WO2023155093A1 - 探测装置及探测方法 - Google Patents

探测装置及探测方法 Download PDF

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Publication number
WO2023155093A1
WO2023155093A1 PCT/CN2022/076593 CN2022076593W WO2023155093A1 WO 2023155093 A1 WO2023155093 A1 WO 2023155093A1 CN 2022076593 W CN2022076593 W CN 2022076593W WO 2023155093 A1 WO2023155093 A1 WO 2023155093A1
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Prior art keywords
signal
laser pulse
laser
width
detection
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PCT/CN2022/076593
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English (en)
French (fr)
Inventor
阳光耀
石现领
黄志臻
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华为技术有限公司
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Priority to CN202280005988.3A priority Critical patent/CN116917761A/zh
Priority to PCT/CN2022/076593 priority patent/WO2023155093A1/zh
Publication of WO2023155093A1 publication Critical patent/WO2023155093A1/zh

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
    • G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
    • G01S17/06—Systems determining position data of a target
    • G01S17/08—Systems determining position data of a target for measuring distance only
    • G01S17/10—Systems determining position data of a target for measuring distance only using transmission of interrupted, pulse-modulated waves
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/483—Details of pulse systems
    • G01S7/486—Receivers
    • G01S7/4865—Time delay measurement, e.g. time-of-flight measurement, time of arrival measurement or determining the exact position of a peak

Definitions

  • Embodiments of the present application provide a detection device and a detection method, which are beneficial to improving a signal-to-noise ratio, thereby improving detection accuracy.
  • a detection device including: a first laser emitter, used to emit a first laser pulse signal; a first photodetector, used to respectively accumulate the responses in one or more first time windows The charge generated by the first echo signal is obtained according to the charges accumulated in one or more first time windows respectively, and the first sampling sequence is obtained, the first echo signal includes the reflection signal of the first laser pulse signal, and the first sampling sequence is used for target detection.
  • the photoelectric detection is realized based on the cyclic method of "photogenerated charge accumulation-readout".
  • the sampling value obtained through charge accumulation is relatively large, which can provide sufficient photoelectric conversion gain and avoid introducing obvious noise.
  • the photoelectric conversion element in the photodetector is not limited by the photoelectric conversion gain condition, so that the photoelectric conversion element with higher quantum efficiency can be used, which is beneficial to reduce the influence of background light shot noise, improve the signal-to-noise ratio, and thus improve the detection efficiency. performance.
  • conventional photodiodes do not have any photoelectric conversion gain, and too much noise will be introduced in the subsequent processing process, which will affect the detection performance.
  • the scheme of the embodiment of this application adopts a cycle based on "photogenerated charge accumulation-readout"
  • Photoelectric detection can be achieved by means of photoelectric detection, which can provide sufficient photoelectric conversion gain.
  • the photodiode without gain can also be used as the photoelectric conversion element in the photodetector.
  • the quantum efficiency of the photodiode is high, which is conducive to reducing background light dispersion
  • the effect of particle noise can be improved, the signal-to-noise ratio can be improved, and the detection performance can be improved.
  • the first photodetector may be a photodiode using a floating diffusion amplification principle.
  • a larger sampling value is obtained by amplifying the value of the electrical signal, thereby reducing the influence of noise and improving detection accuracy.
  • the ratio between the charge derivation time and the width of the first time window is less than or equal to the first threshold.
  • the charge derivation time is much shorter than the width of the time window.
  • the width of the first time window is adjustable.
  • the difference between the pulse width of the first laser pulse signal and an integer multiple of the width of the first time window is less than or equal to the second threshold.
  • matching the pulse width and the width of the time window reduces the proportion of received background light noise and improves the signal-to-noise ratio, which is beneficial to realize high-precision detection.
  • the photoelectric conversion gain of the photodetector is greater than or equal to the fifth threshold.
  • the midpoint of the reflected signal is the midpoint of the time window corresponding to the valid sampling point.
  • the signal value of a valid sampling point is greater than the sampling threshold.
  • the pulse width of the laser pulse signal is equal to the width of the time window
  • the sampling sequence includes two effective sampling points
  • the middle point of the reflected signal falls In the time window corresponding to the effective sampling point with a larger signal value; when the signal values of the two effective sampling points are the same, the middle point of the reflected signal is the dividing point of the time window corresponding to the two effective sampling points.
  • t 1 represents the end moment of the time window corresponding to the first effective sampling point among the two effective sampling points
  • ⁇ t window represents the width of the time window
  • K represents the difference between the signal value of the first effective sampling point and the second The result of the ratio determination between the signal values of the valid sample points.
  • the first valid sampling point refers to the valid sampling point that is located before other valid sampling points in time.
  • K may be a result obtained after adjusting a ratio between signal values through an arctan function.
  • the arctan function is used to adjust the ratio between the signal values, so as to reduce the influence of the extreme value on the ranging result, improve the accuracy of the calculation result, and ensure the detection precision.
  • the detecting device 400 may further include a parity check circuit, and the parity check circuit is used to output the first subsequence and the second subsequence.
  • the first aspect further includes: a second laser emitter, configured to: emit a second laser pulse signal, the pulse interval or pulse width of the second laser pulse signal is the same as that of the first laser pulse signal
  • the pulse signals are different; the second photodetector is used for: respectively accumulating charges generated in response to the second echo signal in one or more second time windows, according to the respectively accumulated charges in one or more second time windows A second sampling sequence is obtained, the second echo signal includes a reflection signal of the second laser pulse signal, and the second sampling sequence or the first sampling sequence is used for target detection.
  • the modulation format can be adjusted so that at least one modulation format exists, so that the echo signal corresponding to the laser pulse signal does not have the problem of pulse self-overlapping.
  • the photoelectric detection is realized based on the cyclic method of "photogenerated charge accumulation-readout".
  • the sampling value obtained through charge accumulation is relatively large, which can provide sufficient photoelectric conversion gain and avoid introducing obvious noise.
  • the photoelectric conversion element in the photodetector is not limited by the photoelectric conversion gain condition, so that the photoelectric conversion element with higher quantum efficiency can be used, which is beneficial to reduce the influence of background light shot noise, improve the signal-to-noise ratio, and thus improve the detection efficiency. performance.
  • conventional photodiodes do not have any photoelectric conversion gain, and too much noise will be introduced in the subsequent processing process, which will affect the detection performance.
  • the scheme of the embodiment of this application adopts a cycle based on "photogenerated charge accumulation-readout"
  • Photoelectric detection can be achieved by means of photoelectric detection, which can provide sufficient photoelectric conversion gain.
  • the photodiode without gain can also be used as the photoelectric conversion element in the photodetector.
  • the quantum efficiency of the photodiode is high, which is conducive to reducing background light dispersion
  • the effect of particle noise can be improved, the signal-to-noise ratio can be improved, and the detection performance can be improved.
  • the difference between the pulse width of the first laser pulse signal and an integer multiple of the width of the first time window is less than or equal to the second threshold.
  • the difference between the pulse width of the first laser pulse signal and the width of the first time window is less than or equal to the second threshold.
  • a ratio between signal values in the first sampling sequence is used for target detection.
  • the first laser pulse signal includes multiple pulses.
  • the processing unit is configured to send second control information, where the second control information is used to indicate the width of the first time window.
  • the terminal may be a vehicle, for example, a smart transportation device (vehicle or drone), smart home device, smart manufacturing device, surveying and mapping device, or robot.
  • the intelligent transport device may be, for example, an automated guided vehicle (AGV) or an unmanned transport vehicle.
  • the terminal can also be a mobile phone, a tablet computer (Pad), a computer with a wireless transceiver function, a virtual reality (virtual reality, VR) terminal, an augmented reality (augmented reality, AR) terminal, an industrial control (industrial control) Terminals in self driving, terminals in remote medical, terminals in smart grid, terminals in transportation safety, smart city ), a terminal in a smart home (smart home), and the like.
  • FIG. 7 is a schematic diagram of a correspondence between a reflection signal, a time window, and a sampling sequence provided in an embodiment of the present application;
  • FIG. 8 is a schematic diagram of a laser pulse signal provided by an embodiment of the present application.
  • FIG. 9 is a schematic diagram of a parity check circuit provided in an embodiment of the present application.
  • FIG. 10 is a schematic diagram of a processing flow of a parity sampling sequence provided by an embodiment of the present application.
  • FIG. 12 is a schematic diagram of an echo signal provided by an embodiment of the present application.
  • connection in this application can be understood as the physical contact and electrical conduction of components; it can also be understood as the connection between different components in the circuit structure through printed circuit board (printed circuit board, PCB) copper foil or wires It can also be understood as the form of electrical connection through indirect coupling.
  • connection can refer to a mechanical or physical connection relationship.
  • the connection between A and B or the connection between A and B can mean that there are fastening components (such as screws, bolts, etc.) between A and B. rivets, etc.), or A and B are in contact with each other and A and B are difficult to separate.
  • lidar can be applied in various fields such as automatic driving system, advanced driver assistance system (advanced driver assistance system, ADAS), robot or drone.
  • automatic driving system advanced driver assistance system (advanced driver assistance system, ADAS), robot or drone.
  • advanced driver assistance system advanced driver assistance system
  • robot robot or drone.
  • ADAS relies on the cooperation of computer vision, radar, monitoring devices and global positioning systems to detect the surrounding environment during vehicle driving, collect data, identify objects, and combine the navigator map data to carry out systematic monitoring. Calculation and analysis, so that the driver can be aware of possible dangers, effectively increasing driving safety and comfort.
  • LiDAR the highly reliable long-distance and high-precision measurement of the external environment is usually completed by LiDAR.
  • the application of the laser radar to the vehicle is used as an example for illustration, and the application scenario in the embodiment of the present application is not limited.
  • the lidar of the embodiment of the present application can also be applied to other scenarios that require ranging or space modeling, and is suitable for scenarios that require high device stability, channel isolation, and the like.
  • the lidar in the embodiment of the present application can be used as a vehicle-mounted LiDAR or an airborne LiDAR to implement surveying and mapping or remote sensing technologies.
  • LiDAR mostly uses TOF to achieve ranging.
  • Time of flight refers to the time between the moment when the laser signal is emitted to the target and the moment when the reflected signal is received after being reflected by the target.
  • the distance between the target and the detection device can be determined by TOF and the speed of light.
  • FIG. 2 shows a schematic diagram of a ranging principle of a laser radar.
  • the laser pulse signal generated by the pulse laser is transmitted to the target through the optics, and the reflected signal reflected by the target is converged to the single photon avalanche photodiode (single photon avalanche) through the optics.
  • the photodiode (SPAD) array that is, the SPADs in Figure 2, converts the optical signal into an electrical signal by the SPADs, and the electrical signal is processed by the front end circuit and then input to the time-to-digital converter (time to digital converter, TDC) ), to obtain the flight time ⁇ T.
  • TDC time to digital converter
  • the measurement accuracy of the lidar will be affected by the signal noise ratio (SNR), pulse width and sampling rate.
  • SNR signal noise ratio
  • an avalanche photo-detector (APD) array is used as a photodetector, although it has a high quantum efficiency, the cost is too high and it is difficult to prepare the array on a large scale. Amplifies background light shot noise.
  • APD avalanche photo-detector
  • the detection device in the embodiment of the present application can be applied to various fields such as intelligent driving, intelligent transportation, intelligent manufacturing, environmental monitoring, surveying and mapping, and unmanned aerial vehicles, and completes target detection tasks such as distance measurement, speed measurement, target tracking, and imaging recognition. one or more of .
  • the detection device in the embodiment of the present application can be used as a vehicle-mounted detection device (eg, vehicle-mounted LiDAR) or an airborne detection device (eg, airborne LiDAR), etc., or as a detection device on a robot or a base station.
