Polarization-based crosstalk suppression in optical ranging sensors

Abstract

The invention relates to polarization-based crosstalk suppression in optical ranging sensors. An example optical ranging sensor, a method for determining proximity of a target at an optical ranging sensor, and a mobile electronic device including an optical ranging sensor are provided. An example optical ranging sensor includes an optical transmitter, an optical receiver, and a controller. The optical transmitter is configured to generate a first signal having a first polarization state and a second signal having a second polarization state. The optical receiver is configured to generate a first feedback signal resulting from one or more reflections of the first signal and a second feedback signal resulting from one or more reflections of the second signal. The controller is configured to generate a target feedback signal based on a comparison of the first feedback signal and the second feedback signal, and determine a proximity of the target based on the target feedback signal.

Description

Technical Field

[0001] The embodiments of this disclosure generally relate to optical ranging sensors, and more specifically to mitigating inconsistencies caused by crosstalk at optical ranging sensors. Background Technology

[0002] An optical rangefinder sensor may include an optical transmitter and an optical receiver. During operation, the optical rangefinder sensor emits light toward a target object through one or more optical transmission elements (such as a cover glass). The emitted light is reflected by the target object and received by the optical receiver on the optical rangefinder sensor. The received light is used to extract useful information, such as the distance to the target object, the motion of the target object, the speed of the target object, and the surface characteristics of the target object. Light received at the optical receiver from unwanted sources (such as crosstalk light reflected from the cover glass) may adversely affect the accuracy of the optical rangefinder sensor.

[0003] The applicant has identified numerous technical challenges and difficulties associated with mitigating crosstalk at optical ranging sensors. Through applied effort, ingenuity, and innovation, the applicant has addressed the problems related to crosstalk at optical ranging sensors by developing solutions embodied in this disclosure, which will be described in detail below. Summary of the Invention

[0004] Various embodiments relate to an example optical rangefinder, a method for determining the proximity of a target at the optical rangefinder, and a mobile electronic device including the optical rangefinder.

[0005] An example optical ranging sensor is provided. The example optical ranging sensor includes an optical transmitter, an optical receiver, and a controller. The optical transmitter is configured to generate a first signal having a first polarization state and a second signal having a second polarization state. The optical receiver is configured to generate a first feedback signal generated by one or more reflections of the first signal and a second feedback signal generated by one or more reflections of the second signal. The controller is configured to generate a target feedback signal based on a comparison of the first and second feedback signals; and to determine the proximity of a target based on the target feedback signal.

[0006] In some embodiments, the target feedback signal corresponds to a portion of the first signal reflected from the target.

[0007] In some embodiments, in order to generate a target feedback signal, the controller is further configured to: generate a first histogram corresponding to a first feedback signal; generate a second histogram corresponding to a second feedback signal; and generate a target feedback signal based on a comparison of the first and second histograms.

[0008] In some embodiments, in order to generate a target feedback signal, the controller is further configured to: determine a crosstalk difference signal by performing the difference between a first feedback signal and a second feedback signal; and apply a crosstalk function to determine a total crosstalk signal, wherein the crosstalk function correlates the crosstalk difference with the total crosstalk signal.

[0009] In some embodiments, the crosstalk function is determined during the calibration period.

[0010] In some embodiments, the proximity of a target is based on the flight time associated with the target's feedback signal.

[0011] In some embodiments, the first polarization state and the second polarization state are orthogonal.

[0012] In some embodiments, the optical transmitter is configured to alternate between generating a first signal having a first polarization state and generating a second signal having a second polarization state.

[0013] In some embodiments, after each integration period, the optical transmitter alternates between generating a first signal with a first polarization state and generating a second signal with a second polarization state.

[0014] In some embodiments, the optical emitter is a vertical cavity surface-emitting laser.

[0015] In some embodiments, the vertical cavity surface-emitting laser is configured to generate a first signal having a first polarization state and a second signal having a second polarization state based on a polarization control signal emitted by a controller.

[0016] An example method for determining the proximity of a target at an optical rangefinder is also provided. The example method includes: causing an optical transmitter to emit a first signal having a first polarization state; receiving from an optical receiver a first feedback signal generated by one or more reflections of the first signal; causing the optical transmitter to emit a second signal having a second polarization state; receiving from the optical receiver a second feedback signal generated by one or more reflections of the second signal; generating a target feedback signal based on a comparison of the first and second feedback signals; and determining the proximity of the target based on the target feedback signal.

[0017] In some embodiments, the target feedback signal corresponds to a portion of the first signal reflected from the target.

[0018] In some embodiments, generating the target feedback signal further includes: generating a first histogram corresponding to the first feedback signal; generating a second histogram corresponding to the second feedback signal; and generating the target feedback signal based on a comparison of the first histogram and the second histogram.

[0019] In some embodiments, generating the target feedback signal further includes: determining a crosstalk difference signal by performing the difference between the first feedback signal and the second feedback signal; and applying a crosstalk function to determine a total crosstalk signal, wherein the crosstalk function correlates the crosstalk difference with the total crosstalk signal.

[0020] In some embodiments, determining the proximity of a target further includes determining the flight time associated with a target feedback signal.

[0021] In some embodiments, the first polarization state and the second polarization state are orthogonal.

[0022] In some embodiments, the method further includes causing the optical transmitter to alternate between generating a first signal having a first polarization state and generating a second signal having a second polarization state.

[0023] In some embodiments, after each integration period, the optical transmitter alternates between generating a first signal with a first polarization state and generating a second signal with a second polarization state.

[0024] An example mobile electronic device is also provided. The example mobile electronic device includes a housing, a display screen, and an optical range sensor. The display screen, attached to the housing, includes a first side configured to emit transmitted light into the external environment via a plurality of display pixels. The optical range sensor, disposed within the housing and opposite the first side of the display screen, includes an optical transmitter, an optical receiver, and a controller. The optical transmitter is configured to generate a first signal having a first polarization state and a second signal having a second polarization state. The optical receiver is configured to receive: a first feedback signal generated by one or more reflections of the first signal; and a second feedback signal generated by one or more reflections of the second signal. The controller is configured to: generate a target feedback signal based on a comparison of the first and second feedback signals; and determine the proximity of a target based on the target feedback signal. Attached Figure Description

[0025] Referring now to the accompanying drawings. In some embodiments described herein, the components shown in the drawings may or may not be present. According to exemplary embodiments of this disclosure, some embodiments may include fewer (or more) components than those shown in the figures.

[0026] Figure 1 An example block diagram of an optical ranging sensor according to an example embodiment of the present disclosure is shown.

