Tunable lens with lens surface measurement

Abstract

An electronic device may include a lens module having a tunable lens. To determine the optical power associated with the lens module, components within the electronic device may measure the real-time position and / or curvature of an adjustable surface of the tunable lens. A head-mounted device may include a camera formed separately from a display for measuring a flash pattern, a photodiode integrated into the display for measuring a flash pattern, a camera formed separately from the display for measuring stray light from the lens module, a plurality of peripheral position sensors distributed around the periphery of the adjustable surface of the tunable lens, and / or a layer of capacitive electrodes for capacitive sensing.

Description

[0001] This application claims priority to U.S. Patent Application No. 19 / 032,654, filed January 21, 2025, and U.S. Provisional Patent Application No. 63 / 573,399, filed April 2, 2024, the entire contents of which are incorporated herein by reference. Background Technology

[0002] This application relates generally to electronic devices, and more specifically to wearable electronic device systems.

[0003] Electronic devices are sometimes configured to be worn by a user. For example, head-mounted devices have a head-mounted structure that allows the device to be worn on a user's head. Head-mounted devices may include an optical system with lenses.

[0004] Head-mounted devices typically include lenses with fixed shapes and properties. If not carefully adjusted, these types of lenses can be difficult to optimally present content to each user of the head-mounted device. Summary of the Invention

[0005] An electronic device may include a tunable lens, at least one infrared light source configured to direct infrared light toward the tunable lens to generate a flash pattern on an adjustable surface of the tunable lens, an image sensor configured to capture an image of the flash pattern, and control circuitry configured to determine the optical power of the tunable lens based on the image of the flash pattern.

[0006] An electronic device may include a tunable lens having a lens element with adjustable curvature, position sensors distributed around the periphery of the lens element, wherein each position sensor is configured to sense the position of a corresponding point on the periphery of the lens element, and control circuitry configured to determine the optical power of the tunable lens based on the position sensed by the position sensors.

[0007] An electronic device may include a tunable lens having a fluid-filled chamber defined by a first lens element and a second lens element, a first capacitor electrode layer formed on a first side of the fluid-filled chamber, a second capacitor electrode layer formed on a second side of the fluid-filled chamber, and control circuitry configured to determine the optical power of the tunable lens based on a sensed capacitance between the first and second capacitor electrode layers. The fluid-filled chamber and an air gap may be interposed between the first and second capacitor electrode layers.

[0008] An electronic device may include a lens module comprising a plurality of lens elements, a display configured to emit light toward the lens module, an image sensor configured to capture reflections of light from a plurality of surfaces within the lens module, and a control circuit configured to determine the optical power of a tunable lens based on the reflections of the captured light from the plurality of surfaces within the lens module. Attached Figure Description

[0009] Figure 1 This is a schematic diagram of an exemplary electronic device according to some implementation schemes.

[0010] Figure 2 This is a top view of an exemplary head-mounted device with a lens module according to some implementation schemes.

[0011] Figure 3 This is a side view of an exemplary lens module according to some implementation schemes.

[0012] Figure 4 and Figure 5 The image shows a side view of an illustrative tunable lens in different tuning states according to some implementation schemes.

[0013] Figure 6 A side view of an exemplary head-mounted device having an image sensor for determining the optical power of a tunable lens, according to some embodiments.

[0014] Figures 7A to 7C This is a top view of an exemplary flash pattern that can be detected on an adjustable surface of a tunable lens according to some embodiments.

[0015] Figure 8 This is a side view of an exemplary head-mounted device according to some embodiments, which has an integrated photodiode with an integrated photodiode for determining the optical power of a tunable lens.

[0016] Figure 9A A side view of an exemplary head-mounted device having a position sensor for determining the optical power of a tunable lens, according to some embodiments.

[0017] Figure 9B This is a top view of an exemplary tunable lens having position sensors distributed around the periphery of the tunable lens according to some embodiments.

[0018] Figure 10 A side view of an exemplary head-mounted device according to some embodiments, having capacitive sensing for determining the optical power of a tunable lens. Detailed Implementation

[0019] Figure 1 A schematic diagram of an exemplary electronic device is shown. For example... Figure 1As shown, electronic device 10 (sometimes referred to as head-mounted device 10, system 10, head-mounted display 10, etc.) may have control circuitry 14. Besides being a head-mounted device, electronic device 10 can also be other types of electronic devices, such as cellular phones, laptops, speakers, computer monitors, electronic watches, tablet computers, etc. Control circuitry 14 may be configured to perform operations in head-mounted device 10 using hardware (e.g., dedicated hardware or circuitry), firmware, and / or software. Software code and other data used to perform operations in head-mounted device 10 are stored on a non-transitory computer-readable storage medium (e.g., a tangible computer-readable storage medium) in control circuitry 14. Software code may sometimes be referred to as software, data, program instructions, commands, or code. Non-transitory computer-readable storage medium (sometimes commonly referred to as memory) may include non-volatile memory such as non-volatile random access memory (NVRAM), one or more hard disk drives (e.g., disk drives or solid-state drives), one or more removable flash drives, or other removable media, etc. Software stored on non-transitory computer-readable storage medium may be executed on processing circuitry of control circuitry 14. The processing circuit may include an application-specific integrated circuit (ASIC) with processing circuitry, one or more microprocessors, digital signal processors, graphics processing units, central processing units (CPUs), or other processing circuitry.

[0020] The head-mounted device 10 may include input-output circuitry 16. Input-output circuitry 16 can be used to allow a user to provide user input to the head-mounted device 10. Input-output circuitry 16 can also be used to collect information about the environment in which the head-mounted device 10 operates. Output components in circuitry 16 can allow the head-mounted device 10 to provide output to the user.

[0021] like Figure 1As shown, the input-output circuitry 16 may include a display, such as display 18. Display 18 can be used to display images to a user of the head-mounted device 10. Display 18 may be a transparent or translucent display so that the user can view physical objects through the display while computer-generated content is superimposed on top of the physical objects by presenting computer-generated images on the display. The transparent or translucent display may be formed from a transparent or translucent pixel array (e.g., a transparent organic light-emitting diode display panel), or it may be formed from a display device that provides images to the user through transparent structures such as beam splitters, holographic couplers, or other optical couplers (e.g., display devices such as liquid crystal on silicon). Alternatively, display 18 may be an opaque display that blocks light from the physical objects when the user operates the head-mounted device 10. In this type of arrangement, a see-through camera may be used to display the physical objects to the user. The see-through camera can capture images of the physical environment, and these images can be displayed on the display for the user to view. Additional computer-generated content (e.g., text, game content, other visual content, etc.) may optionally be overlaid on top of the physical environment image to provide the user with an extended realistic environment. When the display 18 is opaque, the display may also optionally display the entire computer-generated content (e.g., without displaying the image of the physical environment).

