Patent Description:
This relates generally to electronic devices, and, more particularly, to electronic devices such as head-mounted devices having optical components.

Electronic devices such as head-mounted devices may have displays for displaying images and may have other optical components. The US patent application <CIT> describes a head-mounted device having a body containing one or more lens units and a display unit, the lens units being configured to present information from the display unit to a user's eyes. The head-mounted device further comprises a lens position sensor based on magnetism.

A head-mounted device according to the present invention is specified in appended claim <NUM>. Optical components are supported by the head-mounted housing. The optical components may include cameras such as front-facing.

Optical self-mixing sensors are provided in the head-mounted device to detect changes in position between portions of the head-mounted device. These changes may include changes in the positions between optical module components such as lenses and displays. These changes may also involve movement of optical components such as cameras.

In response to detecting a change in optical component position using the optical self-mixing sensors (e.g., a change indicating that a component or other structure has moved from its desired position), actuators in the device are adjusted to move the optical components or other action may be taken to compensate for the change.

An electronic device such as a head-mounted device according to the claimed invention has optical components. The optical components include optical modules that are used to provide images to a user's eyes. The head-mounted device may also have other optical components such as cameras. Components in a head-mounted have the potential to experience misalignment if the device is subjected to stress during a drop event or other high stress event. To ensure that the device operates satisfactory, optical self-mixing sensors are used to accurately measure the positions of components in the head-mounted device. Actuators then move the optical components to compensate for any detected changes in position and/or other compensating action may be taken.

A top view of an illustrative head-mounted device is shown in <FIG>. As shown in <FIG>, head-mounted devices such as electronic device <NUM> may have head-mounted support structures such as housing <NUM>. Housing <NUM> may include portions (e.g., head-mounted support structures 12T) to allow device <NUM> to be worn on a user's head. Support structures 12T may be formed from fabric, polymer, metal, and/or other material. Support structures 12T may form a strap or other head-mounted support structures to help support device <NUM> on a user's head. A main support structure (e.g., a head-mounted housing such as main housing portion <NUM>) of housing <NUM> may support electronic components such as displays <NUM>.

Main housing portion <NUM> may include housing structures formed from metal, polymer, glass, ceramic, and/or other material. For example, housing portion <NUM> may have housing walls on front face F and housing walls on adjacent top, bottom, left, and right side faces that are formed from rigid polymer or other rigid support structures and these rigid walls may optionally be covered with electrical components, fabric, leather, or other soft materials, etc. Housing portion <NUM> may also have internal support structures such as a frame and/or structures that perform multiple functions such as controlling airflow and dissipating heat while providing structural support. The walls of housing portion <NUM> may enclose internal components <NUM> in interior region <NUM> of device <NUM> and may separate interior region <NUM> from the environment surrounding device <NUM> (exterior region <NUM>). Internal components <NUM> may include integrated circuits, actuators, batteries, sensors, and/or other circuits and structures for device <NUM>. Housing <NUM> may be configured to be worn on a head of a user and may form glasses, a hat, a helmet, goggles, and/or other head-mounted device. Configurations in which housing <NUM> forms goggles may sometimes be described herein as an example.

Front face F of housing <NUM> may face outwardly away from a user's head and face. Opposing rear face R of housing <NUM> may face the user. Portions of housing <NUM> (e.g., portions of main housing <NUM>) on rear face R may form a cover such as cover 12C. The presence of cover 12C on rear face R may help hide internal housing structures, internal components <NUM>, and other structures in interior region <NUM> from view by a user.

Device <NUM> may have one or more cameras such as cameras <NUM> of <FIG>. For example, forward-facing (front-facing) cameras may allow device <NUM> to monitor movement of the device <NUM> relative to the environment surrounding device <NUM> (e.g., the cameras may be used in forming a visual odometry system or part of a visual inertial odometry system). Forward-facing cameras may also be used to capture images of the environment that are displayed to a user of the device <NUM>. If desired, images from multiple forward-facing cameras may be merged with each other and/or forward-facing camera content can be merged with computer-generated content for a user.

Device <NUM> may have any suitable number of cameras <NUM>. For example, device <NUM> may have K cameras, where the value of K is at least one, at least two, at least four, at least six, at least eight, at least ten, at least <NUM>, less than <NUM>, less than <NUM>, less than <NUM>, less than ten, <NUM>-<NUM>, or other suitable value. Cameras <NUM> may be sensitive at infrared wavelengths (e.g., cameras <NUM> may be infrared cameras), may be sensitive at visible wavelengths (e.g., cameras <NUM> may be visible cameras), and/or cameras <NUM> may be sensitive at other wavelengths. If desired, cameras <NUM> may be sensitive at both visible and infrared wavelengths.

Cameras <NUM> that are mounted on front face F and that face outwardly (towards the front of device <NUM> and away from the user) may sometimes be referred to herein as forward-facing or front-facing cameras. Cameras <NUM> may capture visual odometry information, image information that is processed to locate objects in the user's field of view (e.g., so that virtual content can be registered appropriately relative to real-world objects), image content that is displayed in real time for a user of device <NUM>, and/or other suitable image data.

Device <NUM> may have left and right optical modules <NUM>. Optical modules <NUM> support electrical and optical components such as light-emitting components and lenses and may therefore sometimes be referred to as optical assemblies, optical systems, optical component support structures, lens and display support structures, electrical component support structures, or housing structures. Each optical module includes a respective display <NUM>, lens <NUM>, and may include support structure such as support structure <NUM>. Support structure <NUM>, which may sometimes be referred to as a lens support structure, optical component support structure, optical module support structure, optical module portion, or lens barrel, may include hollow cylindrical structures with open ends or other supporting structures to house displays <NUM> and lenses <NUM>. Support structures <NUM> may, for example, include a left lens barrel that supports a left display <NUM> and left lens <NUM> and a right lens barrel that supports a right display <NUM> and right lens <NUM>.

Displays <NUM> may include arrays of pixels or other display devices to produce images. Displays <NUM> may, for example, include organic light-emitting diode pixels formed on substrates with thin-film circuitry and/or formed on semiconductor substrates, pixels formed from crystalline semiconductor dies, liquid crystal display pixels, scanning display devices, and/or other display devices for producing images.

Lenses <NUM> may include one or more lens elements for providing image light from displays <NUM> to respective eyes boxes <NUM>. Lenses may be implemented using refractive glass lens elements, using mirror lens structures (catadioptric lenses), using Fresnel lenses, using holographic lenses, and/or other lens systems.

When a user's eyes are located in eye boxes <NUM>, displays (display panels) <NUM> operate together to form a display for device <NUM> (e.g., the images provided by respective left and right optical modules <NUM> may be viewed by the user's eyes in eye boxes <NUM> so that a stereoscopic image is created for the user). The left image from the left optical module fuses with the right image from a right optical module while the display is viewed by the user.