[0027] Figure 2 The behavior of different polarization states incident on a transmissive object according to an example embodiment of the present disclosure is illustrated.

[0028] Figure 3An example optical ranging sensor configured to transmit an optical signal having a first polarization state and a second polarization state at a target object is shown according to an example embodiment of the present disclosure.

[0029] Figure 4 An example method for removing crosstalk signals from a feedback signal received from an optical ranging sensor, according to an example embodiment of the present disclosure, is shown.

[0030] Figure 5 An example histogram of the data received at a reference array of an optical receiver and an optical ranging sensor, according to an example embodiment of the present disclosure, is shown.

[0031] Figure 6 An example flowchart illustrating a method for removing crosstalk signals from a feedback signal according to an exemplary embodiment of the present disclosure is shown.

[0032] Figure 7 An example mobile electronic device including an optical ranging sensor is shown according to an example embodiment of the present disclosure.

[0033] Figure 8 A block diagram of an example component of a controller according to an example embodiment of the present disclosure is shown. Detailed Implementation

[0034] Exemplary embodiments will now be described more fully with reference to the accompanying drawings, which illustrate some, but not all, embodiments of the invention disclosed herein. In fact, embodiments of the present disclosure may be embodied in many different forms and should not be construed as limited to the embodiments described herein. Rather, these embodiments are provided so that the content of this disclosure will meet applicable legal requirements. The same numerals consistently refer to the same elements.

[0035] Various example embodiments address technical problems associated with mitigating crosstalk at optical range sensors when determining proximity parameters of a target object. As those skilled in the art to which this disclosure pertains will understand, there are numerous example scenarios in which users can benefit from mitigating crosstalk at optical range sensors.

[0036] Optical ranging sensors, such as time-of-flight sensors, are widely used across various industries due to their ability to measure distances with high precision, track objects, detect presence, and / or map the environment. For example, optical ranging sensors are used in consumer electronics for facial recognition, augmented reality, and enhanced camera focus. In robotics and autonomous vehicles, they enable obstacle avoidance, improved navigation, and enhanced safety by creating real-time 3D maps of the surrounding environment. In industrial automation, they are used for precise object detection and monitoring.

[0037] During operation, the optical rangefinder emits light from an optical transmitter toward a target object in the external environment. The emitted light is reflected by the target object and received by an optical receiver on the optical rangefinder. Based on the time required for the emitted light to travel to the target object, be reflected from the target object, and travel back to the optical rangefinder, certain physical aspects of the target object can be determined, such as the target object's distance, motion, velocity, and surface characteristics.

[0038] Many optical rangefinders are positioned behind a cover glass. A cover glass is a transmissive object on or near the optical rangefinder. The cover glass can provide protection for internal components of the optical rangefinder and / or other components of the electronic device. In some embodiments, the cover glass can also be configured to perform optical operations on emitted or received light, such as focusing or dispersion.

[0039] In addition to receiving reflected light originating from a light source and bouncing off the target, the optical receiver on an optical rangefinder may also receive light from unwanted sources, such as light reflected from the coverslip and / or light internally reflected within the coverslip and exiting at the optical receiver. This unwanted light is called crosstalk. Crosstalk received at the optical receiver can make it difficult to detect and analyze signals reflected from the target object, especially when the target object is very close to the coverslip. Crosstalk can further lead to errors or inconsistencies in distance and proximity determination because the crosstalk level may vary over time.

[0040] Previous examples attempted to overcome inaccuracies caused by crosstalk by determining the crosstalk during the calibration period and adjusting the time-of-flight results of the crosstalk during operation. However, crosstalk levels vary over time due to obstructions on the coverslip (such as foreign objects, dust, dirt, scratches, etc.), component aging, and other variables. Various crosstalk monitors placed outside the field of view of electronic devices have been used to compensate for crosstalk signals. However, these monitors are placed outside the field of view, increasing component size, and may be subject to additional interference from target-returned signals when the target object is close to the sensor.

[0041] The various example embodiments described herein utilize various techniques to dynamically mitigate crosstalk at optical rangefinders. For example, an optical transmitter configured to alternately emit a first signal having a first polarization state and a second signal having a second polarization state is employed. When light encounters a medium with a new refractive index, the amount of reflection and refraction can depend on the polarization of the incident light. Therefore, the crosstalk received at the optical receiver of the rangefinder varies based on the polarization of the emitted light. By emitting signals with different polarization states, the optical rangefinder can be configured to determine the amount of light returned to the optical transmitter that is attributable to crosstalk.

[0042] For example, during the operation of an optical rangefinder, multiple optical pulses are emitted toward the target. The light received at the optical receiver includes a portion of the reflected light from the target and a portion of the crosstalk light reflected by the cover glass and / or other components of the optical rangefinder.

[0043] Crosstalk in the received light can be identified and removed by emitting light with different polarities. For example, a light source with dynamic polarization control can be used to alternately emit light with a first polarization followed by light with a second polarization. It is assumed that a portion of the reflected light from the target object is the same regardless of the light polarization. However, a portion of the crosstalk light differs based on the light polarization.

[0044] During the calibration period, the crosstalk function can be determined. The crosstalk function correlates the difference in crosstalk generated by the two transmitted signals received by the optical receiver with the total crosstalk signal in the combination of these two signals.

[0045] For example, a first signal having a first polarization state can be emitted, and a resulting first feedback signal having a first target feedback portion (corresponding to light reflected from the target) and a first crosstalk portion (corresponding to light received through crosstalk) can be generated based on the received reflected first signal. The first crosstalk portion may depend on the first polarization of the first state. Next, a second signal having a second polarization state can be emitted, and a second feedback signal having a second target feedback portion (corresponding to light reflected from the target) and a second crosstalk portion (corresponding to light received through crosstalk) can be generated based on the received reflected second signal. Although the first target feedback portion and the second target feedback portion are assumed to be equal, the first crosstalk portion and the second crosstalk portion depend on the polarization of the emitted light. Therefore, based on the comparison of the first feedback signal and the second feedback signal, a portion of the feedback signal attributable to the target (e.g., the target feedback signal) can be isolated. Using the target feedback signal alone, the accurate determination of the target proximity parameter can be made.

[0046] In some embodiments, the target feedback signal can be determined by adding the first feedback signal and the second feedback signal to generate a combined feedback signal. The combined feedback signal includes a total crosstalk signal and a target feedback signal (e.g., the target feedback portion is added twice). By performing a subtraction between the first and second feedback signals, the target portion of the feedback signal (where the two signals are equal) is removed, leaving only the crosstalk difference signal. A crosstalk function can be used to determine the total crosstalk signal based on the crosstalk difference signal. After being determined, the total crosstalk signal can be removed from the combined feedback signal, leaving only the target feedback signal.

