Proximity sensing device with frequency modulated continuous wave light source and single photon avalanche diode array

Abstract

The invention provides a proximity sensing device. The proximity sensing device comprises: a frequency modulated continuous wave (FMCW) light source; an array of single photon avalanche diodes (SPADs); an optical splitter positioned to receive light emitted by the FMCW light source and to output a first split light and a second split light; a transmission light pipe configured to guide the first split light toward a target; an optical combiner positioned to receive a combination of the second split light and a portion of the first split light returned from the target and to direct the combination toward the SPAD array; a receiving light pipe configured to guide the portion of the first split light returned from the target toward the optical combiner; and an optical bridge element extending between the transmit light pipe and the receive light pipe and propagating the second split light from the optical splitter to the optical combiner.

Description

TECHNICAL FIELD

[0001] The described implementations relate generally to proximity sensors. More specifically, the described implementations relate to single-photon avalanche diode (SPAD)-based proximity sensors. BACKGROUND

[0002] Maximizing the user-facing display and touch input area provided by a consumer electronic product can enhance device aesthetics and improve the user experience. This can be particularly true on smaller consumer electronic products, such as mobile phones (e.g., smartphones) or wearable devices, but also on medium-sized consumer electronic products, such as tablets, and on larger consumer electronic products, such as televisions. Maximizing the user-facing display and touch input area can require minimizing the non-display user-facing area. However, a problem is that the non-display user-facing area can be used to provide a window through which a user-facing sensor or illuminator interacts with a user. The user-facing sensor can include, for example, a front-facing camera, a depth image sensor, a proximity sensor, an ambient light sensor, a fingerprint reader, etc. In some cases, the area provided by the user-facing display and touch input area can be maximized by moving the user-facing sensor and illuminator behind the display. However, this can sometimes degrade the performance of the sensor and / or the display.

[0003] In some cases, the size of the aperture through which a user-facing sensor or illuminator interacts with a user or the device environment can be reduced to provide the minimum optical requirements of the user-facing sensor or illuminator. This can sometimes be achieved by using an optical fiber, fiber bundle, or light guide to direct the transmission and reception of light between a full-size sensor or illuminator module and an optical window that is much smaller than the size of the sensor or illuminator module.

[0004] Cross-talk (XT) is defined as the amount of undesired signal received by a sensor receiver (RX) from an internal optical path that does not involve redirection of light by an external or intended target. Reducing the amount of system and module level cross-talk and its drift while not sacrificing near-field target signal is often one of the main design considerations for a bistatic optical sensor. Excessive XT and XT drift can significantly degrade near-field object detection and impact far-field time-of-flight object detection and ranging performance. For some types of proximity sensors that can be mounted under a device cover, sometimes with an air gap between the proximity sensor and the device cover, variations in the size of the air gap and changing cover surface conditions (e.g., smudges, scratches, application of a screen protector, etc.) during use can cause changes in XT and XT drift that adversely impact proximity sensor performance. For example, a heavily smudged screen protector on top of a device cover can increase XT by more than a hundred-fold.

[0005] A common technique for determining a distance to each point of a target (e.g., to one or more objects in a field of view (FoV)) involves a measurement of a round-trip time-of-flight (ToF) of a pulse of an emission of electromagnetic radiation (e.g., a pixel-by-pixel measurement of a round-trip ToF of one or more photons in each of a plurality of pulses of electromagnetic radiation). However, the precision of ToF measurements made by SPAD-based photon detectors can be affected by a variety of factors. For example, the use of a time-to-digital converter (TDC) or histogram memory with too few memory locations or the use of memory locations with too shallow depth can provide too coarse resolution or too much uncertainty for a desired application (e.g., a sampling rate below the Nyquist frequency). However, TDCs and histogram memories capable of finer resolution or higher measurement certainty can be expensive in terms of area requirements, power consumption, manufacturing costs, and the like. SUMMARY

[0006] Embodiments of systems, devices, methods, and apparatuses described in this disclosure relate to SPAD-based photon detectors, and more specifically to frequency-modulated continuous-wave (FMCW) SPAD-based proximity sensors and proximity sensing devices.

[0007] In a first aspect, the disclosure describes a proximity sensing device. The proximity sensing device can include a FMCW light source, a SPAD array, an optical splitter, a transmitting light pipe, an optical combiner, a receiving light pipe, and an optical bridge element. The optical splitter can be positioned to receive light emitted by the FMCW light source and output a first split beam of light and a second split beam of light. The transmitting light pipe can be configured to direct the first split beam of light toward a target. The optical combiner can be positioned to receive a combination of the second split beam of light and a portion of the first split beam of light returned from the target and direct the combination toward the SPAD array. The receiving light pipe can be configured to direct the portion of the first split beam of light returned from the target toward the optical combiner. The optical bridge element can extend between the transmitting light pipe and the receiving light pipe and propagate the second split beam of light from the optical splitter to the optical combiner.

[0008] In a second aspect, the disclosure describes another proximity sensing device. The proximity sensing device can include a FMCW light source, a SPAD array, an optical splitter, an optical combiner, a set of SPAD output pulse counters, and a SPAD output selection and routing network. The optical splitter can be positioned to receive light emitted by the laser light source and output a first split beam of light and a second split beam of light. The optical combiner can be positioned to receive a combination of the second split beam of light and a portion of the first split beam of light returned from a target and direct the combination toward the SPAD array. The SPAD output selection and routing network can be operable to couple a set of SPAD outputs received from a subset of SPADs in the SPAD array to the set of SPAD output pulse counters.

[0009] In a third aspect, the disclosure describes another proximity sensing device. The proximity sensing device can include a FMCW light source, a SPAD array, an optical splitter positioned to receive light emitted by the laser light source and output a first split beam of light and a second split beam of light, an optical combiner positioned to receive a combination of the second split beam of light and a portion of the first split beam of light returned from a target and direct the combination toward the SPAD array, and a set of one or more optical elements that direct the first split beam of light toward a target and direct the second split beam of light toward the optical combiner. The set of one or more optical elements in combination with the optical combiner can direct a coherent mixing of the second split beam of light and the portion of the first split beam of light toward a subset of SPADs in the SPAD array.

