Apparatus, system, and method for eye tracking based on coherent light and event sensors

Abstract

An eyewear device comprising (1) at least one coherent light source configured to illuminate an eye of a user, (2) at least one event sensor that comprises a set of pixels and is configured to detect changes in brightness across the set of pixels based at least in part on the illumination of the eye, and (3) circuitry configured to track the eye of the user based at least in part on the changes in brightness detected across the set of pixels. Various other apparatuses, systems, and methods are also disclosed.

Description

APPARATUS, SYSTEM, AND METHOD FOR EYE TRACKING BASED ON COHERENT LIGHT AND EVENT SENSORS CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims benefit of and priority to U.S. provisional patent application Ser. No. 63 / 652,416 filed May 28, 2024.TECHNICAL FIELD

[0002] The present disclosure is generally directed to apparatuses, systems, and methods for eye tracking based at least in part on coherent light and event sensors.BACKGROUND

[0003] Current eye-tracking techniques are often incorporated into different types of eyewear devices, such as head-mounted displays (HMDs). For example, these techniques typically include physical components that observe a viewer’s eye movement to determine what the viewer is looking at within a display. In some implementations, these components may include one or more lights that shine onto the viewer’s eyes and one or more optical sensors (e.g., cameras) that observe how the one or more lights are reflected by the viewer’s eyes.SUMMARY

[0004] According to a first aspect, there is provided an eyewear device comprising: at least one coherent light source configured to illuminate an eye of a user; at least one event sensorthat comprises a set of pixels and is configured to detect changes in brightness across the set of pixels based at least in part on the illumination of the eye; and circuitry configured to track the eye of the user based at least in part on the changes in brightness detected across the set of pixels.

[0005] The circuitry may be further configured to perform at least one action in response to the tracking of the eye.

[0006] The tracking of the eye may involve monitoring at least one of: a state of the eye; an orientation of the eye; a movement of the eye; and a position of the eye.

[0007] The coherent light source may be further configured to produce a speckle pattern on the eye of the user via the illumination. The event sensor may be further configured to generate one or more events corresponding to one or more changes in the speckle pattern on the eye. The circuitry may be further configured to: detect a movement of the eye based at least in part on the events; and track the eye based at least in part on the movement.

[0008] The circuitry may be further configured to: identify locations of one or more capillaries in the eye of the user based at least in part on the events; map the capillaries in the eye of the user based at least in part on the locations; and track the eye based at least in part on the mapping of the capillaries.

[0009] The circuitry may be further configured to: detect contrast in the specklepattern on the eye across the events; and track the eye based at least in part on the contrast in the speckle pattern on the eye across the events.

[0010] The coherent light source may be further configured to produce the speckle pattern on a sclera of the eye via the illumination.

[0011] The eyewear device may further comprise a light-emitting device configured to facilitate tracking the eye of the user based at least in part on a pupil of the eye. The circuitry may be further configured to detect the movement of the eye based at least in part on the speckle pattern produced on the sclera during a moment in which the sclera is perceptible to the event sensor and the pupil is imperceptible to the event sensor.

[0012] The circuitry may be further configured to: deactivate the coherent light source when the pupil is perceptible to the event sensor; and activate the coherent light source when the pupil is imperceptible to the event sensor.

[0013] The light-emitting device may comprise a light-emitting diode. The coherent light source may comprise at least one of: a laser; or a vertical-cavity surface-emitting laser (VCSEL) device.

[0014] The eyewear device may further comprise a waveguide that is optically coupled between the eye of the user and the event sensor and is configured to relay the illumination of the eye to the event sensor.

[0015] The eyewear device may further comprise: a frame that is dimensioned to be worn by the user and is equipped with an optical element; and at least one additional coherent light source configured to illuminate the eye of the user. The coherent light source and the additional coherent light source may each be coupled to either the frame or the optical element.

[0016] The eyewear device may further comprise at least one additional event sensor that comprises an additional set of pixels and is configured to detect changes in brightness across the additional set of pixels based at least in part on the illumination of the eye. The circuitry may be further configured to track the eye of the user based at least in part on: the changes in brightness detected across the set of pixels; or the changes in brightness detected across the additional set of pixels.

[0017] The eyewear device may further comprise at least one camera configured to image the eye of the user at a first frame rate. The event sensor may be configured to image the eye at a second frame rate that is faster than the first frame rate.

[0018] The circuitry may be further configured to: determine that the user is looking at a certain target by tracking the eye; and perform at least one action due at least in part to the user looking at the certain target.

[0019] The circuitry may be further configured to monitor blood flow in the eye of the user based at least in part on the changes in brightness. The circuitry may be furtherconfigured to evaluate a health feature of the user based at least in a part on the blood flow. The circuitry may be further configured to perform at least one action based at least in part on the health feature of the user. For example, the action may be to provide a notification to a user and / or a health professional. The notification may notify the user and / or health professional that the health feature is outside a predetermined healthy range and that further investigation may be required.

[0020] According to a second aspect, there is provided an artificial-reality system comprising: the eyewear device of any preceding claim, wherein the at least one coherent light source is configured to facilitate eye tracking based at least in part on a sclera of the eye; and a light-emitting device configured to illuminate the eye of the user and to facilitate eye tracking based at least in part on a pupil of the eye.

[0021] According to a third aspect, there is provided a method comprising: configuring at least one coherent light source to illuminate an eye of a user of an eyewear device; configuring an event sensor that comprises a set of pixels to detect changes in brightness across the set of pixels based at least in part on the illumination of the eye; and configuring circuitry to track the eye of the user based at least in part on the changes in brightness detected across the set of pixels.BRIEF DESCRIPTION OF DRAWINGS

[0022] The accompanying drawings illustrate a number of examples and are a part of the specification. Together with the following description, these drawings demonstrate and explain various principles of the instant disclosure.

[0023] FIG. 1 is an illustration of an exemplary eyewear device for eye tracking based on coherent light and event sensors according to one or more implementations of this disclosure.

[0024] FIG. 2 is an illustration of an exemplary eyewear device for eye tracking based on coherent light and event sensors according to one or more implementations of this disclosure.

[0025] FIG. 3 is an illustration of an exemplary implementation of an eyewear device for eye tracking based on coherent light and event sensors according to one or more examples of this disclosure.

[0026] FIG. 4 is an illustration of an exemplary artificial-reality system for eye tracking based on coherent light and event sensors according to one or more examples of this disclosure.

[0027] FIG. 5 is an illustration of an exemplary artificial-reality system for eye tracking based on coherent light and event sensors according to one or more examples of this disclosure.

[0028] FIG. 6 is an illustration of an exemplary artificial-reality system for eyetracking based on coherent light and event sensors according to one or more examples of this disclosure.

[0029] FIG. 7 is a flow diagram of an exemplary method for eye tracking based on coherent light and event sensors according to one or more implementations of this disclosure.

[0030] FIG. 8 is an illustration of exemplary augmented-reality glasses that may be used in connection with one or more implementations of this disclosure.

[0031] FIG. 9 is an illustration of an exemplary virtual-reality headset that may be used in connection with one or more implementations of this disclosure.

[0032] FIG. 10 an illustration of an exemplary system that incorporates an eyetracking subsystem capable of tracking a user’s eye(s).

[0033] FIG. 11 is a more detailed illustration of various aspects of the eye-tracking subsystem illustrated in FIG. 10.

[0034] While the examples described herein are susceptible to various modifications and alternative forms, specific examples have been shown by way of example in the appendices and will be described in detail herein. However, the examples described herein are not intended to be limited to the particular forms disclosed. Rather, the instant disclosure covers all modifications, combinations, equivalents, and alternatives falling within this disclosure.DETAILED DESCRIPTION

[0035] The present disclosure is generally directed to apparatuses, systems, and methods for eye tracking based at least in part on coherent light and event sensors. As will be explained in greater detail below, these apparatuses, systems, and methods may provide numerous features and benefits.

[0036] Current eye-tracking techniques are often incorporated into different types of eyewear devices, such as head-mounted displays (HMDs). For example, these techniques typically include physical components that observe a viewer’s eye movement to determine what the viewer is looking at within a display. In some implementations, these components may include one or more lights that shine onto the viewer’s eyes and one or more optical sensors (e.g., cameras) that observe how the one or more lights are reflected by the viewer’s eyes.

[0037] In some examples, in-field eye-tracking systems may include and / or represent waveguides and / or hot mirrors that lead to certain design constraints and / or tradeoffs. For example, on the one hand, eyewear device manufacturers may want to improve light coupling efficiency and / or visibility or to reduce system complexity and / or costs. To do so, eyewear device manufacturers may try to decrease and / or minimize the optical bandwidth by using coherent light sources, such as lasers and / or vertical-cavity surface-emitting laser (VCSEL) devices. However, on the other hand, eyewear device manufacturers may want toimprove the image quality of the eye being tracked without consuming large amounts of power, without compromising eye-tracking speed, without the need for bulky and / or uncomfortable form factors and / or designs, without introducing speckle patterns or disrupting traditional eyetracking algorithms, and / or without placing cameras in the temple region of the eyewear device.

[0038] In some examples, to achieve the benefits of coherent light sources without succumbing to the corresponding drawbacks, eyewear device manufacturers may combine those coherent light sources with event sensors and / or cameras to facilitate and / or support ultra-low latency and / or data-efficient eye tracking through multiple mechanisms. In one example, an eyewear device may include, implement, and / or represent a coherent light source, such as a one-dimensional or two-dimensional micro-electromechanical systems (MEMS) scanning laser, and an event sensor or camera. In this example, the eyewear device may be able to perform effective eye tracking by taking only a limited number of eye-tracking measurements and / or data points with the MEMS scanning laser and / or the event sensor or camera.

[0039] In some examples, the eyewear device may adaptively change and / or modify these eye-tracking measurements and / or data points to compensate and / or account for certain statuses of the user’s eye. In one example, by taking only sparse eye-tracking measurements and / or data points, the eyewear device may achieve significantly reduced power consumption from both the MEMS scanning laser and / or event sensor. In addition, the eyewear device may achieve improved eye-tracking performance by increasing the speed of the eye-tracking measurements and / or data points.

[0040] In some examples, the eyewear device may detect and / or identify glints and / or light flashes in the user’s eye via the MEMS scanning laser and / or the event sensor or camera. In one example, the eyewear device may monitor and / or track the status of the user’s eye based at least in part on the glints and / or light flashes. Accordingly, the eyewear device may observe, analyze, and / or evaluate the pupil of the user’s eye based at least in part on the glints and / or light flashes. Additionally or alternatively, the eyewear device may be able to capture and / or map the vasculature of the user’s eye based at least in part on the glints and / or light flashes. In certain implementations, the eyewear device may be able to continue monitoring and / or tracking the user’s eye based at least in part on its vasculature even when the pupil and / or corneal glints are obscured.