[0047] As a result of the exemplary embodiments described herein, crosstalk components in the feedback signal can be reduced, thereby improving the overall accuracy of the optical rangefinder. Furthermore, the method described herein for compensating for crosstalk in the optical rangefinder dynamically adjusts the crosstalk. Therefore, the optical rangefinder is resilient to changes in crosstalk values ​​throughout the lifespan of the electronic device. This means that changes in the amount of crosstalk due to obstructions and / or aging on the cover glass can be dynamically mitigated, thereby improving the accuracy of the optical rangefinder over a longer lifespan.

[0048] Now for reference Figure 1 An example optical ranging sensor 100 is provided. For example... Figure 1 As shown, the example optical ranging sensor 100 includes an optical receiver 104 and an optical transmitter 106. (As illustrated...) Figure 1 As further shown, the optical transmitter 106 is electrically connected to the controller 108 and is configured to receive the polarization control signal 112. The optical receiver 104 is also electrically connected to the controller 108 and is configured to transmit a first feedback signal 110 and a second feedback signal 111 to the controller 108.

[0049] like Figure 1 As shown, an example optical rangefinder 100 is provided. The optical rangefinder 100 is any sensing device configured to generate an optical signal and determine the physical characteristics of a target object based on the time elapsed between the emission of the optical signal and the reception of the reflected signal. In some embodiments, the optical rangefinder 100 may include a time-of-flight sensor.

[0050] Typically, time-of-flight sensors work by measuring the time required for an optical signal, usually emitted as a laser or infrared pulse, to reach a target object and reflect back to the sensor. Time-of-flight sensors calculate the distance to the object based on the speed of light and the time delay between the emission and detection of the optical signal. The time-of-flight of the optical signal can be used to measure the distance to a target object with high precision, track the motion of a target object, determine the velocity of a target object, detect the presence of a target object, determine the material properties of a target object, and / or map target objects in the environment.

[0051] like Figure 1As further illustrated, the example optical ranging sensor 100 includes an optical emitter 106. The optical emitter 106 is any device, light bulb, semiconductor, diode, laser, or other photonic emitting structure configured to generate an optical signal. The optical emitter 106 may include any light source, such as a laser diode, light-emitting diode, light bulb, semiconductor device, or other photonic emitting structure. In some embodiments, the optical emitter 106 may include a semiconductor laser diode, such as a vertical-cavity surface-emitting laser (VCSEL) and / or an edge-emitting laser diode. Typically, the optical emitter 106 can output a coherent beam when a current is received.

[0052] The optical transmitter 106 is also configured to generate optical signals with different polarization states. Typically, the optical signal comprises multiple polarization states. The optical signal can be polarized by passing it through a polarization filter that aligns the electromagnetic wave to a single plane. In cases where the electromagnetic wave including the optical signal oscillates in multiple planes, but primarily in a single plane, weak polarization (>70% of the oscillations occur in the polarization plane) may occur. In cases where the electromagnetic wave including the optical signal oscillates strongly in a single plane, strong polarization (e.g., >90% of the oscillations occur in the polarization plane) may occur.

[0053] Figure 1 The optical transmitter 106 is configured to generate an optical signal with at least two polarization states. For example, a first signal oscillating primarily in a first polarization plane and a second signal oscillating primarily in a second polarization plane, wherein the first and second polarization planes are different. In some embodiments, the first and second polarization planes may be orthogonal (e.g., perpendicular).

[0054] In some embodiments, the optical transmitter 106 may include a plurality of light sources, each configured to generate an optical signal with a different polarization state. In some embodiments, the optical transmitter 106 may include a single light source having a plurality of filters that can be used interchangeably to generate an optical signal with a different polarization state.

[0055] In some embodiments, the optical transmitter 106 can alternate the polarization states of the generated optical signal. For example, the optical transmitter 106 can generate a first optical signal with a first polarization state during a first integration state, and then switch to a second polarization state to generate a second optical signal during a second integration state. Therefore, the resulting feedback signals are very close in time.

[0056] In some embodiments, the optical emitter 106 may include a VCSEL with controllable polarization. The VCSEL with controllable polarization may include a plurality of light output apertures, each with a different grating configured to generate an optical signal polarized in alignment with the grating direction. For example, the VCSEL may include a portion of a light output aperture with a vertical grating and a portion of a light output aperture with a horizontal grating. The VCSEL with controllable polarization may also be configured to selectively enable the light output aperture including the vertical grating and the light output aperture including the horizontal grating based on a polarization control signal (e.g., polarization control signal 112). Thus, when the light output aperture including the vertical grating is enabled, an optical signal with a first polarization state can be generated, while when the light output aperture including the horizontal grating is enabled, an optical signal with a second polarization state can be generated.

[0057] like Figure 1 Further shown, optical transmitter 106 is configured to receive polarization control signal 112. Polarization control signal 112 is any signal generated by controller 108 for controlling the polarization of an optical signal from optical transmitter 106. In some embodiments, polarization control signal 112 may include multiple control lines; for example, polarization control information 112 may include a first control line and a second control line, the first control line being configured to activate a first optical transmitter 106 or a portion of optical transmitter 106 when asserted, and the second control line being configured to activate a second optical transmitter 106 or a second portion of optical transmitter 106 when asserted. The first optical transmitter 106 or a portion of optical transmitter 106 is configured to generate an output signal exhibiting a first polarization state, while the second optical transmitter 106 or a portion of optical transmitter 106 is configured to generate an output signal exhibiting a second polarization state. In some embodiments, polarization control signal 112 may include a digital code indicating the polarization state of the output signal.

[0058] like Figure 1As further illustrated, the example optical ranging sensor 100 includes an optical receiver 104. The optical receiver 104 is a collection including one or more photodiodes, integrated circuits, devices, sensors, photosensitive diodes, or other structures that generate an electrical signal due to light received at the optical receiver 104. For example, the electrical signal output by the optical receiver 104 may increase with the number of photons striking the optical receiver 104 per second. In this embodiment, the current output from the optical receiver 104 can be used to determine the intensity or amplitude of the light radiation striking the optical receiver 104. In some embodiments, the optical receiver 104 may be a photosensitive semiconductor diode that generates electron-hole pairs at a pn junction when a photon of sufficient energy strikes the optical receiver 104. In some embodiments, the optical receiver may include one or more single-photon avalanche diodes (SPADs) configured to generate an avalanche current when one or more photons strike the optical receiver 104.