[0010] In addition to the aspects and embodiments described above, further aspects and embodiments will become apparent by reference to the drawings and by reading the following description. BRIEF DESCRIPTION OF DRAWINGS

[0011] The present disclosure will be readily understood by persons skilled in the art with reference to the following detailed description, taken in combination with the accompanying drawings, in which like references indicate like structural elements, and in which:

[0012] Figure 1 An example proximity sensor is shown positioned under a protective cover;

[0013] Figure 2A And Figure 2B An example modification to the proximity sensor shown is illustrated; Figure 1 An example embodiment of the proximity sensor shown;

[0014] Figure 3A And Figure 3B An example modification to the proximity sensor shown is illustrated; Figure 2A An example modification to the proximity sensor shown;

[0015] Figure 4An electrical block diagram showing a laser light source (or multiple laser light sources), a SPAD array, and other components of an example proximity sensor;

[0016] Figure 5A And Figure 5B An example implementation of a SPAD array and associated readout (R / O) circuit is shown;

[0017] Figure 6 An alternative implementation of the R / O circuit shown is shown; Figure 5B An alternative implementation of the R / O circuit shown is shown;

[0018] Figure 7 Examples of how the circuits and proximity sensing devices described can operate are illustrated; Figures 1-6 Examples of how the circuits and proximity sensing devices described can operate are illustrated;

[0019] Figure 8 Examples of how the circuits and / or proximity sensing devices described can transmit and receive light are shown; Figures 1-6 Examples of how the circuits and / or proximity sensing devices described can transmit and receive light are shown;

[0020] Figure 9A And Figure 9B An example of a device that can include a proximity sensor is shown; and

[0021] Figure 10 A sample electrical block diagram of an electronic device that includes a proximity sensor, such as an FMCW SPAD-based proximity sensor, is shown.

[0022] The use of cross-hatching or shading in the drawings is generally provided to clarify boundaries, and to facilitate ease of viewing for the reader. Thus, the presence or absence of cross-hatching or shading is not intended to indicate or imply any preference or requirement for particular materials, material properties, element proportions, element sizes, commonality of like elements, or any other characteristic, property, or nature of any element shown in the drawings.

[0023] Additionally, it is to be understood that the proportions and dimensions (relative or absolute) of the various features and elements (and collections and groupings thereof) and the relationships therebetween presented in the drawings are provided in the drawings merely to facilitate understanding of the various embodiments described herein and thus can not necessarily be presented or shown to scale and are not intended to indicate any preference or requirement for the embodiments shown to the exclusion of the embodiments described in connection therewith. DETAILED DESCRIPTION

[0024] Reference will now be made in detail to representative embodiments illustrated in the drawings. It should be understood that the following description is not intended to limit the embodiments to one preferred embodiment. On the contrary, it is intended to cover alternatives, modifications, and equivalents that can be included within the spirit and scope of the described embodiments and the appended claims.

[0025] Transceiver-separated optical proximity sensors can have various challenges. For example, some transceiver-separated optical proximity sensors experience high levels of XT, which in some cases can come from reflections off or between the surface of a device cover beneath which the sensor is mounted. XT can also be caused by smudges, scratches, application of screen protectors, etc. As one example, in a case where a device has a smudge on the cover through which optical proximity sensing occurs and needs to sense a target that returns a weak optical signal (e.g., a user’s face or wrist, which has a dense black of hair between the proximity sensor and their face or wrist), XT returned from the smudge can mask or drown out the desired optical signal returned from their wrist. As another example, if a transceiver-separated optical proximity sensor has too low a timing resolution (e.g., in the case of a SPAD-based proximity sensor with limited histogram memory), it can be difficult to distinguish between XT due to reflection of the device cover and XT due to reflection of a smudge on the device cover and / or XT due to reflection of a user’s finger that is touching (or approaching) the device cover.

[0026] Described herein are proximity sensors (e.g., proximity detection and ranging sensors) and proximity sensing devices that incorporate a SPAD-based digital FMCW sensing architecture and / or a multi-dimensional optical design.

[0027] Some implementations of the described proximity sensors and proximity sensing devices provide a cost-effective proximity sensing solution; or a solution that requires one or more relatively small windows through a device cover or housing; and / or a solution that is able to distinguish between a target and XT more effectively than some of the currently available proximity sensors and proximity sensing solutions. The described SPAD-based digital FMCW sensing architecture can provide efficient and shot noise limited coherent detection performance with greater two-dimensional (2D) scalability than traditional analog FMCW architectures. The combination of freeform and wave-based optics can provide minimal device surface footprint and good coherent mixing efficiency. The resulting high detection signal-to-noise ratio (SNR), high three-dimensional (3D) ranging resolution, and complementary 3D target velocity information can all be used to improve XT separation (i.e., separation of XT and desired optical signal(s)).

[0028] FMCW operation is achieved by mixing the optical signal emitted by the FMCW light source and returned from the target with a portion of the optical signal emitted by the FMCW light source and directed along a local oscillator (LO) path. Mixed with the return signal and the LO signal is also XT and ambient light. In some embodiments, the LO path can be designed using a wave optical device (e.g., a surface grating, a meta surface, etc.) formed on or in or placed near an input surface or an output surface of the light pipe. In some embodiments, an optical splitter can be formed on an input surface of the transmitting light pipe and / or an optical combiner can be formed on an output surface of the receiving light pipe. Internal reflections and waveguide directions within the flange connecting the transmitting light pipe and the receiving light pipe can be used to define the LO path. Alternatively, the LO path can be established using separate optical components (i.e., components that are not integrally formed with the transmitting light pipe and the receiving light pipe).

[0029] The light received from the target and the light received along the LO path can be coherently mixed and directed toward a SPAD array (e.g., a 2D array of SPADs). The coherently mixed light can be synchronized with a transmitter scan plan (e.g., a triangular intensity variation / frequency chirp scan plan) and can be read out per SPAD (i.e., per SPAD pixel) or per SPAD superpixel (e.g., per group of SPAD pixels) as needed for SNR, resolution, and latency. The signals read out per SPAD pixel or per SPAD superpixel can be sequentially processed in the frequency domain to extract instantaneous 2D range and velocity maps. The high ranging and velocity resolution that can be provided by each SPAD pixel combined with flexible spatial / angle resolution and temporal resolution can provide high-dimensional data for good target / XT signal separation. In some cases, the SPAD pixel or SPAD superpixel output can also be processed to determine the range to more than one target (e.g., both a near-field target and a far-field target) and the velocity of the more than one target.

[0030] The proximity sensor described herein can have an order of magnitude or more resolution (e.g., 1 millimeter (mm) resolution versus 20 mm resolution) compared to a conventional direct ToF (dToF) sensor.

[0031] The described SPAD-based digital FMCW sensing architecture can provide range and angle resolution (which together provide 3D measurement) and also provide velocity (e.g., can indicate whether a target is moving toward or away from the proximity sensor or can provide a Doppler signature that can enable a processor to determine whether a target is, for example, a person or an inanimate object based on changes) compared to proximity sensors that only provide range measurements. The described SPAD-based digital FMCW sensing architecture can also produce multiple data frames, which provides another degree of freedom (e.g., temporal resolution).

[0032] refer to Figures 1-10 However, those skilled in the art will readily appreciate that the detailed description given herein with respect to these drawings is for illustrative purposes only and should not be construed as limiting.