[0041] In some examples, the coherent light source may introduce speckle patterns that tend to degrade the image quality and / or disrupt traditional eye-tracking algorithms. However, the eyewear device may repurpose speckle patterns produced by the coherent light source to supplement the traditional imaging information and / or data about the eye. In other words, instead of impairing the eye-tracking algorithm, the speckle patterns mayactually supply the event sensor and / or camera with additional information and / or data capable of being used to enhance the eye-tracking performance. For example, the event sensor and / or camera may exploit the speckle patterns to generate motion contrast. In this example, when the speckle patterns change due to motion in the user’s eye, the event sensor and / or camera may generate and / or produce a high rate of events corresponding to the changes in the speckle patterns.

[0042] In some examples, the coherent light source and the event sensor or camera may be positioned and / or coupled in close proximity to one another on the eyewear device. In one example, the coherent light source may illuminate (e.g., via pulses) the area of the user’s eye being imaged by the event camera and / or sensor. In certain implementations, the eyewear device may activate the coherent light source only when the pupil of the user’s eye is obscured from and / or invisible to the event camera and / or sensor. In such implementations, the eyewear device may also include and / or represent a light-emitting diode (LED) positioned and / or coupled close to the event sensor or camera. The eyewear device may cause the LED to blink rapidly to produce bright pupil effect for eye tracking, and the coherent light source may supplement the LED when the pupil of the user’s eye is obscured from and / or invisible to the event sensor and / or camera.

[0043] Various eye-tracking designs and / or systems may implement the technology necessary to repurpose speckle patterns produced by the coherent light sources for eye-tracking enhancement. For example, an eyewear device may include and / or implement one or more cameras and / or point scanning sensors that directly capture, detect, and / or sense speckle patterns as illuminated on the eye of a user by a laser or VCSEL device. In another example, an eyewear device may include and / or implement one or more event sensors and / or cameras coupled to a waveguide whose aperture is used for speckle-pattern image collection. In a further example, an eyewear device may include and / or implement a hot mirror, near-infrared mirror, and / or holographic combiner that reflects near-infrared light and transmits visible light to facilitate speckle-pattern image collection.

[0044] In some examples, an eyewear device may modify and / or alter traditional eye-tracking algorithms to ensure that spatial and temporal statistics of the speckle field illuminated on the eye are captured. As a result of such capturing, the eyewear device may obtain and / or derive additional signals for segmentation and / or relative displacement (e.g., in the x-direction, y-direction, and / or z-direction) of the eye and / or periocular surfaces. For example, coherent light may illuminate a surface of the eye that exhibits imperfections and / or irregularities. In this example, the coherent light may reflect and / or scatter off these imperfections and / or irregularities, thereby causing light waves to interfere with each other to form a granular speckle pattern.

[0045] In some examples, each unique surface of the eye may produce and / orpromote a unique speckle pattern when illuminated by the coherent light. As a result, the eyewear device may analyze, process, and / or evaluate the speckle patterns to track otherwise features surfaces of the eye, such as the sclera and / or white of the eye. For example, when coherent light illuminates a featureless and / or rough surface of the eye, the coherent light forms a speckle pattern due to interference of the scattered waves. In this example, the speckle pattern may uniquely identify and / or be used to determine a specific state and / or position of the surface of the eye.

[0046] In some examples, the eyewear device may track the state, position, and / or orientation of the eye or its features based at least in part on changes in the speckle pattern. For example, the eyewear device may compare speckle patterns captured at different moments in time to one another. In this example, the eyewear device may identify and / or determine changes in the state, position, and / or orientation of the eye based at least in part on differences in the speckle patterns from one moment to another.

[0047] In some examples, the sensitivity of the speckle patterns may be high enough that even tiny changes in the surface position and / or orientation are detectible and / or perceptible by the eyewear device. In one example, the eyewear device may implement speckle interferometry in which the coherent light source emits light that includes a reference wave that is combined with a scattered wave from the eye’s surface to produce the speckle pattern.

[0048] In some examples, the eyewear device may include and / or represent a coherent light source (e.g., a laser and / or a VCSEL device) that illuminates the eye of a user. In one example, the eyewear device may include and / or represent an event sensor (e.g., a camera) that generates data that represents brightness changes in the user’s eye based on the illumination. In this example, the eyewear device may include and / or represent circuitry may identify at least one speckle pattern in the plurality of images. Additionally or alternatively, the circuitry may determine at least one attribute (e.g., the state, position, movement, and / or orientation) of the eye based at least in part on the speckle pattern.

[0049] In some examples, the circuitry may track the eye’s movement based at least in part on the attribute of the eye. In one example, the circuitry may perform one or more actions in response to the attribute of the eye. Examples of such actions include, without limitation, generating virtual content presented via optical elements (e.g., lenses), modifying virtual content presented via optical elements, initiating a telephone call, sending a text message or other communication, executing a computing command and / or instruction, record and / or report health information based on blood flow in the eye, combinations of one or more of the same, and / or any other suitable actions.

[0050] In one example, the circuitry may be electrically and / or communicatively coupled to the optical elements, the coherent light source(s), and / or the event sensor(s). Inthis example, the coherent light sources and / or optical sensors may each be integrated into and / or secured to the eyewear frame and / or optical elements. In certain implementations, the event sensors may be configured and / or programmed to detect coherent light emitted by the coherent light sources and / or reflected by the user’s eyes (e.g., in the form of speckle patterns).

[0051] In some examples, each event sensor may include and / or represent an event camera, a neuromorphic camera, and / or a dynamic vision sensor (DVS). In one example, each event sensor may capture and / or measure changes in brightness at each pixel and then generate a stream of events that encode the time and / or location of such changes. Additionally or alternatively, each event sensor may rely on the principle of address-event representation (AER). In certain implementations, each event sensor may include and / or represent an array of pixels that are each paired with a photodetector and / or comparator circuit. When the intensity of light incident on a pixel satisfies a certain threshold, the comparator may generate an event which is represented as and / or converted to a stream of data encoding the time and / or location of the event.

[0052] In some examples, the eyewear device may include and / or represent an HMD and / or an artificial-reality device or system. Artificial reality may provide a rich, immersive experience in which users are able to interact with virtual objects and / or environments in one way or another. In this context, artificial reality may constitute and / or represent a form of reality that has been altered by virtual objects for presentation to a user. Such artificial reality may include and / or represent virtual reality (VR), augmented reality (AR), mixed reality, hybrid reality, or some combination and / or variation of one or more of the same.

[0053] In some examples, the HMD may integrate one or more event sensors, coherent light sources, LEDs, and / or cameras for use in eye tracking. In such examples, the HMD may track the state, position, orientation, and / or movement of the eye or its features based at least in part on brightness changes in the eye illumination captured by the event sensors and / or the cameras. For example, the HMD may compare the brightness levels captured at different moments in time to one another. In this example, the HMD may identify and / or determine changes in the state, position, and / or orientation of the eye based at least in part on differences in the contrast and / or light patterns over different moments in time.

[0054] In some examples, the HMD may include and / or represent circuitry that identifies changes and / or features depicted in the plurality of images. Additionally or alternatively, the circuitry may determine at least one attribute (e.g., the state, position, movement, and / or orientation) of the eye based at least in part on the changes and / or features.

[0055] In some examples, the circuitry may track the eye’s movement based at least in part on the attribute of the eye. In one example, the circuitry may perform one or more actions in response to the attribute of the eye. Examples of such actions include, withoutlimitation, generating virtual content presented via optical elements (e.g., lenses), modifying virtual content presented via optical elements, initiating a telephone call, sending a text message or other communication, executing a computing command and / or instruction, predicting future gaze changes, combinations of one or more of the same, and / or any other suitable actions.

[0056] In some examples, the circuitry may include and / or represent one or more electrical and / or electronic circuits capable of processing, applying, modifying, transforming, displaying, transmitting, receiving, and / or executing data for the HMD. In one example, the circuitry may be electrically and / or communicatively coupled to optical element(s), lightemitting device(s), collimated light source(s), coherent light source(s), lasers, camera(s), and / or event sensor(s). In this example, the light-emitting device(s), coherent light source(s), camera(s), and / or event sensor(s) may each be integrated into and / or secured to the eyewear frame and / or optical element(s).

[0057] In some examples, the eye-tracking components that facilitate and / or support the eye tracking on the HMD may include and / or represent event sensors, cameras, light sensors, light sources, coherent light sources, LEDs, optical modulators, phase shifters, optical switches, optical gates, light detection and ranging (LIDAR) devices, lasers, photodiodes, optical resonators, photonic crystals, light-emitting devices, combinations or variations of one or more of the same, and / or any other suitable components.

[0058] The following will provide, with reference to FIGS. 1-6, detailed descriptions of exemplary apparatuses, devices, systems, components, and corresponding configurations or implementations for eye tracking based on coherent light and event sensors. In addition, detailed descriptions of methods for eye tracking based on coherent light and event sensors will be provided in connection with FIG. 7. The discussion corresponding to FIGS. 8-11 will provide detailed descriptions of types of exemplary artificial-reality devices, wearables, and / or associated systems capable of steered retinal projection via movable cantilevered waveguides.

[0059] FIG. 1 illustrates an exemplary eyewear device 100 for eye tracking based on coherent light and event sensors. As illustrated in FIG. 1 , eyewear device 100 may include and / or represent a frame 102 dimensioned to be worn by a user. In some examples, frame 102 may include and / or be equipped with a coherent light source 104, an event sensor 108, and / or circuitry 106. In one example, circuitry 106 may be communicatively and / or electrically coupled to coherent light source 104 and / or event sensor 108. In this example, circuitry 106 may image, map, monitor, and / or track an eye of the user via event sensor 108 based at least in part on light emitted by coherent light source 104.

[0060] In certain implementations, some or all of circuitry 106 may be integrated into and / or represent part of coherent light source 104 and / or event sensor 108. Additionallyor alternatively, some or all of circuitry 106 may be constitute and / or represent one or more standalone or separate circuits that are communicatively coupled to coherent light source 104 and / or event sensor 108.

[0061] In some examples, coherent light source 104 and / or event sensor 108 may constitute, represent, and / or form some or all of an eye-tracking device or system. In one example, the eye-tracking device may receive, obtain, and / or collect light that has been reflected and / or bounced off the user’s eye to facilitate imaging, mapping, and / or tracking the user’s eye. For example, coherent light source 104 may emit coherent light toward the user’s eye to produce a speckle pattern on and / or over the user’s eye. In this example, event sensor 108 may monitor, detect, and / or identify changes in the speckle pattern produced on the user’s eye. Additionally or alternatively, event sensor 108 may generate events and / or outputs corresponding to changes observed in the speckle pattern.

