Patent Publication Number: US-2020302147-A1

Title: Biometric input device

Description:
BACKGROUND 
     Facilities such as stores, libraries, hospitals, offices, apartments, and so forth, may need the ability to identify users at the facility. 
    
    
     
       BRIEF DESCRIPTION OF FIGURES 
       The detailed description is set forth with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The use of the same reference numbers in different figures indicates similar or identical items or features. The figures are not necessarily drawn to scale, and in some figures, the proportions or other aspects may be exaggerated to facilitate comprehension of particular aspects. 
         FIG. 1  illustrates a biometric input device, according to some implementations. 
         FIG. 2  illustrates a side view of the device with the interior components including a sensor assembly and a mainboard assembly, according to some implementations. 
         FIG. 3  illustrates a cutaway view of the sensor assembly of the device, according to some implementations. 
         FIG. 4  illustrates a perspective view of the sensor assembly of the device, according to some implementations. 
         FIG. 5  illustrates an exploded view of the sensor assembly of the device, according to some implementations. 
         FIG. 6  illustrates a plan view of a portion of the sensor assembly of the device, according to some implementations. 
         FIG. 7  illustrates a view of a camera assembly of the device, according to some implementations. 
         FIG. 8  is a block diagram of the device, according to some implementations. 
     
    
    
     While implementations are described herein by way of example, those skilled in the art will recognize that the implementations are not limited to the examples or figures described. It should be understood that the figures and detailed description thereto are not intended to limit implementations to the particular form disclosed but, on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope as defined by the appended claims. The headings used herein are for organizational purposes only and are not meant to be used to limit the scope of the description or the claims. As used throughout this application, the word “may” is used in a permissive sense (i.e., meaning having the potential to), rather than the mandatory sense (i.e., meaning must). Similarly, the words “include,” “including,” and “includes” mean including, but not limited to. 
     DETAILED DESCRIPTION 
     Accurate and fast identification of a user provides information that may be used in a variety of ways including access, payment, and so forth. In one situation, biometric input may be used to control physical access to a facility or portion thereof. For example, entrance to an office, residence, warehouse, transportation facility, or other location, may be responsive to a user presenting biometric input at an entry portal. If the biometric input corresponds to previously stored data, the user may be permitted to enter. 
     In another situation biometric input may be used to facilitate payment for goods or services. For example, a user may provide biometric input at a point-of-sale (POS). The biometric input may be used to determine an identity of the user. The identity of the user may then be associated with a payment method, such as an account, previously stored bank or credit card account, and so forth. 
     In another situation biometric input may be used to sign an electronic record. For example, the biometric input may be used to provide information as to the particular user who agreed to a contract, accepted a delivery, and so forth. 
     Traditional systems for identifying users suffer from several significant drawbacks including susceptibility to fraud, speed, accuracy, and operational limitations. For example, a traditional system to identify a user by presenting a token, such as an identification card, may be compromised by someone other than an authorized user possessing the token. As a result, systems that involve only the use of “something you have” are vulnerable to misuse. Biometric identification systems deal with this by using a characteristic of the particular individual that is difficult or impossible to copy or be transferred. Operation of traditional biometric identification systems introduce operational problems such as slow data acquisition, limited resolution, increased wear in heavy-use environments, and so forth. For example, traditional palm-based biometric identification systems require physical contact between the user&#39;s hand and a scanning device. This physical contact may be deemed unsanitary and may be difficult to accomplish for some users. The data acquired by these systems may also be of relatively low resolution resulting in decreased confidence in the identification. These and other factors result in existing systems being unsuitable for use in situations where rapid identification of users is called for without significantly impeding the flow of user traffic. For example, the delays introduced by existing systems would produce serious negative impacts such as delays in a busy checkout line or at an entry to the facility at rush hours. 
     Described in this disclosure is a biometric input device (device) that acquires images that may be used for non-contact biometric identification of users. The device includes a sensor assembly that may include a proximity sensor, such as an optical time-of-flight sensor. When the proximity sensor detects a presence of an object, polarized infrared light sources in the device may be activated at different times to provide illumination while a camera in the device that is sensitive to infrared light acquires images at the different times. The images are of objects within the camera&#39;s field of view (FOV) and as illuminated by infrared light with different polarizations at different times. For example, a first set of one or more images may be obtained that use infrared light with a first polarization and a second set of one or more images that use infrared light with a second polarization. The camera may include a polarizer with the first polarization. The first set of images depict external characteristics, such as lines and creases in the user&#39;s palm while the second set of images depict internal anatomical structures, such as veins, bones, soft tissue, or other structures beneath the epidermis of the skin. 
     The images, or information based on those images, may then be sent to an external device. For example, the images or information indicative of features in the images may be encrypted and transmitted to a server for processing to determine identity, payment account information, authorization to pass through a portal, and so forth. 