[0033] Directional terms, such as "top," "bottom," "upper," "lower," "front," "back," "above," "below," "above," "below," "left," "right," and the like, may be used with reference to the orientation of some of the components in some of the figures described below. Because components in various embodiments can be positioned in a number of different orientations, the directional terms are used for illustrative purposes only and are not necessarily limiting. The directional terms are intended to be interpreted broadly and, therefore, should not be interpreted to exclude components oriented in different manners. Additionally, as used herein, the phrase "at least one of" following a list of items any of which are separated by the terms "and" or "or" modifies the list as a whole, rather than modifying each member of the list. The phrase "at least one of" does not require selection of at least one of each item listed; rather, the phrase allows for a meaning that includes at least one of any of the items and / or at least one of any combination of the items and / or at least one of each of the items. For example, the phrase "at least one of A, B, and C" or "at least one of A, B, or C" each refers to only A, only B, or only C; any combination of A, B, and C; and / or one or more of each of A, B, and C. Similarly, it should be understood that the order in which elements are presented for conjoint or separate listings provided herein should not be construed to limit the disclosure to only the order provided.

[0034] Figure 1 An example proximity sensor 100 is shown positioned below a protective cover 102 (e.g., a device cover that extends over a display and / or provides a touch input surface, or another type of cover (e.g., a structural housing member). The proximity sensor 100 and protective cover 102 may be components of a proximity sensing device (e.g., Figure 9A and Figure 9B In addition to being used for proximity sensing, the proximity sensing device can also perform other functions and in some embodiments can be a mobile phone, a computer, or a wearable device.

[0035] The proximity sensor 100 can include a frequency-modulated continuous wave (FMCW) light source 104, which can include a laser light source 106 (e.g., a vertical cavity surface emitting laser (VCSEL) or other type of laser, or another type of coherent or at least partially coherent light source) and associated control circuitry 108. The proximity sensor 100 can also include a single-photon avalanche diode (SPAD) array 110. The array 110 is preferably a two-dimensional (M x N) array, where M > 2 and N > 2, although in some cases the array 110 can be a one-dimensional (1 x N) array, where N > 2. Alternatively, the array 110 can utilize a SPAD ring, a SPAD radial line, or another type of arrangement of multiple SPADs instead.

[0036] Both the laser light source 106 and the SPAD array 110 can be mounted so that they have a fixed spatial relationship relative to one another. For example, the laser light source 106 and the SPAD array 110 can be mounted or formed on a substrate 112 (e.g., on a printed circuit board (PCB) and / or on a substrate of an application-specific integrated circuit (ASIC) 130, attached to a device housing, and / or attached to a module housing (e.g., a metal or plastic container)). In some embodiments, the SPAD array 110 can be formed in the ASIC 130, and the laser light source 106 can be attached to the ASIC 130 (e.g., stacked on it).

[0037] An optical splitter 114 can be positioned to receive light 116 emitted by the FMCW light source 104 and output a first split beam of light 118 and a second split beam of light 120. The first split beam of light 118 can be directed toward a target 122, and the second split beam of light 120 can be directed along a local oscillator (LO) path.

[0038] An optical combiner 124 can be positioned to receive a combination of the second split beam of light 120 (received from the LO path) and a portion 126 of the first split beam of light that returns from the target 122 and direct the combination toward the SPAD array 110. Some or all of the light received by the optical combiner 124 can coherently mix (i.e., interfere).

[0039] An optical bridge element 128 can propagate the second split beam of light 120 from the optical splitter 118 to the optical combiner 124. In some embodiments, the optical bridge element 128 can include an optical fiber or an optical pipe. In some embodiments, the optical splitter 114 and / or the optical combiner 124 can be formed on or in the optical bridge element 128 (e.g., on one or more surfaces of the optical bridge element 128). In some of these latter embodiments, the protective cover 102 can be the optical bridge element 128. In some of these latter embodiments, the optical splitter 118 and / or the optical combiner 124 can be formed on a surface of the protective cover 102.

[0040] In some cases, a screen protector 132 may be applied to the protective cover 102. The screen protector 132 may be thinner, thicker, or about the same thickness as the protective cover 102. The screen protector 132 may be made of glass, plastic, or another material and may include an adhesive layer that enables the screen protector 132 to adhere to the protective cover 102. In some cases, smudges 134 or other material deposits (e.g., oil, dust, organic matter, etc.) may form on or adhere to the screen protector 132 (or to the protective cover 102 in the absence of the screen protector 132). In some cases (not shown), the protective cover 102 and / or the screen protector 132 may have cracks, scratches, or chips therein. All of these features (e.g., screen protector 132, smudges 134 or other material deposits, cracks, scratches, or debris) can cause light to be reflected, refracted, or directed in a manner that causes XT between FMCW light source 104 and SPAD array 110. It would be useful to mitigate or eliminate the effects of such XT on SPAD array 110 and / or measurements determined from its output (i.e., from the SPAD output).

[0041] Figure 2A and Figure 2B Shown Figure 1 Example embodiments of proximity sensor 100 are shown. These embodiments include a transmitting light pipe 200 and a receiving light pipe 202. Transmitting light pipe 200 can be configured to direct first split light beam 118 toward target 122. Receiving light pipe 202 can be configured to direct portion 126 of first split light beam returned from target 122 toward optical combiner 124. Optical bridge element 128 can be positioned between transmitting light pipe 200 and receiving light pipe 202 and extend therebetween.

[0042] exist Figure 2A In some embodiments, the optical bridge element 128 is connected to the transmitting light pipe 200 and the receiving light pipe 202. In some of these embodiments, the optical splitter 114 can be formed on the light receiving end 204 of the transmitting light pipe 200, and / or the optical combiner 124 can be formed on the light emitting end 208 of the receiving light pipe 202 (although in other embodiments, the optical splitter 114 and / or the optical combiner 124 can be implemented spaced apart from the transmitting light pipe 200 or the receiving light pipe 202). In some embodiments, one or both of the optical splitter 114 and the optical combiner 124 can be formed by a surface grating or a metasurface.

[0043] Also in Figure 2AIn one embodiment, the optical bridge element 128 is connected to the transmitting light pipe 200 closer to the light receiving end 204 of the transmitting light pipe 200 than to the light emitting end 206 of the transmitting light pipe 200, and is connected to the receiving light pipe 202 closer to the light emitting end 208 of the receiving light pipe 202 than to the light receiving end 210 of the receiving light pipe 202. In alternative embodiments, the optical bridge element 128 may be connected to the transmitting light pipe 200 closer to the light emitting end 206 of the transmitting light pipe 200 than to the light receiving end 204 of the transmitting light pipe 200, and is connected to the receiving light pipe 202 closer to the light receiving end 210 of the receiving light pipe 202 than to the light emitting end 208 of the receiving light pipe 202. In other embodiments, the optical bridge element 128 may be connected to the midpoints of the transmitting light pipe 200 and the receiving light pipe 202, or the optical bridge element 128 may be connected to each of the transmitting light pipe 202 and the receiving light pipe 202 at different relative positions.