It may be desirable to monitor the user's eyes while the user's eyes are located in eye boxes <NUM>. For example, it may be desirable to use a camera to capture images of the user's irises (or other portions of the user's eyes) for user authentication. It may also be desirable to monitor the direction of the user's gaze. Gaze tracking information may be used as a form of user input and/or may be used to determine where, within an image, image content resolution should be locally enhanced in a foveated imaging system. To ensure that device <NUM> can capture satisfactory eye images while a user's eyes are located in eye boxes <NUM>, each optical module <NUM> may be provided with a camera such as camera <NUM> and one or more light sources such as light-emitting diodes <NUM> or other light-emitting devices such as lasers, lamps, etc. Cameras <NUM> and light-emitting diodes <NUM> may operate at any suitable wavelengths (visible, infrared, and/or ultraviolet). As an example, diodes <NUM> may emit infrared light that is invisible (or nearly invisible) to the user. This allows eye monitoring operations to be performed continuously without interfering with the user's ability to view images on displays <NUM>.

Not all users have the same interpupillary distance IPD. To provide device <NUM> with the ability to adjust the interpupillary spacing between modules <NUM> along lateral dimension X and thereby adjust the spacing IPD between eye boxes <NUM> to accommodate different user interpupillary distances, device <NUM> may be provided with optical module positioning systems in housing <NUM>. The positioning systems may have guide members and actuators <NUM> that are used to position optical modules <NUM> with respect to each other.

Actuators <NUM> can be manually controlled and/or computer-controlled actuators (e.g., computer-controlled motors) for moving support structures (lens barrels) <NUM> relative to each other. Information on the locations of the user's eyes may be gathered using, for example, cameras <NUM>. The locations of eye boxes <NUM> can then be adjusted accordingly.

As shown in the rear view of device <NUM> of <FIG>, cover 12C may cover rear face R while leaving lenses <NUM> of optical modules <NUM> uncovered (e.g., cover 12C may have openings that are aligned with and receive modules <NUM>). As modules <NUM> are moved relative to each other along dimension X to accommodate different interpupillary distances for different users, modules <NUM> move relative to fixed housing structures such as the walls of main portion <NUM> and move relative to each other.

A schematic diagram of an illustrative electronic device such as a head-mounted device or other wearable device is shown in <FIG>. Device <NUM> of <FIG> may be operated as a stand-alone device and/or the resources of device <NUM> may be used to communicate with external electronic equipment. As an example, communications circuitry in device <NUM> may be used to transmit user input information, sensor information, and/or other information to external electronic devices (e.g., wirelessly or via wired connections). Each of these external devices may include components of the type shown by device <NUM> of <FIG>.

As shown in <FIG>, a head-mounted device such as device <NUM> may include control circuitry <NUM>. Control circuitry <NUM> may include storage and processing circuitry for supporting the operation of device <NUM>. The storage and processing circuitry may include storage such as nonvolatile memory (e.g., flash memory or other electrically-programmable-read-only memory configured to form a solid-state drive), volatile memory (e.g., static or dynamic random-access-memory), etc. Processing circuitry in control circuitry <NUM> may be used to gather input from sensors and other input devices and may be used to control output devices. The processing circuitry may be based on one or more microprocessors, microcontrollers, digital signal processors, baseband processors and other wireless communications circuits, power management units, audio chips, application specific integrated circuits, etc. During operation, control circuitry <NUM> may use display(s) <NUM> and other output devices in providing a user with visual output and other output.

To support communications between device <NUM> and external equipment, control circuitry <NUM> may communicate using communications circuitry <NUM>. Circuitry <NUM> may include antennas, radio-frequency transceiver circuitry, and other wireless communications circuitry and/or wired communications circuitry. Circuitry <NUM>, which may sometimes be referred to as control circuitry and/or control and communications circuitry, may support bidirectional wireless communications between device <NUM> and external equipment (e.g., a companion device such as a computer, cellular telephone, or other electronic device, an accessory such as a point device, computer stylus, or other input device, speakers or other output devices, etc.) over a wireless link. For example, circuitry <NUM> may include radio-frequency transceiver circuitry such as wireless local area network transceiver circuitry configured to support communications over a wireless local area network link, near-field communications transceiver circuitry configured to support communications over a near-field communications link, cellular telephone transceiver circuitry configured to support communications over a cellular telephone link, or transceiver circuitry configured to support communications over any other suitable wired or wireless communications link. Wireless communications may, for example, be supported over a Bluetooth® link, a WiFi® link, a wireless link operating at a frequency between <NUM> and <NUM>, a <NUM> link, or other millimeter wave link, a cellular telephone link, or other wireless communications link. Device <NUM> may, if desired, include power circuits for transmitting and/or receiving wired and/or wireless power and may include batteries or other energy storage devices. For example, device <NUM> may include a coil and rectifier to receive wireless power that is provided to circuitry in device <NUM>.

Device <NUM> may include input-output devices such as devices <NUM>. Input-output devices <NUM> may be used in gathering user input, in gathering information on the environment surrounding the user, and/or in providing a user with output. Devices <NUM> may include one or more displays such as display(s) <NUM>. Display(s) <NUM> may include one or more display devices such as organic light-emitting diode display panels (panels with organic light-emitting diode pixels formed on polymer substrates or silicon substrates that contain pixel control circuitry), liquid crystal display panels, microelectromechanical systems displays (e.g., two-dimensional mirror arrays or scanning mirror display devices), display panels having pixel arrays formed from crystalline semiconductor light-emitting diode dies (sometimes referred to as microLEDs), and/or other display devices.

Sensors <NUM> in input-output devices <NUM> may include force sensors (e.g., strain gauges, capacitive force sensors, resistive force sensors, etc.), audio sensors such as microphones, touch and/or proximity sensors such as capacitive sensors such as a touch sensor that forms a button, trackpad, or other input device), and other sensors. If desired, sensors <NUM> may include optical sensors such as optical sensors that emit and detect light, ultrasonic sensors, optical touch sensors, optical proximity sensors, and/or other touch sensors and/or proximity sensors, monochromatic and color ambient light sensors, image sensors (e.g., cameras), fingerprint sensors, iris scanning sensors, retinal scanning sensors, and other biometric sensors, temperature sensors, sensors for measuring three-dimensional non-contact gestures ("air gestures"), pressure sensors, sensors for detecting position, orientation, and/or motion (e.g., accelerometers, magnetic sensors such as compass sensors, gyroscopes, and/or inertial measurement units that contain some or all of these sensors), health sensors such as blood oxygen sensors, heart rate sensors, blood flow sensors, and/or other health sensors, radio-frequency sensors, three-dimensional camera systems such as depth sensors (e.g., structured light sensors and/or depth sensors based on stereo imaging devices that capture three-dimensional images) and/or optical sensors such as self-mixing sensors and light detection and ranging (lidar) sensors that gather time-of-flight measurements (e.g., time-of-flight cameras), humidity sensors, moisture sensors, gaze tracking sensors, electromyography sensors to sense muscle activation, facial sensors, interferometric sensors, time-of-flight sensors, magnetic sensors, resistive sensors, distance sensors, angle sensors, and/or other sensors. In some arrangements, device <NUM> may use sensors <NUM> and/or other input-output devices to gather user input. For example, buttons may be used to gather button press input, touch sensors overlapping displays can be used for gathering user touch screen input, touch pads may be used in gathering touch input, microphones may be used for gathering audio input (e.g., voice commands), accelerometers may be used in monitoring when a finger contacts an input surface and may therefore be used to gather finger press input, etc..

