Multi-detector lidar system and method for mitigating range aliasing

Abstract

Systems, methods, and computer-readable media for multi-detector lidar and methods are disclosed. An example method can include emitting, by a light emitter of a lidar system, a first light pulse. The example method can also include activating a first light detector of the lidar system at a first time, the first time corresponding to a time at which return light corresponding to the first light pulse will be located within a first field of view of the first light detector. The example method can also include activating a second light detector of the lidar system at a second time, the second time corresponding to a time at which return light corresponding to the first light pulse will be located within a second field of view of the second light detector, wherein the first light detector is configured to include the first field of view, the first field of view being associated with a first range from the light emitter, and wherein the second light detector is configured to include the second field of view, the second field of view being associated with a second range from the light emitter.

Description

Background Technology

[0001] In some LiDAR systems (e.g., bistatic LiDAR systems that use a single receiver to detect light emitted by a single transmitter), the transmitter, which emits light into the environment, and the receiver, which detects reflected light from objects in the environment, are physically displaced relative to each other. This LiDAR configuration can inherently be associated with parallax problems because the light emitted by the transmitter and received by the detector may not travel along parallel paths. For example, for a LiDAR system designed to operate at very short distances (e.g., 0.1 meters), the transmitter and receiver may need to be physically tilted towards each other (rather than aligned at infinity). However, this physical tilt can lead to a loss of detection capability at long distances from the LiDAR system. To address this problem, and to have the ability to handle both short-range and long-range detection, some LiDAR systems use a combination of a wide field of view and the aforementioned tilting components. However, this wide field of view can lead to other problems, including increasing the amount of background light detected by the receiver without increasing the amount of light emitted by the transmitter, which can significantly increase the receiver's signal-to-noise ratio.

[0002] Furthermore, using a single receiver (or even an array of receivers pointing in a common direction) for the transmitter can lead to other problems, such as difficulty in resolving range aliasing and crosstalk. Range aliasing can occur when a transmitter emits multiple light pulses and these pulses pass through the environment simultaneously. In this situation, the lidar system may have difficulty determining which emitted light pulse the detected return light originated from. For example, the transmitter emits a first light pulse at a first time, and then emits a second light pulse at a second time before the receiver detects the return light from the first pulse. Thus, the first and second light pulses pass through the environment simultaneously. Subsequently, the receiver can detect the return light pulse shortly after the second light pulse is emitted. However, the lidar system may have difficulty determining whether the return light indicates a short-range reflection based on the second light pulse or a long-range reflection based on the first light pulse. A similar crosstalk problem may arise, but instead of detecting the return light from the first light pulse emitted by the same transmitter, the receiver from one lidar system may detect a second light pulse originating from a transmitter of another lidar system. In this scenario, a lidar system might mistake a second light pulse detected from another lidar system as a return pulse originating from the first. Similar to range aliasing, this could cause the lidar system to incorrectly believe that an object at a short distance is reflecting light back to the lidar system. Attached Figure Description

[0003] A detailed description is given with reference to the accompanying drawings. The drawings are provided for illustrative purposes only and depict only exemplary embodiments of this disclosure. The drawings are provided to facilitate understanding of this disclosure and should not be construed as limiting the breadth, scope, or applicability of this disclosure. In the drawings, the leftmost numeral of the reference numerals identifies the drawing in which the reference numeral first appears. The same reference numerals are used to denote similar but not necessarily identical or the same components. However, different reference numerals may also be used to identify similar components. Various embodiments may utilize elements or components other than those shown in the drawings, and some elements and / or components may not be present in various embodiments. Depending on the context, the use of singular terms to describe components or elements may include multiple such components or elements, and vice versa.

[0004] Figure 1 An example system according to one or more example embodiments of the present disclosure is described.

[0005] Figures 2A to 2B Example usage instances according to one or more example embodiments of this disclosure are depicted.

[0006] Figure 3 Example usage instances according to one or more example embodiments of this disclosure are depicted.

[0007] Figures 4A to 4B Example circuit configurations according to one or more example embodiments of this disclosure are depicted.

[0008] Figures 5A to 5B Example methods according to one or more example embodiments of this disclosure are described.

[0009] Figure 6 A schematic diagram of an example system architecture according to one or more example embodiments of the present disclosure is depicted. Detailed Implementation Overview

[0010] This disclosure relates particularly to multi-detector lidar systems and methods (the lidar detector herein may be referred to as a "receiver," "photodetector," "photodiode," etc. Furthermore, a single "photodetector" or "photodiode" may be mentioned herein, but the lidar system described herein may similarly include any number of such detectors). In some cases, the detector may be a photodiode, which can be a diode capable of converting incident light photons into an electrical signal (e.g., current). The detector can be implemented in a lidar system that emits light into the environment, and subsequently can be used to detect any light returning to the lidar system (e.g., emitted light reflected from objects in the environment). As an example implementation, the lidar system may be implemented in a vehicle (e.g., an autonomous vehicle, a semi-autonomous vehicle, or any other type of vehicle); however, the lidar system may also be implemented in other contexts. The detector may also be more specifically an avalanche photodiode (APD), which may operate in the same manner as a regular photodiode, but may also operate with internal gain. Therefore, an APD that receives the same number of incident photons as a regular photodiode will generate a larger electrical signal through an electron "avalanche," making it more sensitive to fewer incident photons compared to a regular photodiode. The APD can also operate in Geiger mode, which significantly increases its internal gain.

[0011] As described above, a bistatic lidar system may include a transmitter and a receiver physically displaced relative to each other. This lidar configuration may inherently be associated with parallax problems because the light emitted by the transmitter and received by the detector may not travel along parallel paths. For example, for a lidar system detecting objects at short distances, the transmitter and receiver may need to be physically tilted relative to each other (rather than parallel aligned). However, this physical tilt can lead to a loss of detection capability at long distances from the lidar system. To address this problem, and to have the capability to handle both short-range and long-range detection, some systems use a combination of a wide field of view and the aforementioned tilting components. However, this wide field of view can lead to other problems, including increasing the amount of background light detected by the receiver without increasing the amount of light emitted by the transmitter, which can significantly increase the receiver's signal-to-noise ratio. Furthermore, as mentioned above, bistatic lidar systems (or even conventional lidar systems, including, for example, monostatic lidar systems) may have difficulty determining the source of certain backlighting based on range aliasing and / or crosstalk problems.

[0012] To eliminate or mitigate the parallax problem associated with bistatic lidar configurations, a lidar system can be used that includes multiple photodetectors to detect backlighting based on emitted light from a transmitter device (e.g., a laser diode) of the lidar system. The photodetectors can be physically oriented (e.g., pointed at different angles) such that their respective fields of view encompass different distances from the lidar system (e.g., such as...). Figure 1(As shown). In such a configuration, the first photodetector can be physically oriented such that its detection field of view encompasses a physical space within a short range of the lidar system (e.g., a range from 0.1m to 0.195m from the lidar system, including a field of view of 2.85 degrees). The second photodetector can be physically oriented such that its detection field of view covers a physical space just beyond the physical space covered by the first photodetector (e.g., a range from 0.19m to 4.1m from the lidar system, also with a field of view of 2.85 degrees). Similarly, the third photodetector can be physically oriented such that its detection field of view covers a physical space just beyond the physical space covered by the second photodetector (e.g., a range from 4m to infinity from the lidar system, with a field of view of 2.85 degrees. These example distances and fields of view are provided as arbitrary examples, and any other range and / or field of view can be similarly applied). The total number of photodetectors included in the lidar system can be based on many factors. As a first example, this number can be based on the maximum detection range expected to be covered by the photodetectors. If the maximum detection range is a small distance from the lidar system, a smaller number of photodetectors can be used; if the maximum detection range is a large distance from the lidar system, a larger number of photodetectors can be used (note that although the term "maximum detection range" is used, theoretically this distance can extend to infinity). As a second example, the number of photodetectors used can also be based on the size of the field of view of each individual photodetector. If some or all of the photodetectors have a narrow field of view, a larger number of photodetectors may be needed. Similarly, if some or all of the photodetectors have a wide field of view, a smaller number of photodetectors can be used. These are just two non-limiting examples of factors that can affect the number of photodetectors used in a lidar system, and the number may also depend on any number of additional factors. As a third example, the number of photodetectors used can depend on the amount of overlap in the field of view between photodetectors. In some cases, the transition from the field of view of one photodetector to the field of view of another photodetector may involve non-overlapping fields of view (i.e., the end of the field of view of one photodetector may correspond exactly to the beginning of the field of view of another photodetector). In other cases, there may be some overlap between the field of view of different photodetectors. Overlap serves as a safeguard to ensure that the photodetectors can detect enough photons corresponding to the reflected light. The magnitude of the overlap between the fields of view of the photodetectors can vary and can depend on factors such as the relative size of the reflected light and the effective area of ​​the photodetectors. Furthermore, in some cases, the pointing direction of the individual photodetectors can also be dynamically adjusted.In some embodiments, photodetectors can be configured in an array such that they are physically spaced apart from each other at equal distances. However, in some embodiments, the photodetector arrays may also be physically spaced apart with unequal intervals. For example, logarithmic separation may be more advantageous in producing a resolution equal to the minimum range. This may be because using a detector array with linear spacing having the same FoV can result in range asymmetry, with the first detector in the array responsible for a smaller amount of physical space, while the last photodetector in the array is responsible for a much larger amount of physical space (e.g., 4 m to infinity). By moving to a different spacing model (e.g., logarithmic spacing as described above), the range of the individual detectors can be optimized to be more balanced. For example, this can ensure that multiple returns from any area in the environment do not overload the receiver responsible for that area. Alternatively, as the coverage distance increases and the receiver cone becomes very large, detectors that are spaced closer together in the far field can be used to further reduce the FoV, thereby making them less susceptible to far-field noise.