     The device may include output devices. In one implementation the device may include one or more visible light sources. A light emitting diode (LED) that emits visible light may be operated to provide a visual indication to the user that data acquisition was successful or unsuccessful, to provide positioning prompts, and so forth. A light pipe in the shape of a ring may be arranged around the camera, and direct light from the LED to an exterior of the device. For example, as the user moves their hand into the FOV, the visible light LED may be illuminated blue, illuminating the ring and providing a visible indicator to the user that their hand is within the FOV. In another example, after successful image acquisition, the visible light LED may be illuminated green, illuminating the ring to provide a visible indicator to the user that usable images of their hand have been acquired. 
     The device may include other output devices, such as a display, speaker, printer, and so forth. For example, a display screen may be used to provide information to the user such as prompting positioning of the hand, indicating acquisition of images was successful, approval or denial of a transaction, and so forth. 
     The device may include other input devices, such as a card reader, touch sensor, button, microphone, and so forth. The card reader may comprise an EMV card reader that provides wired or wireless communication with an EMV card. For example, the user may insert an EMV card which, along with the images obtained by the sensor assembly, is used to authorize a transaction. The touch sensor may be combined with the display screen to provide a touchscreen. The user may provide input by touching the touchscreen. 
     The device is compact, allowing easy integration with existing or new systems. The device facilitates rapid and non-contact acquisition of biometric input in a variety of situations. The device is easily deployed and different implementations may be used as a portable device, placed on a supporting structure, affixed to a stand, integrated with another device, and so forth. By using the biometric input produced by the device, a computer system is able to determine the physical presence of a particular user at the particular device at a particular time. This information may be used to authorize payment of a transaction, gain entry to a secured area, sign a contract, and so forth. 
     Illustrative System 
       FIG. 1  illustrates a biometric input device  102  (device), according to some implementations. A user may approach the device  102  and place their hand  104  over a sensor window  106  of the device  102 . A sensor assembly underneath the sensor window  106  may include a camera with a field of view (FOV)  108 . During operation, the camera acquires biometric input, such as one or more images of the hand  104  that is within the FOV  108 . The sensor assembly is discussed in more detail below. In this implementation the FOV  108  is oriented generally upwards. In other implementations the FOV  108  may be directed in other directions. For example, the FOV  108  may be directed downward and the user may place their hand  104  beneath the sensor window  106 . 
     The device  102  may include a display device  110  (display). For example, the display  110  may comprise a liquid crystal display that is able to present text, images, and so forth. In some implementations the display  110  may incorporate a touch sensor to operate as a touchscreen. 
     The device  102  may include a card reader  112  that is able to operate in conjunction with a card  114 . The card  114  may comprise a magnetic memory medium such as a magnetic stripe, a microprocessor, or other devices. The card reader  112  may be configured to interact with the card  114  via a wired or physical contact or wirelessly. For example, the card reader  112  may include a magnetic read head, electrical contacts, a near field communication (NFC) communication interface, and so forth. For example, to provide wired connectivity, the card reader  112  may include a plurality of electrical contacts to provide electrical connections to an inserted card  114 . In another example, to provide wireless connectivity the card reader  112  may be compliant with at least a portion of the ISO/IEC 14443 specification as promulgated by the International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC, EMVCo, and so forth). In other implementations the card reader  112  may not be used during operation or may be omitted from the device  102 . 
     A stand  116  may be used to support the device  102 . In some implementations the stand  116  may be affixed to a surface. For example, the stand  116  may be attached to a countertop. 
       FIG. 2  illustrates a side view of the device  102 , according to some implementations. The internal components of the device  102  include a sensor assembly  202  and a mainboard assembly  204 . The sensor assembly  202  may include a camera, illuminators, polarizers, and so forth used to obtain biometric input such as images of the hand  104 . The mainboard assembly  204  may include the card reader  112 , one or more processors, memory, output devices, controllers, input devices, and so forth. 
     The device  102  may include an upper housing  206  and a lower housing  208 . When assembled, the sensor assembly  202  and the mainboard assembly  204  are at least partially enclosed within the upper housing  206  and the lower housing  208 . The upper housing  206  and the lower housing  208  have an interior surface proximate to the components enclosed therein and an exterior surface that is exposed to the ambient environment. The stand  116  is also shown attached to an underside of the lower housing  208 . 
     The device  102 , or portions thereof, may include antitamper features. The antitamper features may be used to disable at least a portion of the device  102  if unauthorized entry to the device  102  is attempted. For example, the card reader  112  may be encapsulated within an enclosure with one or more electrical conductors. Breakage of the one or more electrical conductors may be registered as an attempt at tampering. Other techniques may be used to determine physical tampering such as detectors for ionizing radiation to determine if the device is being x-rayed. A determination of potential or actual tampering may result in mitigating actions including, but not limited to memory erasure, self-destruction, and so forth. 
       FIG. 3  illustrates a cutaway view of the sensor assembly  202  of the device  102 , according to some implementations. A first end of the upper housing  206  includes an opening for the sensor window  106 . In this implementation, the opening and the sensor window  106  are circular in shape. The sensor window  106  may be transmissive to infrared light and opaque to visible light. In some implementations the sensor window  106  may include one or more of an antireflective coating, a coating for scratch resistance, an anti-smudge coating, and so forth. The antireflective coating may be present on the exterior (upper) side, the interior (lower) side, or both. The anti-smudge coating may be presented on the exterior (upper) side. 