If desired, electronic device <NUM> may include additional components (see, e.g., other devices <NUM> in input-output devices <NUM>). The additional components may include haptic output devices, actuators for moving movable housing structures, audio output devices such as speakers, light-emitting diodes for status indicators, light sources such as light-emitting diodes that illuminate portions of a housing and/or display structure, other optical output devices, and/or other circuitry for gathering input and/or providing output. Device <NUM> may also include a battery or other energy storage device, connector ports for supporting wired communication with ancillary equipment and for receiving wired power, and other circuitry.

It is desirable for optical components in device <NUM> to remain in satisfactory alignment during operation of device <NUM>. Due to a drop event or other event imparting stress on device <NUM>, there is a risk that the positions of displays, lenses, cameras, other optical components, and/or other structures in device <NUM> will move relative to their initial positions. To ensure that device <NUM> operates satisfactorily, even if subjected to large amounts of stress, device <NUM> may use sensors to measure component positions. In response to measuring a change in component position, device <NUM> (e.g., control circuitry <NUM>) can take compensating action (e.g., by using an actuator to adjust the position of the component to ensure that the component is positioned satisfactorily, by warping image data associated with a camera or display to compensate, etc.). In an illustrative configuration, which may sometimes be described herein as an example, one or more actuators may be used to reposition a moved optical component so that the optical component remains in its desired position even when device <NUM> is subjected to drop events and other high stress events. Configurations in which actuators use measured position information while moving lenses, displays, and/or other components to adjust focus and/or otherwise adjust the operation of the optical components may also be described herein as examples.

It may be desirable to measure relatively small changes in component position, so that components can be maintained in desired positions. For example, it may be desirable to maintain the position of a lens or other component in its original position within a tolerance of less than <NUM> microns, less than <NUM> microns, less than <NUM> microns, or less than <NUM> microns (as examples). In maintaining tight tolerances for the optical components in device <NUM>, it may be desirable to take correspondingly accurate position measurements. In an illustrative configuration, which is described herein as an example, optical position sensors such as optical self-mixing sensors are used to measure component positions within these tight tolerances (e.g., with an accuracy of better than <NUM> microns, better than <NUM> microns, or better than <NUM> micron, or other suitable accuracy). Submicron position measurement accuracy or other satisfactory measurement precision allows lenses, displays, cameras, and/or other optical components to be placed in desired locations without introducing significant misalignment errors.

An illustrative optical self-mixing sensor is shown in <FIG>. Self-mixing sensor <NUM>, which may sometimes be referred to as an optical self-mixing position sensor or self-mixing orientation sensor may be used to measure distance and therefore determine the relative position between the sensor and a target structure. In some configurations, angular orientation may be measured using one or more self-mixing sensors. For example, angular tilt may be measured by measuring two or more distances. Tilt about one axis may, as an example, be measured using a pair of distance measurements made at different respective locations on a component, whereas tilt about two axes may be measured using three such distance measurements. Arrangements in which self-mixing sensors are referred to as measuring distance, displacement, or position may sometimes be described herein as an example. In general, position, angular orientation, changes in position and/or orientation, and/or other self-mixing sensor measurements may be directly gathered and/or may be derived from the measurements of distance from self-mixing sensors.

In the example of <FIG>, self-mixing sensor <NUM> is being used to measure the separation (distance D) between sensor <NUM> and target <NUM>. Target structures in device <NUM> such as target <NUM> of <FIG> may be portions of lenses (e.g., lenses <NUM> of <FIG>), portions of support structures (e.g., a lens barrel or other support structure <NUM> for a lens and/or other optical module components), display structures (e.g., displays <NUM>), portions of cameras (e.g., cameras <NUM> and/or cameras <NUM>), and/or other structures in device <NUM> (e.g., housing structures in portion <NUM>). Self-mixing sensors such as sensor <NUM> may be mounted on or adjacent to housing structures (e.g., a structure in portion <NUM>) and/or sensor <NUM> may be mounted on or adjacent to lenses (e.g., lenses <NUM> of <FIG>), portions of support structures (e.g., lens barrel <NUM>), display structures (e.g., displays <NUM>), portions of cameras, and/or other structures in device <NUM> (e.g., housing structures in portion <NUM>). In this way, distance D may correspond to a display-to-lens measurement or housing-to-lens measurement that reveals information on lens alignment and/or may otherwise be used in measuring distances between lenses, cameras, displays, housing structures, etc. In the event that measurements with one or more sensors <NUM> reveal that a component is misaligned relative to its desired position, compensating action may be taken. For example, control circuitry <NUM> may use an actuator to move a lens, display, camera, or other component in device <NUM> to compensate for measured changes in component position. If, as an example, lens <NUM> is <NUM> microns too far from display <NUM>, lens <NUM> may be moved towards display <NUM> by <NUM> microns.

As shown in the illustrative configuration of <FIG>, self-mixing sensor <NUM> may include a laser such as vertical cavity surface emitting laser <NUM> (e.g., self-mixing proximity sensor <NUM> may be a coherent self-mixing sensor having a diode laser or other coherent or partially coherent source of light or other electromagnetic radiation). Laser <NUM> may have thin-film interference filter mirrors <NUM> (sometimes referred to as Bragg reflectors) each of which is formed from a stack of thin-film layers of alternating index of refraction. Active region <NUM> may be formed between mirrors <NUM>. The lower mirror in laser <NUM> may have a nominal reflectivity of less than <NUM>% to allow some of the light of laser <NUM> to reach overlapped photodiode <NUM> or, in configurations in which photodiode <NUM> is located elsewhere in sensor <NUM> (e.g., laterally adjacent to laser <NUM>), the lower mirror may have a nominal reflectivity of <NUM>%. The upper mirror in laser <NUM> may have a slightly lower reflectivity, so that laser <NUM> emits light <NUM> towards target <NUM>. Laser <NUM> may be controlled by applying a drive signal to terminals <NUM> using control circuitry <NUM> (e.g., a drive circuit in circuitry <NUM>). Sensing circuitry (e.g., photodiode <NUM> and/or associated sensing circuitry in circuitry <NUM>) can measure the light output of laser <NUM> (as an example).