[0044] exist Figure 2B In some embodiments, the optical bridge element 128 can include at least one of a surface grating or a metasurface. In some cases, the optical bridge element 128 can be etched into or otherwise formed on or in a flange connecting the transmitting light pipe 200 and the receiving light pipe 202.

[0045] In some embodiments, the transmit light pipe 200, receive light pipe 202, and optical bridge element 128 can be provided by a set of one or more optical elements. In some embodiments, the set of one or more optical elements can be composed of a monolithic optical element (i.e., a single, integral structure that defines all of the indicated optical elements). In some embodiments, the monolithic optical element can also define the optical splitter 114 and the optical combiner 124.

[0046] Figure 3A and Figure 3B Shown Figure 2A The illustrated modifications are example modifications of the proximity sensor 100 , but the illustrated modifications may be made to any of the embodiments described herein.

[0047] exist Figure 3A and Figure 3B , the laser light source 106 is a first laser light source 106, and the FMCW light source 104 further includes one or more additional laser light sources (e.g., a second laser light source 300). Each of the first laser light source 106 and the second laser light source 300 can be positioned to emit light toward the optical splitter 114. In this embodiment, the controller 302 can be configured to separately address and operate the first laser light source 106 and the second laser light source 300.

[0048] Depending on the location and characteristics of the target (e.g., size, material, surface quality, etc.), one or more of these laser light sources can provide a better return signal and / or a return signal that mixes better with the second beam-split light 120. For example, in some cases, gating the first laser light source 106 on when the second laser light source 300 is off can provide better mixing of the second beam-split light 120 with the portion 126 of the first beam-split light that returns from the target 122, while saving power. In other cases, gating the second laser light source 300 on when the first laser light source 106 is off can provide better mixing of the second beam-split light 120 with the portion 126 of the first beam-split light that returns from the target 122, while saving power. Alternatively, two of the laser light sources 106, 300 can be gated on or off at the same time.

[0049] In some embodiments, the first laser light source 106 and the second laser light source 300 can emit light of the same wavelength. Alternatively, the first laser light source 106 and the second laser light source 300 can emit light of different wavelengths.

[0050] In addition to and alternative to the first laser light source 106 and the second laser light source 300, one or more configurable optical elements (e.g., movable or electronically reconfigurable optical elements) can be used to direct light emitted by the laser light sources in different directions. Each of the one or more laser light sources can also be configured to have a different polarization, or one or more optical elements can be used to statically or dynamically change the polarization of the emitted light.

[0051] Figure 4 An electrical block diagram 400 of a laser light source (or multiple laser light sources) 402, a SPAD array 404, and other components of an example proximity sensor (e.g., one of the proximity sensors described herein) is shown. In some cases, the laser light source 402 and the SPAD array 404 can be configured as described with reference to any of Figures 1-3B By way of example, the other components can include one or more of: a transmit driver and laser compatible circuitry 406, high voltage generation circuitry 408 for the SPAD array 404, peripheral and readout (R / O) circuitry 410, and / or processing circuitry 412 (e.g., a digital signal processor (DSP) to compute a range or distance to a target).

[0052] Figure 5A and Figure 5B An example implementation of a SPAD array 500 and associated R / O circuitry 502 is shown. In some cases, the SPAD array 500 and the R / O circuitry 502 can be the SPAD array and R / O circuitry described with reference to any of Figure 4

[0053] ​By way of example, the SPAD array 500 is shown in Figure 5A as an 8x8 array of SPADs. In other examples, the SPAD array 500 can be any MxN array of SPADs, where M > 1 and N > 2. The R / O circuit 502 can include a set of SPAD output pulse counters (CNTs) 504 and a SPAD output selection and routing network 506. The SPAD output selection and routing network 506 can be operable to couple a set of SPAD outputs received from a subset of SPADs in the SPAD array 500 to the set of SPAD output pulse counters 504.

[0054] Figure 5A An example incidence of light returned from a target (as dots 508-1; e.g., from a target in any of Figures 1-3B and light received via the LO path (as dots 510; e.g., second split light produced by the optical splitter in Figures 1-3B As shown, the dots 508-1, 510 can overlap, and this overlap represents a mixing (interference) of light received along different paths (i.e., from a target and from the LO path). In some embodiments, there can be more than one dot of light returned from more than one target, such as a first dot of light 508-1 representing light returned from a near-field target and a second dot of light 508-2 representing light returned from a far-field target. A portion of each of the near-field dot 508-1 and the far-field dot 508-2 can mix with the LO dot 510.

[0055] The SPAD output and routing network 506 can be configured in various ways, depending on resource budget (available implementation space, cost, timing margin, etc.). In Figure 5B , the SPAD output selection and routing network 506 is shown as including a set of M power-shaping (PS) circuits 512, each of which receives SPAD outputs 514 of N SPAD pixels 516 (i.e., each SPAD output in a row of N SPAD pixels 516, but in other embodiments, each PS circuit can receive more or fewer SPAD outputs of SPAD pixels 516). Each PS circuit can provide N shaped SPAD outputs to a repackaging circuit 518 (e.g., a switching circuit). Alternatively, the SPAD outputs 514 can be provided directly to the repackaging circuit 518 (i.e., without first being shaped by the set of PS circuits 512).

[0056] The regrouping circuit 518 can be programmed to route different combinations of SPAD outputs 514 to different logic gates 520 (e.g., different OR gates). Each OR gate can generate a pulse whenever one of the SPAD outputs input to the OR gate carries a pulse (i.e., a pulse indicating that the corresponding SPAD has been triggered by received light). Each counter in the set of SPAD output pulse counters 504 can increment its count whenever the corresponding OR gate indicates that a SPAD output pulse has been received. At the end of each time period in the sequence of time periods, the SPAD output pulse counter can output its count to a corresponding multiplexer in the set of multiplexers 522. The multiplexers in the set of multiplexers 522 can be controlled to output the corresponding count from the set of SPAD output pulse counters 504 to one of a plurality of pulse train memories. By way of example, two pulse train memories (i.e., pulse train memory 1 524-1 and pulse train memory 2 524-2) are shown, but any number of one or more pulse train memories may be provided. If only one burst memory is provided, each counter in a set of SPAD output pulse counters 504 may provide its output directly to a single burst memory.