     The sensor assembly  202  includes an optical cradle  302 , a camera assembly  304 , a circuit board  306 , and an illumination ring  308 . The optical cradle  302  provides a frame or structure that supports the components of the sensor assembly  202 . The camera assembly  304  is mounted to the optical cradle  302 . The sensor window  106  is arranged between an external environment and the camera assembly  304 . The camera assembly  304  includes an image sensor and a polarizer and is described in more detail with regard to  FIG. 7 . 
     The circuit board  306  is mounted to an upper surface of the optical cradle  302 . The circuit board  306  may include visible light sources, infrared light sources, and so forth. The illumination ring  308  is arranged above the circuit board  306 . An interior portion of the illumination ring  308  is thus proximate to a portion of the circuit board  306  and components thereon, such as a visible light LED. An exterior portion of the illumination ring  308  depicted here is generally circular and is arranged within the opening in the upper housing  206 . 
     The illumination ring  308  comprises a light pipe, light guide, optical waveguide, and so forth, directing light produced by the visible light sources on the circuit board  306  such that the light may be visible to the user. For example, the illumination ring  308  may comprise an optically transmissive material, such as transparent or translucent plastic or glass. The illumination ring  308  may be mounted to the optical cradle  302 , circuit board  306 , upper housing  206 , or other portion of the device  102 . The sensor window  106  is then affixed to the illumination ring  308 . In other implementations the sensor window  106  may have a different shape, such as rectangular, and a light pipe that extends along at least a portion of the perimeter of the sensor window  106  may be used. 
       FIG. 4  illustrates a perspective view of the sensor assembly  202  of the device  102 , according to some implementations. In this view, the sensor window  106  is in place, mounted to the illumination ring  308 . For example, the sensor window  106  may be mounted to the illumination ring  308  using one or more of mechanical fasteners, mechanical retention features, adhesive, and so forth. The illumination ring  308  is mounted to the optical cradle  302  using a plurality of mechanical fasteners. The circuit board  306  is retained between the illumination ring  308  and the optical cradle  302 . 
       FIG. 5  illustrates an exploded view of the sensor assembly  202  of the device  102 , according to some implementations. The sensor window  106  mounted to the illumination ring  308 . The circuit board  306  is mounted such that an upper side is proximate to an underside of the illumination ring  308 . The circuit board  306  may include one or more visible light sources  502 . For example, the visible light sources  502  may comprise light emitting diodes (LEDs), quantum dots, electroluminescent devices, fluorescent devices, lamps, lasers, and so forth. In this illustration, the visible light sources  502  comprise a plurality of LEDs that are placed in a circular configuration along a circular perimeter that corresponds to at least a portion of an interior portion of the illumination ring  308 . 
     The sensor assembly  202  includes one or more polarized infrared light modules (PIRLMs)  504  on the circuit board  306 . The PIRLM  504  produces infrared light with a particular polarization. Each PIRLM  504  may include one or more infrared light sources  506 . For example, the infrared light sources  506  may comprise LEDs, quantum dots, electroluminescent devices, fluorescent devices, lamps, lasers, and so forth. Continuing the example, the infrared light sources  506  may comprise LEDs that radiate light with a wavelength of between 740 nm and 1000 nm. In one implementation the IR light sources  506  may emit infrared light at 850 nm. In this illustration, each PIRLM  504  includes four infrared LEDs. A polarizer  508  is arranged above the infrared light source  506 . A diffuser  510  is arranged above the polarizer  508 . The diffuser  510  may comprise a micro lens array (MLA) that diffuses light while maintaining the polarization of light passing through. In other implementations other arrangements may be used. For example, the diffuser  510  may be arranged above the infrared light sources  506  and the polarizer  508  may be arranged above the diffuser  510 . In some implementations one or more of the upper or lower surfaces of the diffuser  510  may have an antireflective coating. 
     The polarizer  508  may comprise a dichroic material or structure that passes light with a linear polarization. For example, the polarizer  508  may comprise aligned polyvinylene chains, silver nanoparticles embedded in a transparent substrate such as glass, and so forth. In other implementations, other polarization devices may be used, including but not limited to wire-grid polarizers, beam-splitting polarizers, quarter-wave plates, liquid crystals, photoelastic modulators, and so forth. For example, the photoelastic modulator may comprise a device that is controlled by an electrical signal which drives a piezoelectric transducer to vibrate a half wave resonant bar, such as fused silica. By changing the frequency of the signal, the frequency of the vibration produced by the transducer is changed, and the polarization of light through the resonant bar may be selected. 
     In this implementation, four PIRLMs  504  are arranged around the aperture in the circuit board  306 . When assembled, the camera assembly  304  may extend at least partially through the aperture. Each PIRLM  504 , when activated, emits infrared light with a particular polarization. In some implementations a first pair of PIRLMs  504  may emit infrared light with a first polarization while a second pair of PIRLMs  504  emit infrared light with a second polarization. By selectively operating which pair is illuminated at a particular time, the FOV  108  and objects therein are illuminated by infrared light with a particular polarization. 