Emitted light <NUM> may have an infrared wavelength of <NUM>-<NUM>, <NUM> to <NUM>, <NUM>-<NUM>, at least <NUM>, at least <NUM>, at least <NUM>, less than <NUM>, less than <NUM>, less than <NUM>, or less than <NUM>, or other suitable wavelength (e.g., a visible wavelength, an ultraviolet wavelength, an infrared wavelength, a near-infrared wavelength, etc.). When emitted light <NUM> illuminates target <NUM>, some of emitted light <NUM> will be reflected backwards towards sensor <NUM> as reflected light <NUM> (e.g., light that is specularly reflected from target <NUM> and/or that is backscattered from a matte surface in target <NUM>).

Sensor <NUM> of <FIG> includes a light sensitive element (e.g., a light detector such as photodiode <NUM>). Photodiode <NUM> in the example of <FIG> is located under laser <NUM>, but configurations in which photodiode <NUM> is adjacent to laser <NUM>, is located on a separate substrate than laser <NUM>, is located above active area <NUM>, and/or has other configurations may be used, if desired. The terminals of photodiode <NUM> may be coupled to sensing circuitry in control circuitry <NUM>. This circuitry gathers photodiode output signals that are produced in response to reception of reflected light (specularly reflected and/or backscattered portions of emitted light <NUM>) such as reflected light <NUM>. In addition to using a photodiode, self mixing can be detected using laser junction voltage measurements (e.g., if the laser is driven at a constant bias current) or laser bias current (e.g., if the laser is driven at a constant voltage).

Target <NUM> is located at a distance D from proximity sensor <NUM>. Some of light <NUM> that is reflected or backscattered from target <NUM> as reflected light <NUM> reenters the laser cavity of laser <NUM> (i.e., this fed back light mixes with the light in the laser cavity), perturbing the electric field coherently and causing a perturbation to the carrier density in laser <NUM>. These perturbations in laser <NUM> cause coherent self-mixing fluctuations in the power of emitted light <NUM> and associated operating characteristics of laser <NUM> such as laser junction voltage and/or laser bias current. These fluctuations may be monitored. For example, the fluctuations in the power of light <NUM> may be monitored using photodiode <NUM>. In the example of <FIG>, photodiode <NUM> is an integrated monolithic photodiode that is formed under laser <NUM>, but other configurations may be used, if desired.

Control circuitry <NUM> is configured to supply drive current for laser <NUM> and includes circuitry for sensing the response of photodiode <NUM>. Sensed photodiode output may include measurements of diode current and/or voltage. A modulation scheme may be used for driving laser <NUM> for the purpose of inducing a wavelength modulation and a photodiode output processing scheme (using measurements of photodiode current, junction voltage, bias current, etc.) may be used in processing the measured self-mixing fluctuations in output power to allow control circuitry <NUM> to determine the distance D between sensor <NUM> and target <NUM> in accordance with the principles of self-mixing interferometry.

A modulation scheme for driving laser <NUM> may, for example, use a triangular wave drive signal that, due to the dependence of output wavelength on drive current magnitude of laser <NUM>, continuously varies the wavelength of light <NUM> between a first wavelength WL1 and a second wavelength WL2 during each half-period of the triangular wave. The wavelength variations of light <NUM> cause the self-mixing interference signal of laser <NUM> to exhibit ripples. If desired, other modulation schemes may be used for driving laser <NUM> (e.g., sinusoidal driving schemes, etc.).

The processing scheme used on the photodiode signal uses a frequency extraction transform to extract the period of the ripples, from which distance D may be calculated. Distance D may, for example, be determined with an accuracy of better than <NUM> microns, better than <NUM> microns, better than <NUM> microns, better than <NUM> microns, better than <NUM> microns, better than <NUM> micron, or other suitable accuracy. Due to this high accuracy, measurements of where a lens or other optical component is located within device <NUM> can be determined with sufficient precision to allow actuators to move the lens and/or other optical component to compensate for undesired drop-induced movement or to take other suitable compensating action. The frequency extraction transform can have a temporal resolution (e.g., wavelet transform) or not (e.g., Fourier transform).

An illustrative signal processing approach for sensor <NUM> shown in <FIG>.

The first (uppermost) trace of <FIG> shows how laser drive current Id for laser <NUM> may be modulated using an alternating-current (AC) signal such as a triangle wave. This modulates the temperature of laser <NUM> and therefore the output wavelength of light <NUM>. For example, the wavelength of light <NUM> may vary between a first value WL1 (when drive signal Id is at a minimum) and wavelength WL2 (when drive signal Id is at a maximum). In accordance with the principles of self-mixing interferometry, the modulation of the wavelength of light <NUM> allows the self-mixing proximity sensor to measure target distance D without varying distance D.

The second (second to uppermost) trace of <FIG> shows how the resulting output signal PDout from photodiode <NUM> contains self-mixing interference ripples <NUM>. In configurations in which laser current or laser voltage are measured, the self-mixing interference ripples will appear in the measured current or voltage.

Control circuitry <NUM> (e.g., a sense circuit based on an operational amplifier circuit or other sensing circuitry) may be configured to differentiate signal PDout (or the measured current or voltage of laser <NUM>). As a result, control circuitry <NUM> (e.g., the sense circuit of circuitry <NUM>) may produce an output signal Vsig, as shown in the third (third from uppermost) trace of <FIG>. The signal Vsig is ideally a square wave onto which ripples <NUM> are imposed. To facilitate subsequent signal processing (e.g., processing to perform a frequency extraction transform), the mean of signal Vsig during high periods <NUM> may be subtracted from signal Vsig during high periods <NUM> (digitally or using analog circuitry in control circuitry <NUM>), thereby equalizing the direct-current (DC) component in periods <NUM> and <NUM>, as shown by signal V in the fourth (lowermost) trace of <FIG>.

A frequency-extraction transform such as a fast Fourier transform (FFT) or other frequency-extraction transform (e.g., a Hilbert transform, a continuous or discrete wavelet transform, a multiple signal classification method, etc.) may be applied to signal V to determine the frequency of ripples <NUM>. With one illustrative approach, the ripple frequency can be determined by identifying the frequency associated with a peak in the FFT amplitude curve. Frequencies with lower peaks in the FFT output can be assumed to be associated with noise and can be ignored. A more accurate frequency assessment can be made by fitting a curve to the peaks in the curve (e.g., processing the output amplitude of the FFT algorithm at each of the output frequencies of the FFT algorithm to identify the ripple frequency). For example, a curve such as a Gaussian curve may be fit to the frequency peaks of the output of the FFT process to accurately identify a ripple frequency fp. The frequency fp may then be used in calculating target distance D. In some illustrative configurations, other types of demodulation may be used to determine distance D. For example, IQ demodulation may be used in scenarios in which laser <NUM> is modulated sinusoidally. If desired, a separate phase modulator (e.g., a separate electro-optic modulator such as a lithium niobite electro-optic modulator) may be used in modulating light <NUM>. These self-mixing modulation and signal processing arrangements and/or other arrangements may allow distances such as distance D to be measured in device <NUM> so that this distance information may be used in adjusting components in device <NUM>.

