecessarily obscuring descriptions of the embodiments.

[0053] It shall be noted that, unless the context requires otherwise, throughout the specification and claims which follow, the word “comprise” and variations thereof, such as, “comprises” and “comprising” are to be construed in an open, inclusive sense, that is as “including, but not limited to.”

[0054] It shall be further noted that Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrases “in one embodiment” or “in anAttorney Docket No. ML-5018WO embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. Furthermore, as used in this specification and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the content clearly dictates otherwise. It should also be noted that the term “or” is generally employed in its sense including “and / or” unless the content clearly dictates otherwise.

[0055] Various embodiments will now be described in detail with reference to the drawings, which are provided as illustrative examples of the invention so as to enable those skilled in the art to practice the invention. Notably, the figures and the examples below are not meant to limit the scope of the present invention. Where certain elements of the present invention may be partially or fully implemented using known components (or methods or processes), only those portions of such known components (or methods or processes) that are necessary for an understanding of the present invention will be described, and the detailed descriptions of other portions of such known components (or methods or processes) will be omitted so as not to obscure the invention. Further, various embodiments encompass present and future known equivalents to the components referred to herein by way of illustration.

[0056] VR, AR, and / or MR systems may display virtual content to a user, or viewer. This content may be displayed on a head-mounted display, for example, as part of eyewear, that projects image information to the user's eyes. In addition, where the system is an AR or MR system, the display may also transmit light from a surrounding environment to the user's eyes, to allow a view of the surrounding environment. As usedAttorney Docket No. ML-5018WO herein, it will be appreciated that a “head-mounted” or “head mountable” display is a display that may be mounted on the head of the user or viewer.

[0057] Many head-mounted display systems utilize transmissive or reflective spatial light modulators to form images that are presented to the user. A light source emits light, which is directed to the spatial light modulator, which then modulates the light, which is then directed to the user. Lens structures may be provided between the light source and the spatial light modulator to focus light from the light source onto the spatial light modulator. Undesirably, the light source and related optics may add bulkiness and weight to the display system. This bulkiness or weight may adversely impact the comfort of the display system and the ability to wear the system for long durations.

[0058] In addition, it has been found that the frame rate limitations of some display systems may cause viewing discomfort. Some display systems use spatial light modulators to form images. Many spatial light modulators utilize movement of optical elements to modulate the intensity of light outputted by the spatial light modulator, to thereby form the images. For example, MEMS-based spatial light modulators may utilize moving mirrors to modulate incident light, while LCoS-based displays may utilize the movement of liquid crystal molecules to modulate light. Other AR or VR systems may utilize scanning-fiber displays, in which the end of an optical fiber physically moves across an area while outputting light. The light outputted by the optical fiber is timed with the position of the end of the fiber, thereby effectively mimicking pixels at different locations, and thereby forming images. The requirement that the optical fibers, mirrors, and liquid crystal molecules physically move limits the speed at which individual pixels may change states and also constrains the frame rate of displays using these optical elements.Attorney Docket No. ML-5018WO

[0059] Such limitations may cause viewing discomfort due to, e.g., motion blur and / or mismatches between the orientation of the user's head and the displayed image. For example, there may be latency in the detection of the orientation of the user's head and the presentation of images consistent with that orientation. In the timespan between detecting the orientation and presenting an image to the user, the user's head may have moved. The presented image, however, may correspond to a view of an object from a different orientation. Such a mismatch between the orientation of the user's head and the presented image may cause discomfort in the user (e.g., nausea).

[0060] In addition, scanning-fiber displays may present other undesirable optical artifacts due to, e.g., the small cross-section of the fibers, which requires the use of a high-intensity light source to form images of desirable apparent brightness. Suitable high-intensity light sources include lasers, which output coherent light. Undesirably, the use of coherent light may cause optical artifacts.

[0061] Advantageously, display systems utilizing emissive micro-displays as described herein may allow for a low-weight and compact form factor which may also provide a high frame rate and low motion blur. Preferably, the micro-displays are emissive micro-displays, which provide advantages for high brightness and high pixel density. In some embodiments, the emissive micro-displays are micro-light-emitting diode (microLED) displays. In some other embodiments, the emissive micro-displays are micro-OLED displays. In some embodiments, the emissive micro-displays comprise arrays of light emitters having a pitch of, e.g., less than 10 pm, less than 8 pm, less than 6 pm, less than 5 pm, or less than 2 pm, including 1 -5 pm, and an emitter size of 2 pm or less, 1.7 pm or less, or 1.3 pm or less. In some embodiments, the emitter size is within a range havingAttorney Docket No. ML-5018WO an upper limit of the above-noted sizes and a lower limit of 1 pm. In some embodiments, the ratio of emitter size to pitch is 1:1 to 1:5, 1:2 to 1:4, or 1:2 to 1:3, which may have advantages for individual control of emitters and efficient utilization of emitted light by eyepieces, as discussed further herein.

[0062] In some embodiments, a plurality of emissive micro-displays may be utilized to form images for a head-mounted display system. The light containing the image information for forming these images may be referred to as image light. It will be appreciated that image light may vary in, e.g., wavelength, intensity, polarization, etc. The emissive micro-displays output image light to an eyepiece, which then relays the light to an eye of the user.

[0063] In some embodiments, the plurality of emissive micro-displays may be positioned at different sides of an optical combiner, e.g., an X-cube prism or dichroic X-cube. The X-cube prism receives light rays from different micro-displays on different faces of the cube and outputs the light rays from the same face of the cube. The outputted light may be directed towards projection optics, which is configured to converge or focus the image light onto the eyepiece.

[0064] In some embodiments, the plurality of emissive micro-displays comprises monochrome micro-displays, which are configured to output light of a single component color. Combining various component colors forms a full color image. In some other embodiments, one or more of the emissive micro-displays may have sub-pixels configured to emit light of two or more, but not all, component colors utilized by the display system. For example, a single emissive micro-display may have sub-pixels which emit light of the colors blue and green, while a separate emissive micro-display on a differentAttorney Docket No. ML-5018WO face of the X-cube may have pixels configured to emit red light. In some embodiments, the plurality of micro-displays are each full-color displays comprising, e.g., pixels formed of multiple sub-pixels configured to emit light of different component colors. Advantageously, combining the light of multiple full-color micro-displays may increase display brightness and dynamic range.

[0065] It will be appreciated that the emissive micro-displays may comprise arrays of light emitters. The light emitters may emit light with a Lambertian angular emission profile. Undesirably, such an angular remission profile may “waste” light, since only a small portion of the emitted light may ultimately be incident on the eyepiece. In some embodiments, light collimators may be utilized to narrow the angular emission profile of light emitted by the light emitters. As used herein, a light collimator is an optical structure which narrows the angular emission profile of incident light; that is, the light collimator receives light from an associated light emitter with a relatively wide initial angular emission profile and outputs that light with a narrower angular emission profile than the wide initial angular emission profile. In some embodiments, the rays of light exiting the light collimator are more parallel than the rays of light received by the light collimator, before being transmitted through and exiting the collimator. Examples of light collimators include micro-lenses, nano-lenses, reflective wells, metasurfaces, and liquid crystal gratings. In some embodiments, the light collimators may be configured to steer light to ultimately converge on different laterally-shifted light-coupling optical elements. In some embodiments, each light emitter has a dedicated light collimator. The light collimators are preferably positioned directly adjacent or contacting the light emitters, to capture a large proportion of the light emitted by the associated light emitters.Attorney Docket No. ML-5018WO

[0066] In some embodiments, a single emissive micro-display may be utilized to direct light to the eyepiece. For example, the single emissive micro-display may be a full-color display comprising light emitters that emit light of different component colors. In some embodiments, the light emitters may form groups, which are localized in a common area, with each group comprising light emitters which emit light of each component color. In such embodiments, each group of light emitters may share a common micro-lens. Advantageously, light of different colors from different light emitters take a different path through the micro-lens, which may be manifested in light of different component colors being incident on different in-coupling optical elements of an eyepiece, as discussed herein.

[0067] In some embodiments, the full-color micro-display may comprise repeating groups of light emitters of the same component color. For instance, the micro-display may include rows of light emitters, with the light emitters of each individual row configured to emit light of the same color. Thus, different rows may emit light of different component colors. In addition, the micro-display may have an associated array of light collimators configured to direct light to a desired location on an eyepiece, e.g., to an associated incoupling optical element. Advantageously, while the individual light emitters of such a full-color micro-display may not be positioned to form a high-quality full-color image, as viewed directly on the micro-display, the lens array appropriately steers the light from the light emitters to the eyepiece, which combines monochrome images formed by light emitters of different colors, thereby forming a high-quality full-color image.

[0068] In some embodiments, the eyepiece receiving image light from the microdisplays may comprise a waveguide assembly. The area of a waveguide of theAttorney Docket No. ML-5018WO waveguide assembly on which the image light is incident may include in-coupling optical elements which in-couple incident image light, such that the light propagates through the waveguide by total internal reflection (TIR). In some embodiments, the waveguide assembly may include a stack of waveguides, each of which has an associated incoupling optical element. Different in-coupling optical elements may be configured to incouple light of different colors, such that different waveguides may be configured to propagate light of different colors therein. The waveguides may include out-coupling optical elements, which out-couple light propagating therein, such that the out-coupled light propagates towards the eye of the user. In some other embodiments, the waveguide assembly may include a single waveguide having an associated in-coupling optical element configured to in-couple light of different component colors.

[0069] In some embodiments, the in-coupling optical elements are laterally shifted, as seen from the projection optics. Different in-coupling optical elements may be configured to in-couple light of different colors. Preferably, image light of different colors take different paths to the eyepiece and, thus, impinge upon different corresponding incoupling optical elements.

[0070] In some other embodiments, other types of eyepieces or optics for relaying image light to the eyes of the user may be utilized. For example, as discussed herein, the eyepiece may include one or more waveguides which propagates image light therein by TIR. As another example, the eyepiece may include a birdbath combiner comprising a semitransparent mirror that both directs image light to a viewer and allows a view of the ambient environment.Attorney Docket No. ML-5018WO

[0071] In some embodiments, the eyepiece may be configured to selectively output light with different amounts of wavefront divergence, to provide virtual content at a plurality of virtual depth planes (also referred to simply as “depth planes” herein) perceived to be at different distances away from the user. For example, the eyepiece may comprise a plurality of waveguides each having out-coupling optical elements with different optical power to output light with different amounts of wavefront divergence. In some other embodiments, a variable focus element may be provided between the eyepiece and the user's eye. The variable focus element may be configured to dynamically change optical power to provide the desired wavefront divergence for particular virtual content. In some embodiments, as an alternative to, or in addition to waveguide optical structures for providing optical power, the display systems may also include a plurality of lenses that provide or additionally provide optical powers.