     The sensor assembly  202  may also include one or more proximity sensors  512 . For example, a plurality of proximity sensors  512  may be arranged between the PIRLMs  504  and the visible light sources  502 . In other implementations the one or more proximity sensors  512  may be arranged with their respective fields-of-view to include at least a portion of the FOV  108 . In other implementations the one or more proximity sensor(s)  512  may be placed in other locations. For example, a proximity sensor may be located on the mainboard assembly  204 . 
     The proximity sensor(s)  512  may be used to determine if an object, such as a hand  104 , is within the FOV  108 . An optical proximity sensor  512  may use time-of-flight (ToF), structured light, optical parallax, interferometry, or other techniques to determine if an object is present and distance data indicative of a distance to at least a portion of the object. For example, an optical parallax proximity sensor  512  may use at least two cameras separated by a known distance to obtain images of the object and determine a position of the object based on the disparity of position of the object in the images. The optical proximity sensor  512  may use infrared light during operation. For example, an infrared optical ToF sensor determines a propagation time (or “round-trip” time) of a pulse of emitted infrared light from an optical emitter or illuminator that is reflected or otherwise returned to an optical detector. By dividing the propagation time in half and multiplying the result by the speed of light in air, the distance to an object may be determined. In another implementation, a structured light pattern may be provided by the optical emitter. A portion of the structured light pattern may then be detected on the object using a sensor such as a camera. Based on an apparent distance between the features of the structured light pattern, the distance to the object may be calculated. Other techniques may also be used to determine distance to the object. In another example, the color of the reflected light may be used to characterize the object, such as skin, clothing, and so forth. 
     Proximity sensors  512  using other phenomena may also be used instead of or in addition to optical proximity sensors  512 . For example, a capacitive sensor may determine proximity of an object based on a change in capacitance at an electrode. In another example, an ultrasonic sensor may use one or more transducers to generate and detect ultrasonic sound. Based on the detection of reflected sounds, information such as presence of an object, distance to the object, and so forth may be determined. 
     The distance data provided by the proximity sensor(s)  512  may be used to control operation of one or more of the infrared light sources  506  or operation of the camera. In one implementation intensity of output of the infrared light source(s)  506  may be determined at least in part based on the distance. Continuing the example, as the object moves closer to the sensor assembly  202 , the intensity of the illumination provided by the infrared light source(s)  506  may decrease, and vice versa. In another implementation the intensity of output of the infrared light source(s)  506  may remain constant while an exposure time for the camera changes. For example, as the object moves closer to the sensor assembly  202 , the exposure time used to obtain images may decrease to prevent the resulting images from being overexposed, and vice versa. In yet another implementation the distance data may be used to control both illumination and exposure time. 
     In some implementations, the intensity of illumination by the infrared light sources  506  may be determined at least in part based on images acquired by the image sensor. For example, if the average intensity of pixels within an acquired image is below a threshold value, the intensity of the infrared light source(s)  506  may be increased. Likewise, if the average intensity of pixels within an acquired image is greater than a threshold value, the intensity of the infrared light source(s)  506  may be decreased. In some implementations the distance data and the image data may be used to control operation of the device or components therein. 
     In another implementation, the image sensor may be used to determine if there is an object present within the FOV  108 . For example, the image sensors may be operated. One or more of the infrared light sources  506  may operate to illuminate the FOV  108 . One or more images may be acquired by the image sensor and compared to determine if a change has taken place, either relative to a background image or between successive images. For example, images may be acquired at a rate of  10  images per second. A change that exceeds a threshold would result in an increase in the image acquisition rate and initiate the processed described to acquire images with different polarizations of infrared light. 
     One or more barriers may also be included in the sensor assembly  202 . These barriers may be opaque to infrared light. The barriers may be placed between adjacent PIRLMs  504 , between a PIRLM  504  and at least a portion of the camera assembly  304 , or at other locations within the device  102 . The barriers prevent the light emitted from the IR light source  506  that remains within the device  102  from entering an aperture of the camera assembly  304 , such as a lens or pinhole. For example, the barriers prevent infrared light emitted by the infrared light source  506  from “spilling over” and interfering with the light reflected from the hand  104 . In one implementation the barriers may comprise a housing for a PIRLM  504 . For example, each PIRLM  504  may comprise a unit with a wall that acts as the barrier. In another implementation the barriers may be affixed to, or extend from, the circuit board  306 . In yet another implementation the barriers comprise a structure of infrared opaque material that extends from the camera assembly  304  to the sensor window  106 . For example, an infrared opaque boot or gasket of flexible material may be arranged between the camera assembly  304  and the interior surface of the sensor window  106 . This boot prevents reflections of infrared light that are inside the device  102  from entering the aperture of the camera assembly  304 . 