  • vehicle-mounted detection device eg, vehicle-mounted LiDAR
  • airborne detection device eg, airborne LiDAR
  • This application does not limit the installation position of the detection device.
  • Photodetectors are used to realize photodetection.
  • a photodetector includes a photoelectric conversion element. External photons incident on the photoelectric conversion element can excite free electrons on the photoelectric conversion element, and the free electrons form a current under the influence of an external electric field or a built-in electric field to complete subsequent detection.
  • a photoelectric conversion element may also be called a photodetection device.
  • photoelectric conversion elements are mainly divided into three categories: SPAD, avalanche photodiode (photon avalanche photodiode, PAD) and ordinary photodiode (photodiode, PD).
  • SPAD photon avalanche photodiode
  • PAD photon avalanche photodiode
  • PD ordinary photodiode
  • a photodetector using a single-photon detection photodiode as a photoelectric conversion element may also be called a single-photon avalanche photodetector.
  • a photodetector using an avalanche diode as a photoelectric conversion element may also be called an avalanche photodetector.
  • the basic working mechanism of a photodetector is that an optical signal is injected into a photoelectric conversion element, and the photoelectric conversion element generates a photogenerated charge, and forms a photogenerated current under the influence of a built-in potential difference or an external built-in potential difference to complete photoelectric detection.
  • One end of the photoelectric conversion element is floated, and the photogenerated charge generated in it enters a small capacitor through a bias voltage to complete signal amplification.
  • the light source unit 310 is used to receive the electric driving signal provided by the driving unit 320 and generate a corresponding laser pulse signal, that is, a transmission signal, as the light source of the laser radar 300 .
  • the light source unit 310 may be a light emitting device such as a laser diode, a vertical cavity surface emitting laser, or a distributed feedback laser diode. This embodiment of the present application does not limit it.
  • the driving unit 320 is used for generating an electric driving signal to provide to the light source unit 310 .
  • the electric drive signal may be a modulated current pulse signal.
  • Photodetectors can be used to receive echo signals in a time window and convert them into electrical signals.
  • the photodetector in the photodetection unit 330 may be the photodetector 420 in the embodiment of the present application. For specific description, refer to the description of the photodetector 420 below.
  • the analog-to-digital converter is used to complete the analog-to-digital conversion, that is, to convert the electrical signal output by the photodetector into a digital signal.
  • the processing and control unit 340 is used for providing a driving control signal to the driving unit 320 so that the driving unit 320 generates an electric driving signal.
  • the processing and control unit 340 is also used to provide a detection control signal for the photodetection unit 330 , so that the photodetection unit 330 receives the light signal in a time window, and provides an output result to the processing and control unit 340 .
  • the processing and control unit 340 processes the output result of the photoelectric detection unit 330 to obtain a detection result.
  • the detection result may include a TOF value or point cloud data.
  • the embodiment of the present application does not limit the form of the detection result.
  • the optical structure 350 is used for converging the laser pulse signal of the light source into a collimated beam to complete spatial scanning, and converging the echo signal to the photoelectric detection unit 330 .
  • the echo signal includes the light pulse signal reflected by the target, that is, the reflected signal.
  • the process of target detection is briefly described below by taking the lidar 300 as an example.
  • the processing and control unit 340 sends a driving control signal to the driving unit 320 so that the driving unit 320 sends a modulated current pulse signal.
  • the current pulse signal is input into the light source unit 310, so that the light source unit 310 generates a modulated laser pulse signal.
  • the laser pulse signal is sent to the optical structure 350 to form a collimated beam, which is sent into space. Signals reflected by objects in the space enter the optical structure 350 and are collected into the photoelectric detection unit 330 .
  • the photoelectric detection unit 330 receives the control signal sent by the processing and control unit 340, receives the echo signal in a time window, and performs photoelectric conversion on the received echo signal to form an electrical signal, and forms a digital signal through analog-to-digital conversion, which is provided to processing and control unit 340 .
  • the processing and control unit 340 processes the digital signal, and outputs detection results, such as point cloud data.
  • FIG. 4 is a schematic structural diagram of a detection device 400 provided in an embodiment of the present application.
  • the detecting device 400 may be a laser radar, for example, the laser radar 300 shown in FIG. 3 .
  • the detection device 400 may also be an internal device of the lidar, for example, a chip, an integrated circuit, or a software module.
  • the detection device 400 includes a laser emitter 410 and a photodetector 420 .
  • the detection device 400 may include one or more laser emitters.
  • the detection device 400 may comprise one or more photodetectors.
  • the embodiment of the present application does not limit the number of laser emitters and photodetectors in the detection device 400 .
  • the laser pulse signal emitted by the laser emitter 410 may also be referred to as an emission signal, an emission pulse, or an emission pulse signal.
  • Ranging refers to determining the distance between the target and the lidar, or in other words, determining the position of the target.
  • the photodetector 420 is used for respectively accumulating charges generated in response to the echo signals within one or more time windows, and outputting a sampling sequence according to the accumulated charges.
  • the echo signal includes the reflected signal of the laser pulse signal.
  • the echo signal may also include other optical signals, for example, an optical signal of an ambient light source and the like.
  • the echo signal may also be referred to as a received pulse or a received pulse signal.
  • the photodetector 420 may serve as a photodetector in the photodetection unit 330 in FIG. 3 .
  • the photodetector 420 after receiving the echo signal, the photodetector 420 generates photo-generated charges in response to the echo signal.
  • the photodetector 420 accumulates the photogenerated charges generated within a period of time, that is, accumulates the photogenerated charges generated based on the received optical signals within the period of time, and outputs a sampling sequence based on the accumulated photogenerated charges. This period of time is a time window.
  • the first laser emitter (an example of the laser emitter 410 ) is used to emit a first laser pulse signal (an example of a laser pulse signal).
  • the first photodetector (an example of a photodetector 420) is used to respectively accumulate charges generated in response to a first echo signal (an example of an echo signal) within one or more first time windows (an example of a time window) , and output a first sampling sequence (an example of a sampling sequence) based on the accumulated charges.
  • the first echo signal includes a reflection signal of the first laser pulse signal.
  • the photodetector may output a voltage value according to the charge accumulated in one or more time windows, so that one or more voltage values corresponding to the one or more time windows may be included in the sampling sequence. There may be a one-to-one correspondence between the time window and the voltage value.
  • the sampling sequence may comprise one or more amplified voltage or current values.
  • obtaining the first sampling sequence according to the charges respectively accumulated in one or more first time windows includes: determining the value of the electric signal according to the charges respectively accumulated in the one or more first time windows, and the electric signal The value is amplified to obtain the first sample sequence.
  • the photoelectric conversion gain can be improved, which is conducive to improving the detection accuracy.
  • sampled values in the sampled sequence may also be values of electrical signals that have not been amplified.
  • the upscaling process can also be done by other modules.
  • the photodetector can also input the sampling sequence to the amplifier for amplification processing.
  • the amplifier can be deployed in the detection device 400 , or the amplifier can also be independent from the detection device 400 .
  • the sample sequence may be represented in the form of an analog signal, or alternatively, may be represented in the form of a digital signal.
  • the photodetector can use a CMOS sensor or a CCD sensor.
  • the photodetector can be obtained by using a CMOS sensor based on a 3T architecture or a 4T architecture.
  • Fig. 5 shows a schematic block diagram of a photodetector.
  • one end of the photodiode is floating and the other end is connected to the accumulation gate.
  • One end of the accumulation gate is connected to the photodiode, the other end is connected to a capacitor, one end of the reset gate, and one end of the readout gate.
  • the other end of the reset gate is connected to a power supply (for example, VCC in Figure 5).
  • the other end of the read gate is connected to the input of the amplifier.
  • the output of the amplifier can be used as a sampling sequence.
  • the photodetector shown in FIG. 5 is only an example, and does not limit the solution of the embodiment of the present application.
  • the photoelectric detection is realized by means of a light-voltage-amplifier, that is, the light signal is converted into a voltage signal, and then the signal is amplified by a voltage-voltage amplifier to obtain a sampling sequence.
  • the photoelectric detection can also be implemented by using the photo-current-amplifier architecture, that is, converting the light signal into a current signal, and then amplifying the signal through a transimpedance amplifier to obtain a sampling sequence.
  • the embodiment of the present application does not limit the specific structure of the photodetector.
  • FIG. 6 shows a timing control scheme of the photodetector shown in FIG. 5 .
  • the accumulation gate is turned off, and after the light signal is incident on the photodiode, charges are generated in the photodiode, and the charges cannot flow and are accumulated in the photodiode.
  • the amount of photogenerated charge in the photodiode gradually increases.
  • the reset gate can be opened to clear the charge currently stored in the capacitor.
  • the readout gate can be opened to read out the current capacitor voltage, that is, the first readout voltage. The reset gate is then closed.
  • the accumulation gate is turned on at the end of the accumulation phase, and the charge accumulated on the photodiode is introduced into the capacitor, the amount of photogenerated charge in the photodiode decreases, and the capacitor voltage is read out, which is the second readout voltage. Close the accumulation gate and close the readout gate. After the accumulation gate is closed, the next accumulation process begins. As shown in Fig. 6, the time interval between closing and opening of the cumulative gate is the effective exposure time, that is, the width of a single time window.
  • the capacitor has a high positive charge after reset, and the capacitor voltage is a high voltage at this time.
  • the electrons accumulated on the photodiode flow into the capacitor, neutralizing the positive charge, causing the capacitor voltage to drop.
  • the difference between the two readout voltages is the voltage corresponding to the photogenerated charge accumulated in the photodiode.
  • the reset may not be able to completely clear the current stored charge of the capacitor.
  • the voltage corresponding to the photo-generated charge in the accumulation phase is obtained by the difference between the two read voltages, so as to avoid the charge originally stored in the capacitor when the reset cannot clear the charge.
  • introduced noise that is, the interference of reset noise is eliminated through correlated double sampling, and the noise in the photoelectric detection process is effectively suppressed.
  • the accumulation gate and the reset gate can be turned on simultaneously before the effective exposure time, so as to maintain the bias state of the photodiode and empty the capacitor charge.
  • each gate can be set as required. For example, after the voltage is read out for the first time, the reset gate and the readout gate can be closed first, then the accumulation gate can be opened, the charge on the photodiode can be introduced into the capacitor, the accumulation gate can be closed, the readout gate can be opened, and the second readout voltage.
  • the embodiment of the present application does not limit the specific sequence control sequence.
  • the voltage drop ⁇ U of the capacitor may satisfy the following formula:
  • q represents the electronic charge
  • N sig represents the arrival number of reflected signal photons in this period of accumulation time
  • N noise represents the average arrival number of background photons in this period of accumulation time
  • R represents the quantum efficiency of the photodetector
  • C represents capacitance value.
  • the magnitude of background light noise can be expressed as
  • the amplitude of the reflected signal can be expressed as N sig R, it can be seen that when observing the amount of charge, the signal-to-noise ratio is proportional to That is to say, without considering the noise introduced later, it can be considered that the signal-to-noise ratio is proportional to
  • the voltage value V within a single time window output by the photodetector can satisfy the following formula:
  • the number of arriving photons received by the photodetector includes the arrival number of background photons and the arrival number of reflected signal photons. It can be seen from the above formula that the number of arriving photons received by the photodetector in a single time window is proportional to the output voltage value V. By detecting the output voltage value of the photodetector within the time window, the number of arriving photons received by the photodetector within the time window can be obtained, or in other words, the light energy within the time window, that is, the light pulse energy can be obtained.
  • the photoelectric detection is realized based on the cyclic method of "photogenerated charge accumulation-readout".
  • the sampling value obtained through charge accumulation is relatively large, which can provide sufficient photoelectric conversion gain and avoid introducing obvious noise.