[0013] In some embodiments, the photodetector can be selectively “on” and / or “off” (this can be similarly referred to as “activating” or “deactivating” the photodetector). “On” the photodetector can be achieved by providing a bias voltage to the photodetector that satisfies a threshold voltage level. A bias voltage that satisfies the threshold voltage level (e.g., at or above the threshold voltage level) can provide sufficient voltage to the photodetector to allow it to generate an output current level based on the light received by the photodetector. The output threshold voltage level used and the corresponding output current generated can depend on the type of photodetector used and the desired operating mode of the photodetector. For example, if the photodetector is an APD, the threshold voltage level can be set high enough that the photodetector can avalanche upon receiving light, as described above. Similarly, if the APD is desired to operate in Geiger mode, the threshold voltage level can be set even higher than if the APD is desired to operate outside the Geiger mode operating region. That is, when this higher threshold voltage level is applied, the gain of the photodetector can be much greater than when the photodetector operates as a normal avalanche photodiode. Furthermore, if the photodetector is not an APD and operates in linear mode, where the output current generated based on a similar amount of detection light can be much lower than when the photodetector is an APD, then the threshold bias voltage can be even lower. Additionally, even if the photodetector is an APD, the threshold voltage level can be set lower than the threshold voltage level used to allow the APD to avalanche when it receives light. That is, the bias voltage applied to the APD can be set low enough to allow the APD to still generate output current, but only in linear mode.

[0014] Similarly, in some embodiments, "turning off" the photodetector can refer to reducing the bias voltage supplied to the photodetector below a threshold voltage level. In some cases, "turning off" the photodetector does not necessarily mean that the photodetector cannot detect backlight. That is, when the bias voltage is below the threshold voltage level, the photodetector may still be able to detect backlight, but the output signal generated by the photodetector may be lower than the noise floor established for the signal processing section of the lidar system. As a non-limiting example, the photodetector can be an avalanche photodiode. If a sufficiently large bias voltage is provided to allow the APD to avalanche when receiving light, the APD can produce a large current output. However, if a lower bias voltage is applied, the APD may still produce an output, but the output may be based on a linear operating mode, and the resulting output current may be much lower than if the APD avalancheed when receiving the same number of photons. The signal processing section of the lidar system can have a noise floor configured to correspond to the output of the APD in linear mode, such that when operating with this reduced bias voltage, any output from the APD can be effectively ignored by the lidar system. Therefore, selectively turning photodetectors on and / or off may result in only some photodetectors being able to detect the backlight at a given time.

[0015] In some embodiments, the timing for turning photodetectors on and / or off may depend on predetermined time intervals. As a first example, these predetermined time intervals may be based on the amount of time that has elapsed since the transmitter of the lidar system emitted a given light pulse. Continuing with this first example, the emission of a first light pulse from the transmitter may trigger timing. The timing may involve turning on individual photodetectors when the reflection of light corresponding to the emitted light pulse from an object is expected to be within the field of view of a particular photodetector. Still continuing with this first example, the first photodetector may be pointed in a direction such that its field of view may include a physical spatial range within the closest distance to the lidar system (Rxl shown in Figure 1 can provide a visual example of the field of view of this first photodetector). The first photodetector may be a first photodetector that will be continuously turned on for a first time interval, during which reflection of light originating from the first light pulse from an object within the first field of view is expected. As an example, the field of view of the first photodetector may include a range from 0.19 m to 4.1 m from the lidar system (again, it should be noted that any specific example of the range and / or field of view of any photodetector described herein can be arbitrary, and any other range and / or field of view may be similarly applicable). That is, if emitted light is to be emitted from the lidar system and then reflected back to the first photodetector from an object in the environment within that range from the lidar system, the first photodetector pointing in that direction can be turned on and can detect the reflected light. Once the first time interval has elapsed, a second time interval begins, and the second photodetector can be turned on. Similar to the first time interval, the second time interval may correspond to the time period during which any reflected light expected to be detected by the second photodetector has originated from an object in the field of view of the second photodetector. The process can continue, turning on some or all of the remaining photodetectors in the array after successive time intervals of the previous photodetectors in the array have elapsed. This process can be visualized, for example, in Figure 2, as described below. Furthermore, in some cases, the photodetector may also be turned off once the time interval associated with the field of view of a particular photodetector has elapsed. In other words, at any given time, only the photodetector associated with the current time interval can be turned on. This can provide many benefits, such as reducing irrelevant data received by other photodetectors during this time and / or reducing the power consumption of the lidar system, to name just a few. However, in some embodiments, some or all photodetectors can remain on for multiple time intervals, or can remain on continuously. This can be advantageous because it allows for the capture of as much data as possible from the environment. Furthermore, the time intervals may not necessarily need to be of the same length. For example, the time interval associated with a given photodetector can depend on the size of the photodetector's field of view.In other words, a photodetector with a narrower field of view can be associated with a shorter time interval compared to a photodetector with a wider field of view. This can occur when photodetectors with different field of view sizes are used. Furthermore, in some cases, any other type of time interval can be used to determine when to turn on and / or off any photodetectors included in a lidar system.

[0016] In some embodiments, the bias voltage supplied to an individual photodetector during a given time interval may not necessarily be fixed. That is, the bias voltage supplied to the photodetector may vary over time based on some function (e.g., the "function" may refer to the magnitude of the applied bias voltage relative to time. That is, if a graph of the applied bias voltage over time is created, the function will be visualized through that graph). This function may not necessarily involve only a threshold voltage level, only values ​​at or below the threshold voltage level (that is, if the applied bias voltage is plotted as a function, it may not necessarily look like a step function that rises to the threshold voltage level at the beginning of the time interval and falls below the threshold voltage level at the end of the time interval). Instead, the function may be associated with some degree of variation in the bias voltage throughout the entire time interval. For example, the function may represent a Gaussian function. Using this type of function to specify the supplied bias voltage, for example, the bias voltage may increase during a first time interval to reach a peak bias voltage, and then fall back below the threshold voltage level during a second time interval. In some cases, the peak of an example Gaussian function may remain throughout the entire predetermined time interval associated with a particular photodetector. In some cases, the upward slope of the Gaussian function can begin at the start of a time interval and reach its peak some time after the start of that time interval. This may be necessary if it is desired that the photodetector is most sensitive to backlighting at a specific portion of its field of view. In some cases, the upward slope of the example Gaussian function can begin during the time interval of the previous photodetector (and similarly, the downward slope can extend into the time intervals of successive photodetector time intervals). In some cases, the function can be any function other than a Gaussian function (e.g., in some cases, the function can even be a step function). That is, the bias voltage applied to a given photodetector can vary with time in any other way. Furthermore, different photodetectors can be associated with different types of functions. Different photodetectors can also be associated with the same type of function, but some parameters of the function can vary. For example, the peak value of the Gaussian function used for one photodetector can be greater than the peak value of the Gaussian function used for a second photodetector. The function used can also vary for different emitted light pulses from the lidar system. In other words, when the lidar system emits the first light pulse, a first type of function can be used, but when the lidar emits subsequent light pulses, a second type of function can be used. The above example regarding how different functions can be used to control the bias voltage applied to the photodetector is merely exemplary, and any combination of any other type of function can be applied to the photodetector based on any number of timing considerations.

[0017] In some embodiments, the way photodetectors are turned on and / or off can also be dynamic, rather than based on a fixed time interval used for continuous light pulse emission from the transmitter. That is, the time interval used to determine the bias voltage to be provided to different photodetectors may not always iterate consistently in the same way, but may vary over time. In some cases, the time interval for some or all photodetectors can be changed after each consecutive light pulse emitted by the transmitter. In some cases, the time interval can be changed after the transmitter emits a given number of emitted light pulses. In some cases, the time interval can also be changed within a period of time during which a single emitted light pulse may currently be traversing the environment. That is, light pulses can be emitted, a first photodetector can be turned on for a first time interval, and then a second time interval for a second photodetector can be dynamically changed to a different time interval. In some cases, these time interval changes can be based on data received from the environment. That is, a closed-loop feedback system can be implemented to change the time interval. It should be noted that this closed-loop feedback system can be similarly used to dynamically adjust the type of function used to specify the bias voltage provided to different photodetectors.