Accurate distance measurements of the type that may be produced using sensor <NUM> may be used in providing real-time feedback on optical component positions within device <NUM>. For example, the positions of lenses, displays, image sensors, and/or other optical components and/or the housing structures used in supporting such components may be measured using sensors such as sensor <NUM>, so that control circuitry <NUM> can adjust actuators to reposition such as components and/or can take other appropriate action.

Consider, as an example, the arrangement of <FIG>. In the example of <FIG>, multiple sensors <NUM> are being used to measure the position of lens <NUM> relative to display <NUM> (e.g., a pixel array) in optical module <NUM>. A first sensor <NUM> may measure distance D1 between display <NUM> and lens <NUM> (e.g., along a right-hand edge of lens <NUM>) and a second sensor <NUM> may measure distance D2 between display <NUM> and lens <NUM> (e.g., along a left-hand edge of lens <NUM>). A third sensor <NUM> may, if desired, measure the separation between lens <NUM> and display <NUM> (e.g. so that the angular orientation of lens <NUM> in all dimensions may be determined).

By using sensors <NUM>, the separation of lens <NUM> from display <NUM> and the orientation of lens <NUM> relative to display <NUM> may be measured. Using this type of arrangement, undesired movement of lens <NUM> relative to display <NUM>, undesired movement of lens <NUM> relative to a housing chassis or other structural members in housing portion <NUM>, undesired movement of display <NUM> relative to lens <NUM> and/or housing portion <NUM>, and/or other undesired movements of portions of optical module <NUM> in device <NUM> may be detected.

If desired, sensors <NUM> may also be used to actively monitor the position of lens <NUM> during lens position adjustments that are being made to vary the distances of virtual images as the user is viewing content on display <NUM> from eye box <NUM>. Such lens position adjustments may be made, for example, to adjust the focus of module <NUM> and thereby adjust the amount of accommodation needed by a user to view the image on display <NUM>. Control circuitry <NUM> may, as an example, adjust lens focus to minimize or eliminate vergence-accommodation mismatch as three-dimensional content associated with the left and right images on left and right optical modules <NUM> is being presented to the user.

In the illustrative configuration of <FIG>, sensors <NUM> are being used to monitor the relative position between camera lens <NUM>' in a camera (camera <NUM> in the example of <FIG>) and camera image sensor 46I while camera <NUM> is capturing an image of real-world object <NUM>. A first sensor <NUM> may, for example, measure distance D1 while a second sensor measure distance D2. Additional sensors(s) <NUM> may be used, if desired. In this way, the position of lens <NUM>', image sensor 46I, and/or associated housing structures may be measured during operation of device <NUM> so that appropriate action may be taken (e.g., compensating movements of lens <NUM>', image sensor 46I, etc.).

<FIG> is a cross-sectional side view of a portion of an illustrative optical module with sensors <NUM>. In the example of <FIG>, optical module <NUM> includes lens <NUM> (e.g., a catadioptric lens or other lens) and display <NUM> (e.g., a display with an array of organic light-emitting diodes). Lens <NUM> may be supported in optical module support structure <NUM> (e.g., a lens barrel). Self-mixing sensors <NUM> and display <NUM> may be supported by support structures <NUM> and <NUM>, respectively. Display <NUM> and support structure <NUM> may be coupled to support structure <NUM> (e.g., structure <NUM> may be part of a lens barrel structure) or, as shown in <FIG>, structure <NUM> may be a structure that is separate from support structure <NUM> (e.g., a support structure in housing portion <NUM>, a display substrate for a display panel associated with display <NUM>) and that is optionally coupled to support structure <NUM>.

During operation, control circuitry <NUM> may measure the position of lens <NUM> using sensors <NUM>. For example, sensors <NUM> may be mounted directly to a support structure such as support structure <NUM> of <FIG> (e.g. a chassis or other housing structure in housing portion <NUM>) that is separate from support structure <NUM> of optical module <NUM> and which therefore serves to establish a fixed reference frame from which the position of lens <NUM> may be measured). In arrangements in which display <NUM> and support <NUM> are attached to support <NUM>, the sensing arrangement of <FIG> may allow sensors <NUM> to measure the relative position between lens <NUM> and display <NUM>.

In response to the information on the position of lens <NUM> gathered by sensor(s) <NUM>, control circuitry <NUM> can adjust the position of lens <NUM> (e.g., the position of lens <NUM> relative to support structure <NUM> and display <NUM>) using actuators <NUM>. Actuators <NUM> may, if desired, be mounted between support structure <NUM> (which serves as the fixed reference frame) and lens <NUM>. Actuators <NUM> may be piezoelectric actuators, electromagnetic actuators (e.g., motors), and/or other computer-controlled positioners. Two or more, three or more, or other suitable number of actuators <NUM> may be used to position lens <NUM>. For example, three actuators <NUM> spaced <NUM>° apart from each other around the perimeter of lens <NUM> may be used to adjust the orientation of lens <NUM>. Actuators <NUM> may adjust the separation along axis Z between display <NUM> and lens <NUM> and/or may be configured to shift lens <NUM> laterally (e.g., along dimensions X and/or Y).

Adhesive may be used in mounting lens <NUM> to support structure <NUM>. In this type of arrangement, there may be a potential for glue shrinkage to affect the relative position between lens <NUM> and support structure <NUM>. This can affect the measurement of the position of lens <NUM>, because the arrangement of <FIG> involves indirect lens position measurements (measurements in which lens position is determined by measuring lens barrel position and inferring lens position from measured lens barrel position), rather than direct lens position measurements.

If desired, the position of lens <NUM> may be measured directly (rather than indirectly through support structure <NUM> as shown in <FIG>). <FIG> is a cross-sectional side view of an illustrative optical module in which the position of lens <NUM> relative to structure <NUM> is measured directly (e.g., because light <NUM> reflects directly from the inwardly facing surface of lens <NUM>).