[0059] The optical ranging sensor 100 can be configured to generate a histogram based on the reflected signal received at the optical receiver 104.

[0060] refer to Figure 5 An example process 592 is provided for generating a feedback signal histogram 596 and a reference signal histogram 594 based on the reflected signal 340 received at the optical range sensor 100. During operation, the optical transmitter 106 can emit optical pulses (e.g., optical signal 338) into the external environment. The optical receiver 104 can collect data related to the reflected signal 340 received at the optical receiver 104 based on the time elapsed since the optical pulse was emitted. For example, a first interval 598a of the feedback signal histogram 596 can capture light received at the optical receiver 104 within a first bin time period after the optical pulse was emitted; a second interval 598b of the feedback signal histogram 596 can capture light received at the optical receiver 104 within a second bin time period after the optical pulse was emitted; a third interval 598c of the feedback signal histogram 596 can capture light received at the optical receiver 104 within a third bin time period after the optical pulse was emitted; and so on. In some embodiments, the interval time period can be 250 picoseconds or approximately 250 picoseconds.

[0061] Similarly, reference array 332 can be positioned to receive a portion of the optical pulse at the time of emission. Reference array 332 can be configured to generate a reference signal histogram 594 as a baseline for determining the physical properties of target object 336. Figure 5 An example reference signal histogram is shown. Figure 5As shown, the first interval 599a of the reference signal histogram 594 can capture the light received at the reference array 332 within the first interval time period after the optical pulse is emitted; the second interval 599b of the reference signal histogram 594 can capture the light received at the reference array 332 within the second interval time period after the optical pulse is emitted; the third interval 599c of the reference signal histogram 594 can capture the light received at the reference array 332 within the third interval time period after the optical pulse is emitted; and so on.

[0062] Optical pulses are periodically emitted, and the reflected signal 340 accumulates within intervals (e.g., intervals 598a, 598b, 598c) during an integration time period. For example, the integration time period may include hundreds of thousands of pulses and last for tens of milliseconds. During the integration time period, counts are accumulated in each interval of the histogram. The accumulated counts in an interval represent the amount of light received at the optical receiver 104 or reference array 332 within the time period corresponding to that interval. Therefore, at the end of the integration time period, the data values ​​(e.g., peak values) in the histogram can indicate one or more times the optical signal was reflected. These data values ​​in the histogram can be used to determine the physical properties of a target object in the external environment.

[0063] Back to Figure 1 The optical receiver 104 is configured to generate a first feedback signal 110 and a second feedback signal 111. The feedback signals generated by the optical receiver 104 (e.g., the first feedback signal 110 / the second feedback signal 111) correspond to the amount of light received at the optical receiver 104 within a given time period. In some embodiments, the feedback signals may correspond to one or more intervals in a histogram generated at the optical receiver 104.

[0064] Because the feedback signal is associated with the reflected signal received at optical receiver 104, the feedback signal includes at least a target feedback portion and a crosstalk portion. The target feedback portion corresponds to the portion of the emitted optical signal reflected from the target object and returning to optical receiver 104. The crosstalk portion corresponds to the light received from a crosstalk source. The crosstalk source can include light propagating directly from optical transmitter 106 to optical receiver 104, which may propagate at and through the cover glass or optical element via reflection. The crosstalk portion of the feedback signal may cause inaccuracies in determining the physical properties of the target object.

[0065] like Figure 1As shown, the feedback signals include a first feedback signal 110 and a second feedback signal 111. The first feedback signal 110 corresponds to a reflected signal received in response to the emission of a first optical signal having a first polarization state. The second feedback signal 111 corresponds to a reflected signal received in response to the emission of a second optical signal having a second polarization state. In some embodiments, the first feedback signal 110 may be collected after a first integration period, and the second feedback signal 111 may be collected after a second integration period. In some embodiments, the optical ranging sensor 100 may alternate the polarization state of the optical signal after each integration period, thus generating the first feedback signal 110 and the second feedback signal 111 after alternating integration periods.

[0066] like Figure 1 As further shown, the example optical ranging sensor 100 includes a controller 108. The controller 108 includes any processing device configured to receive feedback signals (e.g., a first feedback signal 110, a second feedback signal 111) from the optical receiver 104 and determine the physical characteristics of a target object based on the feedback signals. The controller 108 is also configured to mitigate the effects of crosstalk in the feedback signals by comparing the first feedback signal 110 with the second feedback signal 111. Furthermore, the controller 108 is configured to generate a polarization control signal 112 to coordinate the polarization of the optical signals generated by the optical transmitter 106. For example, the controller 108 may alternately generate a first signal having a first polarization state and a second signal having a second polarization state. Regarding... Figures 4-5 This further describes the process used to mitigate the effects of crosstalk in the feedback signal. Regarding... Figure 8 A block diagram illustrating an example architecture of controller 108 is further described.

[0067] Now for reference Figure 2 This illustrates the behavior of an optical signal 220 comprising at least two distinct polarization states (s) and (p) upon encountering a transmissive object 222. For example... Figure 2 As shown, the magnitudes of the light emitted through the transmissive object 222 (e.g., emitted light 220a) and the light reflected by the transmissive object 222 (e.g., reflected light 220b) can depend on the polarization state of the incident light (e.g., optical signal 220). For example, as Figure 2 As shown, a larger portion of the optical signal 220 associated with the first polarization state (p) (e.g., transmitted light 220a) is emitted through the transmissive object 222, while a larger portion of the optical signal 220 associated with the second polarization state (s) (e.g., reflected light 220b) is reflected by the transmissive object 222.

[0068] Figure 2This optical characteristic can be used to detect crosstalk signals at an optical rangefinder (e.g., optical rangefinder 100). For example, when a first optical signal with a first polarization state encounters a transmissive object 222 (e.g., a lens, cover glass, etc.), a first portion of the first optical signal is reflected by the transmissive object 222 and can reach the optical receiver as crosstalk. When a second optical signal with a second polarization state encounters a transmissive object 222 (e.g., a lens, cover glass, etc.), a second portion of the second optical signal is reflected by the transmissive object 222 and can also reach the optical receiver as crosstalk. Importantly, the first reflected portion of the first optical signal and the second reflected portion of the second optical signal can be different because the polarization states of the first and second optical signals are different. Furthermore, it is assumed that the target feedback portion of the first reflected signal (e.g., the portion of the first optical signal reflected from the target) and the target feedback portion of the second reflected signal (e.g., the portion of the second optical signal reflected from the target) are the same. Therefore, by comparing the first feedback signal (generated in response to the first reflected signal) and the second feedback signal (generated in response to the second reflected signal), crosstalk signals can be identified, and the physical characteristics of the target can be determined. Figures 4-5 An example process is discussed for comparing a first feedback signal and a second feedback signal to mitigate crosstalk in the feedback signal.