[0018] In some embodiments, the physical orientation of the photodetectors can also be fixed and / or dynamically configurable. That is, each photodetector can include an actuation mechanism that allows the direction in which the photodetector is pointing to be dynamically adjusted (therefore, the field of view of the photodetector can be dynamically adjustable). For example, the actuation mechanism can include a microelectromechanical system (MEMS), or any other type of actuation mechanism that allows the photodetector to adjust its pointing direction. This dynamic adjustment of the physical orientation of one or more photodetectors can be performed for any other reason. As a first example, a first photodetector can be activated during a period of time when a particular emitted light pulse is traversing the environment, and data can be captured by the first photodetector. The pointing direction of a second photodetector can then be adjusted based on the data captured by the first photodetector. As a second example, multiple photodetectors can be aligned to point in the same direction. This may be desirable because it allows more data to be captured from that particular part of the environment compared to using a single photodetector to capture data from that particular part of the environment. This can be beneficial because one photodetector can serve as a failover protection for another (that is, one photodetector can be used to verify data received by the other, or to capture data from that part of the environment if the other photodetector fails to capture data within a given time period). This can also be useful if that part of the environment is identified as the region of interest, and therefore it is desirable to obtain as much data as possible from that part of the environment. However, these are merely examples of reasons for adjusting the physical orientation of one or more photodetectors, and such adjustments can also be made for any and all other reasons.

[0019] In some embodiments, a circuit for capturing data generated by the individual photodetectors within the photodetector array (examples of which may be...) Figures 4A to 4B(As shown in the diagram) This can involve providing a separate analog-to-digital converter (ADC) for each photodetector. The ADC can take an analog signal as input and produce a corresponding digital output. The current output of the photodetector can be an analog signal, so the ADC can take this signal as input and convert it into a digital form usable by the signal processing section of the lidar system. However, in some embodiments, a single ADC can be used for multiple photodetectors or all photodetectors. In such embodiments, the outputs of the individual photodetectors can be summed and provided as a single output to the ADC. Summation can be performed using a summer circuit, which may include more than one circuit capacitively coupled together, or it may be in the form of an operational amplifier summer. Furthermore, before summing the outputs of the individual photodetectors, attenuation can be performed using one or more attenuators, or attenuation can be performed on one of the outputs of one or more photodetectors. For example, if all detectors are always on, the attenuator can be used to attenuate the output of some detectors at certain times. For example, attenuation can be performed to attenuate the output of all detectors except one. For example, this one detector may correspond to the field of view where the expected return light from the emitted light pulse will currently be located. Therefore, the attenuator can be used to reduce the amount of detector output noise provided to the ADC and signal processing component 410. The attenuator can also be used in other ways. For example, all outputs of the detector can remain unattenuated unless it is determined that it is desirable to block the outputs of one or more detectors. In some cases, any of the circuit embodiments described above can be used when some or all photodetectors remain on continuously, rather than being selectively turned on and off during a single light pulse emission. However, in some embodiments, the circuit can also be used when photodetectors are selectively turned on and / or off. For example, in scenarios where the photodetector is selectively turned on based on the expected return light from the emitted light pulse entering the photodetector's field of view (i.e., only one photodetector is turned on at a time), a single ADC can be used. In this case, summation and / or attenuation may not be necessary, which may be the case when multiple or all photodetectors are turned on simultaneously. This configuration can help prevent background noise from reducing dynamic range if the photodetectors used have a long recovery period.

[0020] In some embodiments, the use of multiple photodetectors as described herein can also have the additional benefit of mitigating range aliasing problems that may occur in lidar systems. Range aliasing can occur when two or more different light pulses emitted by the transmitter of a lidar system simultaneously pass through the environment. For example, the transmitter of a lidar system may emit a light pulse at a first moment, and the time expected for that light pulse to return to the lidar system from its maximum detection range may have elapsed. The lidar system may then emit a second light pulse. Shortly after the second light pulse is emitted, a return pulse based on reflection from an object outside the maximum detection range may be detected. In this case, the lidar system may incorrectly identify this return pulse as a short-range return of the second light pulse, rather than a long-range return of the first light pulse. This can be problematic because light associated with multiple emitted light pulses from the lidar system may be present in the environment during any given time interval. This may lead to a reduction in the lidar system's emission rate (the rate at which the transmitter can emit subsequent light pulses) to decrease the likelihood of a large number of light pulses simultaneously passing through the environment and causing this range aliasing problem.

[0021] In some embodiments, using multiple photodetectors in the manner described herein can mitigate or eliminate distance aliasing because more data about the environment can be determined compared to using only a single photodetector. This concept can be applied to... Figure 3 The following example further illustrates this. For instance, a first light pulse can be emitted at a very early time. The first light pulse can travel through the environment, and as it travels further away from the transmitter, successive photodetectors can be turned on and / or off at varying time intervals. However, when the first light pulse travels beyond the field of view of the last photodetector without being reflected from an object and detected by it, instead of turning off the last photodetector (e.g., the photodetector with the furthest detection range from the lidar system), the last photodetector can remain on as the first light pulse continues to travel beyond its field of view. Continuing this example, the transmitter can then emit a second light pulse. Shortly after the second light pulse is emitted (e.g., when it is within the field of view of the first photodetector, which includes the distance range closest to the transmitter), the last photodetector may detect a return light. In this case, it is known that the second light pulse has not traveled far enough to be detected as a return light by the last photodetector, so the detection by the last photodetector is more likely to be associated with the first light pulse. In this way, it is easier to determine which light pulse the detected return light can be associated with.

[0022] As another example of how range aliasing can be mitigated and / or eliminated by using multiple photodetectors, if the photodetectors are controlled to turn on and / or off based on predetermined time intervals as described above, backlight reflected from objects beyond the maximum detection range of the lidar system may never be detected (this eliminates the possibility of range aliasing). The reason for this can be enumerated as follows. In this example, a first light pulse is emitted. The photodetectors then operate in the order of their on and / or off as described above until (when any expected backlight would come from outside the maximum detection range) the final photodetector (the one with the field of view furthest from the lidar system) is turned off. A second light pulse is then emitted from the lidar system. If only one photodetector is always on, then the backlight from the first light pulse may return and be detected by that photodetector. However, if multiple photodetectors are present, and each photodetector is only on for a given time interval, then the backlight detected by a given photodetector is more likely to originate from the second light pulse. That is, unless the backlight based on the first light pulse arrives in the field of view during the time interval during which a particular photodetector is on. Even if this scenario does occur (the return light from the first light pulse reaches the field of view of the photodetector, which is on), using multiple photodetectors still allows for the determination that the detected return light may potentially originate from the first light pulse. That is, if the return light from the first pulse returns and is detected by one of the on photodetectors, but the second light pulse has not yet reflected back from the object to the photodetector, the return light from the first pulse can be detected by the subsequent on photodetector. This means that return light from both light pulses may be received, and the lidar system can therefore determine that at least one return light detection is based on range aliasing. If this is the case, the lidar system can simply ignore both detected return lights.

[0023] In some embodiments, mitigating range aliasing as described above can have the additional benefit of allowing a greater number of light pulses to be emitted within a time frame compared to not using these systems and methods to mitigate range aliasing. This can be because if the lidar system is more likely to determine which backlight is associated with which emitted light pulse, then having more light pulses traversing the environment simultaneously may be less concerning. The ability to emit more light pulses within a given time period allows for the collection of a larger amount of data about the environment at a faster rate.

[0024] In some embodiments, the bistatic lidar system with multiple photodetectors described herein also has the additional benefit of mitigating or eliminating crosstalk between different lidar systems. Crosstalk can refer to a scenario that occurs when a transmitter from a first lidar system is pointed at a second lidar system. If the first lidar system emits a light pulse, that light pulse can then travel toward the second lidar system and be detected by the photodetector of the second lidar system. Similar to the range aliasing problem, if only one photodetector is used, the second lidar system may have difficulty distinguishing between its own emitted light pulse and light pulses originating from another lidar system. This crosstalk scenario can be mitigated or eliminated in a similar manner to mitigate or eliminate range aliasing.

[0025] In some embodiments, the bistatic lidar system with multiple photodetectors described herein may also have benefits beyond mitigating parallax, range aliasing, and / or crosstalk issues. For example, using multiple photodetectors can mitigate the possibility that a particular photodetector might be saturated by bright light. In this case, the photodetector may enter a recovery period during which it may be unable to detect any subsequent light. If only one photodetector is used in the lidar system, the lidar system may be unable to detect the backlight during this recovery period. However, if multiple photodetectors are used, any other photodetector can serve as a backup for the photodetector currently in its recovery period.