[0062] In some examples, event sensor 108 may include and / or represent a set of pixels 1 10 that capture, detect, and / or respond to changes in brightness. In one example, event sensor 108 may be aimed, arranged, and / or trained to detect changes in brightness relative to the illumination of the user’s eye. For example, the pixels 1 10 of event sensor 108 may store reference brightness levels that are compared to the current brightness levels. In this example, if the difference between the reference and current brightness levels for a given pixel exceeds a certain threshold, then that pixel may generate an event comprising a variety of data, examples of which include, without limitation, a timestamp, an address of the pixel, an illumination measurement and / or differential, a polarity (e.g., increase or decrease) of the brightness change relative to the reference, combinations or variations of one or more of the same, and / or any other suitable data.

[0063] In some examples, event sensor 108 may operate differently from conventional frame-based imaging systems. For example, unlike conventional cameras that capture static images at fixed intervals, event sensor 108 may operate asynchronously by detecting changes in brightness at individual pixels in real time. In this example, the asynchronous operation may enable event sensor 108 to achieve ultra-low latency, high temporal resolution, and / or efficient data processing, thus making event sensor 108 particularly advantageous for rapid motion detection (e.g., in eye tracking).

[0064] In some examples, each of pixels 1 10 in event sensor 108 may include and / or represent a photodetector and a comparator circuit. In one example, the photodetector may continuously measure the intensity of light incident on the pixel, and the comparator may monitor changes in brightness over time. In this example, when the intensity of light at a pixel changes by a certain threshold, the comparator may generate an event. This event may encode the time, location, magnitude of brightness or the brightness change, and / or polarity of the brightness change.

[0065] The independence of each pixel may effectively eliminate the need for a global clock, thereby enabling event sensor 108 to respond to brightness levels in real time with minimal delay and / or enabling event sensor 108 to generate and / or output relatively sparse data (as only the pixels experiencing brightness changes report events). In some examples, event sensor 108 may detect motion contrast, which is useful in tracking subtle changes in the eye’s position or orientation. In certain implementations, event sensor 108 may be highly adaptable to dynamic scenes like tracking eye movements in challenging lighting conditions or when the pupil is fully or partially obscured.

[0066] In some examples, circuitry 106 may track the eye of the user based at least in part on the changes in brightness detected across pixels 1 10. For example, event sensor 108 may generate one or more events indicative of any brightness changes detected across pixels 110. In this example, circuitry 106 may receive the events generated by event sensor 108. Based on these events, circuitry 106 may monitor and / or determine the state of the user’s eye, the orientation of the user’s eye, the movement of the user’s eye, and / or the position of the user’s eye. In one example, circuitry 106 may determine and / or identify a target (e.g., a virtual object, a real object, etc.) of the user’s eye and / or vision.

[0067] In some examples, circuitry 106 may perform, execute, and / or implement one or more actions in response to the tracking of the user’s eye. Examples of such actions include, without limitation, generating virtual content presented via optical elements (e.g., lenses, displays, etc.), modifying virtual content presented via optical elements, monitoring eye health, predicting gaze motions or directions, initiating a telephone call, sending a text message or other communication, executing a computing command and / or instruction, combinations of one or more of the same, and / or any other suitable actions.

[0068] In some examples, circuitry 106 may apply and / or implement various processing techniques on the events generated by event sensor 108 to detect and / or measure motion and / or speed of the user’s eye. Examples of such processing techniques include, without limitation, image segmentation, optical flow, computer vision, speckle interferometry, speckle displacement, wavelength multiplexing, spatial frequency analyses, global crosscorrelation analysis, speckle-contrast analyses, triangulation, Fourier profilometry, phaseshifting profilometry, spectral differentiation, combinations or variations of one or more of the same, and / or any other suitable processing techniques.

[0069] In some examples, circuitry 106 may determine that the user’s eye has moved based at least in part on spatial and / or temporal statistics of the speckle pattern. Additionally or alternatively, circuitry 106 may examine and / or analyze additional signals derived from the spatial or temporal statistics. By doing so, circuitry 106 may perform, implement, and / or achieve image segmentation of the speckle pattern represented in the events received from event sensor 108. In one example, circuitry 106 may determine and / ormeasure the relative displacement of the user’s eye (e.g., XYZ motion and / or translation) from moment to the next based at least in part on the events.

[0070] In some examples, circuitry 106 may perform and / or implement a global cross-correlation analysis, a speckle-contrast analysis, and / or an optical flow on speckle patterns represented in the events. By doing so, circuitry 106 may detect and / or measure the velocity of motion of the user’s eye between the moments in time at which those events were detected and / or generated. Additionally or alternatively, circuitry 106 may detect, measure, and / or predict the magnitude of relative displacement of the user’s eye based at least in part on the velocity of motion of the user’s eye.

[0071] In some examples, the contrast of the speckle pattern represented in the events may indicate, suggest, and / or correspond to the speed at which the user’s eye is moving. For example, high-contrast, developed, and / or defined speckles may indicate, suggest, and / or correspond to relatively slow eye motion and / or a stationary eye. In another example, low-contrast, smoothed, and / or blurred speckles may indicate, suggest, and / or correspond to relatively fast eye motion.

[0072] In some examples, circuitry 106 may predict future eye motion and / or position based at least in part on the events. For example, circuitry 106 may predict the direction and / or speed of the user’s future eye motion if one or more events indicate that the user’s eye is currently moving in a certain direction, at a certain speed, and / or with a certain magnitude. In this example, circuitry 106 may perform, execute, and / or implement one or more actions in response to and / or based on the predicted future eye motion, direction, speed, and / or position.

[0073] In some examples, eyewear device 100 may include and / or represent an HMD dimensioned to be worn by a user. In one example, the HMD may include and / or represent any type or form of display device or system integrated into frame 102. For example, the HMD may include and / or represent a pair of smart glasses and / or AR glasses. In this example, the HMD may be worn on or about the user’s face and may display virtual content, such as computer-generated objects and / or AR content, to the user.

[0074] HMDs may present and / or display content in any suitable way, including via a display screen, a liquid crystal display (LCD), a light-emitting diode (LED) display, a microLED display, a scanning display, a plasma display, a projector, a cathode ray tube, an optical mixer, combinations or variations of one or more of the same. HMDs may present and / or display content in one or more media formats. For example, HMDs may display video, photos, computer-generated imagery (CGI), and / or variations or combinations of one or more of the same. Additionally or alternatively, HMDs may include and / or incorporate see-through lenses that enable the user to see the user’s surroundings in addition to such computergenerated content.

[0075] In some examples, HMDs may provide diverse and / or distinctive user experiences. Some HMDs may provide virtual-reality experiences (i.e., they may display computer-generated or pre-recorded content), while other HMDs may provide real-world experiences (i.e., they may display live imagery from the physical world). HMDs may also provide any mixture of live and virtual content. For example, virtual content may be projected onto the physical world (e.g., via optical or video see-through lenses), which may result in AR and / or mixed-reality experiences.

[0076] In some examples, circuitry 106 may include and / or represent one or more electrical and / or electronic circuits capable of processing, applying, modifying, transforming, displaying, transmitting, receiving, and / or executing data and / or signals for eyewear device 100. In one example, circuitry 106 may provide data and / or signaling that control activation and / or deactivation of coherent light source 104 to facilitate and / or support CGI presentation in connection with an AR application and / or to facilitate additional eye-tracking features provided by one or more LEDs.

[0077] In some examples, circuitry 106 may launch, perform, and / or execute certain executable files, code snippets, and / or computer-readable instructions to facilitate and / or support eye tracking based on speckle patterns formed by coherent light. Although illustrated as a single unit in FIG. 1 , circuitry 106 may include and / or represent a collection of multiple processing units and / or electrical or electronic components that work and / or operate in conjunction with one another. In one example, circuitry 106 may include and / or represent an application-specific integrated circuit (ASIC). Additionally or alternatively, circuitry 106 may include and / or represent a central processing unit (CPU).

[0078] Additional examples of circuitry 106 include, without limitation, processing devices, microprocessors, microcontrollers, graphics processing units (GPUs), field- programmable gate arrays (FPGAs), systems on chips (SoCs), parallel accelerated processors, tensor cores, integrated circuits, chiplets, optical modules, receivers, transmitters, transceivers, optical modules, memory devices, transistors, antennas, resistors, capacitors, diodes, inductors, switches, registers, flipflops, digital logic, connections, traces, buses, semiconductor (e.g., silicon) devices and / or structures, storage devices, audio controllers, portions of one or more of the same, variations or combinations of one or more of the same, and / or any other suitable circuitry.

[0079] In some examples, circuitry 106 may direct and / or cause coherent light source 104 to emit and / or direct light to shine on and / or illuminate a surface of the user’s eye. In one example, the light may travel and / or traverse from coherent light source 104 across, through, and / or to one or more optical elements (e.g., mirrors, reflectors, films, lenses, displays, etc.) on the way to the user’s eye. Such optical elements may diffract, refract, reflect, spread, direct, and / or expand light on the way to the user’s eye.

[0080] In some examples, coherent light source 104 may include and / or represent any type or form of device capable of emitting, outputting, and / or producing coherent light and / or coherent electromagnetic radiation. Examples of coherent light source 104 include, without limitation, laser devices, VCSEL devices, collimated light devices, fiber optics, waveguide-driven lasers, combinations or variations of one or more of the same, and / or any other suitable coherent light source.

[0081] In certain implementations, coherent light source 104 may be positioned and / or disposed on frame 102. In other implementations, coherent light source 104 may be positioned and / or disposed on an optical element and / or lens of eyewear device 100. Although illustrated as a single unit in FIG. 1 , coherent light source 104 may include and / or represent a collection of multiple coherent light sources that work and / or operate in conjunction with one another to illuminate the user’s eye.

[0082] FIG. 2 illustrates an exemplary implementation of eyewear device 100 that facilitates, supports, and / or provides eye tracking based on coherent light and event sensors. In some examples, eyewear device 100 may include and / or represent certain devices, components, and / or features that perform and / or provide functionalities that are similar and / or identical to those described above in connection with FIG. 1 . As illustrated in FIG. 2, eyewear device 100 may include and / or represent frame 102 dimensioned to be worn by a user. In one example, frame 102 may include and / or represent a front frame 202, temples 204(1) and 204(2), optical elements 206(1) and 206(2), endpieces 208(1) and 208(2), nose pads 210, and / or a bridge 212. Additionally or alternatively, frame 102 may include, implement, and / or incorporate coherent light source 104, event sensor 108, and / or circuitry 106 — at least some of which are not necessarily illustrated, visible, and / or labelled in FIG. 2.

[0083] In some examples, optical elements 206(1) and 206(2) may be inserted and / or installed in front frame 202. In other words, optical elements 206(1) and 206(2) may be coupled to, incorporated in, and / or held by frame 102. In one example, optical elements 206(1) and 206(2) may be configured and / or arranged to provide one or more virtual visual features for presentation to a user wearing eyewear device 100. These virtual visual features may be driven, influenced, and / or controlled by one or more wireless technologies supported by eyewear device 100.