[0022] Display 18 may include one or more optical systems (e.g., lenses) (sometimes referred to as optical components) that allow a viewer to view an image on display 18. A single display 18 may generate images for both eyes, or a pair of displays 18 may be used to display images. In a configuration with multiple displays (e.g., a left-eye display and a right-eye display), the focal length and position of the lenses can be selected such that any gaps between the displays will be invisible to the user (e.g., so that the images of the left and right displays seamlessly overlap or merge). A display module (sometimes referred to as a display component) that generates different images for the user's left and right eyes may be referred to as a stereoscopic display. A stereoscopic display may be able to present two-dimensional content (e.g., user notifications with text) and three-dimensional content (e.g., simulations of physical objects such as cubes).

[0023] The example of device 10 including a display is merely illustrative, and display 18 may be omitted from device 10 if desired. Device 10 may include an optically perceptible area, where a user can view real-world content directly or through a tunable lens.

[0024] The input-output circuitry 16 may include a variety of other input-output devices. For example, the input-output circuitry 16 may include one or more speakers 20 configured to play audio, and one or more microphones 26 configured to capture audio data from a user and / or from the physical environment surrounding the user.

[0025] The input-output circuitry 16 may also include one or more cameras, such as an inward-facing camera 22 (e.g., a camera facing the user's face when the head-mounted device is mounted on the user's head) and an outward-facing camera 24 (a camera facing the physical environment surrounding the user when the head-mounted device is mounted on the user's head). Cameras 22 and 24 may capture visible light images, infrared images, or any other desired type of image. If desired, these cameras may be stereo cameras. In one possible arrangement, the inward-facing camera 22 may capture images for gaze detection operations. The outward-facing camera 24 may capture perspective video for the head-mounted device 10.

[0026] like Figure 1 As shown, the input-output circuitry 16 may include position and motion sensors 28 (e.g., compasses, gyroscopes, accelerometers, and / or other devices for monitoring the position, orientation, and movement of the head-mounted device 10, satellite navigation system circuitry such as GPS circuitry for monitoring the user's position, etc.). For example, the control circuitry 14 may use sensor 28 to monitor the current orientation of the user's head relative to the surrounding environment (e.g., the user's head posture). One or more of cameras 22 and 24 may also be considered part of the position and motion sensors 28. The cameras may be used for face tracking (e.g., by capturing images of the user's chin, mouth, etc. when the device is worn on the user's head), body tracking (e.g., by capturing images of the user's torso, arms, hands, legs, etc. when the device is worn on the user's head), and / or for localization (e.g., using visual ranging, visual-inertial ranging, or other simultaneous localization and mapping (SLAM) techniques).

[0027] If needed, the input-output circuit 16 may also include other sensors and input-output components. For example... Figure 1 As shown, the input-output circuit 16 may include an ambient light sensor 30. The ambient light sensor can be used to measure the ambient light level around the head-mounted device 10. The ambient light sensor can measure light of one or more wavelengths (e.g., visible light of different colors and / or infrared light).

[0028] The input-output circuit 16 may include a magnetometer 32. The magnetometer can be used to measure the strength and / or direction of the magnetic field around the head-mounted device 10.

[0029] The input-output circuitry 16 may include a heart rate monitor 34. The heart rate monitor can be used to measure the heart rate of a user wearing the head-mounted device 10 using any desired technology.

[0030] Input-output circuitry 16 may include a depth sensor 36. The depth sensor may be a pixelated depth sensor (e.g., configured to measure multiple depths across a physical environment) or a point sensor (configured to measure a single depth within a physical environment). The depth sensor (whether pixelated or point-based) may use phase detection (e.g., phase detection autofocusing pixels) or light detection and ranging (LIDAR) to measure depth. Any combination of depth sensors can be used to determine the depth of a physical object in the physical environment.

[0031] The input-output circuit 16 may include a temperature sensor 38. The temperature sensor can be used to measure the temperature of the user of the head-mounted device 10, the temperature of the head-mounted device 10 itself, or the ambient temperature of the physical environment surrounding the head-mounted device 10.

[0032] The input-output circuitry 16 may include a touch sensor 40. The touch sensor may be, for example, a capacitive touch sensor configured to detect touches from a user of a head-mounted device.

[0033] The input-output circuit 16 may include a moisture sensor 42. The moisture sensor can be used to detect the presence of moisture (e.g., water) on, in, or around the head-mounted device.

[0034] The input-output circuit 16 may include a gas sensor 44. The gas sensor can be used to detect the presence of one or more gases (e.g., smoke, carbon monoxide, etc.) in or around the head-mounted device.

[0035] The input-output circuit 16 may include a barometer 46. The barometer can be used to measure atmospheric pressure, which can be used to determine the altitude of the head-mounted device above sea level.

[0036] Input-output circuitry 16 may include gaze tracking sensor 48 (sometimes referred to as gaze tracker 48 and gaze tracking system 48). Gaze tracking sensor 48 may include a camera and / or other gaze tracking sensor components (e.g., a light source emitting a light beam so as to detect reflections of the light beam from a user's eye) to monitor the user's eyes. Gaze tracker 48 may be oriented towards the user's eyes and may track the user's gaze. The camera in the gaze tracking system may determine the position of the user's eyes (e.g., the center of the user's pupil), determine the orientation direction of the user's eyes (the direction of the user's gaze), determine the user's pupil size (e.g., such that light modulation and / or other optical parameters, and / or the amount of sequential adjustment used to spatially adjust one or more of these parameters, and / or the area in which one or more of these optical parameters are adjusted based on pupil size), may be used to monitor the current focal length of the lens in the user's eyes (e.g., whether the user is focusing on the near or far field, which can be used to assess whether the user is daydreaming or thinking strategically or tactically), and / or other gaze information. The camera in a gaze tracking system may sometimes be referred to as an inward-facing camera, a gaze detection camera, an eye-tracking camera, a gaze tracking camera, or an eye monitoring camera. Other types of image sensors (e.g., infrared and / or visible light LEDs and light detectors, etc.) may also be used to monitor the user's gaze if desired. The use of a gaze detection camera in gaze tracker 48 is merely illustrative.