  • the photoelectric conversion element in the photodetector is not limited by the photoelectric conversion gain condition, so that the photoelectric conversion element with higher quantum efficiency can be used, which is beneficial to reduce the influence of background light shot noise, improve the signal-to-noise ratio, and thus improve the detection efficiency. performance.
  • conventional photodiodes do not have any photoelectric conversion gain, and too much noise will be introduced in the subsequent processing process, which will affect the detection performance.
  • the scheme of the embodiment of this application adopts a cycle based on "photogenerated charge accumulation-readout"
  • Photoelectric detection can be achieved by means of photoelectric detection, which can provide sufficient photoelectric conversion gain.
  • the photodiode without gain can also be used as the photoelectric conversion element in the photodetector.
  • the quantum efficiency of the photodiode is high, which is conducive to reducing background light dispersion
  • the effect of particle noise can be improved, the signal-to-noise ratio can be improved, and the detection performance can be improved.
  • a photodiode based on the principle of floating diffusion amplification is used as a photodetector.
  • a capacitor is used to collect photogenerated charges in the photodiode, and the voltage drop of the capacitor is read to obtain a sampling sequence to complete photodetection.
  • the photodiode can have a higher quantum efficiency, effectively reduce the influence of background light shot noise, improve the signal-to-noise ratio, and then improve the detection performance.
  • the embodiments of the present application implement photodetection in the form of charge accumulation to achieve high QE, high gain and low noise.
  • correlated double sampling is also used to suppress noise in the process of photoelectric detection.
  • the ratio between the charge derivation time and the width of the time window is less than or equal to the first threshold.
  • the charge derivation time of the first photodetector is shorter than the width of the first time window.
  • the ratio between the charge derivation time and the width of the first time window is less than or equal to the first threshold.
  • the difference between the width of the time window and the charge derivation time is greater than or equal to the third threshold.
  • the charge derivation time is much smaller than the width of the time window. In other words, the charge derivation time is negligible compared to the time window.
  • the photodetector In the process of target detection, the photodetector needs to receive the echo signal continuously, but cannot receive the echo signal when the charge is derived. If the charge derivation time is too long, it may be in the charge derivation state when the echo signal arrives, and the echo signal cannot be received, resulting in signal loss. In the embodiment of the present application, the charge derivation time is much shorter than the width of the time window. When the echo signal arrives, it is beneficial to prevent the photodetector from being in the charge derivation stage, thereby avoiding the problem of signal loss and ensuring the signal-to-noise ratio. Guaranteed detection accuracy.
  • Photodetectors can support control over the width of the time window.
  • the width of the time window in the embodiment of the present application is adjustable. In this way, the width of the time window can be adjusted to match the pulse width, or the pulse width can be adjusted to match the width of the time window to complete high-precision detection.
  • the width of the time window can be adjusted to match the pulse width, or the pulse width can be adjusted to match the width of the time window to complete high-precision detection.
  • the fourth threshold may be 50%.
  • the magnitude of the background light shot noise is proportional to the square root of the quantum efficiency of the photodetector, and the magnitude of the reflected signal is proportional to the quantum efficiency. The higher the quantum efficiency, the less the impact of shot noise.
  • the use of a photodetector with a relatively large quantum efficiency can reduce the impact of shot noise, improve the signal-to-noise ratio, and further improve detection accuracy.
  • the photoelectric conversion gain of the photodetector is greater than or equal to the fifth threshold.
  • the capacitor is used to convert the collected photo-generated charge into a voltage signal. If the amplitude of the voltage signal is too small, noise may be introduced during the amplification process of the amplifier, resulting in signal loss. The noise ratio drops.
  • the photodetector has a relatively large photoelectric conversion gain, which can avoid introducing obvious noise and causing a decrease in the signal-to-noise ratio.
  • the sixth threshold may be 1 photon/per detection. That is, the noise per detection is less than 1 photon.
  • the parameters of the photodetector may include:
  • the minimum width of the time window is ⁇ 10ns
  • the detection noise of the photodetector is less than 1 photon/per detection
  • the detecting device 400 may further include a processing unit 430 .
  • the processing unit 430 may be the processing and control unit 340 in FIG. 3 .
  • the processing unit 430 can be used to control the waveform of the laser pulse signal.
  • the processing unit 430 can be used to control the pulse width or pulse interval of the laser pulse signal.
  • the processing unit 430 may send first control information, where the first control information is used to indicate the waveform of the laser pulse signal.
  • the processing unit 430 may send first control information, the first control information is used to indicate the waveform of the first laser pulse signal, so that the first laser transmitter in the laser transmitter 410 can generate the first laser pulse signal.
  • the first control information may be carried in a driving control signal, for example, the control signal sent by the processing and control unit 340 to the driving unit 310 in FIG. 3 . That is to say, the processing and control unit 340 can send a driving control signal to the driving unit 310 to make the driving unit 310 generate an electric pulse signal, and the electric pulse signal can make the light source unit 320 generate a laser pulse signal indicated by the first control information.
  • a driving control signal for example, the control signal sent by the processing and control unit 340 to the driving unit 310 in FIG. 3 . That is to say, the processing and control unit 340 can send a driving control signal to the driving unit 310 to make the driving unit 310 generate an electric pulse signal, and the electric pulse signal can make the light source unit 320 generate a laser pulse signal indicated by the first control information.
  • the processing unit 430 may be used to control the width of the time window.
  • the processing unit 430 may send second control information, where the second control information is used to indicate the width of the time window.
  • the processing unit 430 may send second control information, where the second control information is used to indicate the width of the first time window.
  • the second control information may be carried in a detection control signal, for example, the control signal sent by the processing and control unit 340 to the photoelectric detection unit 330 in FIG. 3 . That is, the processing unit 430 may send the second control information to the photodetector 420, where the second control information is used to indicate the width of the time window.
  • the processing unit 430 may include a central processing unit (central processor unit, CPU), an off-the-shelf programmable gate array (field programmable gate array, FPGA) or an application specific integrated circuit (application specific integrated circuit, ASIC), or may also for other types of processing chips.
  • CPU central processor unit
  • FPGA field programmable gate array
  • ASIC application specific integrated circuit
  • the processing unit 430 may include multiple sub-processing units.
  • the multiple sub-processing units are respectively used to control the waveform of the laser pulse signal, control the width of the time window and determine the detection result according to the sampling sequence.
  • the detection device 400 in FIG. 4 only shows the laser emitter 410, the photodetector 420 and the processing unit 430, but in the specific implementation process, those skilled in the art should understand that the device 400 also includes all necessary components for normal operation. other necessary devices. Meanwhile, according to specific needs, those skilled in the art should understand that the apparatus 400 may also include hardware devices for implementing other additional functions. In addition, those skilled in the art should understand that the device 400 may only include the devices necessary to realize the embodiment of the present application, and does not necessarily include all the devices shown in FIG. 4 , for example, the processing unit 430 may be arranged inside the detection device, Alternatively, it can also be independent of the detection device 400 .
  • the pulse width should not be greater than 5-6ns, and the sampling rate should be high enough to ensure that one pulse corresponds to more than 3 sampling points.
  • the minimum width of the time window of the photodetector in the embodiment of the present application can only reach the order of several nanoseconds, and the readout rate of the photodetector is limited. In this case, the equivalent sampling rate may only reach the order of 100MHz, and it is difficult to be higher than 100MHz.
  • the existing detection scheme is adopted, theoretically, the pulse width needs to be higher than 20 ns.
  • one pulse needs to correspond to 3 sampling points, and the pulse width needs to be higher than 30 ns, which is difficult to meet the needs of high-precision ranging.
  • the embodiment of the present application provides a detection scheme, which realizes high-precision detection by controlling the pulse width of the laser pulse signal to match the width of the time window.
  • the difference between the pulse width of the laser pulse signal and an integer multiple of the width of the time window is less than or equal to the second threshold.
  • the pulse width of the laser pulse signal is approximately equal to an integer multiple of the width of the time window. There is a matching relationship between the width of the time window and the pulse width.
  • the second threshold may be 20%.
  • the difference between the pulse width of the first laser pulse signal and an integer multiple of the width of the first time window is less than or equal to the second threshold.
  • the processing unit 430 can adjust the width of the time window according to the pulse width of the laser pulse signal, so that the two match, or the photodetector 420 can adjust the width of the time window according to the pulse width of the laser pulse signal, so that both match.
  • the processing unit 430 may adjust the pulse width of the laser pulse signal according to the width of the time window, so as to match the two.
  • the laser transmitter can adjust the pulse width of the laser pulse signal according to the width of the time window so that the two match.
  • matching the pulse width and the width of the time window reduces the proportion of received background light noise and improves the signal-to-noise ratio, which is beneficial to realize high-precision detection.
  • the pulse width is greater than or equal to the width of the time window, if the pulse width is not an integer multiple of the width of the time window, an additional time window may be required to collect a complete reflected signal. If the pulse width is approximately equal to an integer multiple of the time window, the complete reflected signal can be collected with the least time window. For example, if the pulse width is 1.5T, the total energy of the pulse is 3, and T represents the width of the time window. When the pulse center point is at 0.6T, the energy distribution in three consecutive time windows is 0.3, 2 and 0.7. If the pulse width is 1T, the energy distribution in three consecutive time windows is 0, 1.8 and 1.2, requiring fewer time windows and less accumulated noise, reducing the proportion of received background light noise and improving signal-to-noise ratio, thereby improving the detection accuracy.
  • the difference between the pulse width of the laser pulse signal and the width of the time window is less than or equal to the second threshold.
  • the pulse width of the laser pulse signal is approximately equal to the width of the time window.
  • the width of the time window is comparable to the pulse width.
  • the pulse width of the first laser pulse signal is approximately equal to the width of the first time window.
  • the width of the time window is equivalent to the pulse width
  • a smaller pulse width can be used to avoid point cloud adhesion and ensure the detection accuracy.
  • the longer the time window the more background light noise will be accumulated.
  • the width of the time window is equal to the pulse width, it is beneficial to receive a complete reflected signal, avoid signal loss, and reduce the received background light noise. Ratio, improve the signal-to-noise ratio, thereby improving the detection accuracy.
  • Determining the detection result according to the sampling sequence includes: determining the detection result according to the ratio between signal values in the sampling sequence.
  • the position of the reflected signal is determined from the ratio between signal values in the sample sequence.
  • the first photodetector may output a first sampling sequence, and the ratio between signal values in the first sampling sequence may be used for target detection.
  • the process of determining the detection result according to the sampling sequence may be executed by the processing unit 430 .
  • the pulse width of the reflected signal is greater than or equal to the pulse width of the emitted laser pulse signal.
  • the degree of spot broadening is used to describe the difference between the two.
  • the effective pulse width of the reflected signal is generally not greater than twice the pulse width of the emitted laser pulse signal, and correspondingly, the degree of widening of the light spot is generally not greater than the pulse width of the emitted laser pulse signal.
  • the pulse width of the laser pulse signal is equal to the width of the time window, correspondingly, the degree of widening of the spot is generally smaller than the width of the time window.
  • the pulse width of the laser pulse signal is equal to the width of the time window, and the width of the time window is greater than the degree of spot widening, it can be considered that the reflected signal falls within the range of two time windows at most, or in other words, the sampling sequence contains at most two valid sampling points.
  • the effective sampling point can be determined according to the size of the sampling value.
  • the sampling sequence when the pulse width of the laser pulse signal is equal to the width of the time window, when the sampling sequence includes only one valid sampling point, the midpoint of the reflected signal is the midpoint of the time window corresponding to the valid sampling point.
  • the signal value of a valid sampling point is greater than the sampling threshold.
  • the sampling threshold can be set as required.
  • the pulse width of the laser pulse signal is equal to the width of the time window, there is only one effective sampling point in the sampling sequence, which means that the reflected signal falls completely within a time window, that is, the time window corresponding to the effective sampling point.