[0026] Switch to the attached image. Figure 1 A high-level schematic diagram of the example lidar system 101 can be drawn, which can implement multiple detectors as described herein. See also... Figure 6 A more detailed description of the example lidar system is provided below. Referring to the elements shown in the figures, lidar system 101 may include at least: one or more transmitter devices (e.g., transmitter device 102a and / or any number of additional transmitter devices) and one or more detector devices (e.g., detector device 106a, detector device 106b, detector device 106c, and / or any number of additional detector devices). Hereinafter, references may be made to elements such as “transmitter device” or “detector device”; however, such references may be similarly applied to multiple such elements. In some embodiments, lidar system 101 may be integrated with vehicle 101 and may be used at least to provide range determination of vehicle 101. For example, vehicle 101 may traverse environment 108, and lidar system 101 may be used to determine the relative distances of various objects in environment 108 (e.g., pedestrian 107a, stop sign 107b, and / or second vehicle 107c) relative to vehicle 101.

[0027] Still referencing Figure 1 One or more detector devices can be configured such that each detector device is physically oriented to point in a different direction. Therefore, different detectors can have different corresponding fields of view in environment 108. For example, detector device 106c can be associated with field of view 110, detector device 106b can be associated with field of view 111, and detector device 106a can be associated with field of view 112. As shown, the field of view of a single detector device can cover a specific range of distances from transmitter 102a. For example, field of view 110 of detector device 106c is shown covering the closest distance range to transmitter 102a, field of view 111 of detector device 106b is shown covering the intermediate distance range to transmitter 102a, and field of view 112 of detector device 106a is shown covering the farthest distance range from transmitter 102a. Therefore, collectively, the detector devices can cover a total field of view including fields of view 110, 111, and 112. Although the figure depicts three detector devices with three associated fields of view, the total field of view can be similarly divided among any number of detector devices. Furthermore, as shown, a field of view of one photodetector can begin precisely at the end of the previous field of view of another photodetector, thus leaving no blind spots between photodetectors. However, in some cases (not shown in the figure), there may be overlap between the individual fields of view of different photodetectors. Different fields of view allow different detector devices to detect the backlight 120 of emitted light 105 from emitter 102a based on the environment 108. Because the different fields of view cover different distance ranges, each detector device can be configured to detect objects at different distances from vehicle 101. For example, because detector device 106c is associated with field of view 110 covering the closest distance to vehicle 101, detector device 106c can be configured to detect the backlight 120 reflected from an object (e.g., vehicle 107c) at a shorter distance from vehicle 101. As described herein, detector devices can also be selectively turned on and / or off based on time estimates of when the backlight 120 will be within the field of view of each detector device. Example usage instance

[0028] Figures 2A to 2B Example usage instance 200 according to one or more exemplary embodiments of the present disclosure is depicted. Usage instance 200 may illustrate a manner in which one or more detectors can be selectively turned on and / or off (as described above) during various time intervals following the emission of a light pulse from the transmitter. Usage instance 200 may depict a transmitter 202, which can be used with... Figure 1The transmitter 102a described herein is identical to any other transmitter described herein. Example 200 may also depict one or more detectors, including, for example, a first detector 203, a second detector 204, and a third detector 205, which may be identical to detector devices 106a, 106b, and / or 106c, and any other detectors described herein. Each detector may have an associated field of view. For example, the first detector 203 may be associated with field of view 206, the second detector 204 with field of view 207, and the third detector 205 with field of view 208. Figure 1 Similar to the field of view in Figure 2, the various fields of view (e.g., field of view 206, field of view 207, and / or field of view 208) in use example 200 can include a range of varying distances from transmitter 202 (or more broadly, from the lidar system). The field of view allows detectors to detect backlighting (e.g., backlight 211, backlight 213, and / or backlight 215) reflected from objects in the environment (e.g., tree 209, vehicle 214, and / or building 219). As shown in use example 200, field of view 206 associated with the first detector 203 can cover the range of distances closest to transmitter 202 (or lidar system), field of view 207 associated with the second detector 204 can cover the range of distances intermediate from transmitter 202 (or lidar system), and field of view 208 associated with the third detector 205 can cover the range of distances furthest from transmitter 202 (or lidar system). Together, fields of view 206, 207, and 208 can cover the total field of view of the lidar system. That is, each detector with its corresponding field of view can cover a portion of the total field of view of the lidar system, and all fields of view together can cover the desired field of view of the lidar system. For example, the desired total field of view can correspond to the maximum detection range of the lidar system, which can be predefined or selected based on any factor. Although use case 200 may depict only three detectors with three corresponding fields of view, any other number of detectors and associated fields of view can be used to cover the detection range of the lidar system. Detectors can be used with... Figure 1 The detector described herein is the same as any other detector described herein. In some cases, transmitter 202 and one or more detectors can be part of an overall lidar system, such as a bistatic lidar system. That is, using example 200, one can describe, for example, a system composed of... Figure 1 The example shown illustrates the use of a lidar system.

[0029] refer to Figure 2AUse Case 200 can begin with Scenario 201. Scenario 201 may involve a transmitter 202 of a lidar system emitting a light pulse 210 into an environment 210. Scenario 201 may also describe that after the transmitter 202 emits the light pulse 210, a detector (first detector 203) with a field of view 206 covering the distance closest to the transmitter 202 can be activated. The first detector 203 can be activated for a given first time interval ΔT1. During this first time interval, other detectors in the lidar system (e.g., second detector 204 and third detector 205) can be deactivated, which can be represented by their fields of view as dashed lines. The first time interval ΔT1 may correspond to the time interval within the field of view 206 of the first detector 203 where a reflection of light from an object in the environment is expected. For illustrative purposes, Scenario 201 may depict a tree 209 within the field of view 206 that reflects the reflection 211. This reflection 211 can then be detected by the first detector 203. It should be noted that tree 209 (and associated backlight 211) can be depicted with dashed lines as an example of what backlight in field of view 206 can look like. However, in order to continue this example in a subsequent scene of this use case 200, tree 209 can be considered as not actually existing in the environment, so that light pulse 210 can travel through the environment to a greater distance from emitter 202.

[0030] continue Figure 2BUsing example 200, scene 215 can be continued. Scene 215 may involve light pulse 210 continuing to traverse the environment, beyond the position of tree 209 as shown in scene 201. Scene 215 may occur during a second time interval ΔT2. During the second time interval, the first detector 203 may be turned off, and the second detector 204 may be turned on. That is, the second detector 204 may now be the only detector currently on. Similar to the first time interval, the second time interval ΔT2 may correspond to the time interval within the field of view 207 of the second detector 204 where the reflected light from objects in the environment is expected. As shown, the second detector 204 may include a field of view 207, which includes a distance range starting from the end of the distance range covered by the field of view 206 of the first detector 203. In some cases, although not shown in the figure, there may also be some overlap between the field of view 207 and / or the field of view 206. For illustrative purposes, scene 215 may therefore depict a vehicle 214 within the field of view 207 and reflecting the reflected light 213. The reflected light 213 can then be detected by the second detector 204. Similarly, it should be noted that the vehicle 214 (and the associated reflected light 213) can be depicted with dashed lines as an example of what a reflected light in the field of view 207 can look like. However, in order to continue this example in a subsequent scenario of this use case 200, the vehicle 214 can be considered not actually present in the environment, allowing the light pulse 210 to travel a greater distance across the environment, as shown in scenario 230 described below.

[0031] continue Figure 2B This use case can proceed to scenario 230. Scenario 230 may involve light pulse 210 continuing to traverse the environment, beyond the position of vehicle 214 as shown in scenario 215. Scenario 230 may occur during a third time interval ΔT3. During the third time interval, the second detector 204 may be turned off, and the third detector 205 may be turned on. That is, the third detector 205 may now be the only detector currently on. Similar to the first and second time intervals, the third time interval ΔT3 may correspond to the time interval within the field of view 208 of the third detector 205 where the reflected light from objects in the environment is expected to be. As shown, the third detector 205 may include a field of view 208, which includes a distance range starting from the end of the distance range covered by the field of view 207 of the second detector 204. In some cases, although not shown in the figure, there may also be some overlap between the field of view 207 and / or the field of view 208. For illustrative purposes, scenario 230 may depict a house 217 within the field of view 208 and reflecting the reflected light 218. The reflected light 218 can then be detected by the third detector 205.