[0084] In some examples, optical elements 206(1) and 206(2) may each include and / or represent optical stacks, lenses, and / or films. In one example, optical elements 206(1) and 206(2) may each include and / or represent various layers that facilitate and / or support the presentation of virtual features and / or elements that overlay real-world features and / or elements. Additionally or alternatively, optical elements 206(1) and 206(2) may each include and / or represent one or more screens, lenses, and / or fully or partially see-through components. Examples of optical elements 206(1) and 206(2) include, without limitation,electrochromic layers, dimming stacks, transparent conductive layers (such as indium tin oxide films), metal meshes, antennas, transparent resin layers, lenses, films, combinations or variations of one or more of the same, and / or any other suitable optical elements.

[0085] FIG. 3 illustrates an exemplary implementation 300 of eyewear device 100 worn by a user 302. In some examples, eyewear device 100 in FIG. 3 may include, involve, and / or represent certain devices, components, and / or features that perform and / or provide functionalities that are similar and / or identical to those described above in connection with either FIG. 1 or FIG. 2. As illustrated in FIG. 3, eyewear device 100 may include and / or represent coherent light source 104, event sensor 108, and / or circuitry 106. In one example, user 302 may wear eyewear device 100 for an AR experience. For example, eyewear device 100 may reside on, be applied to, and / or be worn on the face of user 302.

[0086] In some examples, coherent light source 104 may illuminate an eye 304 of user 302. In one example, event sensor 108 may detect changes in brightness across pixels 110 based at least in part on the illumination of eye 304. In this example, circuitry 106 may track eye 304 of user 302 based at least in part on such brightness changes.

[0087] FIG. 4 illustrates an exemplary artificial-reality system 400 that facilitates and / or supports eye tracking based on a speckle pattern 408 formed by coherent light. In some examples, artificial-reality system 400 may include and / or involve certain components and / or features that perform and / or provide functionalities that are similar and / or identical to those described above in connection with any of FIGS. 1-3. In one example, artificial-reality system 400 may include and / or represent some or all of eyewear device 100. As illustrated in FIG. 4, artificial-reality system 400 may include and / or represent coherent light source 104, event sensor 108, and / or a waveguide 406 that optically couples event sensor 108 to eye 304 of user 302 via an aperture 402.

[0088] In some examples, waveguide 406 may be visually transparent like optical elements 206(1)-(2). In one example, aperture 402 may facilitate and / or support image collection and / or capture. For example, aperture 402 may be implemented on, integrated into, and / or disposed on waveguide 406. In this example, waveguide 406 may be optically coupled between aperture 402 and event sensor 108. This optical coupling may enable event sensor 108 to receive and / or obtain imaging information representative of speckle pattern 408 formed on eye 304 of user 302 via aperture 402. In certain implementations, waveguide 406 may relay, transmit, and / or carry illumination produced by coherent light source 104 from eye 304 to event sensor 108.

[0089] In certain examples, aperture 402 may be positioned and / or located over eye 304 on optical element 206(1). In one example, this position and / or location of aperture 402 may facilitate and / or support a direct view of eye 304 for imaging by event sensor 108 without impairing the line of sight of user 302. In other words, rather than positioning eventsensor 108 in the optical path of user 302, eyewear device 100 may implement aperture 402 over eye 304 and rely on aperture 402 to pass imaging information about eye 304 to event sensor 108 via waveguide 406.

[0090] In one example, event sensor 108 may effectively scan and / or image eye 304 via information, data, and / or light captured and / or recorded via aperture 402. In this example, such information, data, and / or light may traverse and / or pass from aperture 402 to event sensor 108 via waveguide 406. In certain implementations, coherent light source 104 may be positioned and / or disposed on the frame of artificial-reality system 400. Additionally or alternatively, coherent light source 104 may be positioned and / or disposed on optical element 206(1) of artificial-reality system 400.

[0091] In some examples, circuitry 106 may receive, retrieve, and / or obtain one or more events from event sensor 108. In one example, circuitry 106 may identify and / or detect a representation of a speckle pattern 408 in such events. In this example, speckle pattern 408 may constitute, establish, and / or represent a constellation, grouping, and / or field of illuminated features on the surface of eye 304.

[0092] In some examples, coherent light source 104 may illuminate the surface of eye 304, thereby effectively forming and / or producing speckle pattern 408. In one example, speckle pattern 408 may include, be influenced by, and / or account for irregularities of eye 304. In this example, circuitry 106 may use data that corresponds to and / or represents such irregularities as reference points to track the movements, states, and / or positions of eye 304.

[0093] In some examples, although not necessarily illustrated in this way in FIG. 4, coherent light source 104 may alternatively be configured to emit coherent light toward eye 304 via waveguide 406 and / or another waveguide implemented on optical element 206(1). In other words, waveguide 406 and / or the other waveguide may be optically coupled between aperture 402 or another aperture and coherent light source 104. This optical coupling may enable coherent light source 104 to emit and / or project illumination onto eye 304 to produce speckle pattern 408.

[0094] FIG. 5 illustrates an exemplary artificial-reality system 500 that facilitates and / or supports eye tracking based on speckle pattern 408 formed by coherent light. In some examples, artificial-reality system 500 may include and / or involve certain components and / or features that perform and / or provide functionalities that are similar and / or identical to those described above in connection with any of FIGS. 1-4. As illustrated in FIG. 5, artificial-reality system 500 may include and / or represent coherent light sources 512 and / or event sensors 510 coupled to, secured to, and / or incorporated in eyewear device 100.

[0095] In some examples, one or more of coherent light sources 512 may illuminate eye 304 of user 302. In one example, one or more of event sensors 510 may detect changes in brightness across pixels 110 based at least in part on the illumination of eye 304.In this example, circuitry 106 may track eye 304 of user 302 based at least in part on such brightness changes. In certain examples, the same eye-tracking devices and / or features may be applied to and / or implemented for both eyes of the user for eye tracking via eyewear device 100.

[0096] In some examples, circuitry 106 may map eye 304 of the user based at least in part on events generated by one or more of event sensors 510 and / or speckle pattern 408. For example, circuitry 106 may identify and / or determine locations of capillaries 508 in eye 304 of user 302 based at least in part on the events. In this example, circuitry 106 may map capillaries 508 and / or the vasculature of eye 304 based at least in part on those locations within eye 304. Circuitry 106 may track eye 304 based at least in part on the mapping of capillaries 508.

[0097] In some examples, circuitry 106 may calibrate capillary patterns and / or other features (e.g., speckle patterns, pupils, sclera irregularities, etc.) of the user’s eye. In one example, circuitry 106 may use the feature size, density, and / or pattern to determine the region of interest and / or the minimal resolution requirements. In this example, circuitry 106 may apply and / or employ a power-saving mode and / or strategy based at least in part on the region of interest and / or the minimal resolution requirements.

[0098] In some examples, circuitry 106 may detect contrast in speckle pattern 408 across the events. In one example, circuitry 106 may track eye 304 based at least in part on the contrast in speckle pattern 408 across the events. In this example, coherent light source 104 may direct and / or aim the illumination toward the sclera of eye 304. As a result, coherent light source 104 may generate and / or produce speckle pattern 408 on a sclera 504 and / or a pupil 506 of eye 304.

[0099] In some examples, coherent light sources 512 and / or event sensors 510 may be positioned and / or placed to avoid obstructing and / or impairing an optical path 502 and / or line of sight of the user’s eye. In one example, from this positioning and / or placement, event sensors 510 may be able to directly obtain, capture, and / or record imaging information about the user’s eye. In this example, event sensors 510 may do so directly by imaging the user’s eye without the use of an external waveguide and / or aperture.

[0100] FIG. 6 illustrates an exemplary artificial-reality system 600 that facilitates and / or supports eye tracking based on speckle pattern 408 formed by coherent light. In some examples, artificial-reality system 600 may include and / or involve certain components and / or features that perform and / or provide functionalities that are similar and / or identical to those described above in connection with any of FIGS. 1-5. As illustrated in FIG. 6, artificial-reality system 600 may include and / or represent coherent light source 104, event sensor 108, a lightemitting device 604, and / or a camera 610 coupled to, secured to, and / or incorporated in eyewear device 100. In one example, light-emitting device 604 may include and / or representan LED that illuminates at least some of eye 304 for eye-tracking purposes.

[0101] In some examples, eyewear device 100 may track eye 304 of user 302 based at least in part on pupil 506 of eye 304. For example, eyewear device 100 may perform and / or implement eye tracking that relies on and / or utilizes light-emitting device 604 and / or camera 610 when pupil 506 is perceptible and / or visible to camera 610. In this example, eyewear device 100 may perform and / or implement eye tracking that relies on and / or utilizes coherent light source 104 and / or event sensor 108 when sclera 504 of eye 304 is perceptible and / or visible to event sensor 108 but pupil 506 is imperceptible to, invisible to, and / or obscured from camera 610. In certain implementations, coherent light source 104 may emit coherent light 612 that illuminates eye 304 to produce speckle pattern 408 and / or contrast 602.

[0102] In some examples, coherent light 612 may interfere with and / or disturb the accuracy and / or performance of eye tracking that relies on and / or utilizes light-emitting device 604 and / or camera 610. Additionally or alternatively, light emitted by light-emitting device 604 may interfere with and / or disturb the accuracy and / or performance of eye tracking that relies on and / or utilizes coherent light source 104 and / or event sensor 108. In one example, to mitigate such interference and / or disturbances, circuitry 106 may activate light-emitting device 604 and / or deactivate coherent light source 104 when pupil 506 is optically accessible and / or perceptible to event sensor 108 and / or camera 610. In this example, circuitry 106 may activate coherent light source 104 and / or deactivate light-emitting device 604 when pupil 506 is optically inaccessible and / or imperceptible to event sensor 108 and / or camera 610.

[0103] In some examples, camera 610 may include and / or represent a conventional camera, as opposed to an event sensor, that images eye 304 at a first frame rate. In such examples, event sensor 108 may image eye 304 at a second frame rate that is faster than the first frame rate. In one example, circuitry 106 may detect contrast 602 in speckle pattern 408 across a sequence of events produced by event sensor 108. In this example, circuitry 106 may track eye 304 based at least in part on contrast 602 in speckle pattern 408.

[0104] In some examples, circuitry 106 may monitor the blood flow in eye 304 based at least in part on the changes in brightness detected by event sensor 108. In one example, circuitry 106 may record and / or maintain blood-flow statistics for user 302 by monitoring the blood flow in eye 304. Additionally or alternatively, circuitry 106 may evaluate and / or analyze one or more health features and / or ailments of user 302 based at least in part on the blood flow. In certain implementations, circuitry 106 may perform and / or execute one or more actions based at least in part on the health features and / or ailments. For example, circuitry 106 may direct and / or cause eyewear device 100 to notify user 302 and / or a medical professional about a health feature and / or ailment detected by evaluating the blood flow in eye 304.