[0037] The input-output circuit 16 may include a button 50. This button may include a mechanical switch that detects user pressure during operation of the head-mounted device.

[0038] The input-output circuit 16 may include a light-based proximity sensor 52. The light-based proximity sensor may include a light source (e.g., an infrared light source) and an image sensor (e.g., an infrared image sensor), which are configured to detect the reflection of the emitted light to determine proximity to a nearby object.

[0039] Input-output circuitry 16 may include a Global Positioning System (GPS) sensor 54. The GPS sensor determines the location information of the head-mounted device. The GPS sensor may include one or more antennas for receiving GPS signals. The GPS sensor may be considered part of position and motion sensor 28.

[0040] The input-output circuit 16 may include any other desired components (e.g., capacitive proximity sensors, other proximity sensors, strain gauges, pressure sensors, audio components, tactile output devices such as vibration motors, light-emitting diodes, other light sources, etc.).

[0041] The head-mounted device 10 may also include communication circuitry 56 to allow the head-mounted device to communicate with external equipment, such as a tethered computer, portable devices such as handheld devices or laptops, one or more external servers, or other electrical equipment. Communication circuitry 56 can be used for both wired and wireless communication with external equipment.

[0042] The communication circuit 56 may include an RF transceiver circuit consisting of one or more integrated circuits, a power amplifier circuit, a low-noise input amplifier, passive radio frequency (RF) components, one or more antennas, a transmit line, and other circuitry for processing RF wireless signals. The wireless signals may also be transmitted using light (e.g., using infrared communication).

[0043] For example, the radio frequency transceiver circuit in wireless communication circuit 56 can handle wireless local area network (WLAN) communication frequency bands, such as 2.4 GHz and 5 GHz Wi-Fi. ® (IEEE 802.11) band; Wireless Personal Area Network (WPAN) communication bands, such as 2.4GHz Bluetooth. ® Communication frequency bands; cellular telephone communication frequency bands, such as the cellular low frequency band (LB) (e.g., 600MHz to 960MHz), the cellular low intermediate frequency band (LMB) (e.g., 1400MHz to 1550MHz), the cellular intermediate frequency band (MB) (e.g., 1700MHz to 2200MHz), the cellular high frequency band (HB) (e.g., 2300MHz to 2700MHz), the cellular ultra-high frequency band (UHB) (e.g., 3300MHz to 5000MHz), or other cellular communication frequency bands between approximately 600MHz and approximately 5000MHz (e.g., 3G bands, 4G LTE bands, the 5G New Radio Frequency Range 1 (FR1) band below 10GHz, etc.); near field communication (NFC) bands (e.g., 13.56MHz); satellite navigation bands (e.g., the L1 Global Positioning System (GPS) band at 1575MHz, the L5 at 1176MHz). GPS bands, GLONASS bands, BDS bands, etc.; ultra-wideband (UWB) communication bands supported by the IEEE 802.15.4 protocol and / or other UWB communication protocols (e.g., a first UWB communication band of 6.5 GHz and / or a second UWB communication band of 8.0 GHz); and / or any other desired communication bands.

[0044] Radio frequency transceiver circuits may include millimeter-wave / centimeter-wave transceiver circuits that support communications at frequencies between approximately 10 GHz and 300 GHz. For example, millimeter-wave / centimeter-wave transceiver circuits may support communications in extremely high frequency (EHF) or millimeter-wave communication bands between approximately 30 GHz and 300 GHz and / or in centimeter-wave communication bands (sometimes referred to as ultra-high frequency (SHF) bands) between approximately 10 GHz and 30 GHz. As an example, millimeter-wave / centimeter-wave transceiver circuits may support communications in the following communication bands: the IEEE K communication band between approximately 18 GHz and 27 GHz, and the K band between approximately 26.5 GHz and 40 GHz. a Communication frequency band, between approximately 12 GHz and 18 GHz K u Communication bands, including the V communication band between approximately 40 GHz and 75 GHz, the W communication band between approximately 75 GHz and 110 GHz, or any other desired band between approximately 10 GHz and 300 GHz. If required, millimeter-wave / centimeter-wave transceiver circuitry can support IEEE 802.11ad communication at 60 GHz (e.g., the WiGig or 60 GHz Wi-Fi band between approximately 57 GHz and 61 GHz) and / or the 5G mobile network or 5G wireless system (5G) New Radio (NR) frequency range 2 (FR2) communication band between approximately 24 GHz and 90 GHz.

[0045] The antenna in the wireless communication circuit 56 may include an antenna with a resonant element, which is formed by a loop antenna structure, patch antenna structure, inverted F-shaped antenna structure, slot antenna structure, planar inverted F-shaped antenna structure, helical antenna structure, dipole antenna structure, monopole antenna structure, and combinations of these designs. Different types of antennas can be used in different frequency bands and combinations of frequency bands. For example, one type of antenna can be used to form a local wireless link, and another type of antenna can be used to form a long-range wireless link antenna.

[0046] During operation, the head-mounted device 10 can use communication circuitry 56 to communicate with external equipment 60. External equipment 60 may include one or more external servers, electronic devices paired with the head-mounted device 10 (such as cellular phones, laptops, speakers, computer monitors, smartwatches, tablets, earphones, etc.), vehicles, Internet of Things (IoT) devices (e.g., remote controls, light switches, doorbells, locks, smoke detectors, lights, thermostats, ovens, refrigerators, stoves, grills, coffee makers, toasters, microwave ovens, etc.), etc.

[0047] Electronic device 10 may have a housing structure (e.g., housing wall, strip, etc.), such as Figure 1An exemplary support structure 62 is shown. In configurations where the electronic device 10 is a head-mounted device (e.g., a pair of glasses, goggles, a helmet, a hat, etc.), the support structure 62 may include a head-mounted support structure (e.g., a helmet shell, a headband, temples in a pair of glasses, a goggle shell structure, and / or other head-mounted structures). The head-mounted support structure may be configured to be worn on a user's head during operation of the device 10 and may support the control circuitry 14, the input-output circuitry 16, and / or the communication circuitry 56.