[0057] like Figure 5A As shown, there may be a subset 526 of SPADs that receive a combination of light returned from the target (i.e., spot 508-1) and light received via the LO path (i.e., spot 510). The outputs of the SPADs 516 included in the subset 526 of SPADs may be grouped together by a regrouping circuit 518 and provided to one or more of the logic gates 520. The SPAD output pulse counters 504 associated with these logic gates 520 may then be routed to the same burst memory (524-1 or 524-2) by providing appropriate output select signals to the set of multiplexers 522. In some cases, the outputs of SPADs 516 from different subsets (e.g., the outputs of the SPADs on which light spots 508-2 and 510 impinge) may be routed to different burst memories (524-1 or 524-2). For example, the output pulses of the SPAD that receives returned light from a near-field target or range, combined with the light received from the LO path, can be routed to a first subset of one or more SPAD output pulse counters 504 and a first pulse train memory 524-1; and the output pulses of the SPAD that receives returned light from a far-field target or range, combined with the light received from the LO path, can be routed to a second subset of one or more SPAD output pulse counters 504 and a second pulse train memory 524-2.

[0058] In some embodiments, the SPAD output selection and routing network 506 (or, generally, the R / O circuit 502) can be programmed prior to final use deployment proximate to the proximity sensing device. For example, if the proximity sensing device is to be included in a particular type of device, under a cover (or under a cover and possibly a screen protector), the locations at which the respective points 508-1, 508-1, and / or 510 impinge on the SPAD array 500 can be determined in a laboratory or manufacturing environment, and a subset of SPADs (e.g., the subset of SPADs 526) can be defined, and the SPAD output selection and routing network 506 can be programmed statically or semi-statically. In some embodiments, the proximity sensing device including the array of SPADs 500 and the associated R / O circuit 502 can be configured to sense a target that can be assumed to be within a particular range (e.g., a near field range of the proximity sensing device), and the SPAD output selection and routing network 506 (or, generally, the R / O circuit 502) can be programmed to sense such a target. In some embodiments, the SPAD output selection and routing network 506 (or, generally, the R / O circuit 502) can be programmed to sense more than one target (e.g., a near field target and a far field target) within respective particular ranges (e.g., particular near field and far field ranges of the proximity sensing device).

[0059] In some embodiments, the SPAD output selection and routing network 506 (or, generally, the R / O circuit 502) can be associated with a controller 528, and the controller 528 can be configured to periodically acquire data from the SPAD array 500 and program the SPAD output selection and routing network 506 during final use deployment of the proximity sensor (e.g., in field programming).

[0060] The controller 528 (or processor) can also be used to receive counts of SPAD output pulses (e.g., from the pulse train memory 524-1 or 524-2), and to separate optical signals returned from a near field target from crosstalk.

[0061] Figure 6 An alternative embodiment of the R / O circuit 502 is shown. Figure 5B An alternative embodiment of the R / O circuit 502 is shown. Figure 6In one embodiment, the enable circuit 600 is disposed between the set of logic gates 520 and the set of SPAD output pulse counters 504. The enable circuit 600 is operable to connect the SPAD outputs in the set of SPAD outputs 514 to the set of SPAD output pulse counters 504, or to disconnect the SPAD outputs in the set of SPAD outputs 514 from the set of SPAD output pulse counters. By way of example, the enable circuit 600 may include a set of D flip-flops, each of the D flip-flops in the set of D flip-flops having a D input connected to a count enable signal line (CNT_EN), each of the D flip-flops in the set of D flip-flops having a clock input connected to a corresponding output of a logic gate in the set of logic gates 520, and each of the D flip-flops in the set of D flip-flops having an output (Q output) connected to an input of a corresponding multiplexer in the set of multiplexers 522.

[0062] Figure 7 Reference Figures 1-6 The circuits and proximity sensing devices described herein are examples of how they may operate. At time 700, a ramp of the operating frequency of the FMCW light source may begin, and the operating frequency may sweep through a range of frequencies (e.g., from low frequency to high frequency) between time 700 and time 702. At time 704, a portion of the light emitted by the FMCW light source and returned from the target may initially be at the SPAD array (e.g., at Figure 5A 7. The time difference between times 700 and 704 represents the time of flight (ToF) as the light travels from the FMCW light source to the target and then to the SPAD array. The ToF for the light traveling from the FMCW light source to the SPAD array is negligible and may or may not be considered.

[0063] As the operating frequency of the FMCW light source is swept, various SPADs in the SPAD array may be triggered by photons returned from the target, photons received via the LO path, or a combination of photons received via the LO path and photons returned from the target. Figure 7 The triggering of the first SPAD (output as SPAD1), the second SPAD (output as SPAD2), and the Xth SPAD (output as SPADX) is shown. The triggering of the various SPADs indicated by the SPAD output pulses can be sampled according to a sampling time (or sampling clock) that creates a series of sampling cycles. During each sampling time, the triggering of the various SPADs indicated by the SPAD output pulses can be sampled by the corresponding SPAD output pulse counter. Figure 5AThe number of SPAD output pulses contained in the SPAD output received by one of the logic gates (e.g., OR gate) described above is counted. The count (CNT) of SPAD output pulses generated by the SPAD output pulse counter over a series of sampling periods can be saved to a pulse train memory (PULSE TRAIN MEM). The contents of the pulse train memory can be output to a processor that performs a fast Fourier transform (FFT) and finds a peak value (f) representing the beat frequency. 拍频 ) is controlled by (or read by) a processor. The beat frequency can be used according to known techniques to determine the distance to the target. In some cases, there may be more than one beat frequency, indicating that light is returning from more than one target (e.g., a near-field target and a far-field target).

[0064] Figure 8 As shown by reference Figures 1-6 The example transmission and reception of light by the described circuit and / or proximity sensing device. Figure 7 . At time 700, the ramping of the operating frequency of the FMCW light source begins, and coherent light (or at least partially coherent light) having a changing frequency is emitted by the FMCW light source into the field of view. Light is emitted from time 700 (the start of the frequency ramp) until time 702 (the end of the frequency ramp). In alternative embodiments, the emitted light can be chirped, where the chirp has different frequencies, or the light can be emitted according to other predetermined patterns or characteristics.

[0065] At time 704, the SPAD array may begin to receive a portion of the light emitted by the FMCW light source and returned from the target. The time difference between times 700 and 704 represents the ToF as the light travels from the FMCW light source to the target and then to the SPAD array. The ToF for the light traveling from the FMCW light source to the SPAD array is negligible and may or may not be considered.

[0066] Between times 700 and 704, the SPAD array may receive light along the LO path as well as stray light (e.g., ambient light and light reflected from surfaces within the device, the surface of the screen protector, smudges, etc.). All of this light may be considered noise. Similarly, light received after the end of the frequency ramp (i.e., after time 702) may be considered noise. Figure 6The described enable circuit can be used to gate out the noise so that between times 700 and 704 or after time 702, SPAD output pulses are not counted and counts are not stored in the pulse train memory. Alternatively, the enable signal (CNT EN) supplied to the enable circuit can gate the SPAD output pulse counter on after time 700 but slightly before time 704, and gate the SPAD output pulse counter off at or after time 702.