[0069] Now for reference Figure 3 An example optical ranging sensor 100 is provided. For example... Figure 3 As shown, the optical rangefinder 100 includes an optical transmitter 106 configured to guide rangefinder optical signals 338 and 342 toward a target object 336 via a cover glass 334 placed in a transmission opening of the optical rangefinder 100. Transmitted portions 338a and 342a of the optical signals 338 and 342 are reflected back by the target object 336 and received at an optical receiver 104 via the cover glass 334 and a receiving opening in the optical rangefinder. Furthermore, a portion of the optical signals 338 and 342 is received by a reference array 332 of the optical rangefinder 100.

[0070] like Figure 3 As further shown, a portion of the optical signals 338 and 342 (e.g., crosstalk portions 338b and 342b) is reflected by the cover glass 334 and transmitted to the optical receiver 104 as crosstalk. Therefore, the reflected signals 340 and 344 include both the target reflection portions 340a and 344a and the crosstalk reflection portions 340b and 344b.

[0071] like Figure 3 As shown, the optical transmitter 106 can be configured based on a controller (e.g., Figure 1The polarization control signal generated by the controller 108 in the middle (e.g., in the controller 108) is a polarization control signal (e.g., in the controller 108) Figure 1 The optical transmitter 106 generates optical signals 338 and 342 comprising different polarization states using a polarization control signal 112. In some embodiments, the optical transmitter 106 may include a vertical-cavity surface-emitting laser (VCSEL) configurable to emit optical signals 338 and 342 according to different polarization states. For example, the first optical signal 338 comprises a first polarization state, and the second optical signal 342 comprises a second polarization state different from the first polarization state. The optical receiver 104 is configured to generate a first feedback signal based on a first reflected signal 340 received at the optical receiver 104, and is also configured to generate a second feedback signal based on a second reflected signal 344 received at the optical receiver 104.

[0072] like Figure 3 As further shown, the optical transmitter 106 and the optical receiver 104 are electrically connected to the substrate 346 (e.g., a printed circuit board). Additionally, the housing cover of the optical range sensor 100 is attached to the substrate 346.

[0073] Now for reference Figure 4 An example method 450 is provided for removing crosstalk signals from feedback signals received at an optical range sensor 100.

[0074] like Figure 4 As shown, the exemplary first feedback signal 452 is represented by crosstalk reflection portion 340b and target reflection portion 340a. The exemplary first feedback signal 452 is generated by the optical receiver 104 based on the first reflected signal received at the optical receiver 104 (e.g., as shown in the image). Figure 3 The first reflected signal (340) shown is generated, wherein the first reflected signal includes a first polarization state. Figure 4 As shown, the first reflected signal includes a crosstalk reflection portion 340b attributable to reflections from a crosstalk source and a target reflection portion 340a attributable to reflections from a target.

[0075] An exemplary second feedback signal 454 is generated by the optical receiver 104 based on a second reflected signal received at the optical receiver 104 (e.g., as shown in the image). Figure 3 The second reflected signal (344) is generated, as shown, wherein the second reflected signal includes a second polarization state. Although represented as intervals in the histogram, the principle of process 450 can be applied to any pair of feedback signals originating from optical signals emitted with different polarization states. Figure 4 As shown, the second reflected signal includes a crosstalk reflection portion 344b attributable to reflections from a crosstalk source and a target reflection portion 344a attributable to reflections from a target. Figure 4As shown, since the first feedback signal 452 is generated by an optical signal having a first polarity state, and the second feedback signal 454 is generated by an optical signal having a different second polarity state, the crosstalk reflection portion 340b of the first feedback signal 452 is different from the crosstalk reflection portion 344b of the second feedback signal 454. However, as Figure 3 As further shown, the target reflection portion 340a of the first feedback signal 452 and the target reflection portion 344a of the second feedback signal 454 are the same. Figure 4 Process 450 utilizes these characteristics to mitigate the effects of crosstalk in feedback signals 452 and 454.

[0076] At operation 460 of process 450, the first feedback signal 452 and the second feedback signal 454 are added together to generate a combined feedback signal 456. When performed on histogram intervals, operation 460 includes adding the value in the interval associated with the first feedback signal 452 to the corresponding interval in the second feedback signal 454. The resulting combined feedback signal 456 includes a portion attributable to the combined target reflection portion 456a and a portion attributable to the combined crosstalk reflection portion 456b.

[0077] At operation 470 of process 450, the difference between the first feedback signal 452 and the second feedback signal 454 is determined, thereby generating a crosstalk difference signal 462. When performed on a histogram interval, operation 470 includes subtracting the value in the interval associated with the second feedback signal 454 from the corresponding interval in the first feedback signal 452. The resulting crosstalk difference signal 462 represents the difference between the first crosstalk reflection portion 340b and the second crosstalk reflection portion 344b. Figure 4 As shown, since the target reflection portions 340a and 344a are equivalent or nearly equivalent in the first feedback signal 452 and the second feedback signal 454, the target reflection portions 340a and 344a are removed from the crosstalk difference signal 462.

[0078] At operation 480, a crosstalk function 463 is applied to the crosstalk difference signal 462. The crosstalk function 463 is any function, relation, algorithm, process, or other similar process that associates the crosstalk difference (e.g., crosstalk difference signal 462) between two crosstalk reflection portions 340b and 344b caused by optical signals with two different polarization states with the total crosstalk signal 464 representing the combined crosstalk reflection portions 340b and 344b of the two feedback signals 452 and 454. The crosstalk function 463 can be derived through a calibration process. For example, during calibration, a relational function can be determined based on changes in the coverslip, coverslip state, target, and target distance. The crosstalk function 463 can then be used to derive the total crosstalk signal 464 from the crosstalk difference signal 462 during operation. When performed over a histogram interval, operation 480 includes inserting the value of the crosstalk difference signal 462 into a crosstalk function 463, which is configured to generate a total crosstalk signal 464 based on the crosstalk difference signal 462.