     A first flexible printed circuit (FPC)  514  extends from the circuit board  306 . The first FPC  514  may be used to provide electrical connections to the mainboard assembly  204 . A second FPC  516  extends from the camera assembly  304 . For example, the first FPC  514  may provide power and control signals to operate the visible light sources  502 , the PIRLMs  504 , and the proximity sensor  512 . The second FPC  516  may be used to provide electrical connections to the mainboard assembly  204 . For example, the second FPC  516  may be used to provide control signals to operate an image sensor, operate a variable polarizer, transfer data from the image sensor to the mainboard assembly  204 , and so forth. 
       FIG. 6  illustrates a plan view of a portion of the sensor assembly  202  of the device  102 , according to some implementations. In this view the first FPC  514  and the second FPC  516  are visible. An outline of the illumination ring  308  is indicated with a dotted line. 
     An upper portion of the camera assembly  304  is visible in an aperture in the circuit board  306 . The camera assembly  304  has an entry for light, such as a lens (as shown here), pinhole, and so forth. Arranged around the entry for light of the camera assembly  304  are four PIRLMs  504 ( 1 )- 504 ( 4 ). The PIRLMs  504  may be arranged such that pairs on opposite sides of the camera assembly  304  will emit light with the same polarization. For example, PIRLMs  504 ( 1 ) and  504 ( 3 ) may emit infrared light with a first polarization while PIRLMs  504 ( 2 ) and  504 ( 4 ) emit infrared light with a second polarization. 
     Arranged around the PIRLMs  504  are four proximity sensors  512 . The proximity sensors  512  are configured to, either individually or in aggregate, be able to detect the presence of an object such as a hand  104  within the FOV  108 . 
     Arranged around a perimeter of the circuit board  306  that encompasses the camera assembly  304  are the visible light sources  502 , such as visible light LEDs. In the implementation shown here, the visible light sources  502  are in a circular arrangement. When assembled, a lower portion of the illumination ring  308  is proximate to at least one of the visible light sources  502 . When active, at least a portion of the light from the visible light source  502  may be transferred via internal reflection to an exterior portion of the illumination ring  308 . 
     In other implementations other quantities and arrangements of the various components may be used. For example, a different quantity of visible light sources  502 , PIRLMs  504 , proximity sensors  512 , and so forth may be used. While the entry for light of the camera assembly  304  is arranged generally in the center of the sensor assembly  202 , in other implementations the camera assembly  304  may be off center, the arrangement of PIRLMs  504  may be asymmetrical, and so forth. 
       FIG. 7  illustrates a view of the camera assembly  304  of the device  102 , according to some implementations. The camera assembly  304  may include a lens  702 , lens body  704 , polarizer  706 , and an image sensor  708 . In this illustration, light from the FOV  108  enters the camera assembly  304  through an aperture that includes the lens  702 . In other implementations a pinhole may be used to allow for entry of light from the FOV  108 . Other lenses or components (not shown) may be present in the optical path that extends from the FOV  108  to the image sensor  708 . For example, an optical bandpass filter may be included the optical path. The optical bandpass filter may be configured to pass the wavelength of light generated by the infrared light sources  506 . For example, the optical bandpass filter may be transmissive to wavelengths of between  790  nm to  900  nm. In another example, a shutter may be present in the optical path. During operation, the light reaching the image sensor  708  is limited to light with a particular polarization, as restricted by the polarizer  706  in the optical path. 
     The second FPC  516  connects the image sensor  708  or any associated electronics to the mainboard assembly  204 . The second FPC  516  may include one or more traces for transferring power, data, control, and other signals between the electronics in the camera assembly  304  and the mainboard assembly  204 . The second FPC  516  may also include one or more antitamper features. For example, the second FPC  516  may include one or more additional layers of an antitamper trace or security mesh. An attempt to physically compromise the second FPC  516  may be detected by breakage of the trace or security mesh. 
     The polarizer  706  may be fixed or variable. A static polarizer is fixed at time of assembly. The polarizer  706  may comprise a wire-grid polarizer or other structure that passes light with a linear polarization. Materials such as a dichroic material may be used. For example, the polarizer  706  may comprise aligned polyvinylene chains, silver nanoparticles embedded in a transparent substrate such as glass, and so forth. In other implementations, other polarization devices may be used, including but not limited to beam-splitting polarizers, quarter-wave plates, liquid crystals, photoelastic modulators, and so forth. 
     A variable polarizer  706  allows for control over the polarization selected based on an input. This allows the variable polarizer  706  to change between the first polarization and the second polarization on command from a controller or other electronics. For example, a variable polarizer  706  may comprise a photoelastic modulator that is controlled by an electrical signal which drives a piezoelectric transducer to vibrate a half wave resonant bar, such as fused silica. By changing the frequency of the signal, the frequency of the vibration produced by the transducer is changed, and the polarization of light through the resonant bar may be selected. In another implementation the variable polarizer  706  may comprise a mechanically switchable polarizer that includes two or more different static polarizers that may be selectively inserted into the optical path. For example, one or more actuators such as linear motors, rotary motors, piezoelectric motors, and so forth may be used to move a first static polarizer to be in the optical path, or switch to a second static polarizer in the optical path. The first static polarizer may have the first polarization while the second static polarizer has the second polarization. In yet another implementation, the mechanically switchable polarizer may rotate a static polarizer from a first orientation to a second orientation. 