[0067] The time period between time 700 and time 702 can be considered a non-gated signal accumulation time (T 信号 ), and the time period between time 700 and time 800 can be considered a stray accumulation time (T 杂散 ), where T 杂散 is a subset of T 信号 . Accumulation times of interest can be represented by T 信号 -T 杂散 .

[0068] Figure 9A and Figure 9B shows an example of a device 900 that can include a proximity sensor (thereby making the device 900 a proximity sensing device, although the device 900 can also have other purposes). The size and form factor of the device, including the ratio of the length of its long side to the length of its short side, indicate that the device 900 is a mobile phone (e.g., a smartphone). However, the size and form factor of the device are arbitrary choices, and the device 900 can alternatively be any portable electronic device, including, for example, a tablet computer, a portable computer, a portable music player, a wearable device (e.g., an electronic watch, a health monitoring device, a fitness tracking device, a headset, or glasses), an augmented reality (AR) device, a virtual reality (VR) device, a mixed reality (MR) device, a gaming device, a portable terminal, a digital single-lens reflex (DSLR) camera, a video camera, a vehicle navigation system, a robot navigation system, or other portable or mobile device. The device 900 can also be a device that is semi-permanently located (or installed) at a single location. Figure 9A shows a front isometric view of the device 900, and Figure 9B shows a back isometric view of the device 900. The device 900 can include a housing 902 that at least partially surrounds a display 904. The housing 902 can include or support a front cover 906 or a back cover 908. The front cover 906 can be positioned over the display 904 and can provide a window through which the display 904 can be viewed. In some embodiments, the display 904 can be attached to (or abut) the housing 902 and / or the front cover 906. In alternative embodiments of the device 900, the display 904 can not be included and / or the housing 902 can have an alternative configuration.

[0069] Display 904 can include one or more light-emitting elements, and in some cases can be a light-emitting diode (LED) display, an organic LED (OLED) display, a liquid crystal display (LCD), an electroluminescent (EL) display, or another type of display. In some embodiments, display 904 can include, or be associated with, one or more touch sensors and / or force sensors configured to detect touches and / or forces applied to a surface of front cover 906.

[0070] The various components of housing 902 can be formed from the same or different materials. For example, sidewall 918 of housing 902 can be formed using one or more metals (e.g., stainless steel), polymers (e.g., plastic), ceramics, or composite materials (e.g., carbon fiber). In some cases, sidewall 918 can be a multi-segment sidewall that includes a set of antennas. The antennas can form structural components of sidewall 918. The antennas can be structurally coupled (to each other or to other components) and electrically isolated (from each other or from other components) by one or more non-conductive segments of sidewall 918. Front cover 906 can be formed, for example, using one or more of glass, crystal (e.g., sapphire), or transparent polymers (e.g., plastic) that enable a user to view display 904 through front cover 906. In some cases, a portion of front cover 906 (e.g., a peripheral portion of front cover 906) can be coated with an opaque ink to obscure components included within housing 902. Rear cover 908 can be formed using the same materials used to form sidewall 918 or front cover 906. In some cases, rear cover 908 can be part of a monolithic element that also forms sidewall 918 (or those portions of sidewall 918 that are electrically conductive or non-conductive, in cases where sidewall 918 is a multi-segment sidewall). In still other embodiments, all of the exterior components of housing 902 can be formed from transparent materials, and components within device 900 can or can not be obscured by opaque ink or opaque structures within housing 902.

[0071] Front cover 906 can be mounted to sidewall 918 to cover an opening defined by sidewall 918 (i.e., an opening into an interior volume in which various electronic components of device 900, including display 904, can be positioned). Front cover 906 can be mounted to sidewall 918 using fasteners, adhesives, seals, gaskets, or other components.

[0072] A display stack or device stack (hereinafter “stack”) including display 904 can be attached (or abutted) to an interior surface of front cover 906 and extend into the interior volume of device 900. In some cases, the stack can include a touch sensor (e.g., a grid of capacitive, resistive, strain-based, ultrasonic, or other types of touch sensing elements) or other layers of optical, mechanical, electrical, or other types of components. In some cases, the touch sensor (or a portion of a touch sensor system) can be configured to detect touches applied to an outer surface of front cover 906 (e.g., to a display surface of device 900).

[0073] In some cases, a force sensor (or a portion of a force sensor system) can be positioned within the interior volume above, below, and / or to the side of display 904 (and in some cases, within the device stack). The force sensor (or force sensor system) can be triggered in response to the touch sensor detecting one or more touches on front cover 906 (or one or more locations of one or more touches on front cover 906) and can determine a magnitude of force associated with each touch, or a magnitude of force associated with the entire set of touches. In some embodiments, the force sensor (or force sensor system) can be used to determine the location of a touch, or the location of a touch in combination with the magnitude of force of the touch. In these latter embodiments, device 900 can not include a separate touch sensor.

[0074] As Figure 9A As generally shown, device 900 can include various other components. For example, a front portion of device 900 can include one or more front-facing cameras 910 (including one or more 3D image sensors or depth sensors), a speaker 912, a microphone, or other components 914 configured to transmit or receive signals to / from device 900 (e.g., audio, imaging, and / or sensing components (e.g., a proximity sensor such as one of the proximity sensors described herein)). In some cases, front-facing cameras 910, alone or in combination with other sensors, can be configured to operate as a biometric authentication or facial recognition sensor. In some embodiments, a flash or electromagnetic radiation source (e.g., a visible light source or an IR light source) can be positioned near the front-facing cameras. In some cases, front-facing cameras 910 can be positioned behind display 904 and receive electromagnetic radiation (e.g., light) through display 904. In some cases, a proximity sensor or depth sensor can be used to determine a distance to a user or generate a depth map of a user’s face, or determine a distance to or proximity of an object or generate a depth map of an object (or objects in a FoV including the object). Device 900 can also include various input devices, including mechanical or virtual buttons 916 that can be accessed from a front surface (or display surface) of device 900.

[0075] Device 900 can also include buttons or other input devices positioned along a sidewall 918 of device 900 and / or on a rear surface. For example, volume buttons or a multi-function button 920 can be positioned along sidewall 918 and, in some cases, can extend through a hole in sidewall 918. Sidewall 918 can include one or more ports 922 that allow air, but not liquid, to flow into and out of device 900. In some embodiments, one or more sensors can be positioned in or near ports 922. For example, an ambient pressure sensor, an ambient temperature sensor, an internal / external differential pressure sensor, a gas sensor, a particulate matter concentration sensor, or an air quality sensor can be positioned in or near ports 922.