[0032] Continuing with Figure 2, use case 200 thus depicts an example of how various detectors are selectively turned on and / or off over time as the emitted light pulse further enters environment 210. However, this use case 200 should not be considered limiting, and detectors can operate in any other manner described herein. For example, in some cases, all detectors may be on continuously (rather than selectively turning individual detectors on and / or off), more than one detector may be on at any given time, and / or any number of detectors may be on in any other combination over any other time length. Furthermore, in scenarios where detectors are selectively turned on and / or off, as shown in use case 200, the time intervals for turning individual detectors on and / or off can vary. For example, the time interval for one detector to be on may be shorter and / or longer than the time interval for another detector to be on. In some cases, timing may depend on one or more types of functions used to determine the bias voltage applied to a given photodetector over time. For example, as described herein, the bias voltage applied to different photodetectors may be expressed as a time-shifted Gaussian function. In other words, within a given time interval, the bias voltage applied to detector 205 can ramp up to a peak bias voltage value and then ramp down as the time interval nears its end. Similarly, as the end of the first time interval approaches and the start of the second time interval associated with detector 204 approaches, the bias voltage can ramp up with respect to detector 204 using a similar Gaussian function, and so on. Finally, although the fields of view (e.g., fields of view 206, 207, and / or 208) are shown as fixed in use example 200, any of these fields of view can also be adjustable. That is, the fields of view can be widened or narrowed, or the orientation of the fields of view can be changed. The fields of view can also be changed in any other way, for example, by introducing an optical system that can change the orientation of the fields of view. As described herein, the fields of view can be changed for a variety of reasons, such as focusing multiple detectors toward similar locations within the environment.

[0033] Figure 3Example use case 300 according to one or more exemplary embodiments of this disclosure is depicted. Use case 300 may describe one example of how range aliasing problems can be mitigated and / or eliminated by the multi-detector system and methods described herein. Use case 300 may depict two parallel timelines. Scenario 301 and 310 may include one timeline, while scenarios 320 and 340 may include a second parallel timeline. Scenario 301 and 310 may be included to describe how range aliasing problems may occur in a single-detector lidar system, and scenarios 320 and 340 may describe how these problems can be improved by using the multi-detector system described herein. Thus, scenarios 301 and 310 may depict a lidar system that may include only one transmitter 302 and one detector 303. Detector 303 is capable of detecting backlight, and its field of view 304 can cover up to a maximum detection range 305.

[0034] Starting with scenes 301 and 310, scene 301 can depict emitter 302 emitting a first light pulse 306 into the environment. The first light pulse 306 is shown as passing through the environment and eventually moving past the maximum detection distance 305 of detector 303. That is, the first light pulse 306 in scene 301 may not have yet been reflected as a backlight from an object in the environment and has not yet been detected within the field of view 304 of detector 303. In this case, as shown in scene 310, a potential distance aliasing problem may occur. In scene 310, emitter 302 is shown as emitting a second light pulse 307 into the environment. However, at some point while the second light pulse 307 is passing through the environment, the first light pulse may eventually be reflected from an object (e.g., tree 308) and return as a backlight 309 towards the field of view 304 of detector 303. Then, the reflected light 309 can be detected by detector 303 at point 310, which may correspond to the point when the reflected light 309 first enters the field of view of detector 303 (for illustrative purposes, this can happen at the first moment). However, at the first moment when detector 303 detects the reflected light 309 from the first light pulse 306 at point 310, the second light pulse may also be currently at point 311 in the environment. That is, by the time the reflected light 309 from the first light pulse 306 is detected by detector 303, the second light pulse 307 may have only traveled a short distance from transmitter 302. When this happens, the back-end signal processing components (not shown) of the lidar system may have difficulty determining whether the reflected light detected by detector 303 is based on the short-range detection of the second light pulse 307 or the long-range detection of the first light pulse 306. This may be because distance determination based on the emitted light pulse from transmitter 302 can be performed, for example, based on time-of-flight (ToF) determination. In other words, the lidar system can determine when to emit a light pulse, and then compare the emission time with the time when the detector detects the return light. The resulting time difference can then be used to determine the distance at which the emitted light reflects back to the lidar system. Considering this, the lidar system may not be able to distinguish between two light pulses at different distances within the field of view 304 of a single detector 303, because theoretically both light pulses could be sources of the return light detected by detector 303.

[0035] continue Figure 3Scenes 320 and 340 may depict an example configuration in which the multi-detector system described herein can mitigate or eliminate the distance aliasing problem illustrated in the examples of scenes 301 and 310. Therefore, scenes 320 and 340 may depict a multi-detector system that may include a transmitter 302 and one or more detectors (e.g., a first detector 321, a second detector 322, and / or a third detector 323, which may be the same as the first detector 203, the second detector 204, and / or the third detector 205, and any other detectors described herein). Detectors may be associated with a field of view covering a specific distance range from the transmitter 302. For example, the first detector 321 may be shown as associated with a field of view 324, which may include the distance range closest to the transmitter 302. The second detector 322 may be shown as associated with a field of view 325, which may include a distance range beyond the distance range covered by the field of view 324 of the first detector 321. Finally, the third detector 323 can be shown as associated with a field of view 326, which can include a distance range beyond the range covered by the field of view 325 of the second detector 322. Furthermore, for illustrative purposes, a combination of fields of view 324, 325, and 326 can cover the same maximum detection range 305 from the transmitter 302.

[0036] continue Figure 3Similar to scenario 301, scenario 320 may begin with transmitter 302 emitting a first light pulse 306 into the environment. Likewise, the first light pulse 306 is shown as traversing the environment and ultimately traveling a maximum detection distance 305 through the first detector 321, the second detector 322, and the third detector 323. That is, the first light pulse 306 may not yet have been reflected from objects in the environment and may not have been detected by the first detector 321, the second detector 322, or the third detector 323. Also similar to scenario 310, in scenario 340, transmitter 302 may then emit a second light pulse 307. However, the difference between scenario 310 with a single detector 303 and scenario 340 with multiple detectors may be that multiple detectors can be used to provide more data about the detected reflected light than a single detector 303 can provide. For example, as described herein, it may be possible to selectively turn individual detectors on and / or off as the light pulse traverses the environment. Therefore, as the first light pulse 306 travels further away from the transmitter 302, the first detector 321, the second detector 322, and the third detector 323 can be selectively turned on and then off. To mitigate distance aliasing, instead of turning off the third detector 323 when it is determined that the return pulse originating from the first light pulse will exceed the field of view 236 of the third detector 323, the third detector can remain on even if the first light pulse 306 travels beyond the maximum detection range 305 of the detector.

[0037] Still continuing Figure 3Scene 340 shows the same second light pulse 307 being emitted from transmitter 302 before the first light pulse 306 is reflected from an object and detected by a detector. However, the difference here is that the lidar system now has two independent detectors monitoring two different distances from transmitter 302. That is, both the first detector 321, with a known field of view 324 closer to transmitter 302, and the third detector 323, with a known field of view 326 farther from transmitter 302, are now activated. Therefore, as shown in scene 340, if the first light pulse 306 subsequently reflects from an object in the environment (e.g., tree 308) and returns as a backlight 309 to the field of view 326 of the third detector 323, the third detector 323 can produce an output indicating that it detected the backlight at the same first time point described in scenes 301 and 310. In the example depicted in scenario 340, this first time could correspond to the time when the return light originating from the second light pulse 307 might be within the field of view 324 of the first detector 321 (therefore, the first detector 321 is shown as on). In this case, the system is then able to distinguish that the return light detected by the third detector 323 is associated with the first light pulse 306 rather than the second light pulse 307. Therefore, using this multi-detector configuration, the lidar system can track multiple light pulses simultaneously traversing the environment and reduces concerns that range aliasing will make it difficult to distinguish echoes from multiple emitted light pulses. Some of these features can double (or even more) the emission rate.

[0038] continue Figure 3It should be noted that Example 300 (specifically, scenarios 320 and 340 of Example 300) only depicts one example of how a multi-detector system can be used to mitigate or eliminate the distance aliasing problem. As another example of how the distance aliasing problem can be mitigated and / or eliminated by using multiple photodetectors, if the photodetectors are controlled to turn on and / or off based on predetermined time intervals as described above, the reflected light from objects beyond the maximum detection range of the lidar system may never be detected (this eliminates the possibility of distance aliasing). The reason for this can be illustrated as follows. In this example, a first light pulse is emitted. Then, the photodetectors are turned on and / or off in the order described above until the final photodetector (the one with the field of view furthest from the lidar system) is turned off (when any expected reflected light will come from outside the maximum detection range). A second light pulse is then emitted from the lidar system. If only one photodetector is always on, then the reflected light from the first light pulse may subsequently return and be detected by the photodetector. However, if multiple photodetectors are present, and each photodetector is only active for a given time interval, then the backlight detected by a given photodetector is more likely to originate from the second light pulse. That is, unless the backlight based on the first light pulse arrives in the field of view within the time interval during which a particular photodetector is active. Even if this does occur (the backlight from the first light pulse arrives in the field of view of a photodetector that is active), using multiple photodetectors still allows for the determination that the detected backlight may potentially originate from the first light pulse. In other words, if the backlight from the first light pulse returns and is detected by one of the active photodetectors, but the second light pulse has not yet been reflected back from the object to the photodetector, then the backlight from that pulse can be detected by the subsequently active photodetector. This means that the backlight from both pulses can be received, and the lidar system can therefore determine that at least one of the backlight detections is based on range aliasing. If this is the case, the lidar system can simply ignore both detected echoes. Example System Architecture

[0039] Figures 4A to 4B Example circuit configurations according to one or more example embodiments of this disclosure are depicted. Figures 4A to 4B The circuit configuration depicted can represent back-end circuitry connected to the detector's output. For example, this back-end circuitry can be used to preprocess the detector's output for any signal processing component of a lidar system (e.g., a system that can be determined based on calculations received from the detector). In some embodiments, Figure 4AA first circuit configuration 400 is depicted. In this first circuit configuration, individual detectors (e.g., detector 403, detector 404, and / or detector 405) may be associated with their own individual analog-to-digital converters (ADCs) (e.g., detector 403 may be associated with ADC 406, detector 404 with ADC 407, and detector 405 with ADC 408). The ADC can be used to convert analog signals into digital signals. That is, the ADC is capable of receiving the analog output of the detector as input and converting that analog signal into a digital signal. This digital signal can then be used by one or more signal processing components 410 of the lidar system. As a more specific example, the detector may be configured to receive one or more photons as input and provide a current as output. This current output may be in analog form, and the ADC can convert the analog current into a digital current value for use by one or more signal processing components 410.