     The image sensor  708  is configured to detect infrared light that includes the wavelength(s) emitted by the infrared light sources  506 . The image sensor  708  may comprise charge coupled devices (CCD), complementary metal oxide semiconductor (CMOS) devices, microbolometers, and so forth. 
     The mainboard assembly  204  may include electronics that operate the visible light source(s)  502 , operate the infrared light source(s)  506 , operate the proximity sensor(s)  512 , operate the image sensor  708 , and so forth. For example, the proximity sensors  512  may operate to detect the presence of an object, such as a hand  104  in the FOV  108 . When the proximity sensor(s)  512  detects a presence of an object, the infrared light sources  506  may be activated at different times to provide illumination with infrared light having a particular polarization, while the image sensor  708  acquires images at the different times. 
     Distance data obtained by the proximity sensor(s)  512  may be used in the operation of these components. For example, the distance data may be used as an input to control one or more of the intensity of illumination provided by the infrared light source(s)  506  or exposure time of the image sensor  708 . 
     In one implementation intensity of output of the infrared light source(s)  506  may be determined based on the distance data. For example, the intensity of illumination may be proportionate to the distance indicated by the distance data. If the distance to the object is large, the intensity of the illumination is high. Likewise, if the distance to the object is small, the intensity of the illumination is low. In another implementation the exposure time of the image sensor  708  may be proportionate to the distance indicated by the distance data. For example, as the distance to the object decreases, the exposure time used to obtain images may decrease to prevent overexposure of the images. Likewise, if the distance to the object increases the exposure time may increase to prevent underexposure of the images. In another implementation the distance data may be used to control both illumination and exposure time. 
     The images are of the object within the FOV  108  as illuminated by infrared light with different polarizations at different times. For example, a first set of one or more images may be obtained that use infrared light with a first polarization and a second set of one or more images that use infrared light with a second polarization. When an object such as the hand  104  is illuminated with infrared light having the same polarization as that of the polarizer  706  in the optical path of the image sensor  708 , surface features predominate in the resulting image. This is because most of the reflected infrared light has the same polarization due to reflection. In comparison, when the illumination uses a different polarization from the polarizer  706 , the scattering from those internal features changes the polarization of the reflected light. As a result, internal anatomical structures, such as veins, bones, soft tissue, or other structures beneath the epidermis of the skin predominate in the resulting image. 
     The resulting images may be processed and used for biometric identification. The combination of different sets of one or more images that depict predominately surface and predominately deeper anatomical features provide more detail. This increased detail may be used to improve the accuracy of identification, reduce the effect of surface changes impairing identification, and so forth. 
       FIG. 8  is a block diagram of the device  102 , according to some implementations. 
     One or more power supplies  802  are configured to provide electrical power suitable for operating the components in the device  102 . In some implementations, the power supply  802  may comprise an external power supply that is supplied by line voltage, rechargeable battery, photovoltaic cell, power conditioning circuitry, wireless power receiver, and so forth. 
     The device  102  may include one or more hardware processors  804  (processors) configured to execute one or more stored instructions. The processors  804  may comprise one or more cores. One or more clocks  806  may provide information indicative of date, time, ticks, and so forth. For example, the processor  804  may use data from the clock  806  to generate a timestamp, trigger a preprogrammed action, and so forth. 
     The device  102  may include one or more communication interfaces  808  such as input/output (I/O) interfaces  810 , network interfaces  812 , and so forth. The communication interfaces  808  enable the device  102 , or components thereof, to communicate with other devices or components. The communication interfaces  808  may include one or more I/O interfaces  810 . The I/O interfaces  810  may comprise interfaces such as Bluetooth, ZigBee, Inter-Integrated Circuit (I2C), Serial Peripheral Interface bus (SPI), Universal Serial Bus (USB) as promulgated by the USB Implementers Forum, RS-232, and so forth. 
     The network interfaces  812  are configured to provide communications between the device  102  and other devices, such as access points, point-of-sale devices, payment terminals, servers, and so forth. The network interfaces  812  may include devices configured to couple to wired or wireless personal area networks (PANS), local area networks (LANs), wide area networks (WANs), and so forth. For example, the network interfaces  812  may include devices compatible with Ethernet, Wi-Fi, 4G, 5G, LTE, and so forth. 
     The device  102  may also include one or more busses or other internal communications hardware or software that allow for the transfer of data between the various modules and components of the device  102 . 
     The I/O interface(s)  810  may couple to one or more I/O devices  814 . The I/O devices  814  may include input devices  816  and output devices  818 . 
     The input devices  816  may include the proximity sensor(s)  512 , the image sensor  708  in the camera assembly  304  and one or more of the card reader  112 , a switch  816 ( 1 ), a touch sensor  816 ( 2 ), a microphone  816 ( 3 ), and so forth. 