  • the pulse width of the laser pulse signal is equal to the width of the time window
  • the sampling sequence includes two effective sampling points
  • the middle point of the reflected signal falls In the time window corresponding to the effective sampling point with a larger signal value; when the signal values of the two effective sampling points are the same, the middle point of the reflected signal is the dividing point of the time window corresponding to the two effective sampling points.
  • the midpoint ⁇ t of the reflected signal satisfies the following formula:
  • t1 indicates the end moment of the time window corresponding to the first effective sampling point among the two effective sampling points
  • ⁇ t window indicates the width of the time window
  • K indicates that it is determined according to the ratio between the signal values of the two effective sampling points
  • the result of that is, the result determined according to the ratio between the signal value of the first valid sampling point and the signal value of the second valid sampling point.
  • the first valid sampling point refers to the valid sampling point that is located before other valid sampling points in time.
  • the midpoint ⁇ t of the reflected signal can also be understood as the time interval between the midpoint of the reflected signal and the starting point of the laser pulse signal.
  • K may be a ratio between signal values, that is, a ratio between the signal value of the first valid sampling point and the signal value of the second valid sampling point.
  • K may be a result obtained after adjusting a ratio between signal values through an arctan function.
  • the value of the second effective sampling point may have a minimum value, resulting in an extreme value in the ratio between signal values, which affects the stability of the ranging result.
  • the arctan function is used to adjust the ratio between the signal values, so as to reduce the influence of the extreme value on the ranging result, improve the accuracy of the calculation result, and ensure the detection precision.
  • the pulse width of the plurality of pulses is approximately equal to an integer multiple of the width of the time window.
  • FIG. 8 shows a schematic waveform diagram of a laser pulse signal proposed by an embodiment of the present application.
  • the laser pulse signal includes three rectangular pulses. ⁇ w represents the pulse width, and ⁇ s represents the pulse interval.
  • the sampling sequence includes a first subsequence and a second subsequence
  • the first subsequence includes Signal values at odd positions in the sampling sequence
  • the second subsequence includes signal values at even positions in the sampling sequence.
  • the ratio between the signal values in the first subsequence and the signal values in the second subsequence is used for object detection.
  • the detecting device 400 may further include a parity check circuit, and the parity check circuit is used to output the first subsequence and the second subsequence.
  • the parity check circuit includes a check switch, a first analog-to-digital converter, and a second analog-to-digital converter.
  • the verification switch can be used to control the photodetector to be periodically connected alternately with the first analog-to-digital converter and the second analog-to-digital converter, and the switching period of the verification switch is twice the width of the time window.
  • the verification switch is switched every other time window, and if the current time window is connected to the first analog-to-digital converter, then the next time window is connected to the second analog-to-digital converter.
  • the signal values output by the photodetectors are sorted sequentially, the signal values with odd numbers and even signal values are respectively sampled by different analog-to-digital converters, for example, the signal values with odd numbers enter the first An analog-to-digital converter obtains an odd sampling sequence, and signal values with even numbers can enter a second analog-to-digital converter to obtain an even sampling sequence.
  • parity check circuit being independent of the photodetector 420 for illustration, which does not limit the solution of the embodiment of the present application.
  • the parity check circuit can also be located inside the photodetector 420, and the parity check circuit can be connected with the output of the amplifier shown in FIG. Sampling sequence.
  • the pulse width of the laser pulse signal is equal to the width T of the time window, and the starting time points of the emission of the three pulses of the laser pulse signal are 0, 2T and 4T. If the time delay of the target is 5T, the three pulses of the reflected signal The starting moments of the pulses are 5T, 7T and 9T respectively, and the pulse signals will appear in the 5th sampling point, the 7th sampling point and the 9th sampling point, that is, the pulse signal will appear in the odd sampling sequence.
  • the starting moments of the three pulses of the reflected signal are 4T, 6T and 8T respectively, and pulse signals will appear in the 4th sampling point, the 6th sampling point and the 8th sampling point, That is, a pulse signal will appear in the even sampling sequence.
  • Threshold detection is performed on the signal value of the sampled signal to determine whether there is a reflected signal in the sampled signal.
  • Fig. 10 shows a schematic diagram of a processing flow for determining reflected signals according to odd-even sampling sequences. For example, as shown in FIG. 10 , if the signal value in the odd sampling sequence is greater than the threshold, it can be determined that there is a reflection signal in the odd sampling sequence.
  • the position of the target can be determined according to the midpoint of the reflected signal. Through algorithms such as peak search, it is determined that the midpoint of the reflected signal falls within the time window corresponding to the middle sampling point. It should be understood that, here, only the determination of the position of the target according to the middle point of the reflected signal is taken as an example for illustration. For example, the position of the target may also be determined according to the starting point of the reflected signal, or the position of the target may also be determined according to the ending point of the reflected signal, which is not limited in this embodiment of the present application.
  • the embodiments of the present application only take the parity check as an example for illustration.
  • the check method can be determined according to the modulation format of the laser pulse signal to complete the check. For example, when the pulse interval of the laser pulse signal is When the width of the time window is an integer multiple of 2 times or more, and the pulse width is equal to the width of the time window, multi-point joint inspection can be used to complete the verification.
  • Multi-machine interference is the measurement of the same target by multiple detection devices, resulting in one or more pulses in the echo signal than the emitted laser pulse signal, and there is a problem of pulse overlap.
  • the first laser pulse signal and the second laser pulse signal are used as examples of laser pulse signals with different modulation formats in the following text, which does not limit the solution of the embodiment of the present application. In practical applications, more laser pulse signals with different modulation formats can be transmitted, which is not limited in this embodiment of the present application.
  • the second laser transmitter is used to emit a second laser pulse signal (an example of a laser pulse signal); the second photodetector can be used to accumulate responses to the second laser signal in one or more second time windows (an example of a time window) respectively.
  • the charge generated by the echo signal (an example of an echo signal), according to the charges accumulated in one or more second time windows, a second sampling sequence (an example of a sampling sequence) is obtained, and the second echo signal includes a second laser pulse
  • the reflected signal of the signal, the first sampling sequence or the second sampling sequence is used for target detection.
  • the pulse width or pulse interval of the second laser pulse signal is different from that of the first laser pulse signal.
  • first laser emitter and the second laser emitter may be the same laser emitter or different laser emitters, which is not limited in this embodiment of the present application.
  • the first photodetector and the second photodetector may be the same photodetector or different photodetectors, which is not limited in this embodiment of the present application.
  • the pulse width or pulse interval of the second laser pulse signal is different from that of the first laser pulse signal. It can be understood that the second laser pulse signal is different from the first laser pulse signal in at least one of pulse width and pulse interval.
  • the pulse width of the laser pulse signal is matched to the time window.
  • the width of the first time window is also different from the width of the second time window.
  • first and “second” in the “first laser pulse signal” and “second laser pulse signal” in the embodiment of the present application are only used to define the two laser pulse signals as different laser Impulse signal, no other limiting effect.
  • the specific descriptions about the “laser pulse signal” above are all applicable to the “second laser pulse signal”
  • the specific descriptions about the “time window” are all applicable to the “second time window”
  • the specific descriptions about the “echo signal” are all applicable Applicable to “second echo signal”
  • the specific descriptions about “sampling sequence” are applicable to “second sampling sequence”
  • the specific descriptions about “laser emitter” are applicable to “second laser emitter”
  • the specific description of "photodetector” is applicable to “second photodetector", as long as the corresponding content is replaced, in order to avoid repetition, relevant content will not be repeated here.
  • the second laser emitter may determine to emit the second laser pulse signal according to the first echo signal.
  • the laser emitter may emit a second laser pulse signal under the condition that the pulses of the first echo signal overlap.
  • a plurality of laser pulse signals with different modulation formats for example, a first laser pulse signal and a second laser pulse signal
  • Laser pulse signals emitted by other detection devices are usually not modulated pulses, ie usually only include one pulse.
  • the scheme of the embodiment of the present application uses a plurality of laser pulse signals with different modulation formats. Even if it is interfered by the laser pulse signals emitted by other detection devices, only the detection result of the laser pulse signal with one modulation format will be interfered. The detection result of the laser pulse signal will not be affected. Therefore, the use of multiple laser pulse signals with different modulation formats can effectively avoid the problem of multi-machine interference.
  • the pulse duration of the first laser pulse signal is ⁇ K
  • the pulse interval of the second laser pulse signal is greater than ⁇ K .
  • the number of modulation formats is less than or equal to a set threshold.
  • the set threshold may be 5.
  • the modulation format of the laser pulse signal is limited, that is, the number of times the laser pulse signal detects the same target is limited, and the detection frequency can be guaranteed, thereby ensuring the resolution of the detection result.
  • the detection error caused by the self-overlapping of modulation pulses in a multi-target scene is eliminated through the orthogonality between the waveforms of the laser pulse signals, which improves the detection robustness of the system.
  • two laser pulse signals with different modulation formats wherein the pulse interval of one laser pulse signal (ie, the second laser pulse signal) is greater than the other laser pulse signal (ie, the first laser pulse signal), can ensure that the two In the scene of the target, at most one echo signal corresponding to the laser pulse signal is affected by self-overlapping.
  • the second echo signal corresponding to the two laser pulses must not have pulse self-overlapping, that is, the second laser pulse signal can eliminate the problem of pulse self-overlapping.
  • FIG. 13 shows a detection method 1300 provided by an embodiment of the present application.
  • the method shown in FIG. 13 can be executed by the laser radar 300 shown in FIG. 3 or the detection device 400 shown in FIG. 4 , and the specific description can refer to the description in the detection device 400.
  • the detection method is introduced below At 1300, repeated descriptions are appropriately omitted.
  • the method 1300 includes steps S1310 to S1320. Step S1310 to step S1320 will be described in detail below.
  • step S1310 may be performed by the laser emitter 410 in the detection device 400 .
  • step S1320 may be performed by the photodetector 420 in the detecting device 400 .
  • the difference between the pulse width of the first laser pulse signal and an integer multiple of the width of the first time window is less than or equal to the second threshold.
  • the difference between the pulse width of the first laser pulse signal and the width of the first time window is less than or equal to the second threshold.
  • the first laser pulse signal includes a plurality of pulses.
  • the method 1300 further includes step S1330 and step S1340.
  • step S1330 may be performed by the laser emitter 410 in the detection device 400 .
  • step S1340 may be performed by the photodetector 420 in the detecting device 400 .
  • the pulse interval of the second laser signal is greater than the duration of the pulse waveform of the first laser signal.
  • the photoelectric detection is realized by adopting the circular method based on "photogenerated charge accumulation-readout", which provides sufficient photoelectric conversion gain.
  • a photodiode can be used as the photoelectric conversion element, which can achieve The higher quantum efficiency is beneficial to reduce the influence of background light shot noise, improve the signal-to-noise ratio, and then improve the detection performance.
  • a photodiode based on the principle of floating diffusion amplification is used as a photodetector.
  • a capacitor is used to collect photogenerated charges in the photodiode, and the voltage drop of the capacitor is read to obtain a sampling sequence to complete photodetection.
  • the photodiode has a high quantum efficiency, which can effectively reduce the influence of background light shot noise, improve the signal-to-noise ratio, and thus improve the detection performance.
  • the embodiments of the present application implement photodetection in the form of charge accumulation to achieve high QE, high gain and low noise.
  • An embodiment of the present application further provides a laser radar, where the laser radar includes the detection device described above.
  • the laser radar further includes a processing unit, and the processing unit is connected with the detection device.
  • the processing unit is configured to send first control information, where the first control information is used to indicate a waveform of the first laser pulse signal.
  • the processing unit is configured to determine the detection result according to the sampling sequence.
  • processor in the embodiment of the present application can be a CPU, and the processor can also be other general-purpose processors, digital signal processors (digital signal processor, DSP), ASIC, FPGA or other programmable logic devices, discrete gates Or transistor logic devices, discrete hardware components, etc.