[0048] Figure 2 This is a top view of electronic device 10 in an exemplary configuration, where electronic device 10 is a head-mounted device. (See attached image.) Figure 2 As shown, the electronic device 10 may include a support structure (see example...) Figure 1 The support structure 62 is used in accommodating the components of the device 10 and in mounting the device 10 onto the user's head. These support structures may include, for example, structures forming the outer shell wall and other structures for the main unit 62-2 (e.g., outer shell wall, lens module structure, etc.) as well as temples or other supplementary support structures, such as structure 62-1 which helps to hold the main unit 62-2 on the user's face.

[0049] The electronic device may include optical modules such as optical module 70. The electronic device may include a left optical module and a right optical module corresponding to the user's left and right eyes, respectively. Figure 2 The image shows the optical module corresponding to the user's left eye.

[0050] Each optical module 70 includes a corresponding lens module 72 (sometimes referred to as a lens stack 72, lens 72, or adjustable lens 72). Lens 72 may include one or more lens elements arranged along a common axis. Each lens element may have any desired shape and may be formed of any desired material (e.g., having any desired refractive index). Each lens element may have a unique shape and refractive index, and they are combined to focus light (e.g., from a display or from the physical environment) in a desired manner. Each lens element of lens module 72 may be formed of any desired material (e.g., glass, polymeric materials such as polycarbonate or acrylic resin, crystals such as sapphire, etc.).

[0051] Optionally, positioning circuitry such as positioner 58 can be used to individually position modules 70 relative to the user's eye and relative to some of the housing wall structures within the main unit 26-2. Positioner 58 may include a stepper motor, piezoelectric actuator, motor, linear electromagnetic actuator, shape memory alloy (SMA), and / or other electronic components for adjusting the position of the display, optical module 70, and / or lens module 72. During operation of device 10, positioner 58 may be controlled by control circuitry 14. For example, positioner 58 may be used to adjust the spacing between modules 70 (and thus the lens-to-lens spacing between the left and right lenses of module 70) to match the interpupillary distance (IPD) of the user's eye. In another example, the lens module may include adjustable lens elements. The curvature of the adjustable lens elements may be adjusted in real time by positioner 58 to compensate for the user's visual condition and / or viewing conditions.

[0052] Each optical module may optionally include a display, such as Figure 2 The display 18 is located in the device 10. As previously mentioned, the display can be omitted from the device 10 if desired. In this type of arrangement, the device may still include one or more lens modules 72 (through which the user views the real world). In this type of arrangement, real-world content can be selectively focused for the user.

[0053] Figure 3This is a cross-sectional side view of an exemplary lens module having multiple lens elements. As shown, lens module 72 includes a first lens element 72-1 and a second lens element 72-2. Each surface of the lens element can have any desired curvature. For example, each surface can be a convex surface (e.g., a spherical convex surface, a cylindrical convex surface, or an aspherical convex surface), a concave surface (e.g., a spherical concave surface, a cylindrical concave surface, or an aspherical concave surface), a combination of convex and concave surfaces, or a freeform surface. A spherically curved surface (e.g., a spherical convex surface or a spherical concave surface) can have a constant radius of curvature across the entire surface. Conversely, an aspherical curved surface (e.g., an aspherical concave surface or an aspherical convex surface) can have a varying radius of curvature across the entire surface. A cylindrical surface can be curved about only one axis, rather than about multiple axes like a spherical surface. In some cases, a lens surface may have an aspherical surface that changes from convex (e.g., at the center) to concave (e.g., at the edges) at different locations on the surface. This type of surface may be referred to as an aspherical surface, a predominantly convex (e.g., the majority of the surface is convex and / or the surface is convex at its center) aspherical surface, a freeform surface, and / or a predominantly convex (e.g., the majority of the surface is convex and / or the surface is convex at its center) freeform surface. A freeform surface may include convex and concave portions and / or curvature defined by a polynomial series and expansion. Alternatively, a freeform surface may have varying convex curvature or varying concave curvature (e.g., different portions with different radii of curvature, portions with curvature in one direction, and portions with curvature in two directions, etc.). In this paper, a freeform surface that is primarily convex (e.g., the majority of its surface is convex and / or its center is convex) may still be referred to as a convex surface, and a freeform surface that is primarily concave (e.g., the majority of its surface is concave and / or its center is concave) may still be referred to as a concave surface. In one example, such as Figure 3 As shown, lens element 72-1 has a convex surface facing the display 18 and an opposite concave surface. Lens element 72-2 has a convex surface facing lens element 72-1 and an opposite concave surface.

[0054] One or both of lens elements 72-1 and 72-2 may be adjustable. In one example, lens element 72-1 is a non-adjustable lens element, while lens element 72-2 is an adjustable lens element. For example, adjustable lens element 72-2 can be used to adapt to a user's eyeglass prescription. If the user's eyeglass prescription changes, the shape of lens element 72-2 can be adjusted (without replacing any other components within device 10). As another possible use case, a first user with a first eyeglass prescription (or no eyeglass prescription) can use device 10 including lens element 72-2 with a first shape, and a second different user with a second eyeglass prescription can use device 10 including lens element 72-2 with a second shape different from the first shape. Lens element 72-2 may have varying lens power and / or provide varying amounts and orientations of astigmatism correction to provide prescription correction for the user.

[0055] The example of a lens module 72 including two lens elements is merely illustrative. Typically, lens module 72 may include any desired number of lens elements (e.g., one, two, three, four, more than four, etc.). Any subset or all of the lens elements may optionally be adjustable. Any adjustable lens element in the lens module may optionally be a fluid-filled adjustable lens. Lens module 72 may also include any desired additional optical layers (e.g., a partial reflector reflecting 50% of the incident light, a linear polarizer, a retarder such as a quarter-wave plate, a reflective polarizer, a circular polarizer, a reflective circular polarizer, etc.) to manipulate light passing through the lens module.

[0056] In one possible arrangement, lens element 72-1 can be a removable lens element. In other words, a user can easily remove and replace lens element 72-1 within the optical module 70. This allows lens element 72-1 to be customizable. If lens element 72-1 is permanently attached to the lens assembly, the optical power provided by lens element 72-1 is not easily changed. However, by making lens element 72-1 customizable, a user can select the lens element 72-1 best suited to their eyes and place the appropriate lens element 72-1 within the lens assembly. For example, lens element 72-1 can be used to fit a user's eyeglass prescription. If the user's eyeglass prescription changes, the user can replace lens element 72-1 with a newer lens element (without needing to replace any other components within the electronics 10). Lens element 72-1 can have varying optical power and / or provide varying amounts of astigmatism correction to provide prescription correction for the user. Lens element 72-1 may include one or more attachment structures configured to attach to a corresponding attachment structure in another structure included in optical module 70, lens element 72-2, support structure 26, or electronic device 10.