[0040] In some embodiments, Figure 4B The second circuit configuration 420 is depicted. Although Figure 4A The first circuit configuration 400 shown includes multiple ADCs (e.g., one ADC per detector), but the second circuit configuration 420 may include only one ADC for all detectors (or alternatively, may include more than one ADC, but multiple detectors may share a single ADC instead of each individual detector being associated with its own ADC). That is, the second circuit configuration 420 may include the outputs of each detector that are provided as input to a single ADC. The ADC can then provide a digital output to one or more signal processing components 410, as is the case in the first circuit configuration 400. However, the second circuit configuration 420 may also include one or more additional components between the detectors and the ADC. For example, the second circuit configuration 420 may include a summer subcircuit 422. The summer subcircuit 422 may receive the outputs from one or more detectors and combine them into a single output. One or more attenuators may also exist before the summer (e.g., one attenuator for each detector output). Attenuators can be used to attenuate the detector outputs, which can be useful in many scenarios. For example, if all detectors are always on, attenuators can be used to attenuate the outputs of some detectors at certain times. For example, attenuation can be performed to attenuate the outputs of all but one detector. For example, this one detector may correspond to the field of view where the expected return light from the emitted light pulse will currently be located. Therefore, attenuators can be used to reduce the amount of detector output noise supplied to the ADC and signal processing component 410. Attenuators can also be used in other ways. For example, all detector outputs may remain unattenuated unless it is determined that it is desirable to block the outputs of one or more detectors. Explanatory methods

[0041] Figures 5A to 5B Example methods 500A and 500B according to one or more example embodiments of the present disclosure are shown.

[0042] exist Figure 5A At block 502a of method 500A, the method may include emitting a first optical pulse by an optical emitter of a lidar system. Block 504a of method 500A may include activating a first photodetector of the lidar system at a first time corresponding to the time when the return light corresponding to the first optical pulse will be located within a first field of view of the first photodetector. Block 506a of method 500A may include activating a second photodetector of the lidar system at a second time corresponding to the time when the return light corresponding to the first optical pulse will be located within a second field of view of the second photodetector, wherein the first photodetector is configured to include a first field of view associated with a first range of the optical emitter, and wherein the second photodetector is configured to include a second field of view associated with a second range of the optical emitter.

[0043] exist Figure 5B At block 502b of method 500B, the method may include emitting a first light pulse by a light emitter at a first time. Block 504b of method 500B may include activating a first photodetector and a second photodetector, wherein the field of view of the first photodetector includes a range closer to the light emitter than the field of view of the second photodetector. Block 506b of method 500B may include emitting a second light pulse by a light emitter at a second time. Block 508b of method 500B may include receiving a return light by the second photodetector at a third time. Block 510 of method 500B may include determining the return light based on the first light pulse based on the return light detected by the second photodetector.

[0044] In some embodiments, the photodetector can be selectively “on” and / or “off” (this can be similarly referred to as “activating” or “deactivating” the photodetector). “On” the photodetector can mean providing a bias voltage to the photodetector that satisfies a threshold voltage level. A bias voltage that satisfies the threshold voltage level (e.g., at or above the threshold voltage level) can provide sufficient voltage to the photodetector to allow it to generate an output current level based on the light received by the photodetector. The output threshold voltage level used and the corresponding output current generated can depend on the type of photodetector used and the desired operating mode of the photodetector. For example, if the photodetector is an APD, the threshold voltage level can be set high enough that the photodetector can avalanche upon receiving light, as described above. Similarly, if it is desired that the APD operate in Geiger mode, the threshold voltage level can be set even higher than if it is desired that the APD operate outside the Geiger mode operating region. That is, when this higher threshold voltage level is applied, the gain of the photodetector can be much greater than when the photodetector operates as a normal avalanche photodiode. Furthermore, if the photodetector is not an APD and operates in linear mode, where the output current generated based on a similar amount of detection light can be much lower than when the photodetector is an APD, then the threshold bias voltage can be even lower. Additionally, even if the photodetector is an APD, the threshold voltage level can be set lower than the threshold voltage level used to allow the APD to avalanche when it receives light. That is, the bias voltage applied to the APD can be set low enough to allow the APD to still generate output current, but only in linear mode.

[0045] Similarly, in some embodiments, "turning off" the photodetector can refer to reducing the bias voltage supplied to the photodetector below a threshold voltage level. In some cases, "turning off" the photodetector does not necessarily mean that the photodetector cannot detect backlight. That is, when the bias voltage is below the threshold voltage level, the photodetector may still be able to detect backlight, but the output signal generated by the photodetector may be lower than the noise floor established for the signal processing section of the lidar system. As a non-limiting example, the photodetector may be an avalanche photodiode. If a sufficiently large bias voltage is provided to allow the APD to avalanche when receiving light, the APD can produce a large current output. However, if a lower bias voltage is applied, the APD may still produce an output, but the output may be based on a linear operating mode, and the resulting output current may be much lower than that obtained when the APD avalanches when receiving the same number of photons. The signal processing section of the lidar system may have a noise floor configured to correspond to the output of the APD in linear mode, such that when operating with this reduced bias voltage, any output from the APD can be effectively ignored by the lidar system. Therefore, selectively turning photodetectors on and / or off may result in only some photodetectors being able to detect the backlight at a given time.

[0046] In various exemplary embodiments of this disclosure, the operations described and depicted in the illustrative process flow of FIG5 can be performed or executed in any suitable order as needed. Furthermore, in some exemplary embodiments, at least some operations can be performed in parallel. Additionally, in some exemplary embodiments, fewer, more, or different operations than those shown in FIG5 can be performed. Example LiDAR system configuration

[0047] Figure 6 An example lidar system 600 according to one or more embodiments of the present disclosure is shown. The lidar system 600 can represent any number of elements described herein, such as those for... Figure 1 The lidar system 601 described herein, as well as any other lidar system described herein, may include at least a transmitter section 601, a detector section 605, and a computing section 613.

[0048] In some embodiments, the emitter portion 601 may include at least one or more emitters 602 (hereinafter referred to as “emitter” for simplicity, but multiple emitters may be equally applicable) and / or one or more optical elements 604. The emitter 602 may be a device capable of emitting light into the environment. Once in the environment, the light can travel toward the object 612. The light can then be reflected from the object and returned to the lidar system 600, and detected by the detector portion 605 of the lidar device 600, as described below. For example, the emitter 602 may be a laser diode as described above. The emitter 602 may be capable of emitting light as a continuous waveform or as a series of pulses. The optical element 604 may be an element that can be used to modify the emitted light before it enters the environment from the emitter 602. For example, the optical element 604 may be a lens, collimator, or waveplate. In some cases, a lens may be used to focus the emitter light. A collimator may be used to collimate the emitted light. That is, a collimator may be used to reduce the divergence of the emitted light. A waveplate may be used to change the polarization state of the emitted light. Any number or combination of different types of optical elements 604 can be used in the lidar system 600, including optical elements not listed herein.

[0049] In some embodiments, detector section 605 may include at least one or more detectors 606 (hereinafter referred to as "detector" for simplicity, but multiple detectors may be equally applicable) and / or one or more optical elements 608. The detector may be a device capable of detecting backlight from the environment (e.g., light already emitted by lidar system 600 and reflected by object 612). For example, the detector may be a photodiode. A photodiode may specifically include an avalanche photodiode (APD), which in some cases can operate in Geiger mode. However, any other type of detector may be used, such as light-emitting diodes (LEDs), vertical-cavity surface-emitting lasers (VCSELs), organic light-emitting diodes (OLEDs), polymer light-emitting diodes (PLEDs), light-emitting polymers (LEPs), liquid crystal displays (LCDs), microelectromechanical systems (MEMS), and / or any other device configured to selectively transmit, reflect, and / or emit light to provide multiple emitted beams and / or pulses. Typically, arrays of detectors can take various forms. For example, the detector can take the form of a photodiode, an avalanche photodiode (e.g., a Geiger-mode and / or linear-mode avalanche photodiode), a phototransistor, a camera, an active pixel sensor (APS), a charge-coupled device (CCD), a cryogenic detector, and / or any other optical sensor configured to receive focused light with wavelengths within the wavelength range of the emitted light. The functionality of detector 606 in capturing backlight from the environment can be used to enable lidar system 600 to determine information about object 612 in the environment. That is, lidar system 600 is able to determine information such as the distance of the object from the lidar system and the shape and / or size of object 612, as well as other information. Optical element 608 can be an element used to modify the backlight traveling toward detector 606. For example, optical element 608 can be a lens, a waveplate, or a filter such as a bandpass filter. In some cases, a lens can be used to focus the backlight onto detector 606. A waveplate can be used to change the polarization state of the backlight. A filter can be used to allow only light of a specific wavelength to reach the detector (e.g., the wavelength of light emitted by emitter 602). Any number or combination of different types of optical elements 608 can be used in the lidar system 600, including optical elements not listed herein.