[0076] In some embodiments, a rear surface of device 900 can include a rear-facing camera 924 that includes one or more 3D image sensors or depth sensors (see, e.g., FIGS. 1A-1C). A flash or electromagnetic radiation source 926 (e.g., a visible light source or an IR light source) can also be positioned on the rear of device 900 (e.g., near the rear-facing camera). In some cases, a rear surface of device 900 can include multiple rear-facing cameras. Figure 9B )>. A flash or electromagnetic radiation source 926 (e.g., a visible light source or an IR light source) can also be positioned on the rear of device 900 (e.g., near the rear-facing camera). In some cases, a rear surface of device 900 can include multiple rear-facing cameras.

[0077] Figure 10 An example electrical block diagram of an electronic device 1000 is shown that includes a proximity sensor, such as an FMCW SPAD-based proximity sensor configured or arranged in accordance with the principles described in any of Figures 1-9B Reference. Electronic device 1000 can take the form of a handheld or portable device (e.g., a smartphone, a tablet computer, or an electronic watch), a wearable device, a computing device, a navigation system of a vehicle, etc. Electronic device 1000 can include an optional display 1002 (e.g., a light-emitting display), a processor 1004, a power source 1006, a memory 1008 or storage device, a sensor system 1010, and an optional input / output (I / O) mechanism 1012 (e.g., input / output devices and / or input / output ports). Processor 1004 can control some or all of the operations of electronic device 1000. Processor 1004 can be in communication, directly or indirectly, with substantially all of the components of electronic device 1000. For example, a system bus or other communication mechanism 1014 can provide communication between processor 1004, power source 1006, memory 1008, sensor system 1010, and / or input / output mechanism 1012.

[0078] The processor 1004 can be implemented as any electronic device capable of processing, receiving, or transmitting data or instructions. For example, the processor 1004 can be a microprocessor, a central processing unit (CPU), an ASIC, a DSP, a controller, or any combination of such devices. As described herein, the term “processor” is intended to encompass a single processor or processing unit, multiple processors, multiple processing units, or one or more other suitably configured computing elements.

[0079] In some embodiments, components of the electronic device 1000 can be controlled by multiple processors. For example, selected components of the electronic device 1000 can be controlled by a first processor, and other components of the electronic device 1000 can be controlled by a second processor, where the first processor and the second processor can or can not communicate with each other.

[0080] The power source 1006 can be implemented with any device capable of providing energy to the electronic device 1000. For example, the power source 1006 can include one or more disposable or rechargeable batteries. Additionally or alternatively, the power source 1006 can include a power connector or power cord that connects the electronic device 1000 to another power source, such as a wall outlet.

[0081] The memory 1008 can store electronic data that can be used by the electronic device 1000. For example, the memory 1008 can store electrical data or content, such as, for example, audio and video files, documents and applications, device settings and user preferences, timing signals, control signals, data structures or databases, image data, map or focus settings. The memory 1008 can be configured as any type of memory. By way of example only, the memory 1008 can be implemented as random access memory, read only memory, flash memory, removable memory, other types of storage elements, or a combination of such devices.

[0082] The electronic device 1000 can also include one or more sensors that define a sensor system 1010. The sensors can be positioned substantially anywhere on the electronic device 1000. The sensors can be configured to sense substantially any type of characteristic, such as, but not limited to, touch, force, pressure, electromagnetic radiation (e.g., light), heat, movement, relative motion, biometric data, distance, etc. For example, the sensor system 1010 can include touch sensors, force sensors, heat sensors, position sensors, light or optical sensors, accelerometers, pressure sensors (e.g., pressure transducers), gyroscopes, magnetometers, health monitoring sensors, image sensors, proximity sensors, etc. Additionally, the one or more sensors can utilize any suitable sensing technology, including but not limited to capacitive, ultrasonic, resistive, optical, ultrasonic, piezoelectric, and thermal sensing technologies.

[0083] The I / O mechanism 1012 can send and / or receive data from a user or another electronic device. The I / O device can include a display, a touch-sensing input surface such as a trackpad, one or more buttons (e.g., a graphical user interface “home” button or one of the buttons described herein), one or more cameras (including one or more 2D or 3D image sensors (e.g., one or more SPAD-based photodetectors)), one or more microphones or speakers, one or more ports such as a microphone port, and / or a keyboard. Additionally or alternatively, the I / O device or port can send electrical signals via a communication network such as a wireless and / or wired network connection. Examples of wireless and wired network connections include, but are not limited to, cellular networks, Wi-Fi, Bluetooth, IR, and Ethernet connections. The I / O mechanism 1012 can also provide haptic feedback to the user (e.g., tactile outputs).

[0084] The foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the described embodiments. However, it will be apparent to one skilled in the art that specific details are not required in order to practice the described embodiments. Thus, the foregoing descriptions are presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the embodiments to the precise forms disclosed. Many modifications and variations are possible in view of the above teachings. The described embodiments are to be considered merely exemplary, but the scope of the embodiments is not otherwise limited to the specific embodiments described herein.

[0085] As described above, one aspect of the present technology can be gathering and using data from a variety of sources. The present disclosure contemplates that in some instances, the gathered data can include personal information data that uniquely identifies or can be used to identify, locate, or contact a specific person. Such personal information data can include demographic data, location-based data, telephone numbers, email addresses, home addresses, data or records pertaining to health or fitness levels, date of birth, or any other identifying or personal information.

[0086] The present disclosure recognizes that the use of such personal information data, in the present technology, can be used to the benefit of the user. For example, the personal information data can be used to activate or deactivate various features of the user device, or gather performance metrics of the user device or user. Further, other uses for personal information data that benefit the user are also contemplated. For example, health and fitness data can be used to provide insights to a user’s overall health, or can be used as positive feedback to individuals using technology to pursue health goals.

[0087] The present disclosure contemplates that the entities responsible for the collection, analysis, disclosure, transfer, storage, or other use of such personal information data will comply with well-established privacy policies and / or privacy practices. In particular, such entities should implement and consistently use privacy policies and practices that are generally recognized as industry best practices. In addition, such entities should adhere to specialized fields' privacy policies and practices, which are generally considered more stringent. In areas such as health care, financial services, and telecommunications, the entities should implement privacy policies and practices that are more stringent than those otherwise expected under the general purposes described above. In addition, such entities should consider taking any additional steps necessary under the circumstances to preserve the privacy of the information of users. Furthermore, such entities should consider securing user consent before sharing or selling personal information that they have collected, especially if the information is not previously collected as part of a transaction that the user has authorized. Furthermore, such entities should take any additional steps necessary under the circumstances to preserve the privacy of the information of users in accordance with other privacy laws and standards.