  • DSP digital signal processor
  • a general-purpose processor may be a microprocessor, or the processor may be any conventional processor, or the like.
  • the memory in the embodiments of the present application may be a volatile memory or a nonvolatile memory, or may include both volatile and nonvolatile memories.
  • the non-volatile memory can be read-only memory (read-only memory, ROM), programmable read-only memory (programmable ROM, PROM), erasable programmable read-only memory (erasable PROM, EPROM), electrically programmable Erases programmable read-only memory (electrically EPROM, EEPROM) or flash memory.
  • Volatile memory can be random access memory (RAM), which acts as external cache memory.
  • RAM random access memory
  • SRAM static random access memory
  • DRAM dynamic random access memory
  • SDRAM synchronous dynamic random access memory
  • Double data rate synchronous dynamic random access memory double data rate SDRAM, DDR SDRAM
  • enhanced SDRAM enhanced synchronous dynamic random access memory
  • SLDRAM synchronous connection dynamic random access memory
  • direct rambus RAM direct rambus RAM
  • the above-mentioned embodiments may be implemented in whole or in part by software, hardware, firmware or other arbitrary combinations.
  • the above-described embodiments may be implemented in whole or in part in the form of computer program products.
  • the computer program product comprises one or more computer instructions or computer programs.
  • the processes or functions according to the embodiments of the present application will be generated in whole or in part.
  • the computer may be a general purpose computer, a special purpose computer, a computer network, or other programmable devices.
  • the computer instructions may be stored in or transmitted from one computer-readable storage medium to another computer-readable storage medium, for example, the computer instructions may be transmitted from a website, computer, server or data center Transmission to another website site, computer, server or data center by wired (such as infrared, wireless, microwave, etc.).
  • the computer-readable storage medium may be any available medium that can be accessed by a computer, or a data storage device such as a server or a data center that includes one or more sets of available media.
  • the available media may be magnetic media (eg, floppy disk, hard disk, magnetic tape), optical media (eg, DVD), or semiconductor media.
  • the semiconductor medium may be a solid state drive.
  • At least one means one or more, and “multiple” means two or more.
  • At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items.
  • at least one item (piece) of a, b, or c can represent: a, b, c, a-b, a-c, b-c, or a-b-c, where a, b, c can be single or multiple .
  • sequence numbers of the above-mentioned processes do not mean the order of execution, and the execution order of the processes should be determined by their functions and internal logic, and should not be used in the embodiments of the present application.
  • the implementation process constitutes any limitation.
  • the disclosed systems, devices and methods may be implemented in other ways.
  • the device embodiments described above are only illustrative.
  • the division of the units is only a logical function division. In actual implementation, there may be other division methods.
  • multiple units or components can be combined or May be integrated into another system, or some features may be ignored, or not implemented.
  • the mutual coupling or direct coupling or communication connection shown or discussed may be through some interfaces, and the indirect coupling or communication connection of devices or units may be in electrical, mechanical or other forms.
  • the units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place, or may be distributed to multiple network units. Part or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.
  • each functional unit in each embodiment of the present application may be integrated into one processing unit, each unit may exist separately physically, or two or more units may be integrated into one unit.

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Abstract

探测装置及探测方法，激光雷达，终端。该探测装置包括激光发射器和光电探测器，激光发射器用于发射激光脉冲信号，光电探测器用于在一个或多个时间窗内分别累积响应于回波信号产生的电荷，根据一个或多个时间窗内分别累积的电荷得到采样序列，回波信号包括激光脉冲信号的反射信号，采样序列用于目标探测。探测方法用于目标探测。激光雷达包括探测装置。终端包括激光雷达。探测方法有利于提高信噪比，从而提高探测精度。

Description

探测装置及探测方法 技术领域
本申请实施例涉及雷达领域，并且更具体地，涉及一种探测装置及探测方法。
背景技术
随着探测技术的发展，探测装置在各个领域发挥着重要作用。例如，安装在智能终端上的毫米波雷达、激光雷达、摄像头、超声波雷达等传感器，能够感知周围的环境，收集数据，进行物体的辨识，以便智能终端能够预先察觉可能发生的危险并辅助甚至自主采取必要的规避手段，提高了安全性和舒适性。
其中，激光雷达(light detection and ranging,LiDAR)具有分辨率高、探测性能好以及隐蔽性强等优点，成为重要的探测装置之一。目前的LiDAR大多利用飞行时间(time of flight,TOF)的方式实现测距，即发射高功率的超短光脉冲，根据光脉冲被物体反射后的回波信号的接收时间与光脉冲的发射时间之间的时间间隔实现测距。然而，TOF方式的激光雷达的测量精度会受到信噪比的影响，现有方案难以显著提升信噪比，制约了激光雷达性能的进一步提升。
发明内容
本申请实施例提供一种探测装置及探测方法，有利于提高信噪比，从而提高探测精度。
第一方面，提供了一种探测装置，包括：第一激光发射器，用于发射第一激光脉冲信号；第一光电探测器，用于在一个或多个第一时间窗内分别累积响应于第一回波信号产生的电荷，根据一个或多个第一时间窗内分别累积的电荷得到第一采样序列，第一回波信号包括第一激光脉冲信号的反射信号，第一采样序列用于目标探测。
本申请实施例中，采用基于“光生电荷累积-读出”的循环的方式实现光电检测，通过电荷累积得到的采样值较大，能够提供足够的光电转换增益，避免引入明显噪声，在该情况下，光电探测器中的光电转换元件不受光电转换增益条件的限制，从而可以采用量子效率较高的光电转换元件，有利于降低背景光散粒噪声的影响，提高信噪比，进而提高探测性能。以光电二极管为例，常规的光电二极管没有任何光电转换增益，在后续处理过程中会引入过多噪声，影响探测性能，而本申请实施例的方案采用基于“光生电荷累积-读出”的循环的方式实现光电检测，能够提供足够的光电转换增益，在该情况下，没有增益的光电二极管也可以作为光电探测器中的光电转换元件，光电二极管的量子效率较高，有利于降低背景光散粒噪声的影响，提高信噪比，进而提高探测性能。
结合第一方面，在第一方面的某些实现方式中，第一光电探测器可以为采用浮置扩散放大原理的光电二极管。