Other directly lens position sensing arrangements may be used, if desired. In the example of <FIG>, there are multiple sensors <NUM> (e.g., one or more sets of three sensors <NUM>-<NUM>, <NUM>-<NUM>, and <NUM>-<NUM>) for measuring displacement in different directions. In this illustrative configuration, each sensor <NUM>-<NUM> may emit light <NUM> that propagates on the X-Z plane and therefore measures lens position along this first direction, each sensor <NUM>-<NUM> may emit light <NUM> that propagates on the Y-Z plane and therefore measures lens position along this second direction that is different than the first direction, and each sensor <NUM>-<NUM> may emit light <NUM> that propagates in the Z direction (e.g. a direction that is different than the first and second directions). With this configuration, sensors <NUM>-<NUM> and <NUM>-<NUM> can detect lateral motion of lens <NUM> (e.g., motion along the X and Y axes of <FIG>). Each sensor <NUM>-<NUM> measures distance along only the Z dimension (in this example), thereby decoupling these Z-axis measurements from the lateral position measurements made using sensors <NUM>-<NUM> and <NUM>-<NUM>.

In the example of <FIG> according to the claimed invention, an array of self-mixing sensors <NUM> (e.g., a dense array of at least <NUM>, at least <NUM>, fewer than <NUM>, fewer than <NUM>, or other suitable number) has been provided in device <NUM>. Sensors <NUM> may face the inwardly-facing surface of lens <NUM> (e.g., lens surface <NUM>). During operation, sensors <NUM> can sense the position of surface <NUM> and thereby measure deformations to the shape of surface <NUM>. This information may be used dynamically by control circuitry <NUM> (e.g., to adjust lens <NUM> by deforming the shape of surface <NUM> and/or by moving lens <NUM>, to adjust <NUM>, and/or to adjust other structures in device <NUM> using actuators, to adjust image data such as by warping displayed images on display <NUM> to counteract lens distortion, etc.). If desired, the array of sensors <NUM> of <FIG> may be located behind display <NUM> (e.g., display <NUM> may be partially transparent so that light from sensors <NUM> can pass through display <NUM>).

Another illustrative arrangement is shown in <FIG>. As shown in the configuration of <FIG>, one or more sensors <NUM> may be mounted on support structure <NUM> (e.g. a housing support structure, display panel substrate for display <NUM>, and/or other structure forming part of display <NUM> and/or directly attached to and/or supporting display <NUM>).

<FIG> shows how lens <NUM> may be provided with a planar surface such as surface 98P or other surface that deviates from inner optical surface <NUM> of lens <NUM>. Planar surface 98P may help enhance optical feedback to sensor <NUM> by increasing the amount of emitted light from sensor <NUM> that is reflected from the surface of lens <NUM> towards sensor <NUM>. In the absence of a surface such as surface 98P that is oriented to reflect light <NUM> back to sensor <NUM>, light <NUM> may tend to reflect in a direction that is not as well aligned with sensor <NUM>.

Sensors <NUM> can be used to measure the positions of lenses <NUM> in optical modules <NUM> and/or other lenses (e.g., camera lenses). For example, one or more sensors <NUM> may be used to measure the position of a left lens in a left optical module and one or more sensors <NUM> may be used to measure the position of a right lens in a right optical module. Control circuitry <NUM> can measure lens position separately for left and right optical modules <NUM> and can adjust lens position separately for the left and right optical modules using individually adjustable actuators <NUM>. The ability to control left and right lens-to-display separation separately can assist users with vision defects such as users with different optical powers (eye glass prescriptions) for their left and right eyes, thereby reducing or eliminating the need for providing modules <NUM> with user-specific corrective lenses.

If desired, actuators <NUM> may be used to shake (e.g., vibrate) lenses (e.g., lenses <NUM>) to dislodge dust and/or other debris from the surfaces of the lenses. This actuator-based cleaning arrangement may be particularly helpful in cleaning inwardly facing lens surfaces such as surface <NUM> of lens <NUM>, because these surface may not be easily accessed by the user. Vibrations to clean lenses such as lenses <NUM> in optical modules <NUM> may be applied to the lenses each time device <NUM> is powered up and/or at other suitable times.

Illustrative operations associated with using device <NUM> are shown in <FIG>.

At suitable times (e.g. upon power up, in response to detection of a drop event with an inertial measurement unit and/or other sensor in device <NUM>, in response to a user command, according to a schedule, etc.) measurements of position may be made by control circuitry <NUM> (block <NUM>).

During the operations of block <NUM>, sensors <NUM> may measure distances D between sensors <NUM> and adjacent structures in device <NUM>. Distances D may correspond to distances between sensors <NUM> and structures such as the lens surfaces and/or lens barrels for lenses <NUM>, displays <NUM> (e.g., display substrates and/or other display structures), cameras, support structures in device <NUM> for supporting portions of optical modules <NUM> such as lenses <NUM> and/or displays <NUM>, support structures in device <NUM> for supporting other optical components, and/or other structures. Sensors <NUM> may be coupled to lenses <NUM>, displays <NUM>, lens barrels (support structures <NUM>), display support structures, housing structures such as structures for supporting cameras, cameras, and/or other structures in device <NUM>. In this way, information on the relative and/or absolute positions of these structures and therefore associated information on the translational and/or angular alignment and orientation of these structures may be gathered (e.g., information on misalignment of these structures relative to their desired alignment such as information on lens alignment, display alignment, optical module alignment, lens surface shape, camera alignment, housing structure alignment, and/or other information on how structures in device <NUM> may be misaligned relative to their desired positions). In systems with variable focus (e.g., systems in which the distance between lenses <NUM> and displays <NUM> in optical modules <NUM> is adjusted to adjust focus to place computer-generated content on displays <NUM> at various different virtual image distances to help reduce vergence-accommodation mismatch), information can be gathered by sensors <NUM> on misalignment resulting from deviations between the positions of lenses <NUM> and their desired adjusted locations).

During the operations of block <NUM>, control circuitry <NUM> may adjust adjustable components in device <NUM> based on the measurements from sensors <NUM>. For example, actuators in device <NUM> may be adjusted to reposition lenses <NUM>, displays <NUM>, optical modules <NUM>, support structures <NUM>, cameras <NUM>, support structures in housing portion <NUM>, and/or other structures in device <NUM>. In this way, detected misalignment in the position of a component (e.g., misalignment of lenses, displays, support structures, portions of lenses leading to lens deformation, image sensors, camera lenses, other portions of cameras <NUM>, and/or other components and/or structures in device <NUM> relative to each other) can be corrected. In an illustrative configuration, in response to detecting that lens <NUM> is not currently in its desired position, actuators <NUM> may move lens to the desired position (e.g., lens <NUM> may be moved laterally in dimensions X and/or Y, vertically in dimension Z, angularly by tilting about X, Y, and/or Z axes, etc.). If desired, the shape of lens <NUM> may be changed using actuators (e.g., by applying force that deforms lens <NUM>). This allows an undesired lens shape to be corrected.