[0050] In some embodiments, the computing portion may include one or more processors 614 and memory 616. Processor 614 may execute instructions stored in one or more memory devices (referred to as memory 616). For example, the instructions may be instructions for implementing functions described as being performed by one or more modules and systems disclosed above, or instructions for implementing one or more methods disclosed above. Processor 614 may be embodied in, for example, a CPU, multiple CPUs, a GPU, multiple GPUs, a TPU, multiple TPUs, a multi-core processor, a combination thereof, etc. In some embodiments, processor 614 may be arranged in a single processing device. In other embodiments, processor 614 may be distributed across two or more processing devices (e.g., multiple CPUs; multiple GPUs; a combination thereof; etc.). A processor may be implemented as a combination of processing circuitry or computing units (e.g., CPU, GPU, or a combination of both). Therefore, for ease of description, a processor may refer to a single-core processor; a single processor with software multithreading capabilities; a multi-core processor; a multi-core processor with software multithreading capabilities; a multi-core processor employing hardware multithreading technology; a parallel processing (or computing) platform; and a parallel computing platform with distributed shared memory. In addition, or as another example, a processor may refer to an integrated circuit (IC), an ASIC, a digital signal processor (DSP), an FPGA, a PLC, a complex programmable logic device (CPLD), discrete gate or transistor logic, discrete hardware components, or any combination thereof, which is designed or otherwise configured (e.g., manufactured) to perform the functions described herein.

[0051] Processor 614 can access memory 616 via a communication architecture (e.g., a system bus). The communication architecture can be tailored to a specific arrangement (local or distributed) and type of processor 614. In some embodiments, communication architecture 606 may include one or more bus architectures, such as a memory bus or memory controller; a peripheral bus; an accelerated graphics port; a processor or local bus; combinations thereof; and so on. For example, such architectures may include an Industry Standard Architecture (ISA) bus, a Micro Channel Architecture (MCA) bus, an Enhanced ISA (EISA) bus, a Video Electronics Standards Association (VESA) local bus, an Accelerated Graphics Port (AGP) bus, a Peripheral Component Interconnect (PCI) bus, a PCI Express bus, a Personal Computer Memory Card International Association (PCMCIA) bus, a Universal Serial Bus (USB), and so on.

[0052] The memory components or memory devices disclosed herein may be embodied in volatile or non-volatile memory, or may include both volatile and non-volatile memory. Furthermore, the memory components or memory devices may be removable or non-removable, and / or located internally or externally to a computing device or component. Examples of various types of non-transitory storage media may include hard disk drives, zip drives, CD-ROMs, digital versatile discs (DVDs) or other optical storage devices, magnetic tape cassettes, magnetic tapes, disk storage devices or other magnetic storage devices, flash memory cards or other types of memory cards, cassette tapes, or any other non-transitory media suitable for retaining desired information and accessible by a computing device.

[0053] As an example, non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory may include random access memory (RAM) used as external cache memory. By way of illustration and not limitation, RAM has many available forms, such as synchronous RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), and direct Rambus RAM (DRRAM). The memory devices or memories disclosed herein for the operating or computing environment described herein are intended to include one or more of these memories and / or any other suitable types of memory. In addition to storing executable instructions, memory 616 may also hold data.

[0054] Each computing device 600 may also include a mass memory 617 accessible by the processor 614 via a communication architecture 606. The mass memory 617 may include machine-accessible instructions (e.g., computer-readable instructions and / or computer-executable instructions). In some embodiments, the machine-accessible instructions may be encoded in the mass memory 617 and may be arranged in components that can be constructed (e.g., linked and compiled) and stored in the mass memory 617 in a computer-executable form or stored in one or more other machine-accessible non-temporary storage media included in the computing device 600. Such components may embody or constitute one or more of the various modules disclosed herein. Such a module is illustrated as a multi-detector control module 620.

[0055] The multi-detector control module 620 includes computer-executable instructions, code, etc., which, in response to execution by one or more processors 614, can perform functions as described herein, including controlling one or more detectors. For example, this document describes turning any detector on and / or off. Furthermore, these functions may include the execution of any other methods and / or processes described herein.

[0056] It should be further understood that, without departing from the scope of this disclosure, the lidar system 600 may include alternative and / or additional hardware, software, or firmware components beyond those described or depicted. More specifically, it should be understood that the software, firmware, or hardware components depicted as forming part of the computing device 600 are merely illustrative, and some components may be absent or additional components may be provided in various embodiments. While various illustrative program modules have been depicted and described as software modules stored in data memory, it should be understood that the functionality described as being supported by program modules can be implemented by any combination of hardware, software, and / or firmware. It should be further understood that, in various embodiments, each of the above modules may represent a logical division of supported functionality. This logical division is described for ease of interpretation of the functionality and may not represent the structure of the software, hardware, and / or firmware used to implement the functionality. Therefore, it should be understood that, in various embodiments, the functionality described as being provided by a particular module may be provided at least partially by one or more other modules. Furthermore, in some embodiments, one or more described modules may not be present, while in other embodiments, additional modules not described may be present, and these additional modules may support at least a portion of the described functionality and / or additional functionality. Furthermore, while some modules may be described and depicted as submodules of another module, in some embodiments, such modules may be provided as independent modules or submodules of other modules.

[0057] Although specific embodiments of this disclosure have been described, those skilled in the art will recognize that many other modifications and alternative embodiments are within the scope of this disclosure. For example, any functionality and / or processing capabilities described for a particular device or component can be performed by any other device or component. Furthermore, although various illustrative implementations and architectures have been described with reference to embodiments of this disclosure, those skilled in the art will understand that many other modifications to the illustrative implementations and architectures described herein are also within the scope of this disclosure.

[0058] The foregoing description of certain aspects of this disclosure is based on block diagrams and flowcharts of systems, methods, apparatuses, and / or computer program products according to exemplary embodiments. It should be understood that one or more blocks in the block diagrams and flowcharts, as well as combinations of blocks in the block diagrams and flowcharts, can be implemented by executing computer-executable program instructions, respectively. Similarly, according to some embodiments, some blocks in the block diagrams and flowcharts may not necessarily need to be executed in the presented order, or may not need to be executed at all. Furthermore, in some embodiments, additional components and / or operations may be present beyond those shown in the blocks of the block diagrams and / or flowcharts.

[0059] Therefore, the boxes in block diagrams and flowcharts support combinations of components for performing a specified function, combinations of elements or steps for performing a specified function, and program instruction components for performing a specified function. It will also be understood that each box in a block diagram and flowchart, and combinations of boxes in block diagrams and flowcharts, can be implemented by a dedicated, hardware-based computer system, or a combination of dedicated hardware and computer instructions, that performs the specified function, element, or step.

[0060] The contents described in this specification and accompanying drawings include examples of systems, devices, technologies, and computer program products that, individually or in combination, allow for the automatic provision of updates to vehicle profile packages. Of course, for the purpose of describing the various elements of this disclosure, it is impossible to describe every conceivable combination of components and / or methods; however, it will be appreciated that many further combinations and arrangements of the disclosed elements are possible. Therefore, it will be apparent that various modifications can be made to this disclosure without departing from the scope or spirit of this disclosure. Furthermore, or alternatively, other embodiments of this disclosure may become apparent by considering the specification and accompanying drawings and the practice of the disclosure presented herein. The examples presented in the specification and accompanying drawings are intended to be illustrative and not restrictive in all respects. Although specific terms are used herein, they are used only in a general and descriptive sense and not for limiting purposes.

[0061] As used herein, the terms “environment,” “system,” “unit,” “module,” “architecture,” “interface,” “component,” etc., refer to entities related to a computer or to an operating device having one or more defined functions. The terms “environment,” “system,” “module,” “component,” “architecture,” “interface,” and “unit” are used interchangeably and can collectively refer to functional elements. Such entities can be hardware, a combination of hardware and software, software, or software in execution. For example, a module can be embodied in a process running on a processor, a processor, an object, an executable portion of software, a thread of execution, a program, and / or a computing device. As another example, both a software application executing on a computing device and the computing device itself can embody a module. As yet another example, one or more modules can reside within a process and / or a thread of execution. A module can be located on a single computing device or distributed across two or more computing devices. As disclosed herein, a module can be executed from various computer-readable non-transitory storage media on which various data structures are stored. Modules can communicate via local and / or remote processes based on signals (analog or digital) having one or more data packets, for example (e.g., data from a component that interacts with a local system, another component in a distributed system, and / or interacts with other systems via the signal through a network such as a wide area network).