[0057] Unlike lens element 72-1, lens element 72-2 is not a removable lens element. Therefore, lens element 72-2 may sometimes be referred to as a permanent lens element, a non-removable lens element, etc. The example of lens element 72-2 being a non-removable lens element is merely illustrative. In another possible arrangement, lens element 72-2 may also be a removable lens element (similar to lens element 72-1).

[0058] As previously mentioned, one or more adjustable lens elements can be fluid-filled lens elements. This article describes an example where… Figure 3 The lens element 72-2 is a fluid-filled lens element. When the lens element 72-2 is a fluid-filled lens element, the lens element may include one or more components defining the surface of the lens element 72-2. These components may also be referred to as lens elements. In other words, the adjustable lens element 72-2 (sometimes referred to as adjustable lens module 72-2, adjustable lens 72-2, tunable lens 72-2, etc.) may be formed from multiple corresponding lens elements.

[0059] Figure 4 This is a cross-sectional side view of the adjustable fluid-filled lens element 72-2. As shown, a fluid-filled chamber 82 (sometimes referred to as chamber 82, fluid chamber 82, primary chamber 82, etc.) including fluid 92 is inserted between lens elements 84 and 86. Lens elements 84 and 86 may sometimes be referred to as part of chamber 82, or sometimes as separate from chamber 82. Fluid 92 may be a liquid, gel, or gas with a predetermined refractive index (therefore sometimes referred to as liquid 92, gel 92, or gas 92). Fluid may sometimes be referred to as refractive index matching oil, optical oil, optical fluid, refractive index matching material, refractive index matching liquid, etc. Lens elements 84 and 86 may have the same refractive index or may have different refractive indices. The fluid 92 filling the cavity 82 between lens elements 84 and 86 may have the same refractive index as lens element 84 but different refractive index from lens element 86, the same refractive index as lens element 86 but different refractive index from lens element 84, the same refractive index as both lens elements 84 and 86, or a different refractive index from both lens elements 84 and 86. Lens elements 84 and 86 may have circular coverage areas, elliptical coverage areas, or coverage areas of any other desired shape (e.g., irregular coverage areas).

[0060] The amount of fluid 92 in chamber 82 can have a constant volume or an adjustable volume. If the amount of fluid is adjustable, the lens module may also include a fluid reservoir and fluid control components (e.g., a pump, stepper motor, piezoelectric actuator, shape memory alloy (SMA), motor, linear electromagnetic actuator, and / or other electronic components that apply force to the fluid in the fluid reservoir) for selectively transferring fluid between the fluid reservoir and the chamber.

[0061] Lens elements 84 and 86 can be transparent lens elements formed of any desired material, such as glass, polymeric materials such as polycarbonate or acrylic resin, or crystals such as sapphire. Each of lens elements 84 and 86 can be elastomeric, semi-rigid, or rigid. In one example, lens element 84 is an elastomeric lens element, while lens element 86 is a rigid lens element.

[0062] Elastomer lens elements (e.g., Figure 4 and Figure 5 The lens element 84 in the film can be formed from a natural or synthetic polymer having a low Young's modulus to achieve high flexibility. For example, the elastomer film can be formed from materials with a Young's modulus of less than 1 GPa, less than 0.5 GPa, less than 0.1 GPa, etc.

[0063] Semi-rigid lens elements can be formed from semi-rigid materials that are hard and strong, but not inflexible. Semi-rigid lens elements can be formed, for example, from thin layers of polymers or glass. Semi-rigid lens elements can be formed from materials with Young's modulus greater than 1 GPa, greater than 2 GPa, greater than 3 GPa, greater than 10 GPa, greater than 25 GPa, etc. Semi-rigid lens elements can be formed from polycarbonate, polyethylene terephthalate (PET), polymethyl methacrylate (PMMA), acrylic resin, glass, or any other desired material. When the lens element is bent along a second axis perpendicular to the first axis, the properties of the semi-rigid lens element may cause the lens element to become rigid along the first axis, or more generally, when it bends, the product of the curvatures along its two principal curvature axes remains approximately constant. This contrasts with elastomeric lens elements, which remain flexible along the first axis even when bent along a second axis perpendicular to the first axis. The characteristics of semi-rigid lens elements allow them to be formed into cylindrical lenses with tunable optical power and tunable axes.

[0064] Rigid lens elements (e.g., Figure 4 and Figure 5The lens element 86 in the lens module can be formed of glass, polymeric materials such as polycarbonate or acrylic, crystals such as sapphire, etc. Typically, a rigid lens element may not deform when pressure is applied to it within the lens module. In other words, the shape and position of the rigid lens element can be fixed. Each surface of the rigid lens element can be planar, concave (e.g., spherical, aspherical, or cylindrically concave) or convex (e.g., spherical, aspherical, or cylindrically convex). The rigid lens element can be formed of materials with a Young's modulus greater than 25 GPa, greater than 30 GPa, greater than 40 GPa, greater than 50 GPa, etc.

[0065] In addition to lens elements 84 and 86 and the fluid-filled chamber 82, lens module 72-2 also includes a lens forming element 88. Lens forming element 88 may be coupled to one or more actuators 90 (e.g., circumferential positioning around the lens module). Lens forming element 88 may also be coupled to lens element 84. Actuators 90 may be adjusted to position lens forming element 88 (sometimes referred to as lens former 88, deformable lens former 88, lens forming structure 88, lens forming member 88, annular member 88, annular structure 88, etc.). Lens forming element 88 then manipulates the positioning / shape of lens element 84. In this way, the curvature of lens element 84 can be adjusted (and correspondingly, the lens power of lens module 72-2). Figure 5 An example of an actuator 90 and a lens shaper 88 for changing the curvature of a lens element 84 is shown. As shown, the lens shaper 88 is moved in direction 94 by the actuator 90. This causes the lens element 84 to... Figure 5 China and Belgium in Figure 4 It has a greater curvature.

[0066] The tunable lens element 72-2 is merely an example of a fluid-filled lens element. Typically, the tunable lens element 72-2 can be any desired type of tunable lens element with adjustable optical power.

[0067] The shape (and corresponding optical power) of the tunable lens element 72-2 can be adjusted in response to information from any component of the input-output circuit 16.