[0105] In some examples, circuitry 106 may implement and / or perform a health monitoring feature that uses eye-tracking components to analyze retinal blood flow dynamics within eye 304 via speckle variance. In one example, the health monitoring feature may facilitate, support, and / or involve detecting biomarkers for certain conditions like diabetic retinopathy. For example, circuitry 106 may utilize coherent light source 104 and / or event sensor 108 to non-invasively monitor the retinal vasculature of eye 304 and / or provide early detection of ocular and / or systemic health conditions.

[0106] In some examples, circuitry 106 may predict changes in the user’s gaze based at least in part on the past gaze changes and the graphical imagery presented to the user before and / or during those gaze changes. In one example, circuitry 106 may be trained, programmed, and / or configured to predict future changes in the user’s gaze based at least in part on the graphical imagery projected to eye 304 at a certain moment in time and / or the movements made by eye 304 around that moment in time. For example, circuitry 106 may predict and / or anticipate a likely change in the user’s gaze based at least in part on the graphical imagery projected to eye 304 at that time and / or any past gaze changes performed by eye 304 when similar or identical graphical imagery was previously projected to eye 304.

[0107] In some examples, eyewear device 100 may be communicatively coupled to a computing device directly and / or through a network. In one example, eyewear device 100 may leverage and / or harness the computing power of the computing device for one reason or another (e.g., performing certain calculations, generating graphical imagery, coordinating AR / VR environments across multiple HMDs, etc.). Additionally or alternatively, eyewear device 100 may direct and / or cause the computing device to perform one or more actions (e.g., present certain graphical imagery to another user, performing calculations for use on the computing device or eyewear device 100, coordinating AR / VR environments across multiple HMDs, etc.)

[0108] In some examples, the various apparatuses, devices, and systems described in connection with FIGS. 1-6 may include and / or represent one or more additional circuits, components, and / or features that are not necessarily illustrated and / or labeled in FIGS. 1-6. For example, the apparatuses, devices, and systems illustrated in FIGS. 1-6 may also include and / or represent additional analog and / or digital circuitry, onboard logic, transistors, radio-frequency (RF) transmitters, RF receivers, RF transceivers, antennas, resistors, capacitors, diodes, inductors, switches, registers, flipflops, digital logic, connections, traces, buses, semiconductor (e.g., silicon) devices and / or structures, processing devices, storage devices, circuit boards, sensors, packages, substrates, housings, combinations or variations of one or more of the same, and / or any other suitable components. In certain implementations, one or more of these additional circuits, components, and / or features may be inserted and / or applied between any of the existing circuits, components, and / or featuresillustrated in FIGS. 1-6 consistent with the aims and / or objectives described herein. Accordingly, the couplings and / or connections described with reference to FIGS. 1-6 may be direct connections with no intermediate components, devices, and / or nodes or indirect connections with one or more intermediate components, devices, and / or nodes.

[0109] In some examples, the phrase “to couple” and / or the term “coupling”, as used herein, may refer to a direct connection and / or an indirect connection. For example, a direct coupling between two components may constitute and / or represent a coupling in which those two components are directly connected to each other by a single node that provides continuity from one of those two components to the other. In other words, the direct coupling may exclude and / or omit any additional components between those two components.

[0110] Additionally or alternatively, an indirect coupling between two components may constitute and / or represent a coupling in which those two components are indirectly connected to each other by multiple nodes that fail to provide continuity from one of those two components to the other. In other words, the indirect coupling may include and / or incorporate at least one additional component between those two components. In some examples, one or more components and / or features illustrated in FIGS. 1-6 may be excluded and / or omitted from the various apparatuses, devices, and / or systems described in connection with FIGS. 1- 6.

[0111] FIG. 7 is a flow diagram of an exemplary method 700 for eye tracking based on coherent light and event sensors. In one example, the steps shown in FIG. 7 may be achieved and / or accomplished by a computing equipment manufacturer or subcontractor that creates and / or assembles smart eyewear devices. Additionally or alternatively, the steps shown in FIG. 7 may incorporate and / or involve certain sub-steps and / or variations consistent with the descriptions provided above in connection with FIGS. 1-6.

[0112] As illustrated in FIG. 7, method 700 may include the step of configuring at least one coherent light source to illuminate an eye of a user of an eyewear device (710). Step 710 may be performed in a variety of ways, including any of those described above in connection with FIGS. 1-6. For example, a computing equipment manufacturer or subcontractor may configure and / or arrange at least one coherent light source to illuminate an eye of a user of an eyewear device.Method 700 may also include the step of configuring an event sensor that comprises a set of pixels to detect changes in brightness across the set of pixels based at least in part on the illumination of the eye (720). Step 720 may be performed in a variety of ways, including any of those described above in connection with FIGS. 1-6. For example, the computing equipment manufacturer or subcontractor may configure and / or program an event sensor that comprises a set of pixels to detect changes in brightness across the set of pixels based at least in part on the illumination of the eye.

[0113] Method 700 may further include the step of configuring circuitry to track the eye of the user based at least in part on the changes in brightness detected across the set of pixels (730). Step 730 may be performed in a variety of ways, including any of those described above in connection with FIGS. 1-6. For example, the computing equipment manufacturer or subcontractor may configure and / or program circuitry to track the eye of the user based at least in part on the changes in brightness detected across the set of pixels.

[0114] Embodiments of the present disclosure may include or be implemented in conjunction with various types of artificial-reality systems. Artificial reality is a form of reality that has been adjusted in some manner before presentation to a user, which may include, for example, a VR, an AR, a mixed reality, a hybrid reality, or some combination and / or derivative thereof. Artificial-reality content may include completely computer-generated content or computer-generated content combined with captured (e.g., real-world) content. The artificialreality content may include video, audio, haptic feedback, or some combination thereof, any of which may be presented in a single channel or in multiple channels (such as stereo video that produces a 3D effect to the viewer). Additionally, in some embodiments, artificial reality may also be associated with applications, products, accessories, services, or some combination thereof, that are used to, for example, create content in an artificial reality and / or are otherwise used in (e.g, to perform activities in) an artificial reality.

[0115] Artificial-reality systems may be implemented in a variety of different form factors and configurations. Some artificial-reality systems may be designed to work without near-eye displays (NEDs). Other artificial-reality systems may include an NED that also provides visibility into the real world (such as, e.g., augmented-reality system 800 in FIG. 8) or that visually immerses a user in an artificial reality (such as, e.g., virtual-reality system 900 in FIG. 9). While some artificial-reality devices may be self-contained systems, other artificialreality devices may communicate and / or coordinate with external devices to provide an artificial-reality experience to a user. Examples of such external devices include handheld controllers, mobile devices, desktop computers, devices worn by a user, devices worn by one or more other users, and / or any other suitable external system.

[0116] Turning to FIG. 8, augmented-reality system 800 may include an eyewear device 802 with a frame 810 configured to hold a left display device 815(A) and a right display device 815(B) in front of a user’s eyes. Display devices 815(A) and 815(B) may act together or independently to present an image or series of images to a user. While augmented-reality system 800 includes two displays, embodiments of this disclosure may be implemented in augmented-reality systems with a single NED or more than two NEDs.

[0117] In some examples, augmented-reality system 800 may include one or more sensors, such as sensor 840. Sensor 840 may generate measurement signals in response to motion of augmented-reality system 800 and may be located on substantially any portion offrame 810. Sensor 840 may represent one or more of a variety of different sensing mechanisms, such as a position sensor, an inertial measurement unit (IMU), a depth camera assembly, a structured light emitter and / or detector, or any combination thereof. In some examples, augmented-reality system 800 may or may not include sensor 840 or may include more than one sensor. In examples in which sensor 840 includes an IMU, the IMU may generate calibration data based on measurement signals from sensor 840. Examples of sensor 840 may include, without limitation, accelerometers, gyroscopes, magnetometers, other suitable types of sensors that detect motion, sensors used for error correction of the IMU, or some combination thereof.

[0118] In some examples, augmented-reality system 800 may also include a microphone array with a plurality of acoustic transducers 820(A)-820(J), referred to collectively as acoustic transducers 820. Acoustic transducers 820 may represent transducers that detect air pressure variations induced by sound waves. Each acoustic transducer 820 may be configured to detect sound and convert the detected sound into an electronic format (e.g., an analog or digital format). The microphone array in FIG. 8 may include, for example, ten acoustic transducers: 820(A) and 820(B), which may be designed to be placed inside a corresponding ear of the user, acoustic transducers 820(C), 820(D), 820(E), 820(F), 820(G), and 820(H), which may be positioned at various locations on frame 810, and / or acoustic transducers 820(l) and 820(J), which may be positioned on a corresponding neckband 805.

[0119] In some examples, one or more of acoustic transducers 820(A)-(J) may be used as output transducers (e.g., speakers). For example, acoustic transducers 820(A) and / or 820(B) may be earbuds or any other suitable type of headphone or speaker.

[0120] The configuration of acoustic transducers 820 of the microphone array may vary. While augmented-reality system 800 is shown in FIG. 8 as having ten acoustic transducers 820, the number of acoustic transducers 820 may be greater or less than ten. In some examples, using higher numbers of acoustic transducers 820 may increase the amount of audio information collected and / or the sensitivity and accuracy of the audio information. In contrast, using a lower number of acoustic transducers 820 may decrease the computing power required by an associated controller 850 to process the collected audio information. In addition, the position of each acoustic transducer 820 of the microphone array may vary. For example, the position of an acoustic transducer 820 may include a defined position on the user, a defined coordinate on frame 810, an orientation associated with each acoustic transducer 820, or some combination thereof.

[0121] Acoustic transducers 820(A) and 820(B) may be positioned on different parts of the user’s ear, such as behind the pinna, behind the tragus, and / or within the auricle or fossa. Or, there may be additional acoustic transducers 820 on or surrounding the ear in addition to acoustic transducers 820 inside the ear canal. Having an acoustic transducer 820positioned next to an ear canal of a user may enable the microphone array to collect information on how sounds arrive at the ear canal. By positioning at least two of acoustic transducers 820 on either side of a user’s head (e.g., as binaural microphones), AR system 800 may simulate binaural hearing and capture a 3D stereo sound field around about a user’s head. In some examples, acoustic transducers 820(A) and 820(B) may be connected to augmented-reality system 800 via a wired connection 830, and in other examples acoustic transducers 820(A) and 820(B) may be connected to augmented-reality system 800 via a wireless connection (e.g., a BLUETOOTH connection). In still other examples, acoustic transducers 820(A) and 820(B) may not be used at all in conjunction with augmented-reality system 800.