[0088] Notwithstanding the foregoing, the present disclosure also contemplates embodiments in which users can 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, in the case of advertisement delivery services, the present technology can be configured to allow users to selectively "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 emotion-related data for targeted content delivery services. In another example, users can select to limit the length of time for which emotion-related data is maintained, or to completely prohibit the development of underlying emotional profiles. 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 can be notified upon download of an application that their personal information data will be accessed. Additionally, a user can be notified when his / her personal information data is accessed during use of the application.

[0089] Furthermore, it is the intent of the present disclosure that personal information data should be managed and processed in a manner that minimizes risks of unintentional or unauthorized access or use. Risk can be minimized by limiting the collection of data and deleting data once it is no longer needed. In addition, and when applicable, including in certain health related applications, data de-identification can be used to protect user privacy. De-identification can be facilitated, when appropriate, in accordance with practices that are widely accepted as good information hygiene in the art, such as those practices identified in the US Department of Health and Human Services’ "Privacy and Security in Health Programs: The

[0090] Accordingly, while the present disclosure broadly covers technologies using personal information data, the present disclosure also contemplates techniques that do not involve such personal information data. That is, the techniques of the present disclosure are not rendered inoperable due to the lack of personal information data. For example, content can be selected and delivered to users without access to personal information data about those users.

Claims

1. A proximity sensing device, the proximity sensing device comprising: a frequency modulated continuous wave (FMCW) light source; a single photon avalanche diode (SPAD) array; an optical splitter positioned to receive light emitted by the FMCW light source and output a first split beam of light and a second split beam of light; a transmitting light pipe configured to direct the first split beam of light toward a target; an optical combiner positioned to receive a combination of the second split beam of light and a portion of the first split beam of light returned from the target and direct the combination toward the SPAD array; a receiving light pipe configured to direct the portion of the first split beam of light returned from the target toward the optical combiner; and an optical bridge element extending between the transmitting light pipe and the receiving light pipe and propagating the second split beam of light from the optical splitter to the optical combiner.

2. The proximity sensing device of claim 1, wherein the optical bridge element comprises a light pipe.

3. The proximity sensing device of claim 2, wherein: the light pipe is connected to the transmitting light pipe closer to a light receiving end of the transmitting light pipe than to a light emitting end of the transmitting light pipe; and the light pipe is connected to the receiving light pipe closer to a light emitting end of the receiving light pipe than to a light receiving end of the receiving light pipe.

4. The proximity sensing device of claim 2, wherein: the light pipe is connected to the transmitting light pipe closer to a light receiving end of the transmitting light pipe than to a light emitting end of the transmitting light pipe; and the light pipe is connected to the receiving light pipe closer to a light receiving end of the receiving light pipe than to a light emitting end of the receiving light pipe.

5. The proximity sensing device of claim 2, wherein: the optical splitter is formed on a light receiving end of the transmitting light pipe; and the optical combiner is formed on a light emitting end of the receiving light pipe.

6. The proximity sensing device of claim 1, wherein the optical bridge element comprises at least one of a surface grating or a metasurface.

7. The proximity sensing device of claim 1, wherein: the FMCW light source comprises a first laser light source and a second laser light source; and the first laser light source and the second laser light source are each positioned to emit light toward the optical splitter.

8. The proximity sensing device of claim 7, further comprising a controller configured to individually address and operate the first laser light source and the second laser light source.

9. The proximity sensing device of claim 1, further comprising a controller configured to receive a count of SPAD output pulses generated by the SPAD array and separate optical signals returned from near field targets from crosstalk.

10. A proximity sensing device, the proximity sensing device comprising: a frequency modulated continuous wave (FMCW) light source; a single photon avalanche diode (SPAD) array; ​ an optical splitter positioned to receive light emitted by the FMCW light source and output a first split beam of light and a second split beam of light; an optical combiner positioned to receive a combination of the second split beam of light and a portion of the first split beam of light returned from a target and direct the combination toward the SPAD array; a set of SPAD output pulse counters; and a SPAD output selection and routing network operable to couple a set of SPAD outputs received from a subset of SPADs in the SPAD array to the set of SPAD output pulse counters. The SPAD output selection and routing network is operable to couple a set of SPAD outputs received from a subset of SPADs in the SPAD array to the set of SPAD output pulse counters.

11. The proximity sensing device of claim 10, wherein the SPAD output selection and routing network is programmed prior to an end-use deployment of the proximity sensing device.

12. The proximity sensing device of claim 10, further comprising a controller configured to periodically acquire data from the SPAD array and program the SPAD output selection and routing network during an end-use deployment of the proximity sensing device.

13. The proximity sensing device of claim 10, wherein the SPADs in the subset of SPADs include SPADs that receive both the second split beam of light and the portion of the first split beam of light returned from the target.

14. The proximity sensing device of claim 10, wherein the target is assumed to be within a near-field range of the proximity sensing device.

15. The proximity sensing device of claim 14, wherein: the target is a near-field target, the portion of the first split beam of light returned from the target is a first portion of the first split beam of light returned from the near-field target, the set of SPAD outputs is a first set of SPAD outputs, and the subset of SPADs is a first subset of SPADs; the optical combiner is positioned to further receive a combination of the second split beam of light and a second portion of the first split beam of light returned from a far-field target assumed to be within a far-field range of the proximity sensing device; the SPAD output selection and routing network is operable to couple the first set of SPAD outputs to a first subset of SPAD output pulse counters in the set of SPAD output pulse counters; and the SPAD output selection and routing network is operable to couple a second set of SPAD outputs received from a second subset of SPADs in the SPAD array to a second subset of SPAD output pulse counters in the set of SPAD output pulse counters.

16. The proximity sensing device of claim 10, further comprising an enable circuit operable to connect a SPAD output in the set of SPAD outputs to the set of SPAD output pulse counters or disconnect the SPAD output from the set of SPAD output pulse counters. ​ ​ ​ The SPAD output is disconnected from the set of SPAD output pulse counters.

17. A proximity sensing device, the proximity sensing device comprising: a frequency modulated continuous wave (FMCW) light source; a single photon avalanche diode (SPAD) array; an optical splitter positioned to receive light emitted by the FMCW light source and output a first beamlet and a second beamlet; an optical combiner positioned to receive a combination of the second beamlet and a portion of the first beamlet returned from a target and direct the combination toward the SPAD array; and a set of one or more optical elements that direct the first beamlet toward the target and direct the second beamlet toward the optical combiner, the set of one or more optical elements in combination with the optical combiner direct a coherent mixing of the second beamlet and the portion of the first beamlet toward a subset of SPADs in the SPAD array.

18. The proximity sensing device of claim 17, wherein the set of one or more optical elements consists of a monolithic optical element.

19. The proximity sensing device of claim 18, wherein the monolithic optical element defines a transmit light pipe and a receive light pipe.

20. The proximity sensing device of claim 18, wherein the monolithic optical element defines the optical splitter and the optical combiner.

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