[0079] At operation 490 of process 450, the total crosstalk signal 464 is removed from the combined feedback signal 456 to generate the target feedback signal 466. For example... Figure 4 As shown, the total crosstalk signal 464, determined based on the difference between the first feedback signal 452 and the second feedback signal 454 and the application of the crosstalk function 463, is equal to or nearly equal to the combined crosstalk reflection portion 456b of the combined feedback signal 456. Therefore, by determining the difference between the combined feedback signal 456 and the total crosstalk signal 464, only the target reflection portion 456a of the combined feedback signal 456 is retained. Thus, the target feedback signal 466 represents only the portion of the first feedback signal 452 and the second feedback signal 454 attributable to reflections from the target object, or a multiple thereof. Therefore, the target feedback signal 466 can be used to accurately determine one or more physical characteristics of the target, such as the distance to the target object, the motion of the target object, the velocity of the target object, the surface characteristics of the target object, etc. When performed on a histogram interval, operation 490 includes subtracting the value of the total crosstalk signal 464 from the value of the combined feedback signal 456 at the corresponding interval.

[0080] Although shown in one histogram interval, the operations described with reference to procedure 450 (e.g., operations 460, 470, 480, 490) can be performed for each of the multiple histogram intervals.

[0081] Now for reference Figure 6An example method 600 is provided for removing crosstalk signals (e.g., crosstalk portions 338b, 342b) from feedback signals (e.g., feedback signals 452, 454). At block 602, a controller (e.g., controller 108) of an optical ranging sensor (e.g., optical ranging sensor 100) causes an optical transmitter (e.g., optical transmitter 106) to emit a first signal (e.g., optical signal 338) having a first polarization state. As described herein, the optical transmitter can be configured to generate optical signals with different polarizations based on a polarization control signal (e.g., polarization control signal 112). For example, the optical transmitter may include a VCSEL with polarization control, wherein a portion of the light output aperture includes a horizontal grating and a portion of the light output aperture includes a vertical grating. The controller may emit a polarization control signal to the optical transmitter to configure the optical transmitter to emit an optical signal exhibiting the first polarization state.

[0082] At block 604, the controller receives a first feedback signal (e.g., first feedback signal 452) generated by one or more reflections of a first signal from an optical receiver (e.g., optical receiver 104). The optical receiver receives multiple reflections generated by the emitted first optical signal. The reflections may originate from a target object in the external environment. Furthermore, the reflections may originate from a crosstalk source, such as a cover glass of an optical ranging sensor (e.g., cover glass 334). The optical receiver is configured to generate the first feedback signal based on the received reflections. Because the first feedback signal is generated by reflections from both the target and the crosstalk source, the first feedback signal includes a crosstalk reflection portion (e.g., crosstalk reflection portion 340b) and a target reflection portion (e.g., target reflection portion 340a). In some embodiments, the first feedback signal may include a portion (e.g., an interval) of a feedback signal histogram (e.g., feedback signal histogram 596) based on the accumulated light generated by one or more reflections of the first optical signal within an integration period. Each interval of the feedback signal histogram similarly includes a crosstalk reflection portion and a target reflection portion.

[0083] At block 606, the controller causes the optical transmitter to emit a second signal (e.g., optical signal 342) having a second polarization state. As described herein, the controller may emit a polarization control signal to the optical transmitter to configure it to emit an optical signal exhibiting a second polarization state different from the first polarization state. In some embodiments, the second polarization state may be orthogonal to the first polarization state. In some embodiments, the controller may reconfigure the optical transmitter after each integration period to alternately emit optical signals in the first and second polarization states.

[0084] At block 608, the controller receives a second feedback signal (e.g., second feedback information 454) generated by one or more reflections of a second signal from an optical receiver. The optical receiver receives multiple reflections generated by the emitted second optical signal. The reflections can originate from a target object in the external environment. Furthermore, the reflections can originate from a crosstalk source, such as the cover glass of an optical rangefinder. The optical receiver is configured to generate the second feedback signal based on the received reflections. Because the second feedback signal is generated by reflections from both the target and the crosstalk source, the second feedback information includes a crosstalk reflection portion (e.g., crosstalk reflection portion 344b) and a target reflection portion (e.g., target reflection portion 344a). Furthermore, since the second feedback signal is based on a second optical signal having a polarization state different from that of the first optical signal, the magnitude of reflection of the second optical signal at various transmissive components can differ from that of the first optical signal. As a result, the target reflection portion of the second feedback signal is equal to or nearly equal to the target reflection portion of the first feedback signal. However, the crosstalk reflection portion of the second feedback signal can differ from the crosstalk reflection portion of the first feedback signal.

[0085] In some embodiments, the second feedback signal may include a portion (e.g., an interval) of a feedback signal histogram based on one or more reflections of the second optical signal during the integration period. Each interval of the feedback signal histogram similarly includes a crosstalk reflection portion and a target reflection portion.

[0086] At block 610, the controller generates a target feedback signal (e.g., target feedback signal 466) based on a comparison of the first and second feedback signals. (See also: Regarding...) Figure 4 Furthermore, in some embodiments, the controller may combine (or add) the first feedback signal and the second feedback signal to determine a combined feedback signal (e.g., combined feedback signal 456). Additionally, the controller may determine the difference (subtraction) between the first and second feedback signals to determine a crosstalk difference signal (e.g., crosstalk difference signal 462). Since the target reflection portions of the second feedback signal and the first feedback signal are nearly equal, the target reflection portions of the signals are canceled out, and only the difference between the crosstalk reflection portions is retained in the crosstalk difference signal.

[0087] Furthermore, a crosstalk function (e.g., crosstalk function 463) is applied to the crosstalk difference signal to determine the total crosstalk signal (e.g., total crosstalk signal 464). The crosstalk function correlates the difference between the crosstalk reflection portions between polarity states with the total crosstalk signal. The crosstalk function can be determined during the calibration period, for example, by mapping multiple crosstalk differences to a total crosstalk value. The total crosstalk signal represents the crosstalk portion of the combined feedback signal.

[0088] To determine the target feedback signal (e.g., target feedback signal 466), a value equal to the total crosstalk signal is removed from the combined feedback signal. By removing signals attributable to the total crosstalk signal from the combined feedback signal, only the target feedback signal is retained. The target feedback signal represents a multiple of the target reflection portion of the first and second feedback signals.

[0089] At box 612, the controller determines the proximity of the target based on the target feedback signal. The target feedback signal can be used to determine physical characteristics related to the proximity of the target object, such as the distance of the target object, the motion of the target object, the speed of the target object, the surface characteristics of the target object, and the presence of the target object.