[0062] As yet another example, a module can be embodied in or can include a device having defined functions provided by mechanical components operated by electrical or electronic circuitry controlled by a software or firmware application executed by a processor. Such a processor can be internal or external to the device and can execute at least a portion of the software or firmware application. Still in another example, a module can be embodied in or can include a device providing defined functions through electronic components without mechanical components. The electronic components can include a processor for executing software or firmware that at least partially allows or otherwise facilitates the functionality of the electronic components.

[0063] In some embodiments, the module may communicate via local and / or remote processes based on signals (analog or digital) having one or more data packets (e.g., data from a component interacting with another component in a local system, a distributed system, and / or interacting with other systems via the signal through a network such as a wide area network). Furthermore, or in other embodiments, the module may communicate or be otherwise coupled via thermal, mechanical, electrical, and / or electromechanical coupling mechanisms (e.g., conduits, connectors, combinations thereof). The interface may include input / output (I / O) components and associated processors, applications, and / or other programming components.

[0064] Furthermore, in this specification and accompanying drawings, terms such as “storage,” “storage device,” “data storage,” “data storage apparatus,” “memory,” “repository,” and any other information storage component substantially related to the operation and function of the components of this disclosure, refer to a memory component, an entity embodied in one or more memory devices, or a component forming a memory device. Note that the memory components or memory devices described herein are embodied in or include non-transitory computer storage media that are readable or otherwise accessible by a computing device. Such media can be implemented using any method or technique for storing information, such as machine-accessible instructions (e.g., computer-readable instructions), information structures, program modules, or other information objects.

[0065] Conditional languages, such as "can," "could," "might," or "may," are generally intended to convey, unless otherwise specified or understood in the context of their use, that certain implementations may include certain features, elements, and / or operations, while others may not. Therefore, such conditional languages ​​are not typically intended to imply that features, elements, and / or operations are necessary for one or more implementations in any given way, or that one or more implementations necessarily include logic for determining whether such features, elements, and / or operations are included or to be performed in any particular implementation, with or without user input or prompts.

Claims

1. A method for mitigating distance aliasing, comprising: The first light pulse is emitted by the light emitter at the first moment; Activate a first photodetector, wherein the field of view of the first photodetector is associated with a first range from the light emitter, and the activation of the first photodetector corresponds to the time when the return light corresponding to the first light pulse is within the field of view of the first photodetector. Activate a second photodetector, wherein the field of view of the second photodetector is associated with a second range from the light emitter, the second range being farther from the light emitter than the first range, and the activation of the second photodetector corresponds to the time when the return light corresponding to the first light pulse is within the field of view of the second photodetector; The light emitter emits a second light pulse at a second time, wherein the second light pulse is emitted before the backlight based on the first light pulse is detected, so that the first light pulse and the second light pulse travel through the environment simultaneously; The second photodetector receives the return light at a third time; and The second photodetector detects the backlight and determines that the backlight is based on the first light pulse.

2. The method according to claim 1, wherein, Activating the first photodetector further includes providing a first bias voltage to the first photodetector, and activating the second photodetector further includes providing a second bias voltage to the second photodetector.

3. The method according to claim 2, wherein, The first bias voltage is provided to the first photodetector at a second time, and the second bias voltage is provided to the second photodetector at a third time, the second time corresponding to the time when the backlight based on the first light pulse will be within the field of view of the first photodetector, and the third time corresponding to the time when the backlight based on the first light pulse will be within the field of view of the second photodetector.

4. The method according to claim 1, wherein, The determination of the reflected light is based on the first light pulse or on the fact that the first photodetector is activated at the third time.

5. The method according to claim 1, further comprising: It is determined that the first photodetector detected the second backlight at the third time. as well as The second backlight detected by the first photodetector is determined to be based on the second light pulse, based on the second photodetector detecting the backlight at the third time.

6. The method according to claim 1, wherein, The second photodetector detects the backlight before detecting the backlight based on the second light pulse.

7. A non-transitory computer-readable medium comprising computer-executable instructions stored thereon, the instructions, when executed by one or more processors of a wireless access point, causing the one or more processors to perform the following operations: This enables the light emitter to emit the first light pulse at the earliest possible moment. Activate the first photodetector, where, The field of view of the first photodetector is associated with a first range from the light emitter, and the activation of the first photodetector corresponds to the time when the return light corresponding to the first light pulse is within the field of view of the first photodetector. Activate a second photodetector, wherein the field of view of the second photodetector is associated with a second range from the light emitter, the second range being farther from the light emitter than the first range, and the activation of the second photodetector corresponds to the time when the return light corresponding to the first light pulse is within the field of view of the second photodetector; The light emitter emits a second light pulse at a second time, wherein the second light pulse is emitted before the backlight based on the first light pulse is detected, so that the first light pulse and the second light pulse travel through the environment simultaneously; It is determined that the second photodetector detects the backlight at the third time; and The second photodetector detects the backlight to determine that the backlight is based on the first light pulse.

8. The non-transitory computer-readable medium according to claim 7, wherein, Activating the first photodetector further includes providing a first bias voltage to the first photodetector, and activating the second photodetector further includes providing a second bias voltage to the second photodetector.

9. The non-transitory computer-readable medium according to claim 8, wherein, The first bias voltage is provided to the first photodetector at a second time, and the second bias voltage is provided to the second photodetector at a third time, the second time corresponding to the time when the backlight based on the first light pulse will be within the field of view of the first photodetector, and the third time corresponding to the time when the backlight based on the first light pulse will be within the field of view of the second photodetector.

10. The non-transitory computer-readable medium according to claim 7, wherein, The determination of the reflected light is based on the first light pulse and also on the determination that the first photodetector is activated at the third time.

11. The non-transitory computer-readable medium according to claim 7, wherein, The computer-executable instructions also cause the one or more processors to perform the following operations: It is determined that the first photodetector detected the second backlight at the third time; and The second backlight detected by the first photodetector is determined to be based on the second light pulse, based on the second photodetector detecting the backlight at the third time.

12. The non-transitory computer-readable medium according to claim 7, wherein, The second photodetector detects the backlight before detecting the backlight based on the second light pulse.

13. A system for mitigating distance aliasing, comprising: An optical transmitter configured to emit a first optical pulse and a second optical pulse; A first photodetector is configured to point in a first direction and have a first field of view, the first field of view being associated with a first range from the light emitter; A second photodetector is configured to point in a second direction and have a second field of view, the first field of view being associated with a second range from the light emitter; processor; as well as A memory that stores computer-executable instructions that, when executed by the processor, cause the processor to: This enables the light emitter to emit the first light pulse at the earliest possible moment. Activate a first photodetector, wherein the activation of the first photodetector corresponds to the time when the return light corresponding to the first light pulse is located within a first field of view of the first photodetector, and the first field of view is associated with a first range from the light emitter; Activate the second photodetector, wherein the activation of the second photodetector corresponds to the time when the return light corresponding to the first light pulse is located within the second field of view of the second photodetector, and the second range is farther from the light emitter than the first range; Wherein, the first field of view of the first photodetector includes a range that is closer to the light emitter than the second field of view of the second photodetector; The light emitter emits a second light pulse at a second time, wherein the second light pulse is emitted before the backlight based on the first light pulse is detected, so that the first light pulse and the second light pulse travel through the environment simultaneously for a period of time; It is determined that the second photodetector detects the backlight at the third time; and The second photodetector detects the backlight to determine that the backlight is based on the first light pulse.

14. The system according to claim 13, wherein, Activating the first photodetector further includes providing a first bias voltage to the first photodetector, and activating the second photodetector further includes providing a second bias voltage to the second photodetector.

15. The system according to claim 14, wherein, The first bias voltage is provided to the first photodetector at a second time, and the second bias voltage is provided to the second photodetector at a third time, the second time corresponding to the time when the backlight based on the first light pulse will be within the field of view of the first photodetector, and the third time corresponding to the time when the backlight based on the first light pulse will be within the field of view of the second photodetector.

16. The system according to claim 13, wherein, The determination of the reflected light is based on the first light pulse and also on the determination that the first photodetector is activated at the third time.

17. The system according to claim 13, wherein, The computer-executable instructions also cause the processor to perform the following operations: It is determined that the first photodetector detected the second backlight at the third time; and The second backlight detected by the first photodetector is determined to be based on the second light pulse, based on the second photodetector detecting the backlight at the third time.

18. The system according to claim 13, wherein, The second photodetector detects the backlight before detecting the backlight based on the second light pulse.

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