[0068] When the lens module includes a tunable lens, the overall optical quality of the image viewed through the tunable lens may be sensitive to the optical power of the tunable lens, which can depend on the position and curvature of the tunable lens. Therefore, the head-mounted device 10 may include one or more components to enable the measurement of the real-time position and curvature of the adjustable surface of the tunable lens. Measurement of the curvature and position of the adjustable surface can be used to determine the optical power of the tunable lens (and the entire lens module). Several methods exist for measuring the real-time position and curvature of the adjustable surface of the tunable lens. The head-mounted device may include a camera formed separately from the display that measures the position of a grid of light spots (flashes) to determine the shape of the adjustable surface; a photodiode integrated into the display that measures the position of the grid of light spots (flashes) to determine the shape of the adjustable surface; a camera formed separately from the display that measures stray light from the lens module; multiple peripheral position sensors distributed around the periphery of the adjustable surface of the tunable lens; and / or a capacitive electrode layer for capacitive sensing to identify the curvature and position of the adjustable surface of the tunable lens.

[0069] Figure 6 This is a side view of an exemplary head-mounted device having a camera, formed separately from the display, that measures the position of a grid of light spots (flashes) to determine the shape of an adjustable surface (and, correspondingly, the optical power of a tunable lens). For example... Figure 6 As shown, the lens module 72 in the head-mounted device 10 may include an adjustable lens 72-2 (similar to a combination of lenses). Figure 4 and Figure 5 (As shown and discussed). The adjustable lens 72-2 has a lens element 84 that is manipulated to adjust the optical power of the adjustable lens. Therefore, it may be desirable to measure the curvature and position of the surface 84-S of the lens element 84 in order to determine the optical power provided by the adjustable lens 72-2 (and the lens module 72 as a whole). Figure 6 The lens module 72 is shown to optionally include one or more additional non-adjustable lens elements 108-1 and 108-2 on either side of the adjustable lens element 72-2. As an example, the lens module 72 may be a reflective refractive lens module with one or more additional functional layers, such as a partial reflective layer (e.g., between lens element 108-1 and display 18), a reflective polarizer (e.g., between lens elements 72-2 and 108-2), a quarter-wave plate (e.g., between lens elements 72-2 and 108-1), and / or other desired functional layers.

[0070] To measure the curvature and position of the surface 84-S of the lens element 84, the head-mounted device 10 may include one or more infrared light sources. For example... Figure 6As shown, one or more infrared light sources 104 may be distributed around the periphery of the display 18. The infrared light sources are not formed on the substrate for the display 18. The infrared light sources 104 can emit infrared light toward the optical module 72. There may be at least 10 infrared light sources 104, at least 20 infrared light sources 104, at least 30 infrared light sources 104, at least 40 infrared light sources 104, at least 50 infrared light sources 104, etc.

[0071] Instead of infrared light source 104, or in addition to infrared light source 104, one or more infrared light sources may be integrated into the display 18 itself. Figure 6 An example is shown where the display has a pixel array including visible light pixels 102-P and infrared light pixels 102-IR. The visible light pixels 102-P may include red, green, and blue pixels that emit light for an image perceived by a viewer of the display 18. The infrared light pixels 102-IR may emit infrared light (e.g., light with wavelengths between 780 nanometers and 1000 micrometers). The infrared light pixels 102-IR may be distributed among the visible light pixels 102-P in the display 18. The display 18 may include a total of less than 1,000 infrared light pixels 102-IR, a total of less than 100 infrared light pixels 102-IR, a total of less than 50 infrared light pixels 102-IR, a total of less than 40 infrared light pixels 102-IR, a total of less than 30 infrared light pixels 102-IR, a total of less than 20 infrared light pixels 102-IR, etc. Each infrared light pixel 102-IR may be locally surrounded by visible light pixels 102-P. The display 18 may include at least 100 times more visible light pixels than infrared pixels, at least 1,000 times more visible light pixels than infrared pixels, at least 10,000 times more visible light pixels than infrared pixels, etc.

[0072] Figure 6 Additionally, the head-mounted device 10 is shown to include an image sensor, such as image sensor 106. The image sensor may be attached to the support structure 62-2 or otherwise fixed within the head-mounted device. Image sensor 106 may be an infrared image sensor, a visible light image sensor, or an image sensor capable of sensing both visible and infrared light. Image sensor 106 can detect flashes of infrared light reflected from surface 84-S (after emission by infrared light pixels 102-IR and / or infrared light source 104). The flash pattern detected by image sensor 106 can be used to determine the position and curvature of surface 84-S.

[0073] Figure 6Infrared light from infrared pixel 102-IR is shown to travel along path 110-1 toward surface 84-S and be reflected from surface 84-S toward camera 106. Similarly, infrared light from infrared light source 104 can travel along path 110-2 toward surface 84-S and be reflected from surface 84-S toward camera 106. The point where infrared light is reflected from lens element 84 may be referred to as a flash.

[0074] Figures 7A to 7C A representative flash pattern that can be detected by camera 106 is shown. Figure 7A The nominal flash grid is shown. Figure 7B This shows the effect when surface 84-S has spherical curvature. Figure 7A The shimmering grid, and Figure 7C This shows the effect when surface 84-S has cylindrical curvature. Figure 7A A flash grid. Each infrared light source 104 and 102-IR may have an associated flash. As an example, the infrared light sources can be arranged to produce... Figure 7A An incident flash pattern (e.g., a regular grid of rows and columns). For example... Figure 7B As shown, the spherical curvature in surface 84-S causes the flash pattern to expand radially outward. Figure 7C As shown, the cylindrical curvature in surface 84-S can cause the flash pattern to have a first regular spacing in one direction and a second regular spacing greater than the first regular spacing in a second orthogonal direction. It should be noted that... Figures 7A to 7C The pattern can be corrected for perspective of the image sensor 106.

[0075] The control circuitry 14 may include image processing circuitry that analyzes images captured by the image sensor 106. The image processing circuitry may identify a flash pattern 112 associated with reflections from surface 84-S and determine the position and / or curvature of surface 84-S (and correspondingly, the optical power of the tunable lens 72-2) based on the detected flash pattern. The image processing circuitry may optionally be integrated into the image sensor 106.