利用电容收集光电二极管中的光生电荷，读取电容压降以得到采样序列，完成光电检测。通过优化结构和偏压能够使得光电二极管具有较高的量子效率，有效降低背景光散粒 噪声的影响，提高信噪比，进而提高探测性能。换言之，本申请实施例采用电荷累积的形式完成光电检测能够实现高量子效率(quantum efficiency，QE)、高增益以及低噪声。
结合第一方面，在第一方面的某些实现方式中，根据一个或多个第一时间窗内分别累积的电荷得到第一采样序列，包括：根据一个或多个第一时间窗内分别累积的电荷确定电信号的值，对电信号的值进行放大，以得到第一采样序列。
在本申请实施例中，通过对电信号的值进行放大，得到较大的采样值，从而减少噪声的影响，有利于提高探测精度。
结合第一方面，在第一方面的某些实现方式中，第一光电探测器的电荷导出时间小于第一时间窗的宽度。
结合第一方面，在第一方面的某些实现方式中，电荷导出时间和第一时间窗的宽度之间的比值小于或等于第一阈值。
也就是说，电荷导出时间远小于时间窗的宽度。或者说，电荷导出时间相比于时间窗可以忽略不计。
在本申请实施例中，电荷导出时间远小于时间窗的宽度，当回波信号到达时，有利于避免光电探测器处于电荷导出阶段，从而避免出现信号丢失的问题，保证了信噪比，进而保证探测精度。
结合第一方面，在第一方面的某些实现方式中，光电探测器包括互补性金属氧化物半导体(complementary metal-oxide-semiconductor，CMOS)或电荷耦合器件(charge coupled device，CCD)。
结合第一方面，在第一方面的某些实现方式中，第一时间窗的宽度可调整。
本申请实施例中的时间窗的宽度是可调整的，这样，可以调整时间窗的宽度使其与脉冲宽度匹配，或者，调整脉冲宽度使其与时间窗的宽度匹配，以便完成高精度探测。
结合第一方面，在第一方面的某些实现方式中，第一激光脉冲信号的脉冲宽度与第一时间窗的宽度的整数倍之间的差值小于或等于第二阈值。
本申请实施例的方案中，匹配脉冲宽度与时间窗的宽度，减少接收到的背景光噪声的占比，提高信噪比，有利于实现高精度探测。
结合第一方面，在第一方面的某些实现方式中，第一激光脉冲信号的脉冲宽度与第一时间窗的宽度之间的差值小于或等于第二阈值。
这样，在时间窗的宽度与脉冲宽度相当的情况下，可以采用较小的脉冲宽度，避免出现点云黏连的情况，保证了探测精度。同时，时间窗越长，则累积的背景光噪声越多，在时间窗的宽度与脉冲宽度相当的情况下，有利于接收到完整的反射信号，避免信号丢失，能够减少接收到的背景光噪声的占比，提高信噪比，从而提高探测精度。
结合第一方面，在第一方面的某些实现方式中，光电探测器的量子效率大于或等于第四阈值。
本申请实施例中，采用较大的量子效率的光电探测器，能够减少散粒噪声的影响，提高信噪比，进而提高探测精度。
结合第一方面，在第一方面的某些实现方式中，光电探测器的光电转换增益大于或等于第五阈值。
在本申请实施例的方案中，光电探测器具有较大的光电转换增益，这样可以避免引入 明显的噪声而导致信噪比下降。
结合第一方面，在第一方面的某些实现方式中，第一采样序列中的信号值之间的比例用于目标探测。
根据本申请实施例的方案，利用采样序列中的信号值之间的比例进行目标探测，无需对脉冲波形进行精确测量，能够以较低的采样率和较长的脉冲宽度实现高精度探测。
可选地，在激光脉冲信号的脉冲宽度等于时间窗的宽度的情况下，当采样序列中只包括一个有效采样点时，反射信号的中间点为该有效采样点对应的时间窗的中点。有效采样点的信号值大于采样阈值。
可选地，在激光脉冲信号的脉冲宽度等于时间窗的宽度的情况下，当采样序列中包括两个有效采样点时，在两个有效采样点的信号值不同时，反射信号的中间点落在信号值较大的有效采样点对应的时间窗内；在两个有效采样点的信号值相同时，反射信号的中间点为两个有效采样点对应的时间窗的分界点。
示例性地，在激光脉冲信号为矩形脉冲的情况下，反射信号的中间点Δt满足如下公式：
Figure PCTCN2022076593-appb-000001
其中，t 1表示两个有效采样点中的第一个有效采样点对应的时间窗的结束时刻，Δt window表示时间窗的宽度，K表示根据第一个有效采样点的信号值与第二个有效采样点的信号值之间的比例确定的结果。第一个有效采样点指的是在时间上位于其他有效采样点之前的有效采样点。
示例性地，K可以为信号值之间的比例，即第一个有效采样点的信号值和第二个有效采样点的信号值之间的比例。
示例性地，K可以为通过arctan函数对信号值之间的比例进行调整后得到的结果。在本申请实施例中，在信噪比较低的情况下，采用arctan函数对信号值之间的比例进行调整，减少对极值对测距结果的影响，提高计算结果的准确性，保证探测精度。
结合第一方面，在第一方面的某些实现方式中，第一激光脉冲信号包括多个脉冲。
在本申请实施例中，激光脉冲信号包括多个脉冲，可以通过脉冲能量累积提高信噪比，降低外界干扰。同时，由于激光发射器发射的能量是固定的，通过发射由多个脉冲组成的调制脉冲，能够将能量分散到不同的脉冲中去，多个脉冲可以分摊过高的峰值功率，避免接收机(例如，光电探测器)饱和时的探测结果失真。
可选地，在激光脉冲信号的脉冲宽度等于时间窗的宽度，激光脉冲信号的脉冲间隔等于时间窗的宽度的情况下，采样序列包括第一子序列和第二子序列，第一子序列包括采样序列中的位于奇数位置的信号值，第二子序列包括采样序列中的位于偶数位置的信号值。第一子序列中的信号值和第二子序列中的信号值之间的比例用于目标探测。
可选地，探测装置400还可以包括奇偶校验电路，奇偶校验电路用于输出第一子序列和第二子序列。
结合第一方面，在第一方面的某些实现方式中，还包括：第二激光发射器，用于：发射第二激光脉冲信号，第二激光脉冲信号的脉冲间隔或脉冲宽度与第一激光脉冲信号不同；第二光电探测器，用于：在一个或多个第二时间窗内分别累积响应于第二回波信号产生的电荷，根据一个或多个第二时间窗内分别累积的电荷得到第二采样序列，第二回波信 号包括第二激光脉冲信号的反射信号，第二采样序列或第一采样序列用于目标探测。
根据本申请实施例的方案，采用多个不同调制格式的激光脉冲信号，例如，第一激光脉冲信号和第二激光脉冲信号，对同一目标分别进行测量。其他探测装置发射激光脉冲信号通常不是调制脉冲，即通常只包括一个脉冲。本申请实施例的方案采用多个不同调制格式的激光脉冲信号，即使受到其他探测装置发射的激光脉冲信号的干扰，也只有一个调制格式的激光脉冲信号的探测结果会被干扰，其他调制格式的激光脉冲信号的探测结果不会受到影响，因此，采用多个不同调制格式的激光脉冲信号能够有效避免多机干扰问题。
同时，采用多个不同调制格式的激光脉冲信号进行目标探测，有利于消除脉冲自交叠的问题。具体地，可以通过调整调制格式，使得至少存在一个调制格式，使得激光脉冲信号对应的回波信号不会出现脉冲自交叠的问题。
结合第一方面，在第一方面的某些实现方式中，第二激光脉冲信号的脉冲间隔大于第一激光脉冲信号的脉冲波形的持续时间。
在本申请实施例中，通过激光脉冲信号的波形之间的正交性消除多目标场景下调制脉冲自交叠导致的探测误差，提升了系统探测鲁棒性。具体地，两个调制格式不同的激光脉冲信号，其中一个激光脉冲信号(即第二激光脉冲信号)的脉冲间隔大于另一个激光脉冲信号(即第一激光脉冲信号)，这样可以保证在两个目标的场景下最多只有一个激光脉冲信号对应的回波信号受到自交叠的影响。
第二方面，提供了一种探测方法，包括：发射第一激光脉冲信号；在一个或多个第一时间窗内分别累积响应于第一回波信号产生的电荷，根据一个或多个第一时间窗内分别累积的电荷得到第一采样序列，第一回波信号包括第一激光脉冲信号的反射信号，第一采样序列用于目标探测。
本申请实施例中，采用基于“光生电荷累积-读出”的循环的方式实现光电检测，通过电荷累积得到的采样值较大，能够提供足够的光电转换增益，避免引入明显噪声，在该情况下，光电探测器中的光电转换元件不受光电转换增益条件的限制，从而可以采用量子效率较高的光电转换元件，有利于降低背景光散粒噪声的影响，提高信噪比，进而提高探测性能。以光电二极管为例，常规的光电二极管没有任何光电转换增益，在后续处理过程中会引入过多噪声，影响探测性能，而本申请实施例的方案采用基于“光生电荷累积-读出”的循环的方式实现光电检测，能够提供足够的光电转换增益，在该情况下，没有增益的光电二极管也可以作为光电探测器中的光电转换元件，光电二极管的量子效率较高，有利于降低背景光散粒噪声的影响，提高信噪比，进而提高探测性能。
结合第二方面，在第二方面的某些实现方式中，第一激光脉冲信号的脉冲宽度与第一时间窗的宽度的整数倍之间的差值小于或等于第二阈值。
结合第二方面，在第二方面的某些实现方式中，第一激光脉冲信号的脉冲宽度与第一时间窗的宽度之间的差值小于或等于第二阈值。
结合第二方面，在第二方面的某些实现方式中，第一采样序列中的信号值之间的比例用于目标探测。
结合第二方面，在第二方面的某些实现方式中，第一激光脉冲信号包括多个脉冲。
结合第二方面，在第二方面的某些实现方式中，方法还包括：发射第二激光脉冲信号，第二激光脉冲信号的脉冲间隔或脉冲宽度与第一激光脉冲信号不同；在一个或多个第二时 间窗内分别累积响应于第二回波信号产生的电荷，根据一个或多个第二时间窗内分别累积的电荷得到第二采样序列，第二回波信号包括第二激光脉冲信号的反射信号，第二采样序列或第一采样序列用于目标探测。
结合第二方面，在第二方面的某些实现方式中，第二激光信号的脉冲间隔大于第一激光信号的脉冲波形的持续时间。
应理解，在上述第一方面中对相关内容的扩展、限定、解释和说明也适用于第二方面中相同的内容。
第三方面，提供了一种激光雷达，激光雷达包括如第一方面中任一项的探测装置。
结合第三方面，在第三方面的某些实现方式中，激光雷达还包括处理单元，处理单元与探测装置连接。
结合第三方面，在第三方面的某些实现方式中，处理单元用于发送第一控制信息，第一控制信息用于指示第一激光脉冲信号的波形。
结合第三方面，在第三方面的某些实现方式中，处理单元用于发送第二控制信息，第二控制信息用于指示第一时间窗的宽度。
结合第三方面，在第三方面的某些实现方式中，处理单元用于根据采样序列确定探测结果。
第四方面，提供了一种终端，所述终端包括如第三方面中任一项所述的激光雷达。
结合第四方面，在第四方面的某些实现方式中，该终端可以为车辆，例如，智能运输设备(车辆或者无人机)、智能家居设备、智能制造设备、测绘设备或者机器人等。该智能运输设备例如可以是自动导引运输车(automated guided vehicle，AGV)、或无人运输车。该终端还可以是手机(mobile phone)、平板电脑(Pad)、带无线收发功能的电脑、虚拟现实(virtual reality，VR)终端、增强现实(augmented reality，AR)终端、工业控制(industrial control)中的终端、无人驾驶(self driving)中的终端、远程医疗(remote medical)中的终端、智能电网(smart grid)中的终端、运输安全(transportation safety)中的终端、智慧城市(smart city)中的终端、智慧家庭(smart home)中的终端等等。
附图说明
图1为一种车辆探测范围的示意图；
图2为激光雷达的一种测距原理的示意图；
图3为本申请实施例提供的一种激光雷达的示意性结构图；
图4为本申请实施例提供的一种探测装置的示意性结构图；
图5为本申请实施例提供的一种光电探测器的示意性框图；
图6为本申请实施例提供的一种光电探测器的一种时序控制方案；
图7为本申请实施例提供的一种反射信号、时间窗和采样序列之间的对应关系的示意图；
图8为本申请实施例提供的一种激光脉冲信号的示意图；
图9为本申请实施例提供的一种奇偶校验电路的示意图；
图10为本申请实施例提供的一种奇偶采样序列的处理流程的示意图；
图11为本申请实施例提供的一种脉冲交叠和脉冲不交叠的情况的示意图；
图12为本申请实施例提供的一种回波信号的示意图；
图13为本申请实施例提供的一种探测方法的示意性流程图。
具体实施方式
下面将结合附图，对本申请实施例中的技术方案进行描述。
应理解，在本申请中“电连接”可理解为元器件物理接触并电导通；也可理解为线路构造中不同元器件之间通过印制电路板(printed circuit board，PCB)铜箔或导线等可传输电信号的实体线路进行连接的形式；也可理解为通过间接耦合的方式，隔空电导通。“连接”、“相连”均可以指一种机械连接关系或物理连接关系，例如，A与B连接或A与B相连可以指，A与B之间存在紧固的构件(如螺钉、螺栓、铆钉等)，或者A与B相互接触且A与B难以被分离。
LiDAR具有分辨率高、探测性能好以及隐蔽性强等优点，在自动驾驶、空间建模、地理测绘、交会对接等诸多场合得到应用。
激光雷达作为一种主动式的传感器，可以应用于自动驾驶系统、高级驾驶辅助系统(advanced driver assistance system，ADAS)、机器人或无人机等多种领域上。