[0122] Acoustic transducers 820 on frame 810 may be positioned in a variety of different ways, including along the length of the temples, across the bridge, above or below display devices 815(A) and 815(B), or some combination thereof. Acoustic transducers 820 may also be oriented such that the microphone array is able to detect sounds in a wide range of directions surrounding the user wearing the augmented-reality system 800. In some examples, an optimization process may be performed during manufacturing of augmented- reality system 800 to determine relative positioning of each acoustic transducer 820 in the microphone array.

[0123] In some examples, augmented-reality system 800 may include or be connected to an external device (e.g., a paired device), such as neckband 805. Neckband 805 generally represents any type or form of paired device. Thus, the following discussion of neckband 805 may also apply to various other paired devices, such as charging cases, smart watches, smart phones, wrist bands, other wearable devices, hand-held controllers, tablet computers, laptop computers, other external compute devices, etc.

[0124] As shown, neckband 805 may be coupled to eyewear device 802 via one or more connectors. The connectors may be wired or wireless and may include electrical and / or non-electrical (e.g., structural) components. In some cases, eyewear device 802 and neckband 805 may operate independently without any wired or wireless connection between them. While FIG. 8 illustrates the components of eyewear device 802 and neckband 805 in example locations on eyewear device 802 and neckband 805, the components may be located elsewhere and / or distributed differently on eyewear device 802 and / or neckband 805. In some examples, the components of eyewear device 802 and neckband 805 may be located on one or more additional peripheral devices paired with eyewear device 802, neckband 805, or some combination thereof.

[0125] Pairing external devices, such as neckband 805, with augmented-reality eyewear devices may enable the eyewear devices to achieve the form factor of a pair of glasses while still providing sufficient battery and computation power for expandedcapabilities. Some or all of the battery power, computational resources, and / or additional features of augmented-reality system 800 may be provided by a paired device or shared between a paired device and an eyewear device, thus reducing the weight, heat profile, and form factor of the eyewear device overall while still retaining desired functionality. For example, neckband 805 may allow components that would otherwise be included on an eyewear device to be included in neckband 805 since users may tolerate a heavier weight load on their shoulders than they would tolerate on their heads. Neckband 805 may also have a larger surface area over which to diffuse and disperse heat to the ambient environment. Thus, neckband 805 may allow for greater battery and computation capacity than might otherwise have been possible on a stand-alone eyewear device. Since weight carried in neckband 805 may be less invasive to a user than weight carried in eyewear device 802, a user may tolerate wearing a lighter eyewear device and carrying or wearing the paired device for greater lengths of time than a user would tolerate wearing a heavy standalone eyewear device, thereby enabling users to more fully incorporate artificial-reality environments into their day-to-day activities.

[0126] Neckband 805 may be communicatively coupled with eyewear device 802 and / or to other devices. These other devices may provide certain functions (e.g., tracking, localizing, depth mapping, processing, storage, etc.) to augmented-reality system 800. In the example of FIG. 8, neckband 805 may include two acoustic transducers (e.g., 820(l) and 820(J)) that are part of the microphone array (or potentially form their own microphone subarray). Neckband 805 may also include a controller 825 and a power source 835.

[0127] Acoustic transducers 820 (I) and 820(J) of neckband 805 may be configured to detect sound and convert the detected sound into an electronic format (analog or digital). In the example of FIG. 8, acoustic transducers 820(l) and 820(J) may be positioned on neckband 805, thereby increasing the distance between the neckband acoustic transducers 820(l) and 820(J) and other acoustic transducers 820 positioned on eyewear device 802. In some cases, increasing the distance between acoustic transducers 820 of the microphone array may improve the accuracy of beamforming performed via the microphone array. For example, if a sound is detected by acoustic transducers 820(C) and 820(D) and the distance between acoustic transducers 820(C) and 820(D) is greater than, e.g., the distance between acoustic transducers 820(D) and 820(E), the determined source location of the detected sound may be more accurate than if the sound had been detected by acoustic transducers 820(D) and 820(E).

[0128] Controller 825 of neckband 805 may process information generated by the sensors on neckband 805 and / or augmented-reality system 800. For example, controller 825 may process information from the microphone array that describes sounds detected by the microphone array. For each detected sound, controller 825 may perform a direction-of-arrival(DOA) estimation to estimate a direction from which the detected sound arrived at the microphone array. As the microphone array detects sounds, controller 825 may populate an audio data set with the information. In examples in which augmented-reality system 800 includes an inertial measurement unit, controller 825 may compute all inertial and spatial calculations from the IMU located on eyewear device 802. A connector may convey information between augmented-reality system 800 and neckband 805 and between augmented-reality system 800 and controller 825. The information may be in the form of optical data, electrical data, wireless data, or any other transmittable data form. Moving the processing of information generated by augmented-reality system 800 to neckband 805 may reduce weight and heat in eyewear device 802, making it more comfortable to the user.

[0129] Power source 835 in neckband 805 may provide power to eyewear device 802 and / or to neckband 805. Power source 835 may include, without limitation, lithium-ion batteries, lithium-polymer batteries, primary lithium batteries, alkaline batteries, or any other form of power storage. In some cases, power source 835 may be a wired power source. Including power source 835 on neckband 805 instead of on eyewear device 802 may help better distribute the weight and heat generated by power source 835.

[0130] As noted, some artificial-reality systems may, instead of blending an artificial reality with actual reality, substantially replace one or more of a user’s sensory perceptions of the real world with a virtual experience. One example of this type of system is a head-worn display system, such as virtual-reality system 900 in FIG. 9, that mostly or completely covers a user’s field of view. Virtual-reality system 900 may include a front rigid body 902 and a band 904 shaped to fit around a user’s head. Virtual-reality system 900 may also include output audio transducers 906(A) and 906(B). Furthermore, while not shown in FIG. 9, front rigid body 902 may include one or more electronic elements, including one or more electronic displays, one or more inertial measurement units (IMUs), one or more tracking emitters or detectors, and / or any other suitable device or system for creating an artificial-reality experience.

[0131] Artificial-reality systems may include a variety of types of visual feedback mechanisms. For example, display devices in augmented-reality system 800 and / or virtual- reality system 900 may include one or more liquid crystal displays (LCDs), light emitting diode (LED) displays, microLED displays, organic LED (OLED) displays, digital light project (DLP) micro-displays, liquid crystal on silicon (LCoS) micro-displays, and / or any other suitable type of display screen. These artificial-reality systems may include a single display screen for both eyes or may provide a display screen for each eye, which may allow for additional flexibility for varifocal adjustments or for correcting a user’s refractive error. Some of these artificial-reality systems may also include optical subsystems having one or more lenses (e.g., concave or convex lenses, Fresnel lenses, adjustable liquid lenses, etc.) through which a usermay view a display screen. These optical subsystems may serve a variety of purposes, including to collimate (e.g., make an object appear at a greater distance than its physical distance), to magnify (e.g., make an object appear larger than its actual size), and / or to relay (to, e.g., the viewer’s eyes) light. These optical subsystems may be used in a non-pupil- forming architecture (such as a single lens configuration that directly collimates light but results in so-called pincushion distortion) and / or a pupil-forming architecture (such as a multi-lens configuration that produces so-called barrel distortion to nullify pincushion distortion).

[0132] In addition to or instead of using display screens, some of the artificial-reality systems described herein may include one or more projection systems. For example, display devices in augmented-reality system 800 and / or virtual-reality system 900 may include micro-LED projectors that project light (using, e.g., a waveguide) into display devices, such as clear combiner lenses that allow ambient light to pass through. The display devices may refract the projected light toward a user’s pupil and may enable a user to simultaneously view both artificial-reality content and the real world. The display devices may accomplish this using any of a variety of different optical components, including waveguide components (e.g., holographic, planar, diffractive, polarized, and / or reflective waveguide elements), light-manipulation surfaces and elements (such as diffractive, reflective, and refractive elements and gratings), coupling elements, etc. Artificial-reality systems may also be configured with any other suitable type or form of image projection system, such as retinal projectors used in virtual retina displays.

[0133] The artificial-reality systems described herein may also include various types of computer vision components and subsystems. For example, augmented-reality system 800 and / or virtual-reality system 900 may include one or more optical sensors, such as two-dimensional (2D) or 3D cameras, structured light transmitters and detectors, time-of- flight depth sensors, single-beam or sweeping laser rangefinders, 3D LiDAR sensors, and / or any other suitable type or form of optical sensor. An artificial-reality system may process data from one or more of these sensors to identify a location of a user, to map the real world, to provide a user with context about real-world surroundings, and / or to perform a variety of other functions.

[0134] The artificial-reality systems described herein may also include one or more input and / or output audio transducers. Output audio transducers may include voice coil speakers, ribbon speakers, electrostatic speakers, piezoelectric speakers, bone conduction transducers, cartilage conduction transducers, tragus-vibration transducers, and / or any other suitable type or form of audio transducer. Similarly, input audio transducers may include condenser microphones, dynamic microphones, ribbon microphones, and / or any other type or form of input transducer. In some examples, a single transducer may be used for both audio input and audio output.

[0135] In some examples, the artificial-reality systems described herein may also include tactile (i.e., haptic) feedback systems, which may be incorporated into headwear, gloves, body suits, handheld controllers, environmental devices (e.g., chairs, floormats, etc.), and / or any other type of device or system. Haptic feedback systems may provide various types of cutaneous feedback, including vibration, force, traction, texture, and / or temperature. Haptic feedback systems may also provide various types of kinesthetic feedback, such as motion and compliance. Haptic feedback may be implemented using motors, piezoelectric actuators, fluidic systems, and / or a variety of other types of feedback mechanisms. Haptic feedback systems may be implemented independent of other artificial-reality devices, within other artificial-reality devices, and / or in conjunction with other artificial-reality devices.

[0136] By providing haptic sensations, audible content, and / or visual content, artificial-reality systems may create an entire virtual experience or enhance a user’s real-world experience in a variety of contexts and environments. For instance, artificial-reality systems may assist or extend a user’s perception, memory, or cognition within a particular environment. Some systems may enhance a user’s interactions with other people in the real world or may enable more immersive interactions with other people in a virtual world. Artificial-reality systems may also be used for educational purposes (e.g., for teaching or training in schools, hospitals, government organizations, military organizations, business enterprises, etc.), entertainment purposes (e.g., for playing video games, listening to music, watching video content, etc.), and / or for accessibility purposes (e.g., as hearing aids, visual aids, etc.). The examples and embodiments disclosed herein may enable or enhance a user’s artificial-reality experience in one or more of these contexts and environments and / or in other contexts and environments.