     Additional proximity sensors  512  may be employed by the device  102 . A proximity sensor  512  may be positioned on the device  102  to detect the presence of an object outside of the FOV  108  as well. For example, a proximity sensor  512  may be arranged to detect a user as they approach the device  102 . Responsive to this detection, the device  102  may present information on the display  110 , illuminate the visible light sources  502 , operate the image sensor  708  and infrared light sources  506 , and so forth. 
     The switch  816 ( 1 ) is configured to accept input from the user. The switch  816 ( 1 ) may comprise mechanical, capacitive, optical, or other mechanisms. For example, the switch  816 ( 1 ) may comprise mechanical switches configured to accept an applied force from a user&#39;s finger press to generate an input signal. 
     The touch sensor  816 ( 2 ) may use resistive, capacitive, surface capacitance, projected capacitance, mutual capacitance, optical, Interpolating Force-Sensitive Resistance (IFSR), or other mechanisms to determine the position of a touch or near-touch of the user. For example, the IFSR may comprise a material configured to change electrical resistance responsive to an applied force. The location within the material of that change in electrical resistance may indicate the position of the touch. 
     The microphone  816 ( 3 ) may be configured to acquire information about sound present in the environment. In some implementations, a plurality of microphones  816 ( 3 ) may be used to form a microphone array. The microphone array may implement beamforming techniques to provide for directionality of gain. For example, the gain may be directed towards the expected location of the user during operation of the device  102 . 
     Output devices  818  may include one or more of the visible light source(s)  502 , the infrared light source  506 , the display  110 , a speaker  818 ( 1 ), printer, haptic output device, or other devices. For example, the display  110  may be used to provide information via a graphical user interface to the user. In another example, a printer may be used to print a receipt. 
     In some embodiments, the I/O devices  814  may be physically incorporated with the device  102  or may be externally placed. 
     The device  102  may include one or more memories  820 . The memory  820  comprises one or more computer-readable storage media (CRSM). The CRSM may be any one or more of an electronic storage medium, a magnetic storage medium, an optical storage medium, a quantum storage medium, a mechanical computer storage medium, and so forth. The memory  820  provides storage of computer-readable instructions, data structures, program modules, and other data for the operation of the device  102 . A few example functional modules are shown stored in the memory  820 , although the same functionality may alternatively be implemented in hardware, firmware, or as a system on a chip (SOC). 
     The memory  820  may include at least one operating system (OS) module  822 . The OS module  822  is configured to manage hardware resource devices such as the I/O interfaces  810 , the network interfaces  812 , the I/O devices  814 , and provide various services to applications or modules executing on the processors  804 . The OS module  822  may implement a variant of the FreeBSD operating system as promulgated by the FreeBSD Project; other UNIX or UNIX-like operating system; a variation of the Linux operating system as promulgated by Linus Torvalds; the Windows operating system from Microsoft Corporation of Redmond, Washington, USA; the Android operating system from Google Corporation of Mountain View, Calif., USA; the iOS operating system from Apple Corporation of Cupertino, Calif., USA; or other operating systems. 
     A data store  824  that includes one or more of the following modules may be stored in the memory  820 . These modules may be executed as foreground applications, background tasks, daemons, and so forth. The modules may include one or more of a communication module  826 , data acquisition module  828 , or other modules  830 . The data store  824  may use a flat file, database, linked list, tree, executable code, script, or other data structure to store information. In some implementations, the data store  824  or a portion of the data store  824  may be distributed across one or more other devices. 
     A communication module  826  may be configured to establish communications with one or more other devices. The communications may be authenticated, encrypted, and so forth. The communication module  826  may also control the communication interfaces  808 . 
     The data acquisition module  828  is configured to acquire data from the input devices  816 . One or more acquisition parameters  832  may be stored in the memory  820 . The acquisition parameters  832  may specify operation of the data acquisition module  828 , such as data sample rate, sample frequency, scheduling, and so forth. The data acquisition module  828  may be configured to operate the image sensor  708 , infrared light source(s)  506 , and so forth. For example, the data acquisition module  828  may acquire data from the proximity sensor  512 , image sensor  708 , or both to determine that an object is in the FOV  108 . Based on this determination, at a first time a first set of IR light sources  506  associated with one or more PIRLMs  504  are activated to provide infrared illumination with a first polarization while the image sensor  708  is used to acquire images. At a second time a second set of IR light sources  506  associated with one or more PIRLMs  504  are activated to provide infrared illumination with a second polarization while the image sensor  708  is used to acquire images. Alternatively, at the second time the one or more PIRLMs  504  may be activated to provide infrared illumination with the first polarization while the polarizer  706  in the optical path of the image sensor  708  is set to the second polarization. The images may be stored as image data  834  in the data store  824 . 