以ADAS为例，ADAS依靠计算机视觉、雷达、监控装置和全球定位系统等协同合作，在车辆行驶过程中探测周围的环境，收集数据，进行物体的识别，并结合导航仪地图数据，进行系统的运算和分析，从而让驾驶者察觉到可能发生的危险，有效增加驾驶的安全性和舒适性。在L3及其以上水平的ADAS中，对外界环境的高可靠长距离高精度的测量通常通过激光雷达来完成。
图1示出了车辆100的探测范围示意图。如图1所示，激光雷达能够用于提供高精度大范围的感知结果。示例性地，该感知结果可以用于实现紧急制动(emergency braking)、行人检测(pedestrian detection)以及碰撞避免(collision avoidance)等。应理解，图1仅为示例，不对激光雷达的数量或安装位置构成限定。
需要说明的是，此处仅以激光雷达应用于车辆上为例进行说明，不对本申请实施例中的应用场景构成限定。示例性地，本申请实施例的激光雷达还可以应用于其他需要测距或空间建模的场景中，适用于对器件稳定性、通道隔离度等要求较高的场景。例如，本申请实施例的激光雷达，可以作为车载LiDAR或机载LiDAR，用于实现测绘或遥感技术等。
测距是激光雷达的一个基本功能。由于激光具有的高相干性、方向性、单色性等优点，激光雷达能够实现远距离、高精度的测距功能。
LiDAR大多利用TOF的方式实现测距。飞行时间指的是向目标发射激光信号的时刻与被目标反射后的反射信号的接收时刻之间的时间。通过TOF和光速可以确定目标与探测装置之间的距离。
图2示出了激光雷达的一种测距原理的示意图。如图2所示，脉冲激光器(pulse laser)产生的激光脉冲信号通过光学器件(optics)发射至目标(target)，被目标反射的反射信号经由光学器件汇聚到单光子雪崩光电二极管(single photon avalanche photodiode，SPAD)阵列，即图2中的SPADs，由SPADs将光信号转换为电信号，由前端电路(frontend circuitry)对电信号进行处理后输入到时间-数字转换器(time to digital converter，TDC)，得到飞行时间ΔT。根据飞行时间ΔT和光速即可计算出激光雷达与目标之间的距离。
通过分析激光雷达的链路可知，激光雷达的测量精度会受到信噪比(signal noise ratio，SNR)、脉冲宽度以及采样率的影响。
具体来说，SNR会受到脉冲峰值功率和链路噪声的影响。链路预算结果表明，背景光散粒噪声是激光雷达的主要噪声源。当假定进入探测器的背景光功率和信号光功率恒定时，影响SNR的主要因素则变为量子效率。量子效率越高，则信噪比越高。若采用SPAD或者硅光电倍增器(silicon photomultiplier，SiPM)等器件作为光电探测器，受限于其工作区、物理机制以及生产工艺等，量子效率通常较低，例如，SPAD的量子效率通常难以超过15％，探测结果受背景光影响较为严重。若采用雪崩光电探测器(avalanche photo-detector，APD)阵列作为光电探测器，虽然具有较高的量子效率，但成本过高，难以大规模制备阵列，而且，受到过剩噪声系数的影响，会进一步放大背景光散粒噪声。
现有方案难以显著提升信噪比，这制约了激光雷达性能的进一步提升。
本申请实施例提供了一种探测装置，采用基于电荷累积形式的光电探测器，有利于提高信噪比，从而提高探测性能。本申请实施例中的探测装置可以为激光雷达，或者，也可以为激光雷达内部的器件，例如，芯片、集成电路或软件模块等。
本申请实施例中的探测装置能够应用于智能驾驶、智能运输、智能制造、环境监测、测绘以及无人机等各种领域，完成距离测量、速度测量、目标跟踪、成像识别等目标探测任务中的一项或多项。
示例性地，本申请实施例中的探测装置能够作为车载探测装置(例如，车载LiDAR)或机载探测装置(例如，机载LiDAR)等，也可以作为机器人或基站等装置上的探测装置。本申请对探测装置的安装位置不做限定。
为了更好地理解本申请实施例的方案，下面对本申请中的部分术语进行解释。
(1)光电探测器
光电探测器用于实现光电检测。
光电探测器包括光电转换元件。外来光子入射到光电转换元件上，可以在光电转换元件上激发出自由电子，自由电子在外加电场或者内建电场的影响下形成电流，以完成后续检测。光电转换元件也可以称为光电检测器件。
目前，光电转换元件主要分为三类：SPAD、雪崩光电二极管(photon avalanche photodiode，PAD)和普通的光电二极管(photodiode，PD)。其中，采用单光子探测光电二极管作为光电转换元件的光电探测器也可以称为单光子雪崩光电探测器。采用雪崩二极管作为光电转换元件的光电探测器也可以称为雪崩光电探测器。
在本申请实施例中，自由电子也可以称为光生电荷、电荷或电子。
光电探测器的基本工作机制即为，光信号注入光电转换元件，光电转换元件产生光生电荷，在内建电势差或外建电势差的影响下形成光生电流，以完成光电检测。
(2)浮置扩散放大(float diffusion amplification)
令光电转换元件的一端浮置，通过偏压使得其中产生的光生电荷进入小电容以完成信号放大。
图3示出了本申请实施例提供的一种激光雷达300的示意性结构图。
如图3所示，激光雷达300可以包括光源单元310、驱动单元320、光电检测单元330、处理与控制单元340和光学结构350。
具体地，光源单元310用于接收驱动单元320提供的电驱动信号，产生相应的激光脉冲信号，即发射信号，作为激光雷达300的光源。
示例性地，光源单元310可以为激光二极管、垂直腔面发射激光器或分布式反馈激光二极管等发光器件。本申请实施例对此不做限定。
驱动单元320用于产生电驱动信号提供给光源单元310。例如，该电驱动信号可以为经过调制的电流脉冲信号。
光电检测单元330用于完成光电转换和模数转换，将输出结果提供给处理与控制单元340。
示例性地，光电检测单元330可以包括模数转换器(analog to digital converter，ADC)和光电探测器。
光电探测器可以用于时间窗式地接收回波信号，并转换为电信号。光电检测单元330中的光电探测器可以采用本申请实施例中的光电探测器420。具体描述可以参见后文中的光电探测器420的描述。
模数转换器用于完成模数转换，即将光电探测器输出的电信号转换为数字信号。
处理与控制单元340用于为驱动单元320提供驱动控制信号，以使驱动单元320产生电驱动信号。处理与控制单元340还用于为光电检测单元330提供检测控制信号，以使光电检测单元330时间窗式地接收光信号，并将输出结果提供给处理与控制单元340。处理与控制单元340对该光电检测单元330的输出结果进行处理，以得到探测结果。
示例性地，该探测结果可以包括TOF值或者点云数据等。本申请实施例对探测结果的形式不做限定。
光学结构350用于将光源的激光脉冲信号汇聚成准直光束，完成空间扫描，并将回波信号汇聚到光电检测单元330。回波信号包括目标反射的光脉冲信号，即反射信号。
下面以激光雷达300为例对目标探测的过程进行简要说明。
处理与控制单元340向驱动单元320发出驱动控制信号，使得驱动单元320发出经过调制的电流脉冲信号。电流脉冲信号输入至光源单元310中，以使光源单元310产生经过调制的激光脉冲信号。激光脉冲信号发射至光学结构350后形成准直光束，发射到空间中。空间中的目标反射的信号进入光学结构350后，被汇聚到光电检测单元330中。光电检测单元330接收处理与控制单元340发出的控制信号，对回波信号进行时间窗式地接收，并对接收到回波信号进行光电转换形成电信号，经过模数转换形成数字信号，提供给处理与控制单元340。处理与控制单元340对数字信号进行处理，输出探测结果，例如，点云数据。
值得注意的是，图3仅是本申请实施例提供的一种激光雷达的示意图，图中所示设备、器件、模块等之间的位置关系不构成任何限制，例如，激光雷达300中的数据处理功能和控制功能集成在同一个单元中，即处理与控制单元340。在另一种可能的实现方式中，数据处理功能可以由处理单元完成，控制功能可以由控制单元完成，即处理单元和控制单元可以是独立的两个单元。
图4为本申请实施例提供的一种探测装置400的结构示意图。探测装置400可以为激光雷达，例如，图3所示的激光雷达300。或者，探测装置400也可以为激光雷达内部的器件，例如，芯片、集成电路或软件模块等。
如图4所示，探测装置400包括激光发射器410和光电探测器420。
需要说明的是，探测装置400可以包括一个或多个激光发射器。探测装置400可以包括一个或多个光电探测器。本申请实施例对探测装置400中的激光发射器和光电探测器的数量不作限定。
激光发射器410用于发射激光脉冲信号。示例性地，激光发射器410可以包括图3中的光源单元310。激光发射器也可以称为脉冲激光器。
在本申请实施例中，激光发射器410发射的激光脉冲信号也可以称为发射信号、发射脉冲、发射脉冲信号。
在目标探测过程中，激光发射器410向空间发送激光脉冲信号。空间中的物体，即目标，可以反射该激光脉冲信号，形成反射信号。
测距是激光雷达的一个基本功能，为了更好地描述本申请实施例的方案，后文中以测距任务为例对目标探测过程进行说明。
测距指的是确定目标到激光雷达之间的距离，或者说，确定目标的位置。
如前所述，根据反射信号的位置即可完成测距。因此，确定目标的位置，也可以理解为确定反射信号的位置，本申请实施例中不作区分。反射信号也可以称为反射脉冲、反射脉冲信号、反射脉冲波形。
光电探测器420用于在一个或多个时间窗内分别累积响应于回波信号产生的电荷，并根据累积的电荷输出采样序列。回波信号包括激光脉冲信号的反射信号。此外，回波信号还可以包括其他光信号，例如，环境光源的光信号等。在本申请实施例中，回波信号也可以称为接收脉冲或接收脉冲信号。示例性地，光电探测器420可以作为图3中的光电检测单元330中的光电探测器。
换言之，光电探测器420可以用于时间窗式地接收回波信号，并转换为电信号输出。即光电探测器420以时间窗为单位接收回波信号，分别累积各个时间窗内的光能量，并转换为电信号输出。或者说，光电探测器420能够累积光生电荷，实现光电转换。采样序列中包括一个或多个信号值，信号值是根据时间窗内累积的光生电荷得到的，该一个或多个信号值可以用于指示一个或多个时间窗内的光能量。
具体地，光电探测器420在接收到回波信号后，会响应于回波信号，产生光生电荷。光电探测器420累积一段时间内产生的光生电荷，即累积基于该段时间内接收的光信号所产生的光生电荷，基于累积的光生电荷输出采样序列。该段时间即为一个时间窗。
本申请实施例中，时间窗也可以称为时间窗口或时间门。
示例性地，第一激光发射器(激光发射器410的一例)用于发射第一激光脉冲信号(激光脉冲信号的一例)。第一光电探测器(光电探测器420的一例)用于在一个或多个第一时间窗(时间窗的一例)内分别累积响应于第一回波信号(回波信号的一例)产生的电荷，并根据累积的电荷输出第一采样序列(采样序列的一例)。第一回波信号包括第一激光脉冲信号的反射信号。
需要说明的是，本申请实施例中关于“激光脉冲信号”的具体描述均适用于“第一激光脉冲信号”，关于“时间窗”的具体描述均适用于“第一时间窗”，关于“回波信号”的具体描述均适用于“第一回波信号”，关于“采样序列”的具体描述均适用于“第一采样序列”，关于“激光发射器”的具体描述均适用于“第一激光发射器”，关于“光电探测器”的具体描述均适用于 “第一光电探测器”。为了便于描述，后文中主要以第一激光脉冲信号为例进行说明，不对本申请实施例的方案构成限定。
采样序列是电信号的采样序列，采样序列中的一个或多个信号值即为一个或多个电信号的采样点对应的信号值，或者说，信号的幅值。该一个或多个信号值也可以称为一个或多个采样值。光电探测器根据该一个或多个时间窗内累积的电荷输出电信号的值，该电信号可以为电流信号，也可以为电压信号。时间窗和采样点可以是一一对应的。
换言之，光电探测器可以根据一个或多个时间窗内累积的电荷输出电压值，这样，采样序列中可以包括该一个或多个时间窗对应的一个或多个电压值。时间窗和电压值可以是一一对应的。
或者，光电探测器可以根据一个或多个时间窗内累积的电荷输出电流值，这样，采样序列中可以包括该一个或多个时间窗对应的一个或多个电流值。时间窗和电流值可以是一一对应的。
可选地，根据累积的电荷输出采样序列，包括：根据累积的电荷确定电信号的值，对电信号的值进行放大，以得到采样序列。
在该情况下，采样序列可以包括一个或多个放大后的电压值或电流值。
示例性地，根据一个或多个第一时间窗内分别累积的电荷得到第一采样序列，包括：根据一个或多个第一时间窗内分别累积的电荷确定电信号的值，对电信号的值进行放大，以得到第一采样序列。
这样能够提高光电转换增益，有利于提高探测精度。
需要说明的是，采样序列中的采样值也可以是未经过放大处理的电信号的值。在该情况下，放大处理也可以由其他模块完成。光电探测器也可以将采样序列输入至放大器进行放大处理。放大器可以部署于探测装置400中，或者，放大器也可以独立于探测装置400。