[0137] In some examples, the systems described herein may also include an eyetracking subsystem designed to identify and track various characteristics of a user’s eye(s), such as the user’s gaze direction. The phrase “eye tracking” may, in some examples, refer to a process by which the position, orientation, and / or motion of an eye is measured, detected, sensed, determined, and / or monitored. The disclosed systems may measure the position, orientation, and / or motion of an eye in a variety of different ways, including through the use of various optical-based eye-tracking techniques, ultrasound-based eye-tracking techniques, etc. An eye-tracking subsystem may be configured in a number of different ways and may include a variety of different eye-tracking hardware components or other computer-vision components. For example, an eye-tracking subsystem may include a variety of different optical sensors, such as two-dimensional (2D) or 3D cameras, time-of-flight depth sensors, singlebeam or sweeping laser rangefinders, 3D LiDAR sensors, and / or any other suitable type or form of optical sensor. In this example, a processing subsystem may process data from one or more of these sensors to measure, detect, determine, and / or otherwise monitor the position,orientation, and / or motion of the user’s eye(s).

[0138] FIG. 10 is an illustration of an exemplary system 1000 that incorporates an eye-tracking subsystem capable of tracking a user’s eye(s). As depicted in FIG. 10, system 1000 may include a light source 1002, an optical subsystem 1004, an eye-tracking subsystem 1006, and / or a control subsystem 1008. In some examples, light source 1002 may generate light for an image (e.g., to be presented to an eye 1001 of the viewer). Light source 1002 may represent any of a variety of suitable devices. For example, light source 1002 can include a two-dimensional projector (e.g., a LCoS display), a scanning source (e.g., a scanning laser), or other device (e.g., an LCD, an LED display, an OLED display, an active-matrix OLED display (AMOLED), a transparent OLED display (TOLED), a waveguide, or some other display capable of generating light for presenting an image to the viewer). In some examples, the image may represent a virtual image, which may refer to an optical image formed from the apparent divergence of light rays from a point in space, as opposed to an image formed from the light ray’s actual divergence.

[0139] In some examples, optical subsystem 1004 may receive the light generated by light source 1002 and generate, based on the received light, converging light 1020 that includes the image. In some examples, optical subsystem 1004 may include any number of lenses (e.g., Fresnel lenses, convex lenses, concave lenses), apertures, filters, mirrors, prisms, and / or other optical components, possibly in combination with actuators and / or other devices. In particular, the actuators and / or other devices may translate and / or rotate one or more of the optical components to alter one or more aspects of converging light 1020. Further, various mechanical couplings may serve to maintain the relative spacing and / orthe orientation of the optical components in any suitable combination.

[0140] In one example, eye-tracking subsystem 1006 may generate tracking information indicating a gaze angle of an eye 1001 of the viewer. In this example, control subsystem 1008 may control aspects of optical subsystem 1004 (e.g., the angle of incidence of converging light 1020) based at least in part on this tracking information. Additionally, in some examples, control subsystem 1008 may store and utilize historical tracking information (e.g., a history of the tracking information over a given duration, such as the previous second or fraction thereof) to anticipate the gaze angle of eye 1001 (e.g., an angle between the visual axis and the anatomical axis of eye 1001). In some examples, eye-tracking subsystem 1006 may detect radiation emanating from some portion of eye 1001 (e.g., the cornea, the iris, the pupil, or the like) to determine the current gaze angle of eye 1001. In other examples, eyetracking subsystem 1006 may employ a wavefront sensor to track the current location of the pupil.

[0141] Any number of techniques can be used to track eye 1001. Some techniques may involve illuminating eye 1001 with infrared light and measuring reflections with at leastone optical sensorthat is tuned to be sensitive to the infrared light. Information about how the infrared light is reflected from eye 1001 may be analyzed to determine the position(s), orientation(s), and / or motion(s) of one or more eye feature(s), such as the cornea, pupil, iris, and / or retinal blood vessels.

[0142] In some examples, the radiation captured by a sensor of eye-tracking subsystem 1006 may be digitized (i.e., converted to an electronic signal). Further, the sensor may transmit a digital representation of this electronic signal to one or more processors (for example, processors associated with a device including eye-tracking subsystem 1006). Eyetracking subsystem 1006 may include any of a variety of sensors in a variety of different configurations. For example, eye-tracking subsystem 1006 may include an infrared detector that reacts to infrared radiation. The infrared detector may be a thermal detector, a photonic detector, and / or any other suitable type of detector. Thermal detectors may include detectors that react to thermal effects of the incident infrared radiation.

[0143] In some examples, one or more processors may process the digital representation generated by the sensor(s) of eye-tracking subsystem 1006 to track the movement of eye 1001. In another example, these processors may track the movements of eye 1001 by executing algorithms represented by computer-executable instructions stored on non-transitory memory. In some examples, on-chip logic (e.g., an application-specific integrated circuit or ASIC) may be used to perform at least portions of such algorithms. As noted, eye-tracking subsystem 1006 may be programmed to use an output of the sensor(s) to track movement of eye 1001. In some examples, eye-tracking subsystem 1006 may analyze the digital representation generated by the sensors to extract eye rotation information from changes in reflections. In one example, eye-tracking subsystem 1006 may use corneal reflections or glints (also known as Purkinje images) and / or the center of the eye’s pupil 1022 as features to track overtime.

[0144] In some examples, eye-tracking subsystem 1006 may use the center of the eye’s pupil 1022 and infrared or near-infrared, non-collimated light to create corneal reflections. In these examples, eye-tracking subsystem 1006 may use the vector between the center of the eye’s pupil 1022 and the corneal reflections to compute the gaze direction of eye 1001. In some examples, the disclosed systems may perform a calibration procedure for an individual (using, e.g., supervised or unsupervised techniques) before tracking the user’s eyes. For example, the calibration procedure may include directing users to look at one or more points displayed on a display while the eye-tracking system records the values that correspond to each gaze position associated with each point.

[0145] In some examples, eye-tracking subsystem 1006 may use two types of infrared and / or near-infrared (also known as active light) eye-tracking techniques: bright-pupil and dark-pupil eye tracking, which may be differentiated based on the location of anillumination source with respect to the optical elements used. If the illumination is coaxial with the optical path, then eye 1001 may act as a retroreflector as the light reflects off the retina, thereby creating a bright pupil effect similar to a red-eye effect in photography. If the illumination source is offset from the optical path, then the eye’s pupil 1022 may appear dark because the retroreflection from the retina is directed away from the sensor. In some examples, bright-pupil tracking may create greater iris / pupil contrast, allowing more robust eye tracking with iris pigmentation, and may feature reduced interference (e.g., interference caused by eyelashes and other obscuring features). Bright-pupil tracking may also allow tracking in lighting conditions ranging from total darkness to a very bright environment.

[0146] In some examples, control subsystem 1008 may control light source 1002 and / or optical subsystem 1004 to reduce optical aberrations (e.g., chromatic aberrations and / or monochromatic aberrations) of the image that may be caused by or influenced by eye 1001. In some examples, as mentioned above, control subsystem 1008 may use the tracking information from eye-tracking subsystem 1006 to perform such control. For example, in controlling light source 1002, control subsystem 1008 may alter the light generated by light source 1002 (e.g., by way of image rendering) to modify (e.g., pre-distort) the image so that the aberration of the image caused by eye 1001 is reduced.

[0147] The disclosed systems may track both the position and relative size of the pupil (since, e.g., the pupil dilates and / or contracts). In some examples, the eye-tracking devices and components (e.g., sensors and / or sources) used for detecting and / or tracking the pupil may be different (or calibrated differently) for different types of eyes. For example, the frequency range of the sensors may be different (or separately calibrated) for eyes of different colors and / or different pupil types, sizes, and / or the like. As such, the various eye-tracking components (e.g., infrared sources and / or sensors) described herein may need to be calibrated for each individual user and / or eye.

[0148] The disclosed systems may track both eyes with and without ophthalmic correction, such as that provided by contact lenses worn by the user. In some examples, ophthalmic correction elements (e.g., adjustable lenses) may be directly incorporated into the artificial-reality systems described herein. In some examples, the color of the user’s eye may necessitate modification of a corresponding eye-tracking algorithm. For example, eye-tracking algorithms may need to be modified based at least in part on the differing color contrast between a brown eye and, for example, a blue eye.

[0149] FIG. 11 is a more detailed illustration of various aspects of the eye-tracking subsystem illustrated in FIG. 10. As shown in this figure, an eye-tracking subsystem 1 100 may include at least one source 1 104 and at least one sensor 1 106. Source 1 104 generally represents any type or form of element capable of emitting radiation. In one example, source 1104 may generate visible, infrared, and / or near-infrared radiation. In some examples, source1104 may radiate non-collimated infrared and / or near-infrared portions of the electromagnetic spectrum towards an eye 1102 of a user. Source 1104 may utilize a variety of sampling rates and speeds. For example, the disclosed systems may use sources with higher sampling rates in order to capture fixational eye movements of a user’s eye 1102 and / or to correctly measure saccade dynamics of the user’s eye 1102. As noted above, any type or form of eye-tracking technique may be used to track the user’s eye 1102, including optical-based eye-tracking techniques, ultrasound-based eye-tracking techniques, etc.

[0150] Sensor 1106 generally represents any type or form of element capable of detecting radiation, such as radiation reflected off the user’s eye 1102. Examples of sensor 1106 include, without limitation, a charge coupled device (CCD), a photodiode array, a complementary metal-oxide-semiconductor (CMOS) based sensor device, and / or the like. In one example, sensor 1106 may represent a sensor having predetermined parameters, including, but not limited to, a dynamic resolution range, linearity, and / or other characteristic selected and / or designed specifically for eye tracking.

[0151] As detailed above, eye-tracking subsystem 1100 may generate one or more glints. As detailed above, a glint 1103 may represent reflections of radiation (e.g., infrared radiation from an infrared source, such as source 1104) from the structure of the user’s eye. In various examples, glint 1103 and / or the user’s pupil may be tracked using an eye-tracking algorithm executed by a processor (either within or external to an artificial-reality device). For example, an artificial-reality device may include a processor and / or a memory device in order to perform eye tracking locally and / or a transceiver to send and receive the data necessary to perform eye tracking on an external device (e.g., a mobile phone, cloud server, or other computing device).

[0152] FIG. 11 shows an example image 1105 captured by an eye-tracking subsystem, such as eye-tracking subsystem 1100. In this example, image 1105 may include both the user’s pupil 1108 and a glint 1110 near the same. In some examples, pupil 1108 and / or glint 1110 may be identified using an artificial-intelligence-based algorithm, such as a computer-vision-based algorithm. In one example, image 1105 may represent a single frame in a series of frames that may be analyzed continuously in order to track the eye 1102 of the user. Further, pupil 1108 and / or glint 1110 may be tracked over a period of time to determine a user’s gaze.

[0153] In one example, eye-tracking subsystem 1100 may be configured to identify and measure the inter-pupillary distance (IPD) of a user. In some examples, eye-tracking subsystem 1100 may measure and / or calculate the IPD of the user while the user is wearing the artificial-reality system. In these examples, eye-tracking subsystem 1100 may detect the positions of a user’s eyes and may use this information to calculate the user’s IPD.