[0090] Now for reference Figure 7 An example mobile electronic device 770 including an optical ranging sensor 100 is provided. For example... Figure 7 As shown, the example mobile electronic device 770 includes a housing 772 and a display screen 778, which defines an enclosed area in which an optical ranging sensor 100 and a controller 108 are disposed. The controller 108 is electrically coupled to the optical ranging sensor 100 to receive at least a first feedback signal and a second feedback signal (e.g., a first feedback signal 110 and a second feedback signal 111) and to generate a polarization control signal (e.g., a polarization control signal 112).

[0091] like Figure 7 As further shown, the example mobile electronic device 770 includes a housing 772. The housing 772 can be any structure, package, container, or similar mechanism designed to provide a protective enclosure for internal components of the mobile electronic device 770, such as including the optical ranging sensor 100. In some embodiments, the housing 772, together with the display screen 778, defines an enclosed area.

[0092] like Figure 7 As further shown, the display screen 778 includes a first surface 778a configured to emit transmitted light into the external environment via a plurality of display pixels and a second surface 778b opposite to the first surface 778a. In some embodiments, the display screen 778 may also include a cover glass (e.g., cover glass 334) configured to protect the display screen 778 and / or the electronic components (e.g., the optical range sensor 100) below it.

[0093] like Figure 7 As further shown, the mobile electronic device 770 includes an optical ranging sensor 100, which is used to detect the proximity characteristics of a target object 776. For example... Figure 7As shown, a portion of the optical signals 338 and 342 (e.g., crosstalk portions 338b and 342b) is reflected by the cover glass 334 and transmitted to the optical receiver 104 as crosstalk. To compensate for the crosstalk reflection portions (e.g., crosstalk reflection portions 340b and 344b) of the reflected signals 340 and 344, the optical transmitter 106 is configured to generate optical signals 338 and 342 with different polarity states. The difference in polarity states can cause a difference in the magnitude of the crosstalk reflection portions 340b and 344b. Utilizing this difference, the optical range sensor 100 can mitigate the crosstalk reflection portions of the reflected signals 340 and 344 before determining the proximity characteristics of the target object 776. By utilizing multiple polarity states when determining the proximity characteristics of the target object 776 by the optical range sensor 100, crosstalk mitigation can be dynamically adjusted in the event of changes in the conditions of the mobile electronic device 770 (e.g., smudges, fingerprints, dirt on the cover glass 334).

[0094] In some non-limiting examples, mobile electronic device 770 may include mobile phones, laptops, televisions, monitors, computers, wearable electronic devices, or other mobile devices.

[0095] Now for reference Figure 8 , Figure 8 An example controller 108 according to at least some example embodiments of the present disclosure is shown. The controller 108 includes a processor 802, input / output circuitry 804, data storage medium 806, and communication circuitry 808. In some embodiments, the controller 108 is configured to perform and execute the operations described herein using one or more of the respective sets of circuitry 802, 804, 806, and / or 808.

[0096] Although components are described with respect to functional limitations, it should be understood that a particular implementation necessarily includes the use of specific computing hardware. It should also be understood that in some embodiments, certain components described herein include similar or general-purpose hardware. For example, two sets of circuit devices may utilize one or more of the same processors, network interfaces, storage media, etc., to perform their related functions, thus not requiring hardware duplication for each set of circuit devices. Therefore, the use of the term "circuit device" as used herein with respect to components of the devices described herein should be understood to include specific hardware configured to perform the functions associated with the particular circuit device described herein.

[0097] Specifically, the term "circuit device" should be broadly understood to include hardware, and in some embodiments, also includes software for configuring the hardware. For example, in some embodiments, "circuit device" includes processing circuitry, storage media, network interfaces, input / output devices, etc. Alternatively or additionally, in some embodiments, other elements of the controller 108 provide or supplement the functionality of other specific groups of circuitry. For example, in some embodiments, the processor 802 provides processing functionality to any group of circuitry, the data storage medium 806 provides storage functionality to any group of circuitry, the communication circuitry 808 provides network interface functionality to any group of circuitry, and so on.

[0098] In some embodiments, processor 802 (and / or coprocessor, or auxiliary processor, or any other processing circuitry means otherwise associated with the processor) communicates with data storage medium 806 via a bus to transfer information between components of controller 108. In some embodiments, for example, data storage medium 806 is non-transitory and may include, for example, one or more volatile and / or non-volatile memories. In other words, for example, in some embodiments, data storage medium 806 includes or embodies an electronic storage device (e.g., a computer-readable storage medium). In some embodiments, data storage medium 806 is configured to store information, data, content, applications, instructions, etc., so that controller 108 can perform various functions according to exemplary embodiments of this disclosure.

[0099] Processor 802 can be embodied in a variety of different ways. For example, in some example embodiments, processor 802 includes one or more processing devices configured to execute independently. Additionally or alternatively, in some embodiments, processor 802 includes one or more processors configured in series via a bus to enable independent execution of instructions, pipelines, and / or multithreading. The terms “processor” and “processing circuitry means” should be understood to include single-core processors, multi-core processors, multiple processors within controller 108, and / or one or more remote or “cloud” processors outside controller 108.

[0100] In example embodiments, processor 802 is configured to execute instructions stored in data storage medium 806 or otherwise accessible to the processor. Alternatively or additionally, in some embodiments, processor 802 is configured to perform hard-coded functions. Thus, whether configured by hardware or software methods, or by a combination thereof, processor 802 represents an entity (e.g., physically embodied in a circuit arrangement) capable of performing operations according to embodiments of this disclosure when appropriately configured. Alternatively or additionally, as another example in some example embodiments, when processor 802 embodies an executor of software instructions, the instructions specifically configure processor 802 to perform the algorithm embodied in the specific operations described herein when such instructions are executed.

[0101] In some embodiments, controller 108 includes input / output circuitry 804 that provides output to a user and, in some embodiments, receives indications of user input. In some embodiments, input / output circuitry 804 communicates with processor 802 to provide this functionality. Input / output circuitry 804 may include one or more user interfaces (e.g., user interfaces) and, in some embodiments, includes a display that includes interfaces presented as network user interfaces, application user interfaces, user devices, back-end systems, etc. Processor 802 and / or input / output circuitry 804 including a processor may be configured to control one or more functions of one or more user interface elements via computer program instructions (e.g., software and / or firmware) stored in processor-accessible memory (e.g., data storage medium 806, etc.). In some embodiments, input / output circuitry 804 includes or utilizes user-oriented applications to provide input / output functionality to client devices and / or other displays associated with the user.