[0076] Figure 6An example is shown where an infrared flash is used to determine the position and / or curvature of surface 84-S based on a detected flash pattern. In this example, image sensor 106 may be sensitive to infrared light but not to visible light (e.g., image sensor 106 is an infrared image sensor). In another possible example, infrared light source 104 and infrared light pixel 102-IR may be omitted, and image sensor 106 may sense visible light to measure the position and / or curvature of surface 84-S. Specifically, image sensor 106 may be sensitive to visible light but not to infrared light (e.g., image sensor 106 is a visible light image sensor). Visible light image sensor 106 may sense stray light emitted by display 18 and reflected toward the image sensor. Reflections from different surfaces within lens module 72 may be present. Stray light reflections from different surfaces may be sensed by image sensor 106. Combinations of different stray light reflections from different surfaces in the optical module (e.g., the first and second opposing surfaces of lens element 108-1, surface 84-S, the surface of lens element 86, etc.) can be used to determine the position and / or curvature of surface 84-S. Optionally, multiple visible light image sensors 106 may be included to sense stray light at different points to provide additional information for determining the position and / or curvature of surface 84-S.

[0077] It should be noted that, Figure 6 In this configuration, the infrared light source 104, which is formed separately from the display 18, can be omitted, and all infrared light sources can be integrated into the display 18. Alternatively, the infrared light pixel 102-IR, which is integrated into the display 18, can be omitted, and all infrared light sources can be formed separately from the display 18.

[0078] Figure 6 The example of the image sensor 106 being separately formed from the display 18 and attached to the support structure 62-2 is merely illustrative. Figure 8 In another possible arrangement shown, the photodiode used to capture the image of the flash pattern can be integrated into the display 18. For example... Figure 8 As shown, the display 18 may include, as in combination with Figure 6The visible light pixel 102-P and infrared light pixel 102-IR are shown and discussed. Additionally, the display 18 includes a photodiode 102-PD. The photodiode 102-PD may be sensitive to infrared light (in an embodiment where the photodiode senses a flash pattern of infrared light from the infrared light pixel 102-IR) or sensitive to visible light (in an embodiment where the photodiode senses stray light from the lens module as previously discussed). In some embodiments, both a visible light-sensitive photodiode and an infrared light-sensitive photodiode may be included. Control circuitry can use the image captured by the photodiode to determine the position and / or curvature of the surface 84-S. The photodiode 102-PD may be collectively referred to as an image sensor integrated into the display 18.

[0079] Each photodiode may be partially surrounded by a visible light pixel 102-P and / or an infrared pixel 102-IR. Any desired number of photodiodes may be integrated into the display (e.g., at least 50, at least 100, at least 1,000, at least 10,000, etc.). The photodiodes 102-PD, visible light pixels 102-P, and infrared pixels 102-IR may share a common substrate.

[0080] Figure 8 The example in which the photodiode 102-PD, visible light pixel 102-P, and infrared pixel 102-IR all share a common substrate on the display 18 is merely illustrative. In another possible arrangement, the photodiode 102-PD and visible light pixel 102-P may share a common substrate on the display 18, and the peripheral infrared light source 104 may be used to generate a flashing pattern.

[0081] Figure 9A This is a side view of an exemplary head-mounted device having a position sensor for determining the position and / or curvature of surface 84-S. (Example) Figure 9A As shown, the optical module 72 may include one or more position sensors 114. Each position sensor 114 may measure the position of the lens element 84 at a single point on the lens element. The position of the lens element 84 may be measured relative to a fixed reference point, such as lens element 86, lens element 108-1, or another desired fixed point. The position sensor 114 may include a capacitive sensor, an optical sensor, a magnetic sensor, a resistive sensor, and / or other desired types of sensors.

[0082] Measuring the position of the lens element 84 at multiple peripheral points provides information to identify the curvature and position of the surface 84-S of the lens element 84. Position sensors can be distributed around the periphery of the lens element 84. Typically, more position sensors measuring more discrete points will improve the measurement of surface 84-S by position sensor 114. At least 3 position sensors, at least 5 position sensors, at least 8 position sensors, at least 16 position sensors, at least 25 position sensors, etc., may be present.

[0083] Figure 9B This is a top view of an exemplary tunable lens 72-2 having eight position sensors 114 distributed around the circumference of the lens element 84. There may be a 1:1 correspondence between the number of position sensors 114 and the number of actuators 90, or the number of position sensors and actuators may differ. The position sensors may be uniformly distributed around the circumference or non-uniformly distributed around the circumference.

[0084] Optionally, a calibration operation can be performed using the tunable lens 72-2 to determine the optical power of the tunable lens 72-2 associated with a given set of measurements from the position sensor 114. Subsequently, during operation of the head-mounted device 10, real-time measurements from the position sensor can be combined with calibration information to determine the optical power of the tunable lens 72-2.

[0085] Figure 10 This is a side view of an exemplary head-mounted device having a capacitive sensor for determining the position and / or curvature of surface 84-S. (See image) Figure 10 As shown, a first capacitor electrode layer 118-1 may be formed on lens element 86 (e.g., on the first side of fluid-filled chamber 82). A second capacitor electrode layer 118-2 may be formed on lens element 108-2 (e.g., on the second side of fluid-filled chamber 82). Therefore, both fluid-filled chamber 82 and air gap 120 exist between capacitor electrode layers 118-1 and 118-2. Fluid 92 may have a higher dielectric constant than air in air gap 120. Therefore, when fluid 92 displaces the air between the electrode layers, the capacitance between electrode layers 118-1 and 118-2 increases. By measuring the capacitance between electrode layers 118-1 and 118-2 (e.g., using capacitance sensing circuit 116), the curvature and / or position of surface 84-S (and correspondingly, the optical power of tunable lens 72-2) can be determined.

[0086] Each of the capacitor electrode layers 118-1 and 118-2 may include one or more patterned electrodes. The capacitor electrode layers 118-1 and 118-2 may be formed of a transparent conductive material (e.g., indium tin oxide) having a transparency of greater than 80%, greater than 90%, greater than 95%, etc.

[0087] If necessary, the capacitor electrode layer 118-2 can be omitted, and capacitance sensing can rely on the use of the edge field associated with the capacitor electrode layer 118-1.

[0088] According to one embodiment, an electronic device is provided, comprising a tunable lens, at least one infrared light source configured to direct infrared light toward the tunable lens to generate a flash pattern on an adjustable surface of the tunable lens, an image sensor configured to capture an image of the flash pattern, and a control circuit configured to determine the optical power of the tunable lens based on the image of the flash pattern.

[0089] According to another embodiment, the electronic device may optionally include a display that directs visible light toward the tunable lens.