[0154] As noted, the eye-tracking systems or subsystems disclosed herein maytrack a user’s eye position and / or eye movement in a variety of ways. In one example, one or more light sources and / or optical sensors may capture an image of the user’s eyes. The eyetracking subsystem may then use the captured information to determine the user’s inter- pupillary distance, interocular distance, and / or a 3D position of each eye (e.g., for distortion adjustment purposes), including a magnitude of torsion and rotation (i.e., roll, pitch, and yaw) and / or gaze directions for each eye. In one example, infrared light may be emitted by the eyetracking subsystem and reflected from each eye. The reflected light may be received or detected by an optical sensor and analyzed to extract eye rotation data from changes in the infrared light reflected by each eye.

[0155] The eye-tracking subsystem may use any of a variety of different methods to track the eyes of a user. For example, a light source (e.g., infrared light-emitting diodes) may emit a dot pattern onto each eye of the user. The eye-tracking subsystem may then detect (e.g., via an optical sensor coupled to the artificial-reality system) and analyze a reflection of the dot pattern from each eye of the user to identify a location of each pupil of the user. Accordingly, the eye-tracking subsystem may track up to six degrees of freedom of each eye (i.e., 3D position, roll, pitch, and yaw) and at least a subset of the tracked quantities may be combined from two eyes of a user to estimate a gaze point (i.e., a 3D location or position in a virtual scene where the user is looking) and / or an IPD.

[0156] In some cases, the distance between a user’s pupil and a display may change as the user’s eye moves to look in different directions. The varying distance between a pupil and a display as viewing direction changes may be referred to as “pupil swim” and may contribute to distortion perceived by the user as a result of light focusing in different locations as the distance between the pupil and the display changes. Accordingly, measuring distortion at different eye positions and pupil distances relative to displays and generating distortion corrections for different positions and distances may allow mitigation of distortion caused by pupil swim by tracking the 3D position of a user’s eyes and applying a distortion correction corresponding to the 3D position of each of the user’s eyes at a given point in time. Thus, knowing the 3D position of each of a user’s eyes may allow for the mitigation of distortion caused by changes in the distance between the pupil of the eye and the display by applying a distortion correction for each 3D eye position. Furthermore, as noted above, knowing the position of each of the user’s eyes may also enable the eye-tracking subsystem to make automated adjustments for a user’s IPD.

[0157] In some examples, a display subsystem may include a variety of additional subsystems that may work in conjunction with the eye-tracking subsystems described herein. For example, a display subsystem may include a varifocal subsystem, a scene-rendering module, and / or a vergence-processing module. The varifocal subsystem may cause left and right display elements to vary the focal distance of the display device. In one example, thevarifocal subsystem may physically change the distance between a display and the optics through which it is viewed by moving the display, the optics, or both. Additionally, moving or translating two lenses relative to each other may also be used to change the focal distance of the display. Thus, the varifocal subsystem may include actuators or motors that move displays and / or optics to change the distance between them. This varifocal subsystem may be separate from or integrated into the display subsystem. The varifocal subsystem may also be integrated into or separate from its actuation subsystem and / or the eye-tracking subsystems described herein.

[0158] In one example, the display subsystem may include a vergenceprocessing module configured to determine a vergence depth of a user’s gaze based on a gaze point and / or an estimated intersection of the gaze lines determined by the eye-tracking subsystem. Vergence may refer to the simultaneous movement or rotation of both eyes in opposite directions to maintain single binocular vision, which may be naturally and automatically performed by the human eye. Thus, a location where a user’s eyes are verged is where the user is looking and is also typically the location where the user’s eyes are focused. For example, the vergence-processing module may triangulate gaze lines to estimate a distance or depth from the user associated with intersection of the gaze lines. The depth associated with intersection of the gaze lines may then be used as an approximation for the accommodation distance, which may identify a distance from the user where the user’s eyes are directed. Thus, the vergence distance may allow for the determination of a location where the user’s eyes should be focused and a depth from the user’s eyes at which the eyes are focused, thereby providing information (such as an object or plane of focus) for rendering adjustments to the virtual scene.

[0159] The vergence-processing module may coordinate with the eye-tracking subsystems described herein to make adjustments to the display subsystem to account for a user’s vergence depth. When the user is focused on something at a distance, the user’s pupils may be slightly farther apart than when the user is focused on something close. The eyetracking subsystem may obtain information about the user’s vergence or focus depth and may adjust the display subsystem to be closer together when the user’s eyes focus or verge on something close and to be farther apart when the user’s eyes focus or verge on something at a distance.

[0160] The eye-tracking information generated by the above-described eyetracking subsystems may also be used, for example, to modify various aspect of how different computer-generated images are presented. For example, a display subsystem may be configured to modify, based on information generated by an eye-tracking subsystem, at least one aspect of how the computer-generated images are presented. For instance, the computergenerated images may be modified based on the user’s eye movement, such that if a user islooking up, the computer-generated images may be moved upward on the screen. Similarly, if the user is looking to the side or down, the computer-generated images may be moved to the side or downward on the screen. If the user’s eyes are closed, the computer-generated images may be paused or removed from the display and resumed once the user’s eyes are back open.

[0161] The above-described eye-tracking subsystems can be incorporated into one or more of the various artificial-reality systems described herein in a variety of ways. For example, one or more of the various components of system 1000 and / or eye-tracking subsystem 1100 may be incorporated into augmented-reality system 800 in FIG. 8 and / or virtual-reality system 900 in FIG. 9 to enable these systems to perform various eye-tracking tasks (including one or more of the eye-tracking operations described herein).

[0162] The process parameters and sequence of the steps described and / or illustrated herein are given by way of example only and may be varied as desired. For example, while the steps illustrated and / or described herein may be shown or discussed in a particular order, these steps do not necessarily need to be performed in the order illustrated or discussed. The various exemplary methods described and / or illustrated herein may also omit one or more of the steps described or illustrated herein or include additional steps in addition to those disclosed.

[0163] The preceding description has been provided to enable others skilled in the art to best utilize various aspects of the examples disclosed herein. This exemplary description is not intended to be exhaustive or to be limited to any precise form disclosed. Many modifications and variations are possible without departing from the scope of the present disclosure. The examples disclosed herein should be considered in all respects illustrative and not restrictive. Reference should be made to any claims appended hereto and their equivalents in determining the scope of the present disclosure.

[0164] Unless otherwise noted, the terms “connected to” and “coupled to” (and their derivatives), as used in the specification and / or claims, are to be construed as permitting both direct and indirect (i.e. , via other elements or components) connection. In addition, the terms “a” or “an,” as used in the specification and / or claims, are to be construed as meaning “at least one of.” Finally, for ease of use, the terms “including” and “having” (and their derivatives), as used in the specification and / or claims, are interchangeable with and have the same meaning as the word “comprising.”

Claims

CLAIMS1. An eyewear device comprising: at least one coherent light source configured to illuminate an eye of a user; at least one event sensor that comprises a set of pixels and is configured to detect changes in brightness across the set of pixels based at least in part on the illumination of the eye; and circuitry configured to track the eye of the user based at least in part on the changes in brightness detected across the set of pixels.

2. The eyewear device of claim 1 , wherein the circuitry is further configured to perform at least one action in response to the tracking of the eye.

3. The eyewear device of claim 1 or 2, wherein the tracking of the eye involves monitoring at least one of: a state of the eye; an orientation of the eye; a movement of the eye; and a position of the eye.

4. The eyewear device of any preceding claim, wherein: the coherent light source is further configured to produce a speckle pattern on the eye of the user via the illumination; the event sensor is further configured to generate one or more events corresponding to one or more changes in the speckle pattern on the eye; and the circuitry is further configured to: detect a movement of the eye based at least in part on the events; and track the eye based at least in part on the movement.

5. The eyewear device of claim 4, wherein the circuitry is further configured to: identify locations of one or more capillaries in the eye of the user based at least in part on the events; map the capillaries in the eye of the user based at least in part on the locations; and track the eye based at least in part on the mapping of the capillaries; and / or detect contrast in the speckle pattern on the eye across the events; and track the eye based at least in part on the contrast in the speckle pattern on the eye across the events.

6. The eyewear device of claim 4 or 5, wherein the coherent light source is further configured to produce the speckle pattern on a sclera of the eye via the illumination.

7. The eyewear device of claim 6, further comprising a light-emitting device configured to facilitate tracking the eye of the user based at least in part on a pupil of the eye, wherein the circuitry is further configured to detect the movement of the eye based at least inpart on the speckle pattern produced on the sclera during a moment in which the sclera is perceptible to the event sensor and the pupil is imperceptible to the event sensor; preferably wherein the circuitry is further configured to: deactivate the coherent light source when the pupil is perceptible to the event sensor; and activate the coherent light source when the pupil is imperceptible to the event sensor; further preferably wherein: the light-emitting device comprises a light-emitting diode; and the coherent light source comprises at least one of: a laser; or a vertical-cavity surface-emitting laser (VCSEL) device.

8. The eyewear device of any preceding claim, further comprising a waveguide that is optically coupled between the eye of the user and the event sensor and is configured to relay the illumination of the eye to the event sensor.

9. The eyewear device of any preceding claim, further comprising: a frame that is dimensioned to be worn by the user and is equipped with an optical element; and at least one additional coherent light source configured to illuminate the eye of the user, wherein the coherent light source and the additional coherent light source are each coupled to either the frame or the optical element.

10. The eyewear device of any preceding claim, further comprising at least one additional event sensor that comprises an additional set of pixels and is configured to detect changes in brightness across the additional set of pixels based at least in part on the illumination of the eye, wherein the circuitry is further configured to track the eye of the user based at least in part on: the changes in brightness detected across the set of pixels; or the changes in brightness detected across the additional set of pixels.

11. The eyewear device of any preceding claim, further comprising at least one camera configured to image the eye of the user at a first frame rate, wherein the event sensor is configured to image the eye at a second frame rate that is faster than the first frame rate.

12. The eyewear device of any preceding claim, wherein the circuitry is further configured to: determine that the user is looking at a certain target by tracking the eye; and perform at least one action due at least in part to the user looking at the certain target.

13. The eyewear device of any preceding claim, wherein the circuitry is further configured to: monitor blood flow in the eye of the user based at least in part on the changes inbrightness; evaluate a health feature of the user based at least in a part on the blood flow; and perform at least one action based at least in part on the health feature of the user.

14. An artificial-reality system comprising: the eyewear device of any preceding claim, wherein the at least one coherent light source is configured to facilitate eye tracking based at least in part on a sclera of the eye; and a light-emitting device configured to illuminate the eye of the user and to facilitate eye tracking based at least in part on a pupil of the eye.

15. A method comprising: configuring at least one coherent light source to illuminate an eye of a user of an eyewear device; configuring an event sensor that comprises a set of pixels to detect changes in brightness across the set of pixels based at least in part on the illumination of the eye; and configuring circuitry to track the eye of the user based at least in part on the changes in brightness detected across the set of pixels.

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