     In some implementations, instead of or in addition to data from the proximity sensors  512 , data from the image sensor  708  may be used to determine the presence of an object in the FOV  108 . For example, the image sensor  708  and one or more of the PIRLMs  504  may be operated at a first sample rate, such as acquiring and illuminating  10  times per second. An acquired image may be processed to determine if changes in the image exceeds a threshold value. For example, a first image may be compared with a second image to determine if there is a change. The change may be deemed to be indicative of an object within the FOV  108 . Responsive to the change, the system may operate as described above, acquiring images with different polarizations of infrared light. In other implementations other techniques may be used to initiate acquisition of images with different polarizations of infrared light. For example, if a neural network determines a hand is present in the image, the system may increase the sample rate and operate as described above to acquire images with different polarizations of infrared light. 
     In some implementations, the IR bandpass filter may be removed from the optical path while acquiring images to determine the presence of an object. For example, a mechanical actuator may be used to move the IR bandpass filter into and out of the optical path. By removing the IR bandpass filter, the ambient light may be sufficient to allow acquisition of an image for object detection in the FOV  108  without the use of the PIRLM  504 . 
     The image data  832  may be sent to another device, processed by the processor  804 , and so forth. For example, in one implementation the image data  834  may be processed to determine one or more features present in the image data  834 . Data indicative of the features may be encrypted and sent to an external device, such as a server. 
     The data acquisition module  828  may obtain data from other input devices  816 . For example, card data  836  may be obtained from the card reader  112 . The card data  836  may comprise encrypted data provided by a processor of the card reader  112 . 
     Device identification data  838  may be stored in the data store  824 . The device identification data  838  may provide information that is indicative of the specific device  102 . For example, the device identification data  838  may comprise a cryptographically signed digital signature. 
     The data acquisition module  828  may store input data  840  obtained from other sensors. For example, input from a switch  816 ( 1 ) or touch sensor  816 ( 2 ) may be used to generate input data  840 . 
     The other modules  830  may include a feature determination module that generates feature vectors that are representative of features present in the image data  834 . The feature determination module may utilize one or more neural networks that accept image data  834  as input and provide one or more feature vectors as output. 
     The data store  824  may store output data  842 . For example, the output data  842  may comprise the feature vectors generated by processing the image data  834 . 
     The other modules  830  may include a user interface module that provides a user interface using one or more of the I/O devices  814 . The user interface module may be used to obtain input from the user, present information to the user, and so forth. For example, the user interface module may accept input from the user via the touch sensor  816 ( 2 ) and use the visible light source(s)  502  to provide output to the user. 
     Other data  844  may also be stored in the data store  824 . 
     The devices and techniques described in this disclosure may be used in a variety of settings. For example, the system may be used in conjunction with a point-of-sale (POS) device. The user may present their hand  104  to a device  102  that is used to obtain biometric data indicative of intent and authorization to pay with an account associated with their identity. In another example, a robot may incorporate a device  102 . The robot may use the device  102  to obtain biometric data that is then used to determine whether to deliver a parcel to the user  102 , and based on the identification, which parcel to deliver. 
     The processes discussed herein may be implemented in hardware, software, or a combination thereof. In the context of software, the described operations represent computer-executable instructions stored on one or more non-transitory computer-readable storage media that, when executed by one or more processors, perform the recited operations. Generally, computer-executable instructions include routines, programs, objects, components, data structures, and the like that perform particular functions or implement particular abstract data types. Those having ordinary skill in the art will readily recognize that certain steps or operations illustrated in the figures above may be eliminated, combined, or performed in an alternate order. Any steps or operations may be performed serially or in parallel. Furthermore, the order in which the operations are described is not intended to be construed as a limitation. 
     Embodiments may be provided as a software program or computer program product including a non-transitory computer-readable storage medium having stored thereon instructions (in compressed or uncompressed form) that may be used to program a computer (or other electronic device) to perform processes or methods described herein. The computer-readable storage medium may be one or more of an electronic storage medium, a magnetic storage medium, an optical storage medium, a quantum storage medium, and so forth. For example, the computer-readable storage media may include, but is not limited to, hard drives, floppy diskettes, optical disks, read-only memories (ROMs), random access memories (RAMS), erasable programmable ROMs (EPROMs), electrically erasable programmable ROMs (EEPROMs), flash memory, magnetic or optical cards, solid-state memory devices, or other types of physical media suitable for storing electronic instructions. Further, embodiments may also be provided as a computer program product including a transitory machine-readable signal (in compressed or uncompressed form). Examples of transitory machine-readable signals, whether modulated using a carrier or unmodulated, include, but are not limited to, signals that a computer system or machine hosting or running a computer program can be configured to access, including signals transferred by one or more networks. For example, the transitory machine-readable signal may comprise transmission of software by the Internet. 
     Separate instances of these programs can be executed on or distributed across any number of separate computer systems. Thus, although certain steps have been described as being performed by certain devices, software programs, processes, or entities, this need not be the case, and a variety of alternative implementations will be understood by those having ordinary skill in the art. 
     Additionally, those having ordinary skill in the art will readily recognize that the techniques described above can be utilized in a variety of devices, environments, and situations. Although the subject matter has been described in language specific to structural features or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described. Rather, the specific features and acts are disclosed as illustrative forms of implementing the claims.