[0072] In addition to the compact form factor and high frame rates discussed above, emissive micro-displays according to some embodiments may provide one of more of the following advantages. For example, the micro-displays may provide exceptionally small pixel pitches and high pixel density. The micro-displays may also provide high luminance and efficiency. For example, the light emitters of the emissive micro-displays may only consume power to emit light when the light emitters are needed provide content with luminance. This is in contrast to other display technologies in which the light source may illuminate an entire panel of pixels, whether or not some of those pixels are dark. Further, it will be appreciated that the human visual system integrates received light over time and the light emitters of emissive micro-displays, such as micro-LEDs, have advantageously high duty cycles (e.g., including a short activation period for a light emitter in a micro-Attorney Docket No. ML-5018WO display to rise from an “off” to a full “on” state, and a correspondingly short time to fall from an “on” state to “off’ state allow the light emitters to emit light at the on level for a large percentage of each cycle). As a result, the power used to generate an image with a given perceived brightness may be less as compared to conventional display technologies with lower duty cycles. In some embodiments, the duty cycle may be 70% or more, 80% or more, or 90% or more. In some embodiments, the duty cycle may be about 99%. In addition, as noted herein, micro-displays may facilitate exceptionally high frame rates, which may provide advantages including reducing mismatches between the position of a user's head and the displayed content.

[0073] Reference will now be made to the drawings, in which like reference numerals refer to like parts throughout. Unless indicated otherwise, the drawings are schematic and not necessarily drawn to scale.

[0074] Figure 2 illustrates a conventional display system for simulating three-dimensional imagery for a user. It will be appreciated that a user's eyes are spaced apart and that, when looking at a real object in space, each eye will have a slightly different view of the object and may form an image of the object at different locations on the retina of each eye. This may be referred to as binocular disparity and may be utilized by the human visual system to provide a perception of depth. Conventional display systems simulate binocular disparity by presenting two distinct images 190, 200 with slightly different views of the same virtual object — one for each eye 210, 220 — corresponding to the views of the virtual object that would be seen by each eye were the virtual object a real object at a desired depth. These images provide binocular cues that the user's visual system may interpret to derive a perception of depth.Attorney Docket No. ML-5018WO

[0075] With continued reference to Figure 2 , the images 190, 200 are spaced from the eyes 210, 220 by a distance 230 on a z-axis. The z-axis is parallel to the optical axis of the viewer with their eyes fixated on an object at optical infinity directly ahead of the viewer. The images 190, 200 are flat and at a fixed distance from the eyes 210, 220. Based on the slightly different views of a virtual object in the images presented to the eyes 210, 220, respectively, the eyes may naturally rotate such that an image of the object falls on corresponding points on the retinas of each of the eyes, to maintain single binocular vision. This rotation may cause the lines of sight of each of the eyes 210, 220 to converge onto a point in space at which the virtual object is perceived to be present. As a result, providing three-dimensional imagery conventionally involves providing binocular cues that may manipulate the vergence of the user's eyes 210, 220, and that the human visual system interprets to provide a perception of depth.

[0076] Generating a realistic and comfortable perception of depth is challenging, however. It will be appreciated that light from objects at different distances from the eyes have wavefronts with different amounts of divergence. Figures 3A-3C illustrate relationships between distance and the divergence of light rays. The distance between the object and the eye 210 is represented by, in order of decreasing distance, R1 , R2, and R3. As shown in Figures 3A-3C, the light rays become more divergent as distance to the object decreases. Conversely, as distance increases, the light rays become more collimated. Stated another way, it may be said that the light field produced by a point (the object or a part of the object) has a spherical wavefront curvature, which is a function of how far away the point is from the eye of the user. The curvature increases with decreasing distance between the object and the eye 210. While only a single eye 210 isAttorney Docket No. ML-5018WO illustrated for clarity of illustration in Figures 3A-3C and other figures herein, the discussions regarding eye 210 may be applied to both eyes 210 and 220 of a viewer.

[0077] With continued reference to Figures 3A-3C, light from an object that the viewer's eyes are fixated on may have different degrees of wavefront divergence. Due to the different amounts of wavefront divergence, the light may be focused differently by the lens of the eye, which in turn may require the lens to assume different shapes to form a focused image on the retina of the eye. Where a focused image is not formed on the retina, the resulting retinal blur acts as a cue to accommodation that causes a change in the shape of the lens of the eye until a focused image is formed on the retina. For example, the cue to accommodation may trigger the ciliary muscles surrounding the lens of the eye to relax or contract, thereby modulating the force applied to the suspensory ligaments holding the lens, thus causing the shape of the lens of the eye to change until retinal blur of an object of fixation is eliminated or minimized, thereby forming a focused image of the object of fixation on the retina (e.g. , fovea) of the eye. The process by which the lens of the eye changes shape may be referred to as accommodation, and the shape of the lens of the eye required to form a focused image of the object of fixation on the retina (e.g., fovea) of the eye may be referred to as an accommodative state.

[0078] With reference now to Figure 4A, a representation of the accommodationvergence response of the human visual system is illustrated. The movement of the eyes to fixate on an object causes the eyes to receive light from the object, with the light forming an image on each of the retinas of the eyes. The presence of retinal blur in the image formed on the retina may provide a cue to accommodation, and the relative locations of the image on the retinas may provide a cue to vergence. The cue to accommodationAttorney Docket No. ML-5018WO causes accommodation to occur, resulting in the lenses of the eyes each assuming a particular accommodative state that forms a focused image of the object on the retina (e.g., fovea) of the eye. On the other hand, the cue to vergence 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. In these positions, the eyes may be said to have assumed a particular vergence state. With continued reference to Figure 4A, accommodation may be understood to be the process by which the eye achieves a particular accommodative state, and vergence may be understood to be the process by which the eye achieves a particular vergence state. As indicated in Figure 4A, the accommodative and vergence states of the eyes may change if the user fixates on another object. For example, the accommodated state may change if the user fixates on a new object at a different depth on the z-axis.

[0079] Without being limited by theory, it is believed that viewers of an object may perceive the object as being “three-dimensional” due to a combination of vergence and accommodation. As noted above, vergence movements (e.g., rotation of the eyes so that the pupils move toward or away from each other to converge the lines of sight of the eyes to fixate upon an object) of the two eyes relative to each other are closely associated with accommodation of the lenses of the eyes. Under normal conditions, changing the shapes of the lenses of the eyes to change focus from one object to another object at a different distance will automatically cause a matching change in vergence to the same distance, under a relationship known as the “accommodation-vergence reflex.” Likewise, a change in vergence will trigger a matching change in lens shape under normal conditions.Attorney Docket No. ML-5018WO

[0080] With reference now to Figure 4B, examples of different accommodative and vergence states of the eyes are illustrated. The pair of eyes 222 a is fixated on an object at optical infinity, while the pair eyes 222 b are fixated on an object 221 at less than optical infinity. Notably, the vergence states of each pair of eyes is different, with the pair of eyes 222 a directed straight ahead, while the pair of eyes 222 converge on the object 221. The accommodative states of the eyes forming each pair of eyes 222 a and 222 b are also different, as represented by the different shapes of the lenses 210 a, 220 a.

[0081] Undesirably, many users of conventional “3-D” display systems find such conventional systems to be uncomfortable or may not perceive a sense of depth at all due to a mismatch between accommodative and vergence states in these displays. As noted 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, since they, among other things, simply provide different presentations of a scene and cause changes in the vergence states of the eyes, but without a corresponding change in the accommodative states of those eyes. Rather, the images are shown by a display at a fixed distance from the eyes, such that the eyes view all the image information at a single accommodative state. Such an arrangement works against the “accommodationvergence reflex” by causing changes in the vergence state without a matching change in the accommodative state. This mismatch is believed to cause viewer discomfort. Display systems that provide a better match between accommodation and vergence may form more realistic and comfortable simulations of three-dimensional imagery.

[0082] Without being limited by theory, it is believed that the human eye typically may interpret a finite number of depth planes to provide depth perception. Consequently, aAttorney Docket No. ML-5018WO highly believable simulation of perceived depth may be achieved by providing, to the eye, different presentations of an image corresponding to each of these limited numbers of depth planes. In some embodiments, the different presentations may provide both cues to vergence and matching cues to accommodation, thereby providing physiologically correct accommodation-vergence matching.

[0083] With continued reference to Figure 4B, two depth planes 240, corresponding to different distances in space from the eyes 210, 220, are illustrated. For a given depth plane 240, vergence cues may be provided by the displaying of images of appropriately different perspectives for each eye 210, 220. In addition, for a given depth plane 240, light forming the images provided to each eye 210, 220 may have a wavefront divergence corresponding to a light field produced by a point at the distance of that depth plane 240.

[0084] In the illustrated embodiment, the distance, along the z-axis, of the depth plane 240 containing the point 221 is 1 m. As used herein, distances or depths along the z-axis may be measured with a zero-point located at the exit pupils of the user's eyes. Thus, a depth plane 240 located at a depth of 1 m corresponds to a distance of 1 m away from the exit pupils of the user's eyes, on the optical axis of those eyes with the eyes directed towards optical infinity. As an approximation, the depth or distance along the z-axis may be measured from the display in front of the user's eyes (e.g., from the surface of a waveguide), plus a value for the distance between the device and the exit pupils of the user's eyes. That value may be called 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 eye. In practice, the value for the eye relief may be a normalized value used generallyAttorney Docket No. ML-5018WO for all viewers. For example, the eye relief may be assumed to be 20 mm and a depth plane that is at a depth of 1 m may be at a distance of 980 mm in front of the display.

[0085] With reference now to Figures 4C and 4D, examples of matched accommodation-vergence distances and mismatched accommodation-vergence distances are illustrated, respectively. As illustrated in Figure 4C, the display system may provide images of a virtual object to each eye 210, 220. The images may cause the eyes 210, 220 to assume a vergence state in which the eyes converge on a point 15 on a depth plane 240. In addition, the images may be formed by a light having a wavefront curvature corresponding to real objects at that depth plane 240. As a result, the eyes 210, 220 assume an accommodative state in which the images are in focus on the retinas of those eyes. Thus, the user may perceive the virtual object as being at the point 15 on the depth plane 240.

[0086] It will be appreciated that each of the accommodative and vergence states of the eyes 210, 220 are associated with a particular distance on the z-axis. For example, an object at a particular distance from the eyes 210, 220 causes those eyes to assume particular accommodative states based upon the distances of the object. The distance associated with a particular accommodative state may be referred to as the accommodation distance, Ad. Similarly, there are particular vergence distances, Vd, associated with the eyes in particular vergence states, or positions relative to one another. Where the accommodation distance and the vergence distance match, the relationship between accommodation and vergence may be said to be physiologically correct. This is considered to be the most comfortable scenario for a viewer.Attorney Docket No. ML-5018WO

[0087] In stereoscopic displays, however, the accommodation distance and the vergence distance may not always match. For example, as illustrated in Figure 4D, images displayed to the eyes 210, 220 may be displayed with wavefront divergence corresponding to depth plane 240, and the eyes 210, 220 may assume a particular accommodative state in which the points 15 a, 15 b on that depth plane are in focus. However, the images displayed to the eyes 210, 220 may provide cues for vergence that cause the eyes 210, 220 to converge on a point 15 that is not located on the depth plane 240. As a result, the accommodation distance corresponds to the distance from the exit pupils of the eyes 210, 220 to the depth plane 240, while the vergence distance corresponds to the larger distance from the exit pupils of the eyes 210, 220 to the point 15, in some embodiments. The accommodation distance is different from the vergence distance. Consequently, there is an accommodation-vergence mismatch. Such a mismatch is considered undesirable and may cause discomfort in the user. It will be appreciated that the mismatch corresponds to distance (e.g., Vd-Ad) and may be characterized using diopters.

[0088] In some embodiments, it will be appreciated that a reference point other than exit pupils of the eyes 210, 220 may be utilized for determining distance for determining accommodation-vergence mismatch, so long as the same reference point is utilized for the accommodation distance and the vergence distance. For example, the distances could be measured from the cornea to the depth plane, from the retina to the depth plane, from the eyepiece (e.g., a waveguide of the display device) to the depth plane, and so on.Attorney Docket No. ML-5018WO

[0089] Without being limited by theory, it is believed that users may still perceive accommodation-vergence mismatches of up to about 0.25 diopter, up to about 0.33 diopter, and up to about 0.5 diopter as being physiologically correct, without the mismatch itself causing significant discomfort. In some embodiments, display systems disclosed herein (e.g., the display system 250, Figure 6 ) present images to the viewer having accommodation-vergence mismatch of about 0.5 diopter or less. In some other embodiments, the accommodation-vergence mismatch of the images provided by the display system is about 0.33 diopter or less. In yet other embodiments, the accommodation-vergence mismatch of the images provided by the display system is about 0.25 diopter or less, including about 0.1 diopter or less.

[0090] Figure 5 illustrates aspects of an approach for simulating three-dimensional imagery by modifying wavefront divergence. The display system includes a waveguide 270 that is configured to receive light 770 that is encoded with image information, and to output that light to the user's eye 210. The waveguide 270 may output the light 650 with a defined amount of wavefront divergence corresponding to the wavefront divergence of a light field produced by a point on a desired depth plane 240. In some embodiments, the same amount of wavefront divergence is provided for all objects presented on that depth plane. In addition, it will be illustrated that the other eye of the user may be provided with image information from a similar waveguide.

[0091] In some embodiments, a single waveguide may be configured to output light with a set amount of wavefront divergence corresponding to a single or limited number of depth planes and / or the waveguide may be configured to output light of a limited range of wavelengths. Consequently, in some embodiments, a plurality or stack of waveguidesAttorney Docket No. ML-5018WO may be utilized to provide different amounts of wavefront divergence for different depth planes and / or to output light of different ranges of wavelengths. As used herein, it will be appreciated at a depth plane may be planar or may follow the contours of a curved surface.

[0092] Figure 6 illustrates an example of a waveguide stack for outputting image information to a user. A display system 250 includes a stack of waveguides, or stacked waveguide assembly, 260 that may be utilized to provide three-dimensional perception to the eye / brain using a plurality of waveguides 270, 280, 290, 300, 310. It will be appreciated that the display system 250 may be considered a light field display in some embodiments. In addition, the waveguide assembly 260 may also be referred to as an eyepiece.

[0093] In some embodiments, the display system 250 may be configured to provide substantially continuous cues to vergence and multiple discrete cues to accommodation. The cues to vergence may be provided by displaying different images to each of the eyes of the user, and the cues to accommodation may be provided by outputting the light that forms the images with selectable discrete amounts of wavefront divergence. Stated another way, the display system 250 may be configured to output light with variable levels of wavefront divergence. In some embodiments, each discrete level of wavefront divergence corresponds to a particular depth plane and may be provided by a particular one of the waveguides 270, 280, 290, 300, 310.

[0094] With continued reference to Figure 6 , the waveguide assembly 260 may also include a plurality of features 320, 330, 340, 350 between the waveguides. In some embodiments, the features 320, 330, 340, 350 may be one or more lenses. TheAttorney Docket No. ML-5018WO waveguides 270, 280, 290, 300, 310 and / or the plurality of lenses 320, 330, 340, 350 may be configured to send image information to the eye with various levels of wavefront curvature or light ray divergence. Each waveguide level may be associated with a particular depth plane and may be configured to output image information corresponding to that depth plane. Image injection devices 360, 370, 380, 390, 400 may function as a source of light for the waveguides and may be utilized to inject image information into the waveguides 270, 280, 290, 300, 310, each of which may be configured, as described herein, to distribute incoming light across each respective waveguide, for output toward the eye 210. Light exits an output surface 410, 420, 430, 440, 450 of the image injection devices 360, 370, 380, 390, 400 and is injected into a corresponding input surface 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 may be an edge of a corresponding waveguide, or may be part of a major surface of the corresponding waveguide (that is, one of the waveguide surfaces directly facing the world 510 or the viewer's eye 210). In some embodiments, a single beam of light (e.g. a collimated beam) may be injected into each waveguide to output an entire field of cloned collimated beams that are directed toward the eye 210 at particular angles (and amounts of divergence) corresponding to the depth plane associated with a particular waveguide. In some embodiments, a single one of the image injection devices 360, 370, 380, 390, 400 may be associated with and inject light into a plurality (e.g., three) of the waveguides 270, 280, 290, 300, 310.

[0095] In some embodiments, the image injection devices 360, 370, 380, 390, 400 are discrete displays that each produce image information for injection into a corresponding waveguide 270, 280, 290, 300, 310, respectively. In some other embodiments, the imageAttorney Docket No. ML-5018WO injection devices 360, 370, 380, 390, 400 are the output ends of a single multiplexed display which may, e.g., pipe image information via one or more optical conduits (such as fiber optic cables) to each of the image injection devices 360, 370, 380, 390, 400. It will be appreciated that the image information provided by the image injection devices 360, 370, 380, 390, 400 may include light of different wavelengths, or colors (e.g., different component colors, as discussed herein).

[0096] In some embodiments, the light injected into the waveguides 270, 280, 290, 300, 310 is provided by a light projection system 520, which comprises a light module 530, which may include a light emitter, such as a light emitting diode (LED). The light from the light module 530 may be directed to and modified by a light modulator 540, e.g., a spatial light modulator, via a beam splitter 550. The light modulator 540 may be configured to change the perceived intensity of the light injected into the waveguides 270, 280, 290, 300, 310 to encode the light with image information. Examples of spatial light modulators include liquid crystal displays (LCD) including a liquid crystal on silicon (LCOS) displays. In some other embodiments, the spatial light modulator may be a MEMS device, such as a digital light processing (DLP) device. It will be appreciated that the image injection devices 360, 370, 380, 390, 400 are illustrated schematically and, in some embodiments, these image injection devices may represent different light paths and locations in a common projection system configured to output light into associated ones of the waveguides 270, 280, 290, 300, 310. In some embodiments, the waveguides of the waveguide assembly 260 may function as ideal lens while relaying light injected into the waveguides out to the user's eyes. In this conception, the object may be the spatial light modulator 540 and the image may be the image on the depth plane.Attorney Docket No. ML-5018WO

[0097] In some embodiments, the display system 250 may be a scanning fiber display comprising one or more scanning fibers configured to project light in various patterns (e.g., raster scan, spiral scan, Lissajous patterns, etc.) into one or more waveguides 270, 280, 290, 300, 310 and ultimately to the eye 210 of the viewer. In some embodiments, the illustrated image injection devices 360, 370, 380, 390, 400 may schematically represent a single scanning fiber or a bundle of scanning fibers configured to inject light into one or a plurality of the waveguides 270, 280, 290, 300, 310. In some other embodiments, the illustrated image injection devices 360, 370, 380, 390, 400 may schematically represent a plurality of scanning fibers or a plurality of bundles of scanning fibers, each of which are configured to inject light into an associated one of the waveguides 270, 280, 290, 300, 310. It will be appreciated that one or more optical fibers may be configured to transmit light from the light module 530 to the one or more waveguides 270, 280, 290, 300, 310. It will be appreciated that one or more intervening optical structures may be provided between the scanning fiber, or fibers, and the one or more waveguides 270, 280, 290, 300, 310 to, e.g., redirect light exiting the scanning fiber into the one or more waveguides 270, 280, 290, 300, 310.

[0098] A controller 560 controls the operation of one or more of the stacked waveguide assembly 260, including 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, e.g., any of the various schemes disclosed herein. In some embodiments, the controllerAttorney Docket No. ML-5018WO may be a single integral device, or a distributed system connected by wired or wireless communication channels. The controller 560 may be part of the processing modules 140 or 150 (Figure 9E) in some embodiments.

[0099] With continued reference to Figure 6 , the waveguides 270, 280, 290, 300, 310 may be configured to propagate light within each respective waveguide by total internal reflection (TIR). The waveguides 270, 280, 290, 300, 310 may each be planar or have another shape (e.g., curved), with major top and bottom surfaces and edges extending between those major top and bottom surfaces. In the illustrated configuration, the waveguides 270, 280, 290, 300, 310 may each include out-coupling optical elements 570, 580, 590, 600, 610 that are configured to extract light out of a waveguide by redirecting the light, propagating within each respective waveguide, out of the waveguide to output image information to the eye 210. Extracted light may also be referred to as out-coupled light and the out-coupling optical elements light may also be referred to light extracting optical elements. An extracted beam of light may be outputted by the waveguide at locations at which the light propagating in the waveguide strikes a light extracting optical element. The out-coupling optical elements 570, 580, 590, 600, 610 may, for example, be gratings, including diffractive optical features, as discussed further herein. While illustrated disposed at the bottom major surfaces of the waveguides 270, 280, 290, 300, 310, for ease of description and drawing clarity, in some embodiments, the out-coupling optical elements 570, 580, 590, 600, 610 may be disposed at the top and / or bottom major surfaces, and / or may be disposed directly in the volume of the waveguides 270, 280, 290, 300, 310, as discussed further herein. In some embodiments, the out-coupling optical elements 570, 580, 590, 600, 610 may be formed in a layer of material that is attached toAttorney Docket No. ML-5018WO a transparent substrate to form the waveguides 270, 280, 290, 300, 310. In some other embodiments, the waveguides 270, 280, 290, 300, 310 may be a monolithic piece of material and the out-coupling optical elements 570, 580, 590, 600, 610 may be formed on a surface and / or in the interior of that piece of material.

[0100] With continued reference 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 nearest the eye may be configured to deliver collimated light (which was injected into such waveguide 270), to the eye 210. The collimated light may be representative of the optical infinity focal plane. The next waveguide up 280 may be configured to send out collimated light which passes through the first lens 350 (e.g., a negative lens) before it may reach the eye 210; such first lens 350 may be configured to create a slight convex wavefront curvature so that the eye / brain interprets light coming from that next waveguide up 280 as coming from a first focal plane closer inward toward the eye 210 from optical infinity. Similarly, the third up waveguide 290 passes its output light through both the first 350 and second 340 lenses before reaching the eye 210; the combined optical power of the first 350 and second 340 lenses may be configured to create another incremental amount of wavefront curvature so that the eye / brain interprets light coming from the third waveguide 290 as coming from a second focal plane that is even closer inward toward the person from optical infinity than was light from the next waveguide up 280.

[0101] The other waveguide layers 300, 310 and lenses 330, 320 are similarly configured, with the highest waveguide 310 in the stack sending its output through all of the lenses between it and the eye for an aggregate focal power representative of theAttorney Docket No. ML-5018WO closest focal plane to the person. To compensate for the stack of lenses 320, 330, 340, 350 when viewing / interpreting light coming from the world 510 on the other side of the stacked waveguide assembly 260, a compensating lens layer 620 may be disposed at the top of the stack to compensate for the aggregate power of the lens stack 320, 330, 340, 350 below. Such a configuration provides as many perceived focal planes as there are available waveguide / lens pairings. Both the out-coupling optical elements of the waveguides and the focusing aspects of the lenses may be static (i.e., not dynamic or electro-active). In some alternative embodiments, either or both may be dynamic using electro-active features.

[0102] In some embodiments, two or more of the waveguides 270, 280, 290, 300, 310 may have the same associated depth plane. For example, multiple waveguides 270, 280, 290, 300, 310 may be configured to output images set to the same depth plane, or multiple subsets of the waveguides 270, 280, 290, 300, 310 may be configured to output images set to the same plurality of depth planes, with one set for each depth plane. This may provide advantages for forming a tiled image to provide an expanded field of view at those depth planes.

[0103] With continued reference to Figure 6 , the out-coupling optical elements 570, 580, 590, 600, 610 may be configured to both redirect light out of their respective waveguides and to output this light with the appropriate amount of divergence or collimation for a particular depth plane associated with the waveguide. As a result, waveguides having different associated depth planes may have different configurations of out-coupling optical elements 570, 580, 590, 600, 610, which output light with a different amount of divergence depending on the associated depth plane. In some embodiments,Attorney Docket No. ML-5018WO the light extracting optical elements 570, 580, 590, 600, 610 may be volumetric or surface features, which may be configured to output light at specific angles. For example, the light extracting optical elements 570, 580, 590, 600, 610 may be volume holograms, surface holograms, and / or diffraction gratings. In some embodiments, the features 320, 330, 340, 350 may not be lenses; rather, they may simply be spacers (e.g., cladding layers and / or structures for forming air gaps).

[0104] In some embodiments, the out-coupling optical elements 570, 580, 590, 600, 610 are diffractive features that form a diffraction pattern, or “diffractive optical element” (also referred to herein as a “DOE”). Preferably, the DOE's have a sufficiently low diffraction efficiency so that only a portion of the light of the beam is deflected away toward the eye 210 with each intersection of the DOE, while the rest continues to move through a waveguide via TIR. The light carrying the image information is thus divided into a number of related exit beams that exit the waveguide at a multiplicity of locations and the result is a fairly uniform pattern of exit emission toward the eye 210 for this particular collimated beam bouncing around within a waveguide.

[0105] In some embodiments, one or more DOEs may be switchable between “on” states in which they actively diffract, and “off” states in which they do not significantly diffract. For instance, a switchable DOE may comprise a layer of polymer dispersed liquid crystal, in which microdroplets comprise a diffraction pattern in a host medium, and the refractive index of the microdroplets may be switched to substantially match the refractive index of the host material (in which case the pattern does not appreciably diffract incident light) or the microdroplet may be switched to an index that does not match that of the host medium (in which case the pattern actively diffracts incident light).Attorney Docket No. ML-5018WO

[0106] In some embodiments, a camera assembly 630 (e.g., a digital camera, including visible light and infrared light cameras) may be provided to capture images of the eye 210 and / or tissue around the eye 210 to, e.g., detect user inputs and / or to monitor the physiological state of the user. As used herein, a camera may be any image capture device. In some embodiments, the camera assembly 630 may include an image capture device and a light source to project light (e.g., infrared light) to the eye, which may then be reflected by the eye and detected by the image capture device. In some embodiments, the camera assembly 630 may be attached to the frame or support structure 80 (Figure 9E) and may be in electrical communication with the processing modules 140 and / or 150, which may process image information from the camera assembly 630. In some embodiments, one camera assembly 630 may be utilized for each eye, to separately monitor each eye.

[0107] The camera assembly 630 may, in some embodiments, observe movements of the user, such as the user's eye movements. As an example, the camera assembly 630 may capture images of the eye 210 to determine the size, position, and / or orientation of the pupil of the eye 210 (or some other structure of the eye 210). The camera assembly 630 may, if desired, obtain images (processed by processing circuitry of the type described herein) used to determine the direction the user is looking (e.g., eye pose or gaze direction). In some embodiments, camera assembly 630 may include multiple cameras, at least one of which may be utilized for each eye, to separately determine the eye pose or gaze direction of each eye independently. The camera assembly 630 may, in some embodiments and in combination with processing circuitry such as the controller 560 or the local data processing module 140, determine eye pose or gaze direction basedAttorney Docket No. ML-5018WO on glints (e.g., reflections) of reflected light (e.g., infrared light) from a light source included in camera assembly 630.

[0108] With reference now to Figure 7 , an example of exit beams outputted by a waveguide is shown. One waveguide is illustrated, but it will be appreciated that other waveguides in the waveguide assembly 260 (Figure 6 ) may function similarly, where the waveguide assembly 260 includes multiple waveguides. 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 points where the light 640 impinges on the DOE 570, a portion of the light exits the waveguide as exit beams 650. The exit beams 650 are illustrated as substantially parallel but, as discussed herein, they may also be redirected to propagate to the eye 210 at an angle (e.g., forming divergent exit beams), depending on the depth plane associated with the waveguide 270. It will be appreciated that substantially parallel exit beams may be indicative of a waveguide with out-coupling optical elements that out-couple light to form images that appear to be set on a depth plane at a large distance (e.g., optical infinity) from the eye 210. Other waveguides or other sets of out-coupling optical elements may output an exit beam pattern that is more divergent, which would require the eye 210 to accommodate to a closer distance to bring it into focus on the retina and would be interpreted by the brain as light from a distance closer to the eye 210 than optical infinity.

[0109] In some embodiments, a full color image may be formed at each depth plane by overlaying images in each of the component colors, e.g., three or more component colors. Figure 8 illustrates an example of a stacked waveguide assembly in which each depth plane includes images formed using multiple different component colors. TheAttorney Docket No. ML-5018WO illustrated embodiment shows depth planes 240 a-240 f, although more or fewer depths are also contemplated. Each depth plane may have three or more component color images associated with it, including: a first image of a first color, G; a second image of a second color, R; and a third image of a third color, B. Different depth planes are indicated in the figure by different numbers for diopters (dpt) following the letters G, R, and B. Just as examples, the numbers following each of these letters indicate diopters (1 / m), or inverse distance of the depth plane from a viewer, and each box in the figures represents an individual component color image. In some embodiments, to account for differences in the eye's focusing of light of different wavelengths, the exact placement of the depth planes for different component colors may vary. For example, 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 acuity and user comfort and / or may decrease chromatic aberrations.

[0110] In some embodiments, light of each component color may be outputted by a single dedicated waveguide and, consequently, each depth plane may have multiple waveguides associated with it. In such embodiments, each box in the figures including the letters G, R, or B may be understood to represent an individual 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 adjacent to one another in this drawing for ease of description, it will be appreciated that, in a physical device, the waveguides may all be arranged in a stack with one waveguide per level. In some other embodiments, multiple component colors mayAttorney Docket No. ML-5018WO be outputted by the same waveguide, such that, e g., only a single waveguide may be provided per depth plane.

[0111] With continued reference to Figure 8 , in some embodiments, G is the color green, R is the color red, and B is the color blue. In some other embodiments, other colors associated with other wavelengths of light, including magenta and cyan, may be used in addition to or may replace one or more of red, green, or blue.

[0112] It will be appreciated that references to a given color of light throughout this disclosure will be understood to encompass light of one or more wavelengths within a range of wavelengths of light that are perceived by a viewer as being of that given color. For example, red light may include light of one or more wavelengths in the range of about 620-780 nm, green light may include light of one or more wavelengths in the range of about 492-577 nm, and blue light may include light of one or more wavelengths in the range of about 435-493 nm.

[0113] In some embodiments, the light source 530 (Figure 6 ) may be configured to emit light of one or more wavelengths outside the visual perception range of the viewer, for example, infrared and / or ultraviolet wavelengths. In addition, the in-coupling, out-coupling, and other light redirecting structures of the waveguides of the display 250 may be configured to direct and emit this light out of the display towards the user's eye 210, e.g., for imaging and / or user stimulation applications.

[0114] With reference now to Figure 9A, in some embodiments, light impinging on a waveguide may need to be redirected to in-couple that light into the waveguide. An incoupling optical element may be used to redirect and in-couple the light into its corresponding waveguide. Figure 9A illustrates a cross-sectional side view of an exampleAttorney Docket No. ML-5018WO of a plurality or set 660 of stacked waveguides that each includes an in-coupling optical element. The waveguides may each be configured to output light of one or more different wavelengths, or one or more different ranges of wavelengths. It will be appreciated that the stack 660 may correspond to the stack 260 (Figure 6 ) and the illustrated waveguides of the stack 660 may correspond to part 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 waveguides from a position that requires light to be redirected for in-coupling.

[0115] The illustrated set 660 of stacked waveguides includes waveguides 670, 680, and 690. Each waveguide includes an associated in-coupling optical element (which may also be referred to as a light input area on the waveguide), with, e.g., in-coupling optical element 700 disposed on a major surface (e.g., an upper major surface) of waveguide 670, in-coupling optical element 710 disposed on a major surface (e.g., an upper major surface) of waveguide 680, and in-coupling optical element 720 disposed on a major surface (e.g., an upper major surface) of waveguide 690. In some embodiments, one or more of the in-coupling optical elements 700, 710, 720 may be disposed on the bottom major surface of the respective waveguide 670, 680, 690 (particularly where the one or more in-coupling optical elements are reflective, deflecting optical elements). As illustrated, the in-coupling optical elements 700, 710, 720 may be disposed on the upper major surface of their respective waveguide 670, 680, 690 (or the top of the next lower waveguide), particularly where those in-coupling optical elements are transmissive, deflecting optical elements. In some embodiments, the in-coupling optical elements 700, 710, 720 may be disposed in the body of the respective waveguide 670, 680, 690. InAttorney Docket No. ML-5018WO some embodiments, as discussed herein, the in-coupling optical elements 700, 710, 720 are wavelength selective, such that they selectively redirect one or more wavelengths of light, while transmitting other wavelengths of light. While illustrated on one side or corner of their respective waveguide 670, 680, 690, it will be appreciated that the in-coupling optical elements 700, 710, 720 may be disposed in other areas of their respective waveguide 670, 680, 690 in some embodiments.

[0116] As illustrated, the in-coupling optical elements 700, 710, 720 may be laterally offset from one another, as seen in the illustrated head-on view in a direction of light propagating to these in-coupling optical elements. In some embodiments, each incoupling optical element may be offset such that it receives light without that light passing through another in-coupling optical element. For example, each in-coupling optical element 700, 710, 720 may be configured to receive light from a different image injection device 360, 370, 380, 390, and 400 as shown in Figure 6 , and may be separated (e.g., laterally spaced apart) from other in-coupling optical elements 700, 710, 720 such that it substantially does not receive light from the other ones of the in-coupling optical elements 700, 710, 720.

[0117] Each waveguide also includes associated light distributing elements, with, e.g. , light distributing elements 730 disposed on a major surface (e.g., a top major surface) of waveguide 670, light distributing elements 740 disposed on a major surface (e.g., a top major surface) of waveguide 680, and light distributing elements 750 disposed on a major surface (e.g., a top major surface) of waveguide 690. In some other embodiments, the light distributing elements 730, 740, 750, may be disposed on a bottom major surface of associated waveguides 670, 680, 690, respectively. In some other embodiments, theAttorney Docket No. ML-5018WO light distributing elements 730, 740, 750, may be disposed on both top and bottom major surface of associated waveguides 670, 680, 690, respectively; or the light distributing elements 730, 740, 750, may be disposed on different ones of the top and bottom major surfaces in different associated waveguides 670, 680, 690, respectively.

[0118] The waveguides 670, 680, 690 may be spaced apart and separated by, e.g., gas, liquid, and / or solid layers of material. For example, as illustrated, layer 760a may separate waveguides 670 and 680; and layer 760b may separate waveguides 680 and 690. In some embodiments, the layers 760a and 760b are formed of low refractive index materials (that is, materials having a lower refractive index than the material forming the immediately adjacent one of waveguides 670, 680, 690). Preferably, the refractive index of the material forming the layers 760a, 760b is 0.05 or more, or 0.10 or less than the refractive index of the material forming the waveguides 670, 680, 690. Advantageously, the lower refractive index layers 760a, 760b may function as cladding layers that facilitate total internal reflection (TIR) of light through the waveguides 670, 680, 690 (e.g., TIR between the top and bottom major surfaces of each waveguide). In some embodiments, the layers 760a, 760b are formed of air. While not illustrated, it will be appreciated that the top and bottom of the illustrated set 660 of waveguides may include immediately neighboring cladding layers.

[0119] Preferably, for ease of manufacturing and other considerations, the material forming the waveguides 670, 680, 690 are similar or the same, and the material forming the layers 760a, 760b are similar or the same. In some embodiments, the material forming the waveguides 670, 680, 690 may be different between one or moreAttorney Docket No. ML-5018WO waveguides, and / or the material forming the layers 760a, 760b may be different, while still holding to the various refractive index relationships noted above.

[0120] With continued reference to Figure 9A, light rays 770, 780, 790 are incident on the set 660 of waveguides. It will be appreciated that the light rays 770, 780, 790 may be injected into the waveguides 670, 680, 690 by one or more image injection devices 360, 370, 380, 390, 400 (Figure 6 ).

[0121] In some embodiments, the light rays 770, 780, 790 have different properties, e.g., different wavelengths or different ranges of wavelengths, which may correspond to different colors. The in-coupling optical elements 700, 710, 720 each deflect the incident light such that the light propagates through a respective one of the waveguides 670, 680, 690 by TIR. In some embodiments, the in-coupling optical elements 700, 710, 720 each selectively deflect one or more particular wavelengths of light, while transmitting other wavelengths to an underlying waveguide and associated in-coupling optical element.

[0122] For example, in-coupling optical element 700 may be configured to deflect ray 770, which has a first wavelength or range of wavelengths, while transmitting rays 780 and 790, which have different second and third wavelengths or ranges of wavelengths, respectively. The transmitted ray 780 impinges on and is deflected by the in-coupling optical element 710, which is configured to deflect light of a second wavelength or range of wavelengths. The ray 790 is deflected by the in-coupling optical element 720, which is configured to selectively deflect light of third wavelength or range of wavelengths.

[0123] With continued reference to Figure 9A, the deflected light rays 770, 780, 790 are deflected so that they propagate through a corresponding waveguide 670, 680, 690; that is, the in-coupling optical elements 700, 710, 720 of each waveguide deflects lightAttorney Docket No. ML-5018WO into that corresponding waveguide 670, 680, 690 to in-couple light into that corresponding waveguide. The light rays 770, 780, 790 are deflected at angles that cause the light to propagate through the respective waveguide 670, 680, 690 by TIR. The light rays 770, 780, 790 propagate through the respective waveguide 670, 680, 690 by TIR until impinging on the waveguide's corresponding light distributing elements 730, 740, 750.

[0124] With reference now to Figure 9B, a perspective view of an example of the plurality of stacked waveguides of Figure 9A is illustrated. As noted above, the in-coupled light rays 770, 780, 790, are deflected by the in-coupling optical elements 700, 710, 720, respectively, and then propagate by TIR within the waveguides 670, 680, 690, respectively. The light rays 770, 780, 790 then impinge on the light distributing elements 730, 740, 750, respectively. The light distributing elements 730, 740, 750 deflect the light rays 770, 780, 790 so that they propagate towards the out-coupling optical elements 800, 810, 820, respectively.

[0125] In some embodiments, the light distributing elements 730, 740, 750 are orthogonal pupil expanders (OPE's). In some embodiments, the OPE's deflect or distribute light to the out-coupling optical elements 800, 810, 820 and, in some embodiments, may also increase the beam or spot size of this light as it propagates to the out-coupling optical elements. In some embodiments, the light distributing elements 730, 740, 750 may be omitted and the in-coupling optical elements 700, 710, 720 may be configured to deflect light directly to the out-coupling optical elements 800, 810, 820. For example, with reference to Figure 9A, the light distributing elements 730, 740, 750 may be replaced with out-coupling optical elements 800, 810, 820, respectively. In some embodiments, the out-coupling optical elements 800, 810, 820 are exit pupils (EP's) orAttorney Docket No. ML-5018WO exit pupil expanders (EPE's) that direct light in a viewer's eye 210 (Figure 7). It will be appreciated that the OPE's may be configured to increase the dimensions of the eye box in at least one axis and the EPE's may be to increase the eye box in an axis crossing, e.g., orthogonal to, the axis of the OPEs. For example, each OPE may be configured to redirect a portion of the light striking the OPE to an EPE of the same waveguide, while allowing the remaining portion of the light to continue to propagate down the waveguide. Upon impinging 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, upon striking the EPE, a portion of the impinging light is directed out of the waveguide towards the user, and a remaining portion of that light continues to propagate through the waveguide until it strikes the EP again, at which time another portion of the impinging light is directed out of the waveguide, and so on. Consequently, a single beam of in-coupled light may be “replicated” each time a portion of that light is redirected by an OPE or EPE, thereby forming a field of cloned beams of light, as shown in Figure 6. In some embodiments, the OPE and / or EPE may be configured to modify a size of the beams of light.

[0126] Accordingly, with reference to Figures 9A and 9B, in some embodiments, the set 660 of waveguides includes waveguides 670, 680, 690; in-coupling optical elements 700, 710, 720; light distributing elements (e.g., OPE's) 730, 740, 750; and out-coupling optical elements (e.g., EP's) 800, 810, 820 for each component color. The waveguides 670, 680, 690 may be stacked with an air gap / cladding layer between each one. The incoupling optical elements 700, 710, 720 redirect or deflect incident light (with different incoupling optical elements receiving light of different wavelengths) into its waveguide. TheAttorney Docket No. ML-5018WO light then propagates at an angle which will result in TIR within the respective waveguide 670, 680, 690. In the example shown, light ray 770 (e.g., blue light) is deflected by the first in-coupling optical element 700, and then continues to bounce down the waveguide, interacting with the light distributing element (e.g., OPE's) 730 and then the out-coupling optical element (e.g., EPs) 800, in a manner described earlier. The light rays 780 and 790 (e.g., green and red light, respectively) will pass through the waveguide 670, with light ray 780 impinging on and being deflected by in-coupling optical element 710. The light ray 780 then bounces down the waveguide 680 via TIR, proceeding on to its light distributing element (e.g., OPEs) 740 and then the out-coupling optical element (e.g., EP's) 810. Finally, light ray 790 (e.g., red light) passes through the waveguide 690 to impinge on the light in-coupling optical elements 720 of the waveguide 690. The light incoupling optical elements 720 deflect the light ray 790 such that the light ray propagates to light distributing element (e.g., OPEs) 750 by TIR, and then to the out-coupling optical element (e.g., EPs) 820 by TIR. The out-coupling optical element 820 then finally out-couples the light ray 790 to the viewer, who also receives the out-coupled light from the other waveguides 670, 680.

[0127] Figure 9C illustrates a top-down plan view of an example of the plurality of stacked waveguides of Figures 9A and 9B. It will be appreciated that this top-down view may also be referred to as a head-on view, as seen in the direction of propagation of light towards the in-coupling optical elements 800, 810, 820; that is, the top-down view is a view of the waveguides with image light incident normal to the page. As illustrated, the waveguides 670, 680, 690, along with each waveguide's associated light distributing element 730, 740, 750 and associated out-coupling optical element 800, 810, 820, mayAttorney Docket No. ML-5018WO be vertically aligned. However, as discussed herein, the in-coupling optical elements 700, 710, 720 are not vertically aligned; rather, the in-coupling optical elements are preferably non-overlapping (e.g., laterally spaced apart as seen in the top-down view). As discussed further herein, this nonoverlapping spatial arrangement facilitates the injection of light from different sources into different waveguides on a one-to-one basis, thereby allowing a specific light source to be uniquely coupled to a specific waveguide. In some embodiments, arrangements including nonoverlapping spatially-separated in-coupling optical elements may be referred to as a shifted pupil system, and the in-coupling optical elements within these arrangements may correspond to sub-pupils.

[0128] It will be appreciated that the spatially overlapping areas may have lateral overlap of 70% or more, 80% or more, or 90% or more of their areas, as seen in the top-down view. On the other hand, the laterally shifted areas of less than 30% overlap, less than 20% overlap, or less than 10% overlap of their areas, as seen in top-down view. In some embodiments, laterally shifted areas have no overlap.

[0129] Figure 9D illustrates a top-down plan view of another example of a plurality of stacked waveguides. As illustrated, the waveguides 670, 680, 690 may be vertically aligned. However, in comparison to the configuration of Figure 9C, separate light distributing elements 730, 740, 750 and associated out-coupling optical elements 800, 810, 820 are omitted. Instead, light distributing elements and out-coupling optical elements are effectively superimposed and occupy the same area as seen in the top-down view. In some embodiments, light distributing elements (e.g., OPE's) may be disposed on one major surface of the waveguides 670, 680, 690 and out-coupling optical elements (e.g., EPE's) may be disposed on the other major surface of those waveguides.Attorney Docket No. ML-5018WO Thus, each waveguide 670, 680, 690 may have superimposed light distributing and out coupling optical elements, collectively referred to as combined OPE / EPE's 1281, 1282, 1283, respectively. Further details regarding such combined OPE / EPE's may be found in U.S. application Ser. No. 16 / 221,359, filed on Dec. 14, 2018, the entire disclosure of which is incorporated by reference herein. The in-coupling optical elements 700, 710, 720 in-couple and direct light to the combined OPE / EPE's 1281 , 1282, 1283, respectively. In some embodiments, as illustrated, the in-coupling optical elements 700, 710, 720 may be laterally shifted (e.g., they are laterally spaced apart as seen in the illustrated top-down view) in have a shifted pupil spatial arrangement. As with the configuration of Figure 9C, this laterally-shifted spatial arrangement facilitates the injection of light of different wavelengths (e.g., from different light sources) into different waveguides on a one-to-one basis.

[0130] Figure 9E illustrates an example of wearable display system 60 into which the various waveguides and related systems disclosed herein may be integrated. In some embodiments, the display system 60 is the system 250 of Figure 6 , with Figure 6 schematically showing some parts of that system 60 in greater detail. For example, the waveguide assembly 260 of Figure 6 may be part of the display 70.

[0131] With continued reference to Figure 9E, the display system 60 includes a display 70, and various mechanical and electronic modules and systems to support the functioning of that display 70. The display 70 may be coupled to a frame 80, which is wearable by a display system user or viewer 90 and which is configured to position the display 70 in front of the eyes of the user 90. The display 70 may be considered eyewear in some embodiments. The display 70 may include one or more waveguides, such asAttorney Docket No. ML-5018WO the waveguide 270, configured to relay in-coupled image light and to output that image light to an eye of the user 90. In some embodiments, a speaker 100 is coupled to the frame 80 and configured to be positioned adjacent the ear canal of the user 90 (in some embodiments, another speaker, not shown, may optionally be positioned adjacent the other ear canal of the user to provide stereo / shapeable sound control). The display system 60 may 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 inputs or commands to the system 60 (e.g., the selection of voice menu commands, natural language questions, etc.), and / or may allow audio communication with other persons (e.g., with other users of similar display systems. The microphone may further be configured as a peripheral sensor to collect audio data (e.g., sounds from the user and / or environment). In some embodiments, the display system 60 may further include one or more outwardly-directed environmental sensors 112 configured to detect objects, stimuli, people, animals, locations, or other aspects of the world around the user. For example, environmental sensors 112 may include one or more cameras, which may be located, for example, facing outward so as to capture images similar to at least a portion of an ordinary field of view of the user 90. In some embodiments, the display system may also include a peripheral sensor 120 a, which may be separate from the frame 80 and attached to the body of the user 90 (e.g., on the head, torso, an extremity, etc. of the user 90). The peripheral sensor 120 a may be configured to acquire data characterizing a physiological state of the user 90 in some embodiments. For example, the sensor 120 a may be an electrode.Attorney Docket No. ML-5018WO

[0132] With continued reference to Figure 9E, the display 70 is operatively coupled by communications link 130, such as by a wired lead or wireless connectivity, to a local data processing module 140 which may be mounted in a variety of configurations, such as fixedly attached to the frame 80, fixedly attached to a helmet or hat worn by the user, embedded in headphones, or otherwise removably attached to the user 90 (e.g., in a backpack-style configuration, in a belt-coupling style configuration). Similarly, the sensor 120 a may be operatively coupled by communications link 120 b, e.g., a wired lead or wireless connectivity, to the local processor and data module 140. The local processing and data module 140 may comprise a hardware processor, as well as digital memory, such as non-volatile memory (e.g., flash memory or hard disk drives), both of which may be utilized to assist in the processing, caching, and storage of data. Optionally, the local processor and data module 140 may include one or more central processing units (CPUs), graphics processing units (GPUs), dedicated processing hardware, and so on. The data may include data a) captured from sensors (which may be, e.g., operatively coupled to the frame 80 or otherwise attached to the user 90), such as image capture devices (such as cameras), microphones, inertial measurement units, accelerometers, compasses, GPS units, radio devices, gyros, and / or other sensors disclosed herein; and / or b) acquired and / or processed using remote processing module 150 and / or remote data repository 160 (including data relating to virtual content), possibly for passage to the display 70 after such processing or retrieval. The local processing and data module 140 may be operatively coupled by communication links 170, 180, such as via a wired or wireless communication links, to the remote processing module 150 and remote data repository 160 such that these remote modules 150, 160 are operatively coupled to eachAttorney Docket No. ML-5018WO other and available as resources to the local processing and data module 140. In some embodiments, the local processing and data module 140 may include one or more of the image capture devices, microphones, inertial measurement units, accelerometers, compasses, GPS units, radio devices, and / or gyros. In some other embodiments, one or more of these sensors may be attached to the frame 80, or may be standalone structures that communicate with the local processing and data module 140 by wired or wireless communication pathways.

[0133] With continued reference to Figure 9E, in some embodiments, the remote processing module 150 may comprise one or more processors configured to analyze and process data and / or image information, for instance including one or more central processing units (CPUs), graphics processing units (GPUs), dedicated processing hardware, and so on. In some embodiments, the remote data repository 160 may comprise a digital data storage facility, which may be available through the internet or other networking configuration in a “cloud” resource configuration. In some embodiments, the remote data repository 160 may include one or more remote servers, which provide information, e.g., information for generating virtual content, to the local processing and data module 140 and / or the remote processing module 150. In some embodiments, all data is stored and all computations are performed in the local processing and data module, allowing fully autonomous use from a remote module. Optionally, an outside system (e.g., a system of one or more processors, one or more computers) that includes CPUs, GPUs, and so on, may perform at least a portion of processing (e.g., generating image information, processing data) and provide information to, and receive information from, modules 140, 150, 160, for instance via wireless or wired connections.Attorney Docket No. ML-5018WO Illustrative Display Systems

[0134] Figure 10 is a schematic view of a head-mounted display system 1600 according to some embodiments. The head-mounted display system 1600 is configured to present an image to a user. The head-mounted display system 1600 includes a microLED panel 1610, an aspheric lens 1620, a first surface mirror 1630, collimating optics 1640, and an eyepiece 1660. The micro-LED panel 1610 may be an array of micro-LEDs corresponding to pixels of the image the system 1600 presents to a user. The micro-LED panel 1610 outputs image light that defines the image.

[0135] The aspheric lens 1620 receives the image light from the micro-LED panel 1610 and corrects the image light to remove various an aberration / error / distortion therefrom. For instance, the head-mounted display system 1700 depicted in Figure 11 is similar to the head-mounted display system 1600 depicted in Figure 10 except that system 1700 does not include an aspheric lens (see aspheric lens 1620 in Figure 10). With the exception of the missing aspheric lens, the other components of the system 1700 are identical to corresponding components of the system 1600 depicted in Figure 10. The head-mounted display system 1700 includes a micro-LED panel 1710, a first surface mirror 1730, collimating optics 1740, and an eyepiece 1760.

[0136] Figures 12 and 13 are graphs 1800, 1900 illustrating the different relationships between aberrations / errors / distortions and fields of view in the head-mounted display systems 1700, 1600 depicted in Figure 11 and 10, respectively. The X-axes of the graphs 1800, 1900 depict the magnitude of the Zernike coefficients, which are related to wavefront error. The y-axes of the graphs 1800, 1900 depict the field angle in degrees. The graph 1800 in Figure 12 shows that the system 1700 depicted in Figure 11 hasAttorney Docket No. ML-5018WO increasing Zernike coefficient (i.e., wavefront aberration / error / distortion) as the field angle increases. The graph 1900 in Figure 13 demonstrates that the aspheric lens 1620 in the system 1600 depicted in Figure 10, which is the only difference between system 1600 and system 1700, significantly reduces the Zernike coefficient (i.e., wavefront aberration / error / distortion) as the field angle increases. After correcting for the wavefront aberration / error / distortion with the aspheric lens 1620, coma and astigmatism aberrations may remain to be corrected by other components of the system 1600.

[0137] Referring to Figure 10, the first surface mirror 1630 is configured to redirect image light from the aspheric lens 1620 from a first direction to a second direction that is substantially orthogonal (e.g., ± 10° from orthogonal or ± 5° from orthogonal) to the first direction. The first surface mirror 1630 redirecting the image light substantially orthogonally improves compactness of the system 1600.

[0138] The collimating optics 1640 include first and second spherical collimating lenses 1642, 1644. The collimating optics 1640 determine the focal length of the system 1600 and begin focusing the image. Material may be selected for the collimating optics 1640 to achieve a thermal behavior across the operational temperature range of the system 1600. The first spherical collimating lens 1642 may have a positive power and the second spherical collimating lens 1644 may have a negative power. The focal length of the first and second spherical collimating lenses 1642, 1644 may be configured taking into account thermal expansion such that the collimating optics 1640 has the same focal length across the operating temperature range and FOV.

[0139] The folded head-mounted display system 1600 includes an aperture stop 1650 after the collimating optics 1640. From the aperture stop 1650 the image light is inAttorney Docket No. ML-5018WO coupled into the eyepiece 1660 for display of an image formed from the image light to an eye of a user.

[0140] In comparison with the folded head-mounted display system 1600 depicted in Figure 10, Figure 14 is a schematic view of a “linear” head-mounted display system 2000 according to some embodiments. The head-mounted display system 2000 depicted in Figure 14 is similar to the head-mounted display system 1600 depicted in Figure 10 except that system 2000 does not include a first surface mirror (see first surface mirror 1630 in Figure 10). With the exception of the missing first surface mirror, the other components of the system 2000 are identical to corresponding components of the system 1600 depicted in Figure 10. The head-mounted display system 2000 includes a microLED panel 2010, an aspheric lens 2020, collimating optics 2040, and an eyepiece 2060.

[0141] Figures 15 and 16 depicts first and second head-mounted display systems 1600, 2000 and the layouts of same. The first surface mirror 1630 in system 1600 (see Figure 10) redirects the image light approximately 90° thereby facilitating a “folded” display system design. As shown in Figures 15 and 16, a length of the folded headmounted display system 1600 is less than a length of the linear head-mounted display system 2000. Figure 15 also shows that the micro-LED panel 1610 in the folded headmounted display system 1600 is moved approximately perpendicular to the micro-LED panel 2010 in the linear head-mounted display system 2000. Moving the micro-LED panel 1610 to an outer edge of the folded head-mounted display system 1600 optimizes a layout of the electronics as described below and reduces the overall footprint of the system 1600, thereby reducing the size and weight of the system 1600.Attorney Docket No. ML-5018WO

[0142] In the embodiment depicted in Figure 16, the folded head-mounted display system 1600 has a length of 8.4 mm compared to a length of the linear head-mounted display system 2000, which is 10 mm. Figure 16 also shows that the folded headmounted display system 1600 depicted in Figure 10 utilizes the space in the headmounted display system more efficiently by mounting a power management integrated circuit (PMIC) 1670 at an angle in a space behind the first surface mirror 1630 and minimizing the use of flex extenders. Accordingly, the folded head-mounted display system 1600 has more efficient mechanical and electrical packaging compared to the linear head-mounted display system 2000.

[0143] Figure 17 is a table 2300 summarizing various characteristics of linear and folded head-mounted display systems 2000, 1600 depicted in Figures 14 and 10, respectively. Figure 17 illustrates that the folded head-mounted display system summarized in Figure 17 achieves a length reduction from 10.24 mm to 5.62 mm compared to the linear head-mounted display system summarized in Figure 17. Figure 17 also shows that the folded head-mounted display system achieves this length reduction while maintaining identical focal length and field of view (FOV) as the linear head-mounted display system summarized in Figure 17. In some embodiments, a folded head-mounted display system can achieve a 45% reduction in overall length compared to a linear head-mounted display system having the same optical path length and FOV.

[0144] Figure 18 is a schematic view of a folded head-mounted display system 2400 according to some embodiments. The head-mounted display system 2400 depicted in Figure 18 is similar to the head-mounted display system 1600 depicted in Figure 10 except that system 2400 does includes a light redirecting prism 2430 instead of a firstAttorney Docket No. ML-5018WO surface mirror (see first surface mirror 1630 in Figure 10). With the exception of the substituted prism 2430, the other components of the system 2400 are identical to corresponding components of the system 1600 depicted in Figure 10. The head-mounted display system 2400 includes a micro-LED panel 2410, an aspheric lens 2420, a light redirecting prism 2430, collimating optics 2440, and an eyepiece 2460. The light redirecting prism 2430 is a second surface light redirecting optical component.

[0145] Reducing the size of the folded head-mounted display system 1600 reduces its weight compared to the linear head-mounted display system 1100. Further, using a first surface mirror 1630 instead of a heavier light redirecting prism 2430 reduces its weight compared to the folded head-mounted display system 2400.

[0146] Mounting the PMIC 1670 on the backside of the first surface mirror 1630 as shown in Figure 16 instead of a prism, also increases the airspace surrounding the light redirecting optical component (i.e., first surface mirror 1630), thereby increasing passive cooling of the heat generated by the PMIC 1670. Heat generated by the PMIC can also increase aberrations / errors / distortions in folded head-mounted display systems including light redirecting prisms because prisms utilize both refraction and reflection.

[0147] Figure 19 is a schematic view depicting a first surface mirror 2500 for use with head-mounted display systems according to some embodiments. The first surface mirror 2500 includes a substrate 2510 and a coating 2520 disposed on a first surface 2502 of the substrate 2510. The coating 2520 can be configured to optimize performance of the display system incorporating the first surface mirror 2500. Examples of coatings 2520 include, but are not limited to, spectral filtering coatings, polarization control coatings, and apodizing filter coatings.Attorney Docket No. ML-5018WO

[0148] Figure 20A and 20B are schematic views depicting a light redirecting prism 2600 for use with head-mounted display systems according to some embodiments. Figure 20A shows that the light redirecting prism 2600 is a second surface mirror. Figure 20B shows that the light redirecting prism 2600 includes a substrate 2610, a coating 2620 disposed on a second surface 2604 of the substrate 2610, and a protective layer 2630 disposed on the coating 2620. The coating 2620 applied to the second surface 2604 of the light redirecting prism 2600 may have variable optical effect due to the adhesion layers in the coating 2620 that may cause unknown phase effects resulting in unpredictable and inconsistent optical performance. Figure 20B, also shows that light redirecting prisms 2600 may reflect an incoming light beam 2640 twice resulting in primary and secondary reflected light beams 2642, 2644 and ghosting.

[0149] Figure 21 is a schematic view depicting a first surface mirror 2700 for use with head-mounted display systems according to some embodiments. The first surface mirror 2700 includes a substrate 2710, an adhesion or base coating 2720 disposed on a first surface 2702 of the substrate 2710, and a coating 2730 disposed on the adhesion or base coating 2720. The adhesion or base coating 2720 improves bonding of the coating 2732 the substrate 2710. The coating 2730 can be configured to optimize performance of the display system incorporating the first surface mirror 2700. Examples of coatings 2730 include, but are not limited to, spectral filtering coatings, polarization control coatings, and apodizing filter coatings.

[0150] Figure 22 is a schematic view depicting a light redirecting prism 2800 for use with head-mounted display systems according to some embodiments. The light redirecting prism 2800 is a second surface mirror. The light redirecting prism 2800Attorney Docket No. ML-5018WO includes a substrate 2810, an adhesion or base coating 2820 disposed on a second surface 2804 of the substrate 2810, and a coating 2830 disposed on the adhesion or base coating 2820. The light redirecting prism 2800 uses total internal reflection that may not allow as effective spectral selection and separation control when used with a specialized coating compared to the first surface mirror 1600 in Figure 21. Further, light redirecting prisms 2800 may reflect an incoming light beam 2840 twice resulting in primary and secondary reflected light beams 2842, 2844 and ghosting.

[0151] Figure 23 is a cross-sectional schematic view of a folded head-mounted display system 2900 according to some embodiments. The folded head-mounted display system 2900 is very similar to the folded head-mounted display system 1600 depicted in Figure 10. The head-mounted display system 2900 includes a micro-LED panel (not shown), an aspheric lens 2920, a first surface mirror 2930, collimating optics 2940, and an eyepiece (not shown). Figure 23 also depicts a housing 2980 for holding the optical components. The housing 2980 includes side walls 2982 having inner side surfaces that, together with an inner surface of the aspheric lens 2920, a first surface 2932 of the first surface mirror 2930, and an inner surface of the collimating optics 2940 define a front space 2984. A light absorbing coating can be applied to the inner side surfaces of the side walls 2982 to minimize stray light entering the optical light path. The first surface mirror 2930 also includes a second surface 2934 opposite of the first surface 2932.

[0152] Figure 24 is a detailed cross-sectional schematic view of a head-mounted display system 3000 according to some embodiments. The head-mounted display system 3000 includes an aspheric lens 3020 similar to the aspheric lenses describedAttorney Docket No. ML-5018WO herein. The head-mounted display system 3000 also includes an annular baffle 3022 configured to further minimize stray light entering the optical light path.

[0153] Figure 25 is a chart 3100 schematically depicting stray light in head-mounted display systems according to some embodiments. The top row of the chart 3100 depicts reduction in stray light in a linear head-mounted display system as various light absorbing coatings are applied to inner surfaces of the system. The middle row of the chart 3100 depicts reduction in stray light in a folded head-mounted display system as various surfaces finishes and light absorbing coatings are applied to inner surfaces of the system. The bottom row of the chart 3100 depicts reduction in a stray light ring in a folded headmounted display system compared to the middle row as the baffle 3022 is added to the display system 3000 as shown in shown in Figure 24.

[0154] Figure 26 schematically depicts a folded head-mounted display system 3200 having a light redirecting prism 3230 according to some embodiments. The light redirecting prism 3230 includes side walls 3236 that result in internal specular reflection or scattering of light resulting in unacceptable levels of stray light entering the light path. Figure 27 schematically depicts stray light in folded head-mounted display systems system 3300 such as the one schematically depicted in Figure 26.System Architecture Overview

[0155] Figure 28 is a block diagram of an illustrative computing system 3400 suitable for implementing an embodiment of the present disclosure. Computer system 3400 includes a bus 3406 or other communication mechanism for communicating information, which interconnects subsystems and devices, such as processor 3407, system memory 3408 (e.g., RAM), static storage device 3409 (e.g., ROM), disk drive 3410 (e.g., magneticAttorney Docket No. ML-5018WO or optical), communication interface 3414 (e g., modem or Ethernet card), display 3411 (e.g., CRT or LCD), input device 3412 (e.g., keyboard), and cursor control.

[0156] According to one embodiment of the disclosure, computer system 3400 performs specific operations by processor 3407 executing one or more sequences of one or more instructions contained in system memory 3408. Such instructions may be read into system memory 3408 from another computer readable / usable medium, such as static storage device 3409 or disk drive 3410. In alternative embodiments, hard-wired circuitry may be used in place of or in combination with software instructions to implement the disclosure. Thus, embodiments of the disclosure are not limited to any specific combination of hardware circuitry and / or software. In one embodiment, the term “logic” shall mean any combination of software or hardware that is used to implement all or part of the disclosure.

[0157] The term “computer readable medium” or “computer usable medium” as used herein refers to any medium that participates in providing instructions to processor 3407 for execution. Such a medium may take many forms, including but not limited to, nonvolatile media and volatile media. Non-volatile media includes, for example, optical or magnetic disks, such as disk drive 3410. Volatile media includes dynamic memory, such as system memory 3408.

[0158] Common forms of computer readable media includes, for example, floppy disk, flexible disk, hard disk, magnetic tape, any other magnetic medium, CD-ROM, any other optical medium, punch cards, paper tape, any other physical medium with patterns of holes, RAM, PROM, EPROM, FLASH-EPROM (e.g., NAN D flash, NOR flash), any other memory chip or cartridge, or any other medium from which a computer can read.Attorney Docket No. ML-5018WO

[0159] In an embodiment of the disclosure, execution of the sequences of instructions to practice the disclosure is performed by a single computer system 3400. According to other embodiments of the disclosure, two or more computer systems 3400 coupled by communication link 3415 (e.g., LAN, PTSN, or wireless network) may perform the sequence of instructions required to practice the disclosure in coordination with one another.

[0160] Computer system 3400 may transmit and receive messages, data, and instructions, including program, i.e., application code, through communication link 3415 and communication interface 3414. Received program code may be executed by processor 3407 as it is received, and / or stored in disk drive 3410, or other non-volatile storage for later execution. Database 3432 in storage medium 3431 may be used to store data accessible by system 3400 via data interface 3433.

[0161] While certain embodiments have been explicitly described, other embodiments will become apparent to those of ordinary skill in the art based on this disclosure.

[0162] The above-described VR / AR / MR systems are provided as examples of various optical systems that can benefit from first surface mirrors. Accordingly, use of the optical systems described herein is not limited to the disclosed VR / AR / MR systems, but rather applicable to any optical system.

[0163] Certain aspects, advantages and features of the disclosure have been described herein. It is to be understood that not necessarily all such advantages may be achieved in accordance with any particular embodiment of the disclosure. Thus, the disclosure may be embodied or carried out in a manner that achieves or optimizes oneAttorney Docket No. ML-5018WO advantage or group of advantages as taught herein without necessarily achieving other advantages as may be taught or suggested herein.

[0164] Embodiments have been described in connection with the accompanying drawings. However, it should be understood that the figures are not drawn to scale. Distances, angles, etc. are merely illustrative and do not necessarily bear an exact relationship to actual dimensions and layout of the devices illustrated. In addition, the foregoing embodiments have been described at a level of detail to allow one of ordinary skill in the art to make and use the devices, systems, methods, and the like described herein. A wide variety of variation is possible. Components, elements, and / or steps may be altered, added, removed, or rearranged.

[0165] The devices and methods described herein can advantageously be at least partially implemented using, for example, computer software, hardware, firmware, or any combination of software, hardware, and firmware. Software modules can include computer executable code, stored in a computer’s memory, for performing the functions described herein. In some embodiments, computer-executable code is executed by one or more general purpose computers. However, a skilled artisan will appreciate, in light of this disclosure, that any module that can be implemented using software to be executed on a general purpose computer can also be implemented using a different combination of hardware, software, or firmware. For example, such a module can be implemented completely in hardware using a combination of integrated circuits. Alternatively or additionally, such a module can be implemented completely or partially using specialized computers designed to perform the particular functions described herein rather than by general purpose computers. In addition, where methods are described that are, or couldAttorney Docket No. ML-5018WO be, at least in part carried out by computer software, it should be understood that such methods can be provided on non-transitory computer-readable media that, when read by a computer or other processing device, cause it to carry out the method.

[0166] While certain embodiments have been explicitly described, other embodiments will become apparent to those of ordinary skill in the art based on this disclosure.

[0167] The various processors and other electronic components described herein are suitable for use with any optical system for projecting light. The various processors and other electronic components described herein are also suitable for use with any audio system for receiving voice commands.

[0168] Various exemplary embodiments of the disclosure are described herein. Reference is made to these examples in a non-limiting sense. They are provided to illustrate more broadly applicable aspects of the disclosure. Various changes may be made to the disclosure described and equivalents may be substituted without departing from the true spirit and scope of the disclosure. In addition, many modifications may be made to adapt a particular situation, material, composition of matter, process, process act(s) or step(s) to the objective(s), spirit or scope of the present disclosure. Further, as will be appreciated by those with skill in the art, each of the individual variations described and illustrated herein has discrete components and features which may be readily separated from or combined with the features of any of the other several embodiments without departing from the scope or spirit of the present disclosure. All such modifications are intended to be within the scope of claims associated with this disclosure.

[0169] The disclosure includes methods that may be performed using the subject devices. The methods may include the act of providing such a suitable device. SuchAttorney Docket No. ML-5018WO provision may be performed by the end user. In other words, the “providing” act merely requires the end user obtain, access, approach, position, set-up, activate, power-up or otherwise act to provide the requisite device in the subject method. Methods recited herein may be carried out in any order of the recited events which is logically possible, as well as in the recited order of events.

[0170] Exemplary aspects of the disclosure, together with details regarding material selection and manufacture have been set forth above. As for other details of the present disclosure, these may be appreciated in connection with the above-referenced patents and publications as well as generally known or appreciated by those with skill in the art. The same may hold true with respect to method-based aspects of the disclosure in terms of additional acts as commonly or logically employed.

[0171] In addition, though the disclosure has been described in reference to several examples optionally incorporating various features, the disclosure is not to be limited to that which is described or indicated as contemplated with respect to each variation of the disclosure. Various changes may be made to the disclosure described and equivalents (whether recited herein or not included for the sake of some brevity) may be substituted without departing from the true spirit and scope of the disclosure. In addition, where a range of values is provided, it is understood that every intervening value, between the upper and lower limit of that range and any other stated or intervening value in that stated range, is encompassed within the disclosure.

[0172] Also, it is contemplated that any optional feature of the variations described may be set forth and claimed independently, or in combination with any one or more of the features described herein. Reference to a singular item, includes the possibility thatAttorney Docket No. ML-5018WO there are plural of the same items present. More specifically, as used herein and in claims associated hereto, the singular forms “a,” “an,” “said,” and “the” include plural referents unless the specifically stated otherwise. In other words, use of the articles allow for “at least one” of the subject item in the description above as well as claims associated with this disclosure. It is further noted that such claims may be drafted to exclude any optional element. As such, this statement is intended to serve as antecedent basis for use of such exclusive terminology as “solely,” “only” and the like in connection with the recitation of claim elements, or use of a “negative” limitation.

[0173] Without the use of such exclusive terminology, the term “comprising” in claims associated with this disclosure shall allow for the inclusion of any additional element- irrespective of whether a given number of elements are enumerated in such claims, or the addition of a feature could be regarded as transforming the nature of an element set forth in such claims. Except as specifically defined herein, all technical and scientific terms used herein are to be given as broad a commonly understood meaning as possible while maintaining claim validity.

[0174] The breadth of the present disclosure is not to be limited to the examples provided and / or the subject specification, but rather only by the scope of claim language associated with this disclosure.

[0175] In the foregoing specification, the disclosure has been described with reference to specific embodiments thereof. It will, however, be evident that various modifications and changes may be made thereto without departing from the broader spirit and scope of the disclosure. For example, the above-described process flows are described with reference to a particular ordering of process actions. However, the ordering of many ofAttorney Docket No. ML-5018WO the described process actions may be changed without affecting the scope or operation of the disclosure. The specification and drawings are, accordingly, to be regarded in an illustrative rather than restrictive sense.

Claims

Attorney Docket No. ML-5018WO Claims1. A head-mounted display system, comprising:an emissive micro-display comprising an array of light emitters corresponding to pixels, wherein the array of light emitters is configured to output image light that defines images;an aspheric lens configured to receive the image light from the emissive microdisplay and correct the image light;a first surface mirror configured to redirect the image light from the aspheric lens from a first direction to a second direction substantially orthogonal to the first direction;a collimating optic configured to receive the image light from the first surface mirror and collimate the image light; andan eyepiece configured to receive the image light from the collimating optic and to direct the image light to an eye of a user.

2. The system of claim 1 , wherein the second direction is orthogonal to the first direction.

3. The system of claims 1 or 2, wherein correcting the image light comprises removing an aberration / error / distortion from the image light to shape the image light into a spherical wavefront.

4. The system of claim 3, wherein the an aberration / error / distortion is selected from the group consisting of wavefront, coma, and astigmatism.Attorney Docket No. ML-5018WO5. The system of any of claims 1 to 4, wherein the first surface mirror maintains a wavefront of the image light when redirecting the image light.

6. The system of any of claims 1 to 5, wherein the collimating optic comprises a first collimating lens and a second collimating lens.

7. The system of claim 6, wherein the first collimating lens have a positive power, andwherein the second collimating lens have a negative power.

8. The system of claims 6 or 7, wherein the first and second collimating lens are spherical lenses.

9. The system of any of claims 1 to 8, wherein the system has an optical path length and a field of view, andwherein the first surface mirror is configured to reduce a length of the system by approximately 45% compared to a straight head-mounted display system having the optical path length and the field of view.

10. The system of any of claims 1 to 9, wherein the system has a field of view, andAttorney Docket No. ML-5018WO wherein the first surface mirror is configured to reduce a weight of the system compared to a head-mounted display system having a light redirecting prism and the field of view.

11. The system of any of claims 1 to 10, further comprising a power management integrated circuit (PMIC) configured to control the emissive micro-display.

12. The system of claim 11, wherein the first surface mirror has a first surface facing the aspheric lens and the collimating optic, and a second surface opposite the first surface.

13. The system of claim 12, wherein the first surface mirror comprises a coating disposed on the first surface of the first surface mirror.

14. The system of claim 13, wherein the coating is selected from the group consisting of a spectral filtering coating, a polarization control coating, and an apodizing filter coating.

15. The system of any of claims 12 to 14, wherein the system comprises a back wall having an inner back surface defining a back space with the second surface of the first surface mirror.Attorney Docket No. ML-5018WO 16. The system of claim 15, wherein the PMIC is disposed on the inner back surface of the back wall in the back space, andwherein the back space is configured to dissipate heat generated by the PMIC.

17. The system of any of claims 12 to 16, wherein the system comprises a side wall having an inner side surface defining a front space with the first surface of the first surface mirror, an inner surface of the aspheric lens, and an inner surface of the collimating optic.

18. The system of claim 17, further comprising a light absorbing coating disposed on the inner side surface of the side wall in the front space.

19. The system of claims 17 or 18, further comprising a baffle disposed adjacent the inner surface of the aspheric lens in the front space.

20. The system of any of claims 1 to 19, wherein the first surface mirror is configured to reduce stray light in the system compared to a head-mounted display system having a light redirecting prism.

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