采样序列可以以模拟信号的形式表示，或者，也可以以数字信号的形式表示。
也就是说，光电探测器内部可以设置模数转换器，进一步将模拟信号转换为数字信号，以数字信号的形式输出采样序列。或者，光电探测器也可以以模拟信号的形式输出采样序列，由模数转换模块进行模数转换。模数转换模块可以部署于探测装置400中，或者，模数转换模块也可以独立于探测装置400。
该光电探测器可以为采用浮置扩散放大原理的光电二极管。
浮置扩散放大能够提供较高的光电转换增益，且光电二极管可以通过调节偏置电压或者衬底厚度等参数来获取较高的量子效率。
具体地，对光电二极管进行浮置处理。在该情况下，光子入射到光电二极管上，将激发起自由电子，产生相应的光生电荷。光电二极管浮置，无法形成光生电流，光电二极管会在光电二极管中累积。经过一段时间后，可以将累积的电荷导出到电容器或其他结构上，以得到电信号的值，或者说，实现电荷数量的读取，以确定在段时间内入射到光电二极管上的光子的数量。
可选地，光电探测器可以采用CMOS传感器或CCD传感器。
例如，光电探测器可以采用基于3T架构或4T架构的CMOS传感器得到。
图5示出了一种光电探测器的示意性框图。如图5所示，光电二极管的一端浮置，另一端连接累积门控。累积门控的一端与光电二极管相连，另一端与电容、复位门控的一端 以及读出门控的一端相连。复位门控的另一端与电源(例如，图5中的VCC)相连。读出门控的另一端与放大器的输入端相连。在图5所示的光电探测器中，放大器的输出结果可以作为采样序列。
应理解，图5所示的光电探测器仅为示例，不对本申请实施例的方案构成限定。例如，在图5中是通过光-电压-放大器的方式实现光电检测，即，将光信号转换为电压信号，然后通过电压-电压放大器实现信号放大，得到采样序列。而在另一种可能的实现方式中，还可以采用光-电流-放大器架构实现光电检测，即，将光信号转换为电流信号，然后通过跨阻放大器实现信号放大，得到采样序列。本申请实施例对光电探测器的具体结构不做限定。
图6示出了图5所示的光电探测器的一种时序控制方案。
如图6所示，在时间窗的起点，即累积阶段开始时，关闭累积门控，在光信号入射到光电二极管后，在光电二极管中产生电荷，电荷无法流动，在光电二极管中被累积。光电二极管中的光生电荷量逐渐增加。在累积阶段，可以将复位门控打开，以清空电容内当前储存的电荷。此时，可以将读出门控打开，读出当前的电容电压，即第一次读出电压。随后关闭复位门控。在时间窗的终点，即累积阶段结束时打开累积门控，将光电二极管上累积的电荷导入电容中，光电二极管中的光生电荷量下降，读出电容电压，即第二次读出电压。关闭累积门控，关闭读出门控。关闭累积门控后，即开始了下一次的累积过程。如图6所示，累积门控关闭至打开之间的时间间隔为有效曝光时间，即单个时间窗的宽度。
如图6所示，电容经过复位后具有高正电荷，此时电容电压为高电压。在累积门控打开后，光电二极管上累计的电子流入电容中，中和正电荷，导致电容电压下降。两次读出的电压之间的差值即为光电二极管累积的光生电荷对应的电压。复位可能无法完全清空电容当前存储的电荷，通过两次读出的电压之间的差值得到累积阶段的光生电荷对应的电压，避免在复位无法清空电容电荷的情况下由电容原本存储的电荷所引入的噪声。即通过相关双采样消除复位噪声的干扰，有效抑制了光电检测过程中的噪声。
此外，如图6所示，还可以在有效曝光时间之前同时打开累积门控和复位门控，以便维持光电二极管的偏置状态，清空电容电荷。
应理解，以上工作过程仅为示例性说明，在实际应用中，各个门控的开关时间可以根据需要设置。例如，在第一次读出电压后，可以先关闭复位门控和读出门控，然后打开累积门控，将光电二极管上的电荷导入电容中，关闭累积门控，打开读出门控，第二次读出电压。本申请实施例对具体的时序控制顺序不做限定。
示例性地，在一次累积时间内，即一个时间窗内，电容的压降ΔU可以满足如下公式：
Figure PCTCN2022076593-appb-000002
其中，q表示电子电荷，N sig表示在该段累积时间内的反射信号光子到达数量，N noise表示在该段累积时间内的平均背景光子到达数量，R表示光电探测器的量子效率，C表示电容值。
背景光噪声的幅值可以表示为
Figure PCTCN2022076593-appb-000003
反射信号的幅值可以表示为N sig·R，可以看出在观察电荷数量时，信噪比正比于
Figure PCTCN2022076593-appb-000004
也就是说，在不考虑后续引入的噪声的情况下，可以认为信噪比正比于
Figure PCTCN2022076593-appb-000005
经过放大器放大后，光电探测器输出的单个时间窗内的电压值V可以满足如下公式：
Figure PCTCN2022076593-appb-000006
光电探测器接收到的到达光子数量包括背景光子到达数量和反射信号光子到达数量。从上述公式可以看出，单个时间窗内光电探测器接收到的到达光子数量和输出的电压值V成正比。通过检测光电探测器在时间窗内输出的电压值，即可得到该时间窗内的光电探测器接收到的到达光子数量，或者说，得到该时间窗内的光能量，即光脉冲能量。
本申请实施例中，采用基于“光生电荷累积-读出”的循环的方式实现光电检测，通过电荷累积得到的采样值较大，能够提供足够的光电转换增益，避免引入明显噪声，在该情况下，光电探测器中的光电转换元件不受光电转换增益条件的限制，从而可以采用量子效率较高的光电转换元件，有利于降低背景光散粒噪声的影响，提高信噪比，进而提高探测性能。以光电二极管为例，常规的光电二极管没有任何光电转换增益，在后续处理过程中会引入过多噪声，影响探测性能，而本申请实施例的方案采用基于“光生电荷累积-读出”的循环的方式实现光电检测，能够提供足够的光电转换增益，在该情况下，没有增益的光电二极管也可以作为光电探测器中的光电转换元件，光电二极管的量子效率较高，有利于降低背景光散粒噪声的影响，提高信噪比，进而提高探测性能。
示例性地，本申请实施例中采用基于浮置扩散放大原理的光电二极管作为光电探测器，例如，利用电容收集光电二极管中的光生电荷，读取电容压降以得到采样序列，完成光电检测。通过优化结构和偏压能够使得光电二极管具有较高的量子效率，有效降低背景光散粒噪声的影响，提高信噪比，进而提高探测性能。换言之，本申请实施例采用电荷累积的形式完成光电检测能够实现高QE、高增益以及低噪声。
此外，本申请实施例的方案中采用较小的电容收集光电二极管中的光生电荷，有利于提高信号放大的效率，从而抑制后级电路与ADC采样电路等在处理过程中引入的噪声。
此外，本申请实施例的方案中还通过相关双采样抑制光电检测过程中的噪声。
可选地，光电探测器的电荷导出时间小于时间窗的宽度。
进一步地，电荷导出时间与时间窗的宽度之间的比值小于或等于第一阈值。
示例性地，第一阈值可以为1/10，即电荷导出时间小于或等于时间窗的宽度的1/10。
以激光脉冲信号为第一激光脉冲信号为例，即第一光电探测器的电荷导出时间小于第一时间窗的宽度。
进一步地，电荷导出时间与第一时间窗的宽度之间的比值小于或等于第一阈值。
或者，时间窗的宽度与电荷导出时间之间的差值大于或等于第三阈值。
也就是说，电荷导出时间远小于时间窗的宽度。或者说，电荷导出时间相比于时间窗可以忽略不计。
需要说明的是，电荷导出时间和时间窗的宽度之间的关系还可以采用其他描述方式，本申请实施例对此不作限定，只要电荷导出时间远小于时间窗的宽度即可。
在目标探测过程中，光电探测器需要对回波信号进行连续接收，而在电荷导出时无法对回波信号进行接收。若电荷导出时间过长，那么当回波信号到达时可能处于电荷导出状态，无法接收到回波信号，导致信号丢失。在本申请实施例中，电荷导出时间远小于时间窗的宽度，当回波信号到达时，有利于避免光电探测器处于电荷导出阶段，从而避免出现 信号丢失的问题，保证了信噪比，进而保证探测精度。
可选地，时间窗的宽度是可调整的。
光电探测器可以支持对时间窗的宽度的控制。
本申请实施例中的时间窗的宽度是可调整的，这样，可以调整时间窗的宽度使其与脉冲宽度匹配，或者，调整脉冲宽度使其与时间窗的宽度匹配，以便完成高精度探测，具体描述可以参见后文。
可选地，光电探测器的量子效率大于或等于第四阈值。
示例性地，第四阈值可以为50％。
回波信号在经过光电探测器之后，背景光散粒噪声的幅度与光电探测器的量子效率的平方根呈正比，而反射信号的幅度与量子效率呈正比。量子效率越高，则散粒噪声的影响越小。
本申请实施例中，采用较大的量子效率的光电探测器，能够减少散粒噪声的影响，提高信噪比，进而提高探测精度。
可选地，光电探测器的光电转换增益大于或等于第五阈值。
例如，第五阈值可以为50uV/e-。也就是说，每个光生电荷可以引起50uV以上输出信号的变化。
以图5所示的光电探测器为例，电容用于将收集的光生电荷转换为电压信号，如果电压信号的幅值过小，则在放大器进行放大处理的过程中可能会引入噪声，导致信噪比下降。
在本申请实施例的方案中，光电探测器具有较大的光电转换增益，这样可以避免引入明显的噪声而导致信噪比下降。
可选地，光电探测器的检测噪声小于或等于第六阈值。
例如，第六阈值可以为1光子/每次检测。也就是说，每次检测的噪声小于1光子。
示例性地，光电探测器的参数可以包括：
时间窗的最小宽度＜10ns；
光电探测器的检测噪声＜1光子/每次检测；
量子效率＞50％；
光电转换增益＞50uV/e-；
电荷导出时间＜1ns。
可选地，探测装置400还可以包括处理单元430。
示例性地，处理单元430可以为图3中的处理与控制单元340。
可选地，处理单元430可以用于控制激光脉冲信号的波形。例如，处理单元430可以用于控制激光脉冲信号的脉冲宽度或脉冲间隔。具体地，处理单元430可以发送第一控制信息，第一控制信息用于指示激光脉冲信号的波形。例如，处理单元430可以发送第一控制信息，第一控制信息用于指示第一激光脉冲信号的波形，这样，激光发射器410中的第一激光发射器可以产生第一激光脉冲信号。
示例性地，第一控制信息可以承载于驱动控制信号中，例如，图3中处理与控制单元340向驱动单元310发送的控制信号。也就是说，处理与控制单元340可以向驱动单元310发送驱动控制信号，以使驱动单元310产生电脉冲信号，该电脉冲信号可以使得光源单元320产生第一控制信息所指示的激光脉冲信号。
可选地，处理单元430可以用于控制时间窗的宽度。
具体地，处理单元430可以发送第二控制信息，第二控制信息用于指示时间窗的宽度。例如，在激光脉冲信号为第一激光脉冲信号的情况下，处理单元430可以发送第二控制信息，第二控制信息用于指示第一时间窗的宽度。
示例性地，第二控制信息可以承载于检测控制信号中，例如，图3中处理与控制单元340向光电检测单元330发送的控制信号。即处理单元430可以向光电探测器420发送第二控制信息，第二控制信息用于指示时间窗的宽度。
可选地，处理单元430可以用于根据采样序列确定探测结果。
示例性地，处理单元430可以包括中央处理器(central processor unit,CPU)、现成可编程门阵列(field programmable gate array，FPGA)或应用特有集成电路(application specific integrated circuit，ASIC)，或者也可以为其它类型的处理芯片。
在一种可能的实现方式中，处理单元430可以包括多个子处理单元。例如，该多个子处理单元分别用于控制激光脉冲信号的波形，控制时间窗的宽度以及根据采样序列确定探测结果。
应注意，图4的探测装置400仅示出了激光发射器410、光电探测器420和处理单元430，但在具体实现过程中，本领域的技术人员应当理解，装置400还包括实现正常运行所必须的其他器件。同时，根据具体需要，本领域的技术人员应当理解，装置400还可包括实现其他附加功能的硬件器件。此外，本领域的技术人员应当理解，装置400也可仅仅包括实现本申请实施例所必须的器件，而不必包括图4中所示的全部器件，例如，处理单元430可以设置于探测装置内部，或者，也可以独立于探测装置400。
现有的探测方案依赖于对脉冲波形的精确测量，要完成高精度测距，需要满足窄脉冲宽度以及高采样率。通常来说，脉冲宽度不应大于5-6ns，采样率应足够高以保证一个脉冲对应3个以上的采样点。在一些场景下，本申请实施例的光电探测器的时间窗的最小宽度只能达到数个纳秒量级，光电探测器的读出速率有限。在该情况下，等效采样率可能只能达到100MHz量级，难以高于100MHz。若采用现有的探测方案，理论上需要脉冲宽度高于20ns。而且在实际应用中，为了保证探测精度，一个脉冲需要对应3个采样点，则脉冲宽度需要高于30ns，难以满足高精度测距的需求。
本申请实施例提供一种探测方案，通过控制激光脉冲信号的脉冲宽度与时间窗的宽度匹配实现高精度探测。
可选地，激光脉冲信号的脉冲宽度与时间窗的宽度的整数倍之间的差值小于或等于第二阈值。
换言之，激光脉冲信号的脉