In addition to or instead of moving or otherwise physically adjusting all or some of the components in optical modules <NUM>, cameras in device <NUM>, and/or other optical components and/or housing structures in device <NUM> in response to the data gathered using self-mixing sensors <NUM>, control circuitry <NUM> may make adjustments to image data and/or other data handled by device <NUM>. For example, if measurements from sensors <NUM> indicate that display <NUM> has shifted to the left from its desired position, control circuitry <NUM> can warp (shift, rotate, and/or shear) the data for the image being displayed by display <NUM> to shift the image back to the right by a corresponding amount. In this way, detected optical component misalignments can be corrected digitally (e.g., by processing captured image data from cameras <NUM> and/or by processing image data being supplied to displays <NUM> to adjust images for measured misalignment).

As indicated by line <NUM>, the operations of blocks <NUM> and <NUM> may be performed continuously (e.g., according to a schedule, in response to detected drop events, in response to user input, etc.). In this way, optical components in device <NUM> may be maintained in satisfactory alignment, even if the positions of these devices is affected by drop events or other high-stress conditions.

As described above, one aspect of the present technology is the gathering and use of information such as information from input-output devices. The present disclosure contemplates that in some instances, data may be gathered that includes personal information data that uniquely identifies or can be used to contact or locate a specific person. Such personal information data can include demographic data, location-based data, telephone numbers, email addresses, twitter ID's, home addresses, data or records relating to a user's health or level of fitness (e.g., vital signs measurements, medication information, exercise information), date of birth, username, password, biometric information, or any other identifying or personal information.

The present disclosure recognizes that the use of such personal information, in the present technology, can be used to the benefit of users. For example, the personal information data can be used to deliver targeted content that is of greater interest to the user. Accordingly, use of such personal information data enables users to calculated control of the delivered content. Further, other uses for personal information data that benefit the user are also contemplated by the present disclosure. For instance, health and fitness data may be used to provide insights into a user's general wellness, or may be used as positive feedback to individuals using technology to pursue wellness goals.

For instance, in the United States, collection of or access to certain health data may be governed by federal and/or state laws, such as the Health Insurance Portability and Accountability Act (HIPAA), whereas health data in other countries may be subject to other regulations and policies and should be handled accordingly.

Despite the foregoing, the present disclosure also contemplates embodiments in which users selectively block the use of, or access to, personal information data. That is, the present disclosure contemplates that hardware and/or software elements can be provided to prevent or block access to such personal information data. For example, the present technology can be configured to allow users to select to "opt in" or "opt out" of participation in the collection of personal information data during registration for services or anytime thereafter. In another example, users can select not to provide certain types of user data. In yet another example, users can select to limit the length of time user-specific data is maintained. In addition to providing "opt in" and "opt out" options, the present disclosure contemplates providing notifications relating to the access or use of personal information. For instance, a user may be notified upon downloading an application ("app") that their personal information data will be accessed and then reminded again just before personal information data is accessed by the app.

De-identification may be facilitated, when appropriate, by removing specific identifiers (e.g., date of birth, etc.), controlling the amount or specificity of data stored (e.g., collecting location data at a city level rather than at an address level), controlling how data is stored (e.g., aggregating data across users), and/or other methods.

Therefore, although the present disclosure broadly covers use of information that may include personal information data to implement one or more various disclosed embodiments, the present disclosure also contemplates that the various embodiments can also be implemented without the need for accessing personal information data.

Physical environment: A physical environment refers to a physical world that people can sense and/or interact with without aid of electronic systems. Physical environments, such as a physical park, include physical articles, such as physical trees, physical buildings, and physical people. People can directly sense and/or interact with the physical environment, such as through sight, touch, hearing, taste, and smell.

Computer-generated reality: in contrast, a computer-generated reality (CGR) environment refers to a wholly or partially simulated environment that people sense and/or interact with via an electronic system. In CGR, a subset of a person's physical motions, or representations thereof, are tracked, and, in response, one or more characteristics of one or more virtual objects simulated in the CGR environment are adjusted in a manner that comports with at least one law of physics. For example, a CGR system may detect a person's head turning and, in response, adjust graphical content and an acoustic field presented to the person in a manner similar to how such views and sounds would change in a physical environment. In some situations (e.g., for accessibility reasons), adjustments to characteristic(s) of virtual object(s) in a CGR environment may be made in response to representations of physical motions (e.g., vocal commands). A person may sense and/or interact with a CGR object using any one of their senses, including sight, sound, touch, taste, and smell. For example, a person may sense and/or interact with audio objects that create 3D or spatial audio environment that provides the perception of point audio sources in 3D space. In another example, audio objects may enable audio transparency, which selectively incorporates ambient sounds from the physical environment with or without computer-generated audio. In some CGR environments, a person may sense and/or interact only with audio objects. Examples of CGR include virtual reality and mixed reality.

Virtual reality: A virtual reality (VR) environment refers to a simulated environment that is designed to be based entirely on computer-generated sensory inputs for one or more senses. A VR environment comprises a plurality of virtual objects with which a person may sense and/or interact. For example, computer-generated imagery of trees, buildings, and avatars representing people are examples of virtual objects. A person may sense and/or interact with virtual objects in the VR environment through a simulation of the person's presence within the computer-generated environment, and/or through a simulation of a subset of the person's physical movements within the computer-generated environment.

Mixed reality: In contrast to a VR environment, which is designed to be based entirely on computer-generated sensory inputs, a mixed reality (MR) environment refers to a simulated environment that is designed to incorporate sensory inputs from the physical environment, or a representation thereof, in addition to including computer-generated sensory inputs (e.g., virtual objects). On a virtuality continuum, a mixed reality environment is anywhere between, but not including, a wholly physical environment at one end and virtual reality environment at the other end. In some MR environments, computer-generated sensory inputs may respond to changes in sensory inputs from the physical environment. Also, some electronic systems for presenting an MR environment may track location and/or orientation with respect to the physical environment to enable virtual objects to interact with real objects (that is, physical articles from the physical environment or representations thereof). For example, a system may account for movements so that a virtual tree appears stationery with respect to the physical ground. Examples of mixed realities include augmented reality and augmented virtuality. Augmented reality: an augmented reality (AR) environment refers to a simulated environment in which one or more virtual objects are superimposed over a physical environment, or a representation thereof. For example, an electronic system for presenting an AR environment may have a transparent or translucent display through which a person may directly view the physical environment. The system may be configured to present virtual objects on the transparent or translucent display, so that a person, using the system, perceives the virtual objects superimposed over the physical environment. Alternatively, a system may have an opaque display and one or more imaging sensors that capture images or video of the physical environment, which are representations of the physical environment. The system composites the images or video with virtual objects, and presents the composition on the opaque display. A person, using the system, indirectly views the physical environment by way of the images or video of the physical environment, and perceives the virtual objects superimposed over the physical environment. As used herein, a video of the physical environment shown on an opaque display is called "pass-through video," meaning a system uses one or more image sensor(s) to capture images of the physical environment, and uses those images in presenting the AR environment on the opaque display. Further alternatively, a system may have a projection system that projects virtual objects into the physical environment, for example, as a hologram or on a physical surface, so that a person, using the system, perceives the virtual objects superimposed over the physical environment. An augmented reality environment also refers to a simulated environment in which a representation of a physical environment is transformed by computer-generated sensory information. For example, in providing pass-through video, a system may transform one or more sensor images to impose a select perspective (e.g., viewpoint) different than the perspective captured by the imaging sensors. As another example, a representation of a physical environment may be transformed by graphically modifying (e.g., enlarging) portions thereof, such that the modified portion may be representative but not photorealistic versions of the originally captured images. As a further example, a representation of a physical environment may be transformed by graphically eliminating or obfuscating portions thereof. Augmented virtuality: an augmented virtuality (AV) environment refers to a simulated environment in which a virtual or computer generated environment incorporates one or more sensory inputs from the physical environment. The sensory inputs may be representations of one or more characteristics of the physical environment. For example, an AV park may have virtual trees and virtual buildings, but people with faces photorealistically reproduced from images taken of physical people. As another example, a virtual object may adopt a shape or color of a physical article imaged by one or more imaging sensors. As a further example, a virtual object may adopt shadows consistent with the position of the sun in the physical environment.