[0090] According to another embodiment, at least one infrared light source may optionally include a plurality of infrared light sources distributed around the periphery of the display.

[0091] According to another embodiment, at least one infrared light source may optionally be formed separately from the display.

[0092] According to another embodiment, at least one infrared light source may optionally be integrated with the display.

[0093] According to another embodiment, the display may optionally include visible light pixels, and at least one of the infrared light sources may optionally include infrared light pixels scattered among the visible light pixels.

[0094] According to another embodiment, the display may optionally include a photodiode for an image sensor.

[0095] According to another embodiment, the image sensor may optionally be formed separately from the display.

[0096] According to one embodiment, an electronic device is provided, comprising a tunable lens having a lens element with adjustable curvature, position sensors distributed around the periphery of the lens element (wherein each position sensor is configured to sense the position of a corresponding point on the periphery of the lens element), and control circuitry configured to determine the optical power of the tunable lens based on the position sensed by the position sensors.

[0097] According to another embodiment, the control circuit may optionally be configured to determine the optical power of the tunable lens based on the position sensed by the position sensor and the stored calibration information.

[0098] According to another embodiment, the position sensor may optionally include a capacitive sensor.

[0099] According to another embodiment, the position sensor may optionally include a resistive sensor.

[0100] According to another embodiment, the position sensor may optionally include a magnetic sensor.

[0101] According to another embodiment, the position sensor may optionally include an optical sensor.

[0102] According to one embodiment, an electronic device is provided, comprising a tunable lens having a fluid-filled chamber defined by a first lens element and a second lens element (wherein the fluid-filled chamber has opposing first and second sides), a first capacitor electrode layer formed on the first side of the fluid-filled chamber, a second capacitor electrode layer formed on the second side of the fluid-filled chamber (wherein the fluid-filled chamber and an air gap are interposed between the first capacitor electrode layer and the second capacitor electrode layer), and a control circuit configured to determine the optical power of the tunable lens based on a sensing capacitance between the first capacitor electrode layer and the second capacitor electrode layer.

[0103] According to another embodiment, the first capacitor electrode layer and the second capacitor electrode layer may optionally include patterned transparent conductive material.

[0104] According to another embodiment, the patterned transparent conductive material may optionally include indium tin oxide.

[0105] According to another embodiment, the first lens element may optionally have an adjustable curvature, and wherein a first capacitor electrode layer may optionally be formed on the second lens element.

[0106] According to another embodiment, the electronic device may optionally include an additional lens, wherein an air gap may optionally be inserted between the fluid-filled chamber and the additional lens, and a second capacitor electrode layer is formed on the additional lens.

[0107] According to one embodiment, an electronic device is provided, comprising a lens module including a plurality of lens elements, a display configured to emit light toward the lens module, an image sensor configured to capture reflections of light from a plurality of surfaces within the lens module, and a control circuit configured to determine the optical power of a tunable lens based on the reflections of the captured light from the plurality of surfaces within the lens module.

[0108] The foregoing is merely illustrative and various modifications can be made to the described implementation scheme. The foregoing implementation scheme can be implemented individually or in any combination.

Claims

1. An electronic device, the electronic device comprising: Tunable lens; At least one infrared light source, the at least one infrared light source being configured to direct infrared light toward the tunable lens to generate a flash pattern on the adjustable surface of the tunable lens; An image sensor configured to capture an image of the flash pattern; and A control circuit configured to determine the optical power of the tunable lens based on the image of the flash pattern.

2. The electronic device of claim 1, wherein the electronic device includes a display that directs visible light toward the tunable lens.

3. The electronic device according to claim 2, wherein the at least one infrared light source comprises a plurality of infrared light sources distributed around the periphery of the display.

4. The electronic device according to claim 2, wherein the at least one infrared light source is formed separately from the display.

5. The electronic device according to claim 2, wherein the at least one infrared light source is integrally formed with the display.

6. The electronic device of claim 2, wherein the display comprises visible light pixels, and wherein the at least one infrared light source comprises infrared light pixels scattered among the visible light pixels.

7. The electronic device of claim 2, wherein the display includes a photodiode for the image sensor.

8. The electronic device of claim 2, wherein the image sensor is formed separately from the display.

9. An electronic device, the electronic device comprising: A tunable lens having a lens element with adjustable curvature; Position sensors are distributed around the periphery of the lens element, wherein each position sensor is configured to sense the position of a corresponding point on the periphery of the lens element; and A control circuit configured to determine the optical power of the tunable lens based on the position sensed by the position sensor.

10. The electronic device of claim 9, wherein the control circuitry is configured to determine the optical power of the tunable lens based on the position sensed by the position sensor and stored calibration information.

11. The electronic device of claim 9, wherein the position sensor comprises a capacitive sensor.

12. The electronic device of claim 9, wherein the position sensor comprises a resistive sensor.

13. The electronic device of claim 9, wherein the position sensor comprises a magnetic sensor.

14. The electronic device of claim 9, wherein the position sensor comprises an optical sensor.

15. An electronic device, the electronic device comprising: A tunable lens having a fluid-filled chamber defined by a first lens element and a second lens element, wherein the fluid-filled chamber has opposing first and second sides; A first capacitor electrode layer is formed on the first side of the fluid-filled chamber; A second capacitor electrode layer is formed on the second side of the fluid-filled chamber, wherein the fluid-filled chamber and the air gap are inserted between the first capacitor electrode layer and the second capacitor electrode layer. and A control circuit configured to determine the optical power of the tunable lens based on the sensing capacitance between the first capacitor electrode layer and the second capacitor electrode layer.

16. The electronic device of claim 15, wherein the first capacitor electrode layer and the second capacitor electrode layer comprise patterned transparent conductive materials.

17. The electronic device of claim 16, wherein the patterned transparent conductive material comprises indium tin oxide.

18. The electronic device of claim 15, wherein the first lens element has an adjustable curvature, and wherein the first capacitor electrode layer is formed on the second lens element.

19. The electronic device of claim 18, further comprising: An additional lens, wherein the air gap is inserted between the fluid-filled chamber and the additional lens, and wherein the second capacitor electrode layer is formed on the additional lens.

20. An electronic device, the electronic device comprising: Lens module, the lens module comprising multiple lens elements; A display configured to emit light toward the lens module; An image sensor configured to capture reflections of light from multiple surfaces within the lens module; and A control circuit configured to determine the optical power of the tunable lens based on the reflection of the captured light from the plurality of surfaces within the lens module.

Images