[0102] In some embodiments, controller 108 includes communication circuitry 808. Communication circuitry 808 includes any components configured to receive and / or transmit data to / from a network and / or any other device, circuitry, or module communicating with controller 108, such as devices or circuitry embodied in hardware or a combination of hardware and software. In this regard, for example, in some embodiments, communication circuitry 808 includes a network interface for enabling communication with a wired or wireless communication network. Additionally or alternatively, in some embodiments, communication circuitry 808 includes one or more network interface cards, antennas, buses, switches, routers, modems, and supporting hardware, firmware, and / or software, or any other device suitable for enabling communication via one or more communication networks. Additionally or alternatively, communication circuitry 808 includes circuitry for interacting with one or more antennas and / or other hardware or software to induce signal transmission via one or more antennas or to process reception of signals received via one or more antennas. In some embodiments, communication circuitry 808 enables data transmission to and / or data reception from client devices communicating with controller 108.

[0103] Alternatively or additionally, in some embodiments, one or more of the circuit devices 802-914 are composable. Alternatively or additionally, in some embodiments, one or more of the circuit devices perform some or all of the functions associated with another component. For example, in some embodiments, one or more sets of circuit devices 802-808 are combined into a single module embodied in hardware, software, firmware, and / or a combination thereof. Similarly, in some embodiments, one or more sets of circuit devices are combined such that the processor 802 individually performs one or more of the operations described above with respect to each of these circuit devices.

[0104] While this detailed description illustrates some embodiments of the invention, the appended claims cover other embodiments of the invention that differ from the described embodiments, based on various modifications and improvements. For example, those skilled in the art will recognize that these principles can be applied to any sensing device configured to transmit and receive optical signals through environments susceptible to crosstalk, such as LiDAR systems, ultrasonic sensors, structured light sensors, etc.

[0105] The use of broader terms such as “comprises,” “includes,” and “having” should be understood to support narrower terms such as “composed of,” “substantially composed of,” and “substantially composed of.” The use of terms such as “optionally,” “may,” “might,” and “possibly” for any element of the embodiment indicates that the element is either not essential or essential, both of which are within the scope of the embodiment. Furthermore, references to examples are for illustrative purposes only and do not imply exclusivity.

Claims

1. An optical ranging sensor, comprising: An optical transmitter is configured to generate a first signal having a first polarization state and a second signal having a second polarization state; The optical receiver is configured as follows: Generate a first feedback signal generated by one or more reflections of the first signal; as well as Generate a second feedback signal generated by one or more reflections of the second signal; as well as The controller is configured as follows: The target feedback signal is generated based on the comparison between the first feedback signal and the second feedback signal; as well as The proximity to the target is determined based on the target feedback signal.

2. The optical ranging sensor of claim 1, wherein the target feedback signal corresponds to a portion of the first signal reflected from the target.

3. The optical ranging sensor according to claim 2, wherein, in order to generate the target feedback signal, the controller is further configured to: Generate a first histogram corresponding to the first feedback signal; Generate a second histogram corresponding to the second feedback signal; as well as The target feedback signal is generated based on a comparison between the first histogram and the second histogram.

4. The optical ranging sensor of claim 1, wherein, in order to generate the target feedback signal, the controller is further configured to: The crosstalk difference signal is determined by calculating the difference between the first feedback signal and the second feedback signal; and A crosstalk function is applied to determine the total crosstalk signal, wherein the crosstalk function correlates the crosstalk difference with the total crosstalk signal.

5. The optical ranging sensor according to claim 4, wherein the crosstalk function is determined during the calibration period.

6. The optical ranging sensor of claim 1, wherein the proximity of the target is based on the time of flight associated with the target feedback signal.

7. The optical ranging sensor according to claim 1, wherein the first polarization state is orthogonal to the second polarization state.

8. The optical ranging sensor of claim 1, wherein the optical transmitter is configured to alternate between generating a first signal having the first polarization state and generating a second signal having the second polarization state.

9. The optical ranging sensor of claim 8, wherein after each integration period, the optical transmitter alternates between generating the first signal having the first polarization state and generating the second signal having the second polarization state.

10. The optical ranging sensor according to claim 9, wherein the optical transmitter is a vertical cavity surface-emitting laser.

11. The optical ranging sensor of claim 10, wherein the vertical cavity surface-emitting laser is configured to generate a first signal having a first polarization state and a second signal having a second polarization state based on a polarization control signal emitted by the controller.

12. A method for determining the proximity of a target at an optical range sensor, the method comprising: The optical transmitter emits a first signal with a first polarization state. Receive a first feedback signal generated by one or more reflections of the first signal from the optical receiver; The optical transmitter emits a second signal having a second polarization state; Receive a second feedback signal generated by one or more reflections of the second signal from the optical receiver; The target feedback signal is generated based on the comparison between the first feedback signal and the second feedback signal; as well as The proximity of the target is determined based on the target feedback signal.

13. The method of claim 12, wherein the target feedback signal corresponds to a portion of the first signal reflected from the target.

14. The method of claim 13, wherein generating the target feedback signal further comprises: Generate a first histogram corresponding to the first feedback signal; Generate a second histogram corresponding to the second feedback signal; as well as The target feedback signal is generated based on a comparison between the first histogram and the second histogram.

15. The method of claim 12, wherein generating the target feedback signal further comprises: The crosstalk difference signal is determined by subtracting the first feedback signal from the second feedback signal. as well as A crosstalk function is applied to determine the total crosstalk signal, wherein the crosstalk function correlates the crosstalk difference with the total crosstalk signal.

16. The method of claim 12, wherein determining the proximity of the target further comprises: Determine the flight time associated with the target feedback signal.

17. The method of claim 12, wherein the first polarization state is orthogonal to the second polarization state.

18. The method of claim 12, further comprising: The optical transmitter alternates between generating a first signal having the first polarization state and generating a second signal having the second polarization state.

19. The method of claim 18, wherein after each integration period, the optical transmitter alternates between generating the first signal having the first polarization state and generating the second signal having the second polarization state.

20. A mobile electronic device, comprising: case; A display screen attached to the housing, the display screen comprising: The first side is configured to emit light into the external environment via multiple display pixels; and An optical ranging sensor is disposed within the housing, opposite to the first surface of the display screen, and the optical ranging sensor includes: An optical transmitter is configured to generate a first signal having a first polarization state and a second signal having a second polarization state; An optical receiver is configured to receive: A first feedback signal generated by one or more reflections of the first signal; and A second feedback signal generated by one or more reflections of the second signal; and The controller is configured as follows: A target feedback signal is generated based on a comparison of the first feedback signal and the second feedback signal; and The proximity to the target is determined based on the target feedback signal.

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