Hardware: there are many different types of electronic systems that enable a person to sense and/or interact with various CGR environments. Examples include head mounted systems, projection-based systems, heads-up displays (HUDs), vehicle windshields having integrated display capability, windows having integrated display capability, displays formed as lenses designed to be placed on a person's eyes (e.g., similar to contact lenses), headphones/earphones, speaker arrays, input systems (e.g., wearable or handheld controllers with or without haptic feedback), smartphones, tablets, and desktop/laptop computers. A head mounted system may have one or more speaker(s) and an integrated opaque display. Alternatively, a head mounted system may be configured to accept an external opaque display (e.g., a smartphone). The head mounted system may incorporate one or more imaging sensors to capture images or video of the physical environment, and/or one or more microphones to capture audio of the physical environment. Rather than an opaque display, a head mounted system may have a transparent or translucent display. The transparent or translucent display may have a medium through which light representative of images is directed to a person's eyes. The display may utilize digital light projection, OLEDs, LEDs, µLEDs, liquid crystal on silicon, laser scanning light sources, or any combination of these technologies. The medium may be an optical waveguide, a hologram medium, an optical combiner, an optical reflector, or any combination thereof. In one embodiment, the transparent or translucent display may be configured to become opaque selectively. Projection-based systems may employ retinal projection technology that projects graphical images onto a person's retina. Projection systems also may be configured to project virtual objects into the physical environment, for example, as a hologram or on a physical surface.

In accordance with an embodiment, a head-mounted device is provided that includes a head-mounted housing, at least one optical module in the head-mounted housing, the optical module has a display and has a lens that is configured to present an image from the display to an eye box, an optical self-mixing sensor configured to measure distance to the lens, and an actuator configured to adjust the lens based on the measured distance.

In accordance with another embodiment, the actuator is configured to move the lens in response to the measured distance.

In accordance with another embodiment, the lens has a planar portion and the optical self-mixing sensor is configured to emit a beam of light that reflects from the planar portion back to the optical self-mixing sensor.

In accordance with another embodiment, the optical module includes a lens barrel configured to support the lens and the optical self-mixing sensor is configured to measure the distance to the lens by measuring a distance between the self-mixing sensor and the lens barrel.

In accordance with another embodiment, the lens has a lens surface and the optical self-mixing sensor is configured to measure the distance to the lens by emitting light that reflects from the surface and detecting the reflected emitted light.

In accordance with another embodiment, the self-mixing sensor includes a laser diode configured to emit light having a wavelength of <NUM>-<NUM>.

In accordance with another embodiment, the distance measured by the optical self-mixing sensor is a separation between the lens and the display.

In accordance with another embodiment, the optical self-mixing sensor is configured to measure lateral movement of the lens relative to the optical self-mixing sensor independently of measuring separation between the lens and the display.

In accordance with an embodiment, a head-mounted device is provided that includes a head-mounted housing, optical modules supported in the head-mounted housing, each optical module has a display and a has a lens configured to present an image from the display to a corresponding eye box, optical self-mixing sensors configured to measure the lenses of the movable optical modules, and actuators, each actuator is associated with a respective one of the optical modules and is configured to move the lens of that optical module relative to the display of that optical module based on the lens measurements.

In accordance with another embodiment, there are at least two of the optical self-mixing sensors for each of the lenses.

In accordance with another embodiment, each optical module has an array of the optical self-mixing sensors.

In accordance with another embodiment, each lens has a lens surface and the array of optical self-mixing sensors in each optical module measures deformation of the lens surface in that optical module by measuring distances between the optical self-mixing sensors of the array and the lens surface.

In accordance with another embodiment, each optical self-mixing sensor has a laser that emits light and has a detector, each of the lenses has a lens surface, and the detectors of the optical self-mixing sensors are each configured to detect the emitted light from that optical self-mixing sensor after the emitted light has reflected from the lens surface.

In accordance with another embodiment, the optical self-mixing sensors include at least first, second, and third optical self-mixing sensors in each optical module.

In accordance with another embodiment, the first optical self-mixing sensor of each optical module is configured to measure a distance between the first optical self-mixing sensor and the lens in that optical module.

In accordance with another embodiment, the second and third optical self-mixing sensors of each optical module are configured to measure lateral shifting of the lens relative to the second and third optical self-mixing sensors.

In accordance with an embodiment, a head-mounted device is provided that includes a head-mounted support structure, an optical component supported by the head-mounted support structure, an optical self-mixing sensor configured to measure distance to the optical component, and an actuator configured to move the optical component based at least partly on information from the optical self-mixing sensor.

In accordance with another embodiment, the optical component includes a lens.

In accordance with another embodiment, the optical component includes a camera.

In accordance with another embodiment, the optical component has a surface and the optical self-mixing sensor is configured to emit light that reflects from the surface and is configured to receive the emitted light after the emitted light has reflected from the surface.

Claim 1:
A head-mounted device (<NUM>), comprising:
a head-mounted housing (<NUM>);
optical modules (<NUM>) supported in the head-mounted housing, wherein each optical module has a display (<NUM>) and a lens (<NUM>) configured to present an image from the display to a corresponding eye box;
optical self-mixing sensors (<NUM>) configured to measure the lenses of the optical modules, wherein each optical module has an array of the optical self-mixing sensors (<NUM>), wherein each lens has a lens surface (<NUM>), and wherein the array of optical self-mixing sensors in each optical module is configured to measure deformation of the lens surface in that optical module by measuring distances between the optical self-mixing sensors of the array and the lens surface; and
actuators (<NUM>), wherein each actuator is associated with a respective one of the optical modules and is configured to move the lens of that optical module relative to the display of that optical module based on the lens measurements.