Patent Description:
Modern computing and display technologies have facilitated the development of systems for so called "virtual reality" or "augmented reality" experiences, wherein 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 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 are integrated into, and responsive to, the natural world. For example, in an MR scenario, AR image content may be blocked by or otherwise be perceived as interacting with objects in the real world.

Referring to <FIG>, an augmented reality scene <NUM> is depicted wherein a user of an AR technology sees a real-world park-like setting <NUM> featuring people, trees, buildings in the background, and a concrete platform <NUM>. In addition to these items, the user of the AR technology also perceives that he "sees" "virtual content" such as a robot statue <NUM> standing upon the real-world platform <NUM>, and a cartoon-like avatar character <NUM> flying by which seems to be a personification of a bumble bee, even though these elements <NUM>, <NUM> do not exist in the real world. Because the human visual perception system is complex, it is challenging to produce an AR technology that facilitates a comfortable, natural-feeling, rich presentation of virtual image elements amongst other virtual or real-world imagery elements.

<CIT> discloses an augmented reality display system comprising a frame configured to mount on the wearer, an augmented reality display attached to the frame and configured to direct images to an eye of the wearer, a light source configured to illuminate the surrounding environment, a light sensor configured to image the surrounding environment illuminated by the light source using the invisible light, and processing circuitry configured to analyze the image of the surrounding environment in order to detect orders by a user and provide corresponding instructions. This augmented reality display system is focused on detecting movements of a user in order to control electronic systems.

Systems and methods disclosed herein address various challenges related to AR and VR technology.

The invention is directed to an augmented reality display system according to claim <NUM>.

Any subsequent augmented reality display system configured to align 3D content with a real object not comprising skin of a wearer of the augmented reality display system or of a person other than the wearer does not form part of the claimed invention. Reference will now be made to the figures, in which like reference numerals refer to like parts throughout. It will be appreciated that embodiments disclosed herein include optical systems, including display systems, generally. In some embodiments, the display systems are wearable, which may advantageously provide a more immersive VR or AR experience. For example, displays containing one or more waveguides (e.g., a stack of waveguides) may be configured to be worn positioned in front of the eyes of a user, or viewer. In some embodiments, two stacks of waveguides, one for each eye of a viewer, may be utilized to provide different images to each eye.

<FIG> illustrates an example of wearable display system <NUM>. The display system <NUM> includes a display <NUM>, and various mechanical and electronic modules and systems to support the functioning of that display <NUM>. The display <NUM> may be coupled to a frame <NUM>, which is wearable by a display system user or viewer <NUM> and which is configured to position the display <NUM> in front of the eyes of the user <NUM>. The display <NUM> may be considered eyewear in some embodiments. In some embodiments, a speaker <NUM> is coupled to the frame <NUM> and configured to be positioned adjacent the ear canal of the user <NUM> (in some embodiments, another speaker, not shown, is positioned adjacent the other ear canal of the user to provide stereo/shapeable sound control). In some embodiments, the display system may also include one or more microphones <NUM> 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 <NUM> (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 may also include a peripheral sensor 120a, which may be separate from the frame <NUM> and attached to the body of the user <NUM> (e.g., on the head, torso, an extremity, etc. of the user <NUM>). The peripheral sensor 120a may be configured to acquire data characterizing the physiological state of the user <NUM> in some embodiments. For example, the sensor 120a may be an electrode.

With continued reference to <FIG>, the display <NUM> is operatively coupled by communications link <NUM>, such as by a wired lead or wireless connectivity, to a local data processing module <NUM> which may be mounted in a variety of configurations, such as fixedly attached to the frame <NUM>, fixedly attached to a helmet or hat worn by the user, embedded in headphones, or otherwise removably attached to the user <NUM> (e.g., in a backpack-style configuration, in a belt-coupling style configuration). Similarly, the sensor 120a may be operatively coupled by communications link 120b, e.g., a wired lead or wireless connectivity, to the local processor and data module <NUM>. The local processing and data module <NUM> 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. The data include data a) captured from sensors (which may be, e.g., operatively coupled to the frame <NUM> or otherwise attached to the user <NUM>), 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 <NUM> and/or remote data repository <NUM> (including data relating to virtual content), possibly for passage to the display <NUM> after such processing or retrieval. The local processing and data module <NUM> may be operatively coupled by communication links <NUM>, <NUM>, such as via a wired or wireless communication links, to the remote processing module <NUM> and remote data repository <NUM> such that these remote modules <NUM>, <NUM> are operatively coupled to each other and available as resources to the local processing and data module <NUM>. In some embodiments, the local processing and data module <NUM> 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 <NUM>, or may be standalone structures that communicate with the local processing and data module <NUM> by wired or wireless communication pathways.

With continued reference to <FIG>, in some embodiments, the remote processing module <NUM> may comprise one or more processors configured to analyze and process data and/or image information. In some embodiments, the remote data repository <NUM> 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 <NUM> may include one or more remote servers, which provide information, e.g., information for generating augmented reality content, to the local processing and data module <NUM> and/or the remote processing module <NUM>. 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.

The perception of an image as being "three-dimensional" or "<NUM>-D" may be achieved by providing slightly different presentations of the image to each eye of the viewer. <FIG> illustrates a conventional display system for simulating three-dimensional imagery for a user. Two distinct images <NUM>, <NUM>-one for each eye <NUM>, <NUM>-are outputted to the user. The images <NUM>, <NUM> are spaced from the eyes <NUM>, <NUM> by a distance <NUM> along an optical or z-axis that is parallel to the line of sight of the viewer. The images <NUM>, <NUM> are flat and the eyes <NUM>, <NUM> may focus on the images by assuming a single accommodated state. Such <NUM>-D display systems rely on the human visual system to combine the images <NUM>, <NUM> to provide a perception of depth and/or scale for the combined image.

It will be appreciated, however, that the human visual system is more complicated and providing a realistic perception of depth is more challenging. For example, many viewers of conventional "<NUM>-D" display systems find such systems to be uncomfortable or may not perceive a sense of depth at all. 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. Vergence movements (i.e., 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 focusing (or "accommodation") of the lenses and pupils of the eyes. Under normal conditions, changing the focus of the lenses of the eyes, or accommodating 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," as well as pupil dilation or constriction. Likewise, a change in vergence will trigger a matching change in accommodation of lens shape and pupil size, under normal conditions. As noted herein, many stereoscopic or "<NUM>-D" display systems display a scene using slightly different presentations (and, so, slightly different images) to each eye such that a three-dimensional perspective is perceived by the human visual system. Such systems are uncomfortable for many viewers, however, since they, among other things, simply provide a different presentation of a scene, but with the eyes viewing all the image information at a single accommodated state, and work against the "accommodation-vergence reflex. " Display systems that provide a better match between accommodation and vergence may form more realistic and comfortable simulations of three-dimensional imagery contributing to increased duration of wear and in turn compliance to diagnostic and therapy protocols.

<FIG> illustrates aspects of an approach for simulating three-dimensional imagery using multiple depth planes. With reference to <FIG>, objects at various distances from eyes <NUM>, <NUM> on the z-axis are accommodated by the eyes <NUM>, <NUM> so that those objects are in focus. The eyes <NUM>, <NUM> assume particular accommodated states to bring into focus objects at different distances along the z-axis. Consequently, a particular accommodated state may be said to be associated with a particular one of depth planes <NUM>, with has an associated focal distance, such that objects or parts of objects in a particular depth plane are in focus when the eye is in the accommodated state for that depth plane. In some embodiments, three-dimensional imagery may be simulated by providing different presentations of an image for each of the eyes <NUM>, <NUM>, and also by providing different presentations of the image corresponding to each of the depth planes. While shown as being separate for clarity of illustration, it will be appreciated that the fields of view of the eyes <NUM>, <NUM> may overlap, for example, as distance along the z-axis increases. In addition, while shown as flat for ease of illustration, it will be appreciated that the contours of a depth plane may be curved in physical space, such that all features in a depth plane are in focus with the eye in a particular accommodated state.

The distance between an object and the eye <NUM> or <NUM> may also change the amount of divergence of light from that object, as viewed by that eye. <FIG> illustrate relationships between distance and the divergence of light rays. The distance between the object and the eye <NUM> is represented by, in order of decreasing distance, R1, R2, and R3. As shown in <FIG>, the light rays become more divergent as distance to the object decreases. 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 <NUM>. Consequently, at different depth planes, the degree of divergence of light rays is also different, with the degree of divergence increasing with decreasing distance between depth planes and the viewer's eye <NUM>. While only a single eye <NUM> is illustrated for clarity of illustration in <FIG> and other figures herein, it will be appreciated that the discussions regarding eye <NUM> may be applied to both eyes <NUM> and <NUM> of a viewer.

Without being limited by theory, it is believed that the human eye typically can interpret a finite number of depth planes to provide depth perception. Consequently, a 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 number of depth planes. The different presentations may be separately focused by the viewer's eyes, thereby helping to provide the user with depth cues based on the accommodation of the eye required to bring into focus different image features for the scene located on different depth plane and/or based on observing different image features on different depth planes being out of focus.

<FIG> illustrates an example of a waveguide stack for outputting image information to a user. A display system <NUM> includes a stack of waveguides, or stacked waveguide assembly, <NUM> that may be utilized to provide three-dimensional perception to the eye/brain using a plurality of waveguides <NUM>, <NUM>, <NUM>, <NUM>, <NUM>. In some embodiments, the display system <NUM> is the system <NUM> of <FIG>, with <FIG> schematically showing some parts of that system <NUM> in greater detail. For example, the waveguide assembly <NUM> may be part of the display <NUM> of <FIG>. It will be appreciated that the display system <NUM> may be considered a light field display in some embodiments.

With continued reference to <FIG>, the waveguide assembly <NUM> may also include a plurality of features <NUM>, <NUM>, <NUM>, <NUM> between the waveguides. In some embodiments, the features <NUM>, <NUM>, <NUM>, <NUM> may be one or more lenses. The waveguides <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and/or the plurality of lenses <NUM>, <NUM>, <NUM>, <NUM> 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 <NUM>, <NUM>, <NUM>, <NUM>, <NUM> may function as a source of light for the waveguides and may be utilized to inject image information into the waveguides <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, each of which may be configured, as described herein, to distribute incoming light across each respective waveguide, for output toward the eye <NUM>. Light exits an output surface <NUM>, <NUM>, <NUM>, <NUM>, <NUM> of the image injection devices <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and is injected into a corresponding input surface <NUM>, <NUM>, <NUM>, <NUM>, <NUM> of the waveguides <NUM>, <NUM>, <NUM>, <NUM>, <NUM>. In some embodiments, the each of the input surfaces <NUM>, <NUM>, <NUM>, <NUM>, <NUM> 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 <NUM> or the viewer's eye <NUM>). 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 <NUM> 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 <NUM>, <NUM>, <NUM>, <NUM>, <NUM> may be associated with and inject light into a plurality (e.g., three) of the waveguides <NUM>, <NUM>, <NUM>, <NUM>, <NUM>.

In some embodiments, the image injection devices <NUM>, <NUM>, <NUM>, <NUM>, <NUM> are discrete displays that each produce image information for injection into a corresponding waveguide <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, respectively. In some other embodiments, the image injection devices <NUM>, <NUM>, <NUM>, <NUM>, <NUM> 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 <NUM>, <NUM>, <NUM>, <NUM>, <NUM>. It will be appreciated that the image information provided by the image injection devices <NUM>, <NUM>, <NUM>, <NUM>, <NUM> may include light of different wavelengths, or colors (e.g., different component colors, as discussed herein).

In some embodiments, the light injected into the waveguides <NUM>, <NUM>, <NUM>, <NUM>, <NUM> is provided by a light projector system <NUM>, which comprises a light module <NUM>, which may include a light emitter, such as a light emitting diode (LED). The light from the light module <NUM> may be directed to and modified by a light modulator <NUM>, e.g., a spatial light modulator, via a beam splitter <NUM>. The light modulator <NUM> may be configured to change the perceived intensity of the light injected into the waveguides <NUM>, <NUM>, <NUM>, <NUM>, <NUM>. Examples of spatial light modulators include liquid crystal displays (LCD) including a liquid crystal on silicon (LCOS) displays.

In some embodiments, the display system <NUM> 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 <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and ultimately to the eye <NUM> of the viewer. In some embodiments, the illustrated image injection devices <NUM>, <NUM>, <NUM>, <NUM>, <NUM> 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 <NUM>, <NUM>, <NUM>, <NUM>, <NUM>. In some other embodiments, the illustrated image injection devices <NUM>, <NUM>, <NUM>, <NUM>, <NUM> 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 <NUM>, <NUM>, <NUM>, <NUM>, <NUM>. It will be appreciated that one or more optical fibers may be configured to transmit light from the light module <NUM> to the one or more waveguides <NUM>, <NUM>, <NUM>, <NUM>, <NUM>. 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 <NUM>, <NUM>, <NUM>, <NUM>, <NUM> to, e.g., redirect light exiting the scanning fiber into the one or more waveguides <NUM>, <NUM>, <NUM>, <NUM>, <NUM>.

A controller <NUM> controls the operation of one or more of the stacked waveguide assembly <NUM>, including operation of the image injection devices <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, the light source <NUM>, and the light modulator <NUM>. In some embodiments, the controller <NUM> is part of the local data processing module <NUM>. The controller <NUM> includes programming (e.g., instructions in a non-transitory medium) that regulates the timing and provision of image information to the waveguides <NUM>, <NUM>, <NUM>, <NUM>, <NUM> according to, e.g., any of the various schemes disclosed herein. In some embodiments, the controller may be a single integral device, or a distributed system connected by wired or wireless communication channels. The controller <NUM> may be part of the processing modules <NUM> or <NUM> (<FIG>) in some embodiments.

With continued reference to <FIG>, the waveguides <NUM>, <NUM>, <NUM>, <NUM>, <NUM> may be configured to propagate light within each respective waveguide by total internal reflection (TIR). The waveguides <NUM>, <NUM>, <NUM>, <NUM>, <NUM> 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 <NUM>, <NUM>, <NUM>, <NUM>, <NUM> may each include out-coupling optical elements <NUM>, <NUM>, <NUM>, <NUM>, <NUM> 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 <NUM>. 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 <NUM>, <NUM>, <NUM>, <NUM>, <NUM> may, for example, be gratings, including diffractive optical features, as discussed further herein. While illustrated disposed at the bottom major surfaces of the waveguides <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, for ease of description and drawing clarity, in some embodiments, the out-coupling optical elements <NUM>, <NUM>, <NUM>, <NUM>, <NUM> may be disposed at the top and/or bottom major surfaces, and/or may be disposed directly in the volume of the waveguides <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, as discussed further herein. In some embodiments, the out-coupling optical elements <NUM>, <NUM>, <NUM>, <NUM>, <NUM> may be formed in a layer of material that is attached to a transparent substrate to form the waveguides <NUM>, <NUM>, <NUM>, <NUM>, <NUM>. In some other embodiments, the waveguides <NUM>, <NUM>, <NUM>, <NUM>, <NUM> may be a monolithic piece of material and the out-coupling optical elements <NUM>, <NUM>, <NUM>, <NUM>, <NUM> may be formed on a surface and/or in the interior of that piece of material.

With continued reference to <FIG>, as discussed herein, each waveguide <NUM>, <NUM>, <NUM>, <NUM>, <NUM> is configured to output light to form an image corresponding to a particular depth plane. For example, the waveguide <NUM> nearest the eye may be configured to deliver collimated light (which was injected into such waveguide <NUM>), to the eye <NUM>. The collimated light may be representative of the optical infinity focal plane. The next waveguide up <NUM> may be configured to send out collimated light which passes through the first lens <NUM> (e.g., a negative lens) before it can reach the eye <NUM>; such first lens <NUM> may be configured to create a slight convex wavefront curvature so that the eye/brain interprets light coming from that next waveguide up <NUM> as coming from a first focal plane closer inward toward the eye <NUM> from optical infinity. Similarly, the third up waveguide <NUM> passes its output light through both the first <NUM> and second <NUM> lenses before reaching the eye <NUM>; the combined optical power of the first <NUM> and second <NUM> lenses may be configured to create another incremental amount of wavefront curvature so that the eye/brain interprets light coming from the third waveguide <NUM> 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 <NUM>.

The other waveguide layers <NUM>, <NUM> and lenses <NUM>, <NUM> are similarly configured, with the highest waveguide <NUM> in the stack sending its output through all of the lenses between it and the eye for an aggregate focal power representative of the closest focal plane to the person. To compensate for the stack of lenses <NUM>, <NUM>, <NUM>, <NUM> when viewing/interpreting light coming from the world <NUM> on the other side of the stacked waveguide assembly <NUM>, a compensating lens layer <NUM> may be disposed at the top of the stack to compensate for the aggregate power of the lens stack <NUM>, <NUM>, <NUM>, <NUM> 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.

In some embodiments, two or more of the waveguides <NUM>, <NUM>, <NUM>, <NUM>, <NUM> may have the same associated depth plane. For example, multiple waveguides <NUM>, <NUM>, <NUM>, <NUM>, <NUM> may be configured to output images set to the same depth plane, or multiple subsets of the waveguides <NUM>, <NUM>, <NUM>, <NUM>, <NUM> may be configured to output images set to the same plurality of depth planes, with one set for each depth plane. This can provide advantages for forming a tiled image to provide an expanded field of view at those depth planes.

With continued reference to <FIG>, the out-coupling optical elements <NUM>, <NUM>, <NUM>, <NUM>, <NUM> 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 <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, which output light with a different amount of divergence depending on the associated depth plane. In some embodiments, the light extracting optical elements <NUM>, <NUM>, <NUM>, <NUM>, <NUM> may be volumetric or surface features, which may be configured to output light at specific angles. For example, the light extracting optical elements <NUM>, <NUM>, <NUM>, <NUM>, <NUM> may be volume holograms, surface holograms, and/or diffraction gratings. In some embodiments, the features <NUM>, <NUM>, <NUM>, <NUM> may not be lenses; rather, they may simply be spacers (e.g., cladding layers and/or structures for forming air gaps).

In some embodiments, the out-coupling optical elements <NUM>, <NUM>, <NUM>, <NUM>, <NUM> 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 <NUM> 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 <NUM> for this particular collimated beam bouncing around within a waveguide.

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).

In some embodiments, a camera assembly <NUM> (e.g., a digital camera, including visible light and infrared light cameras) may be provided to capture images of the eye <NUM> and/or tissue around the eye <NUM> 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 <NUM> 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 <NUM> may be attached to the frame <NUM> (<FIG>) and may be in electrical communication with the processing modules <NUM> and/or <NUM>, which may process image information from the camera assembly <NUM> to make various determinations regarding, e.g., the physiological state of the user, as discussed herein. It will be appreciated that information regarding the physiological state of user may be used to determine the behavioral or emotional state of the user. Examples of such information include movements of the user and/or facial expressions of the user. The behavioral or emotional state of the user may then be triangulated with collected environmental and/or virtual content data so as to determine relationships between the behavioral or emotional state, physiological state, and environmental or virtual content data. In some embodiments, one camera assembly <NUM> may be utilized for each eye, to separately monitor each eye.

With reference now to <FIG>, 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 <NUM> (<FIG>) may function similarly, where the waveguide assembly <NUM> includes multiple waveguides. Light <NUM> is injected into the waveguide <NUM> at the input surface <NUM> of the waveguide <NUM> and propagates within the waveguide <NUM> by TIR. At points where the light <NUM> impinges on the DOE <NUM>, a portion of the light exits the waveguide as exit beams <NUM>. The exit beams <NUM> are illustrated as substantially parallel but, as discussed herein, they may also be redirected to propagate to the eye <NUM> at an angle (e.g., forming divergent exit beams), depending on the depth plane associated with the waveguide <NUM>. 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 <NUM>. 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 <NUM> 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 <NUM> than optical infinity.

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. <FIG> illustrates an example of a stacked waveguide assembly in which each depth plane includes images formed using multiple different component colors. The illustrated embodiment shows depth planes 240a - 240f, although more or fewer depths are also contemplated. Each depth plane may have three or more component color images associated 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 (<NUM>/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.

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 may be outputted by the same waveguide, such that, e.g., only a single waveguide may be provided per depth plane.

With continued reference to <FIG>, 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. In some embodiments, features <NUM>, <NUM>, <NUM>, and <NUM> may be active or passive optical filters configured to block or selectively light from the ambient environment to the viewer's eyes.

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 <NUM>-<NUM>, green light may include light of one or more wavelengths in the range of about <NUM>-<NUM>, and blue light may include light of one or more wavelengths in the range of about <NUM>-<NUM>.

In some embodiments, the light source <NUM> (<FIG>) 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 <NUM> may be configured to direct and emit this light out of the display towards the user's eye <NUM>, e.g., for imaging and/or user stimulation applications.

With reference now to <FIG>, in some embodiments, light impinging on a waveguide may need to be redirected to in-couple that light into the waveguide. An in-coupling optical element may be used to redirect and in-couple the light into its corresponding waveguide. <FIG> illustrates a cross-sectional side view of an example of a plurality or set <NUM> 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 <NUM> may correspond to the stack <NUM> (<FIG>) and the illustrated waveguides of the stack <NUM> may correspond to part of the plurality of waveguides <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, except that light from one or more of the image injection devices <NUM>, <NUM>, <NUM>, <NUM>, <NUM> is injected into the waveguides from a position that requires light to be redirected for in-coupling.

The illustrated set <NUM> of stacked waveguides includes waveguides <NUM>, <NUM>, and <NUM>. 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 <NUM> disposed on a major surface (e.g., an upper major surface) of waveguide <NUM>, in-coupling optical element <NUM> disposed on a major surface (e.g., an upper major surface) of waveguide <NUM>, and in-coupling optical element <NUM> disposed on a major surface (e.g., an upper major surface) of waveguide <NUM>. In some embodiments, one or more of the in-coupling optical elements <NUM>, <NUM>, <NUM> may be disposed on the bottom major surface of the respective waveguide <NUM>, <NUM>, <NUM> (particularly where the one or more in-coupling optical elements are reflective, deflecting optical elements). As illustrated, the in-coupling optical elements <NUM>, <NUM>, <NUM> may be disposed on the upper major surface of their respective waveguide <NUM>, <NUM>, <NUM> (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 <NUM>, <NUM>, <NUM> may be disposed in the body of the respective waveguide <NUM>, <NUM>, <NUM>. In some embodiments, as discussed herein, the in-coupling optical elements <NUM>, <NUM>, <NUM> 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 <NUM>, <NUM>, <NUM>, it will be appreciated that the in-coupling optical elements <NUM>, <NUM>, <NUM> may be disposed in other areas of their respective waveguide <NUM>, <NUM>, <NUM> in some embodiments.

As illustrated, the in-coupling optical elements <NUM>, <NUM>, <NUM> may be laterally offset from one another. In some embodiments, each in-coupling 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 <NUM>, <NUM>, <NUM> may be configured to receive light from a different image injection device <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> as shown in <FIG>, and may be separated (e.g., laterally spaced apart) from other in-coupling optical elements <NUM>, <NUM>, <NUM> such that it substantially does not receive light from the other ones of the in-coupling optical elements <NUM>, <NUM>, <NUM>.

Each waveguide also includes associated light distributing elements, with, e.g., light distributing elements <NUM> disposed on a major surface (e.g., a top major surface) of waveguide <NUM>, light distributing elements <NUM> disposed on a major surface (e.g., a top major surface) of waveguide <NUM>, and light distributing elements <NUM> disposed on a major surface (e.g., a top major surface) of waveguide <NUM>. In some other embodiments, the light distributing elements <NUM>, <NUM>, <NUM>, may be disposed on a bottom major surface of associated waveguides <NUM>, <NUM>, <NUM>, respectively. In some other embodiments, the light distributing elements <NUM>, <NUM>, <NUM>, may be disposed on both top and bottom major surface of associated waveguides <NUM>, <NUM>, <NUM>, respectively; or the light distributing elements <NUM>, <NUM>, <NUM>, may be disposed on different ones of the top and bottom major surfaces in different associated waveguides <NUM>, <NUM>, <NUM>, respectively.

The waveguides <NUM>, <NUM>, <NUM> 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 <NUM> and <NUM>; and layer 760b may separate waveguides <NUM> and <NUM>. 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 <NUM>, <NUM>, <NUM>). Preferably, the refractive index of the material forming the layers 760a, 760b is <NUM> or more, or <NUM> or less than the refractive index of the material forming the waveguides <NUM>, <NUM>, <NUM>. Advantageously, the lower refractive index layers 760a, 760b may function as cladding layers that facilitate TIR of light through the waveguides <NUM>, <NUM>, <NUM> (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 <NUM> of waveguides may include immediately neighboring cladding layers.

Preferably, for ease of manufacturing and other considerations, the material forming the waveguides <NUM>, <NUM>, <NUM> 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 <NUM>, <NUM>, <NUM> may be different between one or more waveguides, and/or the material forming the layers 760a, 760b may be different, while still holding to the various refractive index relationships noted above.

With continued reference to <FIG>, light rays <NUM>, <NUM>, <NUM> are incident on the set <NUM> of waveguides. It will be appreciated that the light rays <NUM>, <NUM>, <NUM> may be injected into the waveguides <NUM>, <NUM>, <NUM> by one or more image injection devices <NUM>, <NUM>, <NUM>, <NUM>, <NUM> (<FIG>).

In some embodiments, the light rays <NUM>, <NUM>, <NUM> have different properties, e.g., different wavelengths or different ranges of wavelengths, which may correspond to different colors. Light rays <NUM>, <NUM>, <NUM> may also be laterally displaced to different locations corresponding to the lateral locations of in-coupling optical elements <NUM>, <NUM>, <NUM>. The in-coupling optical elements <NUM>, <NUM>, <NUM> each deflect the incident light such that the light propagates through a respective one of the waveguides <NUM>, <NUM>, <NUM> by TIR.

For example, in-coupling optical element <NUM> may be configured to deflect ray <NUM>, which has a first wavelength or range of wavelengths. Similarly, the transmitted ray <NUM> impinges on and is deflected by the in-coupling optical element <NUM>, which is configured to deflect light of a second wavelength or range of wavelengths. Likewise, the ray <NUM> is deflected by the in-coupling optical element <NUM>, which is configured to selectively deflect light of third wavelength or range of wavelengths.

With continued reference to <FIG>, the deflected light rays <NUM>, <NUM>, <NUM> are deflected so that they propagate through a corresponding waveguide <NUM>, <NUM>, <NUM>; that is, the in-coupling optical elements <NUM>, <NUM>, <NUM> of each waveguide deflects light into that corresponding waveguide <NUM>, <NUM>, <NUM> to in-couple light into that corresponding waveguide. The light rays <NUM>, <NUM>, <NUM> are deflected at angles that cause the light to propagate through the respective waveguide <NUM>, <NUM>, <NUM> by TIR, and thus be guided therein. For example, deflection of light rays <NUM>, <NUM>, <NUM> may be caused by one or more reflective, diffractive, and/or holographic optical elements, such as a holographic, diffractive, and/or reflective turning feature, reflector, or mirror. Deflection may in some cases be caused by microstructure such as diffractive features in one or more gratings, and/or holographic and/or diffractive optical elements configured to turn or redirect light, for example, so as to be guided with the light guide. The light rays <NUM>, <NUM>, <NUM> propagate through the respective waveguide <NUM>, <NUM>, <NUM> by TIR, being guided therein until impinging on the waveguide's corresponding light distributing elements <NUM>, <NUM>, <NUM>.

With reference now to <FIG>, a perspective view of an example of the plurality of stacked waveguides of <FIG> is illustrated. As noted above, the in-coupled light rays <NUM>, <NUM>, <NUM>, are deflected by the in-coupling optical elements <NUM>, <NUM>, <NUM>, respectively, and then propagate by TIR and are guided within the waveguides <NUM>, <NUM>, <NUM>, respectively. The guided light rays <NUM>, <NUM>, <NUM> then impinge on the light distributing elements <NUM>, <NUM>, <NUM>, respectively. The light distributing elements <NUM>, <NUM>, <NUM> may comprise one or more reflective, diffractive, and/or holographic optical elements, such as a holographic, diffractive, and/or reflective turning feature, reflector, or mirror. Deflection may in some cases be caused by microstructure such as diffractive features in one or more gratings, and/or holographic and/or diffractive optical elements configured to turn or redirect light, for example, so as to be guided with the light guide. The light rays <NUM>, <NUM>, <NUM> propagate through the respective waveguide <NUM>, <NUM>, <NUM> by TIR being guided therein until impinging on the waveguide's corresponding light distributing elements <NUM>, <NUM>, <NUM>, where they are deflected, however, in a manner so that the light rays <NUM>, <NUM>, <NUM> are still guided within the waveguide. The light distributing elements <NUM>, <NUM>, <NUM> deflect the light rays <NUM>, <NUM>, <NUM> so that they propagate towards the out-coupling optical elements <NUM>, <NUM>, <NUM>, respectively.

The out-coupling optical elements <NUM>, <NUM>, <NUM> are configured to direct light guided within the waveguide, e.g., the light rays <NUM>, <NUM>, <NUM>, out of the waveguide and toward the viewer's eye. The out-coupling optical elements <NUM>, <NUM>, <NUM> may be configured therefore to deflect and redirect the light guided within the waveguide, e.g., light rays <NUM>, <NUM>, <NUM>, at a more normal angle with respect to the surfaces of the waveguide so as to reduce the effects of total internal reflection (TIR) such that light is not guided within the waveguide but instead exits therefrom. Moreover, these out-coupling optical elements <NUM>, <NUM>, <NUM> may be configured to deflect and redirect this this light, e.g., light rays <NUM>, <NUM>, <NUM>, toward the viewer's eye. Accordingly, the out-coupling optical elements <NUM>, <NUM>, <NUM> may comprise one or more reflective, diffractive, and/or holographic optical elements, such as a holographic, diffractive, and/or reflective turning feature, reflector, or mirror. Deflection may in some cases be caused by microstructure such as diffractive features in one or more gratings, and/or holographic and/or diffractive optical elements configured to turn or redirect light, for example, so as to be guided with the light guide. The optical elements <NUM>, <NUM>, <NUM> may be configured to reflect, deflect, and/or diffract the light rays <NUM>, <NUM>, <NUM> so that they propagate out of the waveguide toward the users eye.

In some embodiments, the light distributing elements <NUM>, <NUM>, <NUM> are orthogonal pupil expanders (OPE's). In some embodiments, the OPE's both deflect or distribute light to the out-coupling optical elements <NUM>, <NUM>, <NUM> and also replicate the beam or beams to form a larger number of beams which propagate to the out-coupling optical elements. As a beam travels along the OPE's, a portion of the beam may be split from the beam and travel in a direction orthogonal to the beam, in the direction of out-coupling optical elements <NUM>, <NUM>, <NUM>. Orthogonal splitting of the beam in the OPE's may occur repeatedly along the path of the beam through the OPE's. For example, OPE's may include a grating having an increasing reflectance along the beam path such that a series of substantially uniform beamlets are produced from a single beam. In some embodiments, the out-coupling optical elements <NUM>, <NUM>, <NUM> are exit pupils (EP's) or exit pupil expanders (EPE's) that direct light in a viewer's eye <NUM> (<FIG>). The OPE's may be configured to increase the dimensions of the eye box, for example, along the x direction, and the EPE's may be to increase the eye box in an axis crossing, for example, orthogonal to, the axis of the OPE's, e.g., along the y direction.

Accordingly, with reference to <FIG> and <FIG>, in some embodiments, the set <NUM> of waveguides includes waveguides <NUM>, <NUM>, <NUM>; in-coupling optical elements <NUM>, <NUM>, <NUM>; light distributing elements (e.g., OPE's) <NUM>, <NUM>, <NUM>; and out-coupling optical elements (e.g., EPE's) <NUM>, <NUM>, <NUM> for each component color. The waveguides <NUM>, <NUM>, <NUM> may be stacked with an air gap and/or cladding layer between each one. The in-coupling optical elements <NUM>, <NUM>, <NUM> redirect or deflect incident light (with different in-coupling optical elements receiving light of different wavelengths) into its respective waveguide. The light then propagates at an angle which will result in TIR within the respective waveguide <NUM>, <NUM>, <NUM>, and the light is guided therein. In the example shown, light ray <NUM> (e.g., blue light) is deflected by the first in-coupling optical element <NUM>, and then continues to propagate within the waveguide being guided therein, interacting with the light distributing element (e.g., OPE's) <NUM> where it is replicated into a plurality of rays propagating to the out-coupling optical element (e.g., EPE's) <NUM>, in a manner described earlier. The light rays <NUM> and <NUM> (e.g., green and red light, respectively) will pass through the waveguide <NUM>, with light ray <NUM> impinging on and being deflected by in-coupling optical element <NUM>. The light ray <NUM> then bounces down the waveguide <NUM> via TIR, proceeding on to its light distributing element (e.g., OPE's) <NUM> where it is replicated into a plurality of rays propagating to the out-coupling optical element (e.g., EPE's) <NUM>. Finally, light ray <NUM> (e.g., red light) passes through the waveguide <NUM> to impinge on the light in-coupling optical elements <NUM> of the waveguide <NUM>. The light in-coupling optical elements <NUM> deflect the light ray <NUM> such that the light ray propagates to light distributing element (e.g., OPE's) <NUM> by TIR, where it is replicated into a plurality of rays propagating to to the out-coupling optical element (e.g., EPE's) <NUM> by TIR. The out-coupling optical element <NUM> then finally further replicates and out-couples the light rays <NUM> to the viewer, who also receives the out-coupled light from the other waveguides <NUM>, <NUM>.

<FIG> illustrates a top-down plan view (or front view) of an example of the plurality of stacked waveguides of <FIG> and <FIG>. As illustrated, the waveguides <NUM>, <NUM>, <NUM>, along with each waveguide's associated light distributing element <NUM>, <NUM>, <NUM> and associated out-coupling optical element <NUM>, <NUM>, <NUM>, may be vertically aligned (e.g., along the x and y directions). However, as discussed herein, the in-coupling optical elements <NUM>, <NUM>, <NUM> are not vertically aligned; rather, the in-coupling optical elements are preferably non-overlapping (e.g., laterally spaced apart along the x direction as seen in the top-down view of front view in this example). Shifting in other directions, such as the y direction, can also be employed. This non-overlapping spatial arrangement facilitates the injection of light from different resources such as different light sources and/or displays 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 non-overlapping laterally-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.

In addition to coupling light out of the waveguides, the out-coupling optical elements <NUM>, <NUM>, <NUM> may cause the light to be collimated or to diverge as if the light originated from an object at a far distance or a closer distance, depth, or depth plane. Collimated light, for example, is consistent with light from an object that is far from the view. Increasing diverging light is consistent with light from an object that is closer, for example, <NUM>-<NUM> feet or <NUM>-<NUM> feet, in front of the viewer. The natural lens of the eye will accommodate when viewing an object closer to the eye and the brain may sense this accommodation, which also then serves as a depth cue. Likewise, by causing the light to be diverging by a certain amount, the eye will accommodate and perceive the object to be at closer distance. Accordingly, the out-coupling optical elements <NUM>, <NUM>, <NUM> can be configured to cause the light to be collimated or to diverge as if the light emanated from a far or close distance, depth, or depth plane. To do so, the out-coupling optical elements <NUM>, <NUM>, <NUM> may include optical power. For example, the out-coupling optical elements <NUM>, <NUM>, <NUM>, may include holographic, diffractive, and/or reflective optical elements that in addition to deflecting or re-directing the light out of the waveguides, these holographic, diffractive, and/or reflective optical elements may further include optical power to cause the light to be collimated or diverging. The out-coupling optical elements <NUM>, <NUM>, <NUM> may in the alternative or in addition include refracting surfaces that include optical power that cause the light to be collimated or diverging. The out-coupling optical elements <NUM>, <NUM>, <NUM> may therefore comprise, for example, in addition to diffractive or holographic turning features, a refractive surface the provides optical power. Such refractive surface may also be included in addition to the out-coupling optical elements <NUM>, <NUM>, <NUM>, for example, on top of the out-coupling optical elements <NUM>, <NUM>, <NUM>. In certain embodiments, for example, optical elements, for example, diffractive optical element, holographic optical elements, refractive lens surfaces, or other structures may be disposed with respect to the out-coupling optical elements <NUM>, <NUM>, <NUM> to provide the optical power cause the collimation or divergence of the light. A layer with optical power such as a layer with a refractive surface or a layer with diffractive and/or holographic features may for example be disposed with respect to the out-coupling optical elements <NUM>, <NUM>, <NUM> to additionally provide optical power. A combination of contributions from both the out-coupling optical elements <NUM>, <NUM>, <NUM> having optical power and an additional layer with optical power such as a layer with a refractive surface or a layer with diffractive and/or holographic features is also possible.

In various implementations, the augmented reality systems and methods described herein can be used to render virtual content, such as virtual objects, that appear to interact with real objects in the world around the wearer. A depth sensor is used to map the world around the wearer and/or body parts of the wearer, and the augmented reality system can render 3D virtual content, such as an object or graphic, onto a real object detected in the world. In one example, the virtual content can be a virtual watch rendered on the wrist of the wearer. Thus, while the wearer of the head mounted augmented reality device is not wearing a real watch, the virtual watch displayed to the wearer through a display of the device can appear to be located on the wearer's wrist. In another example not being part of the invention, the virtual content can be a graphic design for display on a real object, such as a logo or advertising content to be displayed on the side of a coffee cup.

The location of the real object associated with the virtual content is tracked by a depth sensor. The virtual content can be displayed in a location determined based on the location of the real object. For example, as a wearer moves the wrist associated with a virtual watch, the device can change the location of the virtual watch as displayed to the wearer such that the watch continues to appear to be on the wearer's wrist. However, existing depth sensors may be unable to detect the orientation of the real object associated with the virtual content. For example, if the wearer's wrist or the coffee cup described above rotates, the information from the depth sensor may be insufficient to allow the system to distinguish different symmetric or nearly symmetric orientations of the real object. Thus, while a depth sensor can detect the location of the real object, the systems described herein uses secondary tracking of features (sometimes referred to herein as landmarks or fiducial features) of real objects to identify a more precise location and/or orientation information that the depth sensors cannot detect.

Various systems and methods described herein may allow an augmented reality display system to track the location and the orientation of objects based on light reflective and/or scattering properties of visible or invisible markers at or near the surface of the object. In some example embodiments, an augmented reality display system tracks the position of the object using a depth sensor, identify a feature at the surface of the object, and determine an orientation of the object based on the location of the feature relative to the object. The feature (sometimes referred to herein as a fiducial feature or fiducial) is a preexisting feature of the object, such that the orientation of the object can be tracked without separately applying an additional marker for the purpose of orientation tracking. As will be described in greater detail, the feature or fiducial may be detected using invisible light, such as in the infrared or ultraviolet range. The fiducial or feature may be a background feature, such as a birthmark on a wrist, or an invisible feature, such as one or more veins on a wrist, arm, or hand.

Reference will now be made to <FIG>, which shows a schematic view of various components of an example augmented reality display system <NUM> configured to track the location and orientation of real objects as described herein. In some embodiments, the augmented reality display system may be a mixed reality display system. As shown, the augmented reality display system <NUM> includes a frame <NUM> at least partially enclosing left and right waveguide stacks <NUM>, <NUM> configured to deliver augmented reality content to the left and right eyes <NUM>, <NUM> of a wearer of the augmented reality display system <NUM>. The system further includes a depth sensor <NUM>, light sources <NUM>, and light detectors <NUM>. A tracking system <NUM> can include a processing module <NUM> which can control and/or analyze data received from the depth sensor <NUM>, light detectors <NUM>, and/or light sources <NUM>. Depth sensor <NUM>, light detectors <NUM>, and/or light sources <NUM> can communicate with the processing module <NUM> through data links <NUM>, <NUM>.

Depth sensor <NUM> can be configured to detect the shape and location of various objects in the world around the wearer. For example, objects detected by the depth sensor <NUM> can include walls, furniture, and other items in a room surrounding the wearer, other people or animals in the vicinity of the wearer, outdoor objects such as trees, bushes, automobiles, buildings, and the like, and/or parts of the wearer's body, such as arms, hands, legs and feet. In various embodiments, the depth sensor may be effective at mapping objects at a range of distances between <NUM> meters and <NUM> meters from the wearer, <NUM> meter to <NUM> meters, up to <NUM> meters, or any other range. The depth sensor can be an optical depth sensor configured to determine depth using infrared light, visible light, or the like. In various embodiments, the depth sensor may include one or more of a laser source, a laser rangefinder, a camera, an ultrasonic range finder, or other distance sensing, imaging and/or mapping devices.

Light detectors <NUM> can be configured to detect one or more of infrared light, visible light, ultraviolet light, or other range of electromagnetic radiation. Similarly, light sources <NUM> may be configured to emit one or more of infrared light, visible light, ultraviolet light, or other range of electromagnetic radiation. In some embodiments, at least a portion of the spectrum emitted by the light sources <NUM> will be detectable by light detectors <NUM>. In some designs, light sources <NUM> can be mounted on a gimbal or other movable mounting such that the direction of the emitted radiation can be controlled independent of the orientation of the augmented reality display device <NUM>. Light detectors <NUM> can be imaging devices, such as cameras, configured to obtain images of light in at least a portion of the wearer's field of view. In various embodiments, each light detector <NUM> can be a camera and may comprise a two-dimensional array of light sensors. In some example embodiments, light sources <NUM> are configured to emit infrared light within a specified wavelength range, and light detectors <NUM> comprise infrared sensors or infrared light detectors configured to obtain an infrared image using the infrared light reflected by an object within the field of view of the light detectors <NUM>.

In some cases, features not prominent in visible light create discernable features when illuminated with invisible light such as infrared light or ultraviolet light. Veins, for example, that may not be as resolvable to the eye may be clearly resolvable by an infrared camera upon infrared illumination. Such veins may be used as fiducials to identify and track the movement of the object, its translation and/or changes in orientation. Accordingly, illuminating the object with light such as invisible light may cause otherwise invisible features to be detected by cameras or imaging sensors. Movement of these features, which may be referred to as fiducials (or the difference signature as described more fully below), may permit movement of the object to be tracked, for example, so that placement of virtual content with respect to the moving object can be properly placed. Although veins are used as one example, other features may be observable with illumination such as infrared illumination using infrared detectors. For example, other features of the skin may reflect or absorb IR light (or UV light) so as to create a feature, marker or fiducial, that can be tracked with a camera sensitive to the suitable wavelength(s) (e.g., an IR sensor), so as to track the movement of the object, including rotation or change in orientation of the object. With the movement and change in orientation of the object known, the virtual content can be accurately positioned and oriented. Such virtual content, which is designed to follow the object or to have a fixed location and/or orientation with respect to the object, can be appropriately rendered. Similarly, the proper perspectives of the virtual content can be provided. Although infrared and ultraviolet light have been discussed in the examples above, other wavelengths of light or electromagnetic radiation, both visible and invisible, can be used.

In some cases, the illumination may comprise a pattern, such as a grid or array. Additionally, the images of the pattern projected onto the surface may be compared to the emitted pattern of light by the processing module <NUM> to determine a difference between the emitted and reflected light. Likewise, the processing module <NUM> can be configured to identify a difference that is locally unique within the image. A locally unique difference may be caused by a portion of the real object having a reflectivity different from the surrounding area. For example, a birthmark, mole, vein, scar tissue, or other structure of an arm or hand may have different a reflectance different from the reflectance of surrounding tissue in the imaged wavelength range (e.g., infrared or UV). Thus, if a region of scar tissue is present in the area that is irradiated and imaged, the light difference between the emitted and reflected radiation distributions can include an anomalous region in the shape of the scar tissue region. Such features, referred to herein as the difference signature, can be used to track the object so that virtual content can be properly located and oriented with respect to the object.

Referring jointly to <FIG> and <FIG>, an example method <NUM> of tracking the location and/or orientation of a 3D object using detected features will now be described. The method <NUM> may be implemented by any of the systems described herein, such as the wearable augmented reality display systems <NUM>, <NUM> depicted in <FIG> and <FIG>. The method <NUM> begins at block <NUM>, where virtual content is received. In one example, the virtual content can be a 3D rendering of a watch, which may function as a virtual watch visible to the wearer of the augmented reality display system <NUM>. The system <NUM> also receives a location of the virtual content relative to a detected real object. For example, the system <NUM> may detect the wearer's wrist using depth sensor <NUM>, either automatically or based on an indication by the wearer. A location for the virtual watch may be determined automatically or may be indicated by the wearer, such as by a gesture or using any suitable input device. For example, the wearer may select a position of the virtual watch such that the virtual watch appears to be disposed around the wearer's wrist like a real-world wristwatch. In another example, the virtual content may be a virtual name tag or item identifier, an advertising graphic to be displayed on a real object such as a coffee cup, or any other type of virtual content intended to behave as though affixed to a real object. Once a desired location of the virtual content is determined relative to the real object, the relative location may be selected, registered, or otherwise finalized. After the virtual content and its location relative to a real object are received, the method <NUM> continues to block <NUM>.

At block <NUM>, the system <NUM> emits a radiation pattern and determines a difference between the images of the pattern projected on the object. This difference may depend on and be indicative of the structural features of the real object. The difference may, for example, be indicative of variations of absorption, reflectivity, and/or scattering due to structural variations of the object. This difference may be used as a fiducial, difference signature or markers to track movement and/or changes in orientation. A radiation pattern may be emitted by the light sources <NUM>, a light pattern, such as a textured light field, a grid, or a series of dots, crosses, circles, (e.g. concentric circles or contours) or other patterns. Although patterns such as grids are discussed above, the illumination may also comprise substantially uniform illumination or a spot of any shape (e.g., circular, square, etc.), and still a difference signature or marker may be obtained. The emitted radiation pattern comprises invisible light such as infrared light, ultraviolet light, or any other suitable wavelength or range of wavelengths. In some embodiments, an invisible wavelength range such as infrared or ultraviolet may be desirable to avoid distracting the wearer or others by projecting a visible light pattern or visible light. The direction of the radiation pattern may be selected such that at least a portion of the radiation pattern is incident on the surface of the real object. For example, in some configurations, the light source is movable, such as via a gimbal mount or other rotational stages and/or stages that can be tilted. In some embodiments, the radiation may be projected onto a location immediately adjacent to the received location of the virtual object. In the example implementation of a virtual watch, the radiation may be projected onto the back of the wearer's hand or onto the wearer's forearm adjacent to the location of the virtual watch. In other embodiments, the radiation may be projected onto a location spaced from the location of the virtual object.

After the radiation pattern is emitted, a portion of the emitted radiation can be reflected back to the augmented reality display system <NUM> by the real object. Some of the emitted radiation may be reflected by an outer surface or an interior structure below the surface of the object. For example, if the radiation pattern is an infrared light pattern directed at the arm or hand of a user, a portion of the infrared light can be reflected by the outer skin surface, an interior region of the skin, and/or veins or other structures beneath the skin. The reflected portion of the radiation pattern may be detected at light detectors <NUM>. For example, the light sources <NUM> may be infrared sources emitting an infrared radiation pattern, and the light detectors <NUM> may be infrared cameras configured to obtain images in the infrared spectrum. Thus, when a portion of the emitted radiation pattern is reflected to the display system <NUM>, the light detectors <NUM> can obtain an image of the reflected light pattern.

To determine the light difference signature, the image of the reflected light pattern can be compared to the distribution of the emitted radiation pattern. Determination of a light difference signature can occur at processing module <NUM> or any other local or remote processing circuitry associated with the augmented reality display system <NUM>. The processing module <NUM> can look for a unique difference between the emitted and reflected light patterns that can be used as a landmark, marker, or fiducial. If a unique difference is found between the emitted and reflected light patterns, the difference can be stored and a light difference signature or marker recorded. In some cases, a unique difference may be caused by a portion of the real object having a reflectivity different from the surrounding area, e.g., a birthmark, mole, vein, scar tissue, or other structure of an arm or hand. For example, if a region of scar tissue is present in the area that is irradiated and imaged, the light difference between the emitted and reflected radiation distributions can include an anomalous region in the shape of the scar tissue region that can serve as a landmark or difference signature. (Because various types of biological tissue, such as skin, fat, oxygenated blood, deoxygenated blood, etc., may have different infrared absorbance and scattering properties, the radiation pattern may include multiple wavelengths of light in case a unique difference cannot be detected at a first wavelength. ) If a detectable and/or locally unique subregion of the light difference is found between the emitted and reflected light patterns, this difference can be stored as a light difference signature. If a unique difference that can be used as a landmark or fiducial is not found after comparing the emitted and reflected light patterns, block <NUM> can be repeated by emitting the radiation pattern to a different position on the real object, for example, a location adjacent to a different part of the virtual object location and/or spaced slightly further from the virtual object location. If a unique difference that can be used as a landmark is identified and stored as a light difference signature or marker, the method <NUM> continues to block <NUM>.

At block <NUM>, the location of the virtual content is determined relative to the light difference signature, a landmark or "difference marker". A location of the light difference signature or landmark or difference marker can serve as a reference point for rendering the virtual content. A displacement can then be determined for the virtual object relative to the reference point. For example, the displacement can include coordinates in one or more dimensions. In some embodiments, the displacement can be a location within a two-dimensional or three-dimensional coordinate system having an origin at the reference point. Thus, when the same light difference signature or marker or landmark is detected again, the virtual content can be rendered at the same location relative to the light difference signature, marker, or landmark.

In some implementations, the light difference signature, marker, or landmark may further be associated with a physical reference point in the real world detectable by the depth sensor <NUM>. The physical reference point may be a feature of the real object, such as a finger or a wrist bone in the virtual watch example described herein. Similar to the location of the virtual object relative to the light difference signature, marker, or landmark, the location of the light difference signature, marker, or landmark relative to the physical reference point can include coordinates in one or more dimensions. The displacements between the virtual object and the light difference marker, or landmark and between the physical reference point and the light difference marker, or landmark can be recorded in the same or different reference frames or coordinate systems.

After the locations of the virtual content and a physical reference point are determined relative to the light difference marker, or landmark, the system <NUM> can intermittently or continuously monitor the location of the physical reference point using the depth sensor <NUM>. In some embodiments, the depth sensor <NUM> may require less power and/or processing capacity than the light detectors <NUM> and light sources <NUM> to continuously monitor the location of the real object and/or the physical reference point. Thus, the depth sensor <NUM> continuously monitors the location of the physical reference point, while the emission and detection of radiation or the radiation pattern by the light sources <NUM> and light detectors <NUM> is utilized less frequently, such as when a change is detected in the location of the physical reference point, when the virtual content's frame needs to be refreshed, or at any other regular or irregular interval. When the location of the virtual content rendering is to be refreshed, the method <NUM> continues to block <NUM>.

At block <NUM>, radiation or radiation pattern is emitted again. The radiation emitted at block <NUM> can be the same distribution (e.g., a uniform distribution, spot, pattern, texture, or the like) as the radiation emitted at block <NUM>. The direction of emission of the radiation pattern can be determined based on the location of the physical reference point as tracked by the depth sensor <NUM> such that the emitted radiation pattern is at least partially incident on a region of the real object where the light difference signature, marker, or landmark is expected to be found. The direction of emission can be selected by pivoting or otherwise moving the light source(s) <NUM> on a gimbal or other movable mounting platform. For example, in the example of a wearer's arm, the emitted radiation pattern can be directed at the location of the birthmark, veins, or other feature associated with the light difference signature, marker, or landmark based on the calculated displacement from the physical reference point. The radiation or radiation pattern can be emitted by the light sources <NUM> in the same manner described above with reference to block <NUM>. After radiation or radiation pattern is emitted, the method <NUM> continues to block <NUM>.

At block <NUM>, the system <NUM> obtains a reflected radiation distribution or pattern and locates the difference signature, marker, or landmark within the reflected radiation distribution or pattern. The reflected radiation or pattern can be detected and/or imaged by light detectors <NUM> configured to detect light of one or more wavelengths emitted by light sources <NUM>. A difference may then be determined and/or calculated between the emitted radiation pattern and the reflected radiation pattern. The stored light difference signature or marker or landmark can be compared to the difference between the emitted and reflected radiation distributions or pattern to verify the presence and determine the location of the light difference signature, marker or landmark in the newly reflected radiation distribution. The location of the light difference signature, marker, or landmark can then be recorded to serve as a reference point for the rendering of the virtual content when the virtual content is refreshed. After the light difference marker is located within the reflected radiation distribution or difference, the method <NUM> continues to block <NUM>.

At block <NUM>, the virtual content is rendered relative to the location of the light difference signature, marker, or landmark. The location for rendering the virtual content can be determined based on the displacement between the light difference signature, marker or landmark and the virtual content that was calculated at block <NUM>. By using the same displacement that was previously calculated, the augmented reality display system <NUM> can achieve the advantage of displaying virtual content that appears to move with the associated real object. For example, by repeatedly rendering a virtual watch at the same displacement relative to a light difference signature, marker, or landmark caused by a birthmark or group of veins on a wearer's hand, the face of the virtual watch can appear to remain adjacent to the top side of the wearer's wrist, even as the wearer rotates the wrist or otherwise alters the orientation of the wrist in a manner that cannot reliably be detected by the depth sensor <NUM> alone. After the virtual content is rendered relative to the light difference signature, marker, or landmark, the method <NUM> can return to block <NUM>, where blocks <NUM>-<NUM> may be repeated indefinitely at regular or irregular intervals as necessary whenever the virtual content frame is to be refreshed. For example, the method <NUM> can return to block <NUM> any time a change in the location of the physical reference point is detected, or at a regular interval such as every second, five times per second, ten times per second, fifty times per second, one hundred times per second, or any other suitable interval. In some embodiments, the light sources <NUM> may be configured to continuously project radiation such as infrared light, rather than sending discrete pulses of light each time the difference marker is to be located again.

As discussed above, the systems, devices, methods and processes discussed in connection with illumination of a pattern of light apply as well to uniform illumination or projecting a spot of any shape such as a circular spot. Additionally, although the discussion above referred to identifying and using a marker or landmark, multiple markers or landmarks may be identified and used to provide tracking and placement of virtual image content.

It is contemplated that the innovative aspects may be implemented in or associated with a variety of applications and thus includes a wide range of variation. Variations, for example, in the shape, number, and/or optical power of the EPE's are contemplated. The structures, devices and methods described herein may particularly find use in displays such as wearable displays (e.g., head mounted displays) that can be used for augmented and/or virtually reality. More generally, the described embodiments may be implemented in any device, apparatus, or system that can be configured to display an image, whether in motion (such as video) or stationary (such as still images), and whether textual, graphical or pictorial. It is contemplated, however, that the described embodiments may be included in or associated with a variety of electronic devices such as, but not limited to: mobile telephones, multimedia Internet enabled cellular telephones, mobile television receivers, wireless devices, smartphones, Bluetooth® devices, personal data assistants (PDAs), wireless electronic mail receivers, hand-held or portable computers, netbooks, notebooks, smartbooks, tablets, printers, copiers, scanners, facsimile devices, global positioning system (GPS) receivers/navigators, cameras, digital media players (such as MP3 players), camcorders, game consoles, wrist watches, clocks, calculators, television monitors, flat panel displays, electronic reading devices (e.g., e-readers), computer monitors, auto displays (including odometer and speedometer displays, etc.), cockpit controls and/or displays, camera view displays (such as the display of a rear view camera in a vehicle), electronic photographs, electronic billboards or signs, projectors, architectural structures, microwaves, refrigerators, stereo systems, cassette recorders or players, DVD players, CD players, VCRs, radios, portable memory chips, washers, dryers, washer/dryers, parking meters, head mounted displays and a variety of imaging systems. Thus, the teachings are not intended to be limited to the embodiments depicted solely in the Figures, but instead have wide applicability as will be readily apparent to one having ordinary skill in the art.

The word "exemplary" is used exclusively herein to mean "serving as an example, instance, or illustration. Additionally, a person having ordinary skill in the art will readily appreciate, the terms "upper" and "lower", "above" and "below", etc., are sometimes used for ease of describing the figures, and indicate relative positions corresponding to the orientation of the figure on a properly oriented page, and may not reflect the proper orientation of the structures described herein, as those structures are implemented.

Further, the drawings may schematically depict one more example processes in the form of a flow diagram. However, other operations that are not depicted can be incorporated in the example processes that are schematically illustrated. For example, one or more additional operations can be performed before, after, simultaneously, or between any of the illustrated operations.

Various example embodiments of the invention 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 invention.

The invention includes methods that may be performed using the subject devices. The methods may comprise the act of providing such a suitable device. Such 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.

Example aspects of the invention, together with details regarding material selection and manufacture have been set forth above. As for other details of the present invention, 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 invention in terms of additional acts as commonly or logically employed.

In addition, though the invention has been described in reference to several examples optionally incorporating various features, the invention is not to be limited to that which is described or indicated as contemplated with respect to each variation of the invention. 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 invention.

Claim 1:
An augmented reality display system (<NUM>) configured to align 3D content with a real object comprising skin of a wearer of the augmented reality display system or of a person other than the wearer, the system comprising:
a frame (<NUM>) configured to mount on the wearer;
an augmented reality display (<NUM>, <NUM>) attached to the frame (<NUM>) and configured to direct images to an eye (<NUM>, <NUM>) of the wearer;
a light source (<NUM>) configured to illuminate at least a portion of the skin by emitting invisible light;
a light sensor (<NUM>) configured to image said portion of said skin illuminated by said light source using said invisible light; and
processing circuitry (<NUM>) configured to
detect a feature in the image formed using a reflected portion of the invisible light, the feature corresponding to a preexisting feature on or under said skin;
store said feature to be used as a marker for virtual content; and
determine information regarding the location of the object, the orientation of the object, or both based on one or more characteristics of the preexisting feature in the image formed using a reflected portion of the invisible light;
wherein the processing circuity is configured to utilize the light source (<NUM>) and the light sensor (<NUM>) at a first frequency
characterized in that
said system comprises a depth sensor (<NUM>) configured to detect a location of the skin, wherein the processing circuitry is configured to monitor the location of the skin using the depth sensor (<NUM>) periodically at a second frequency higher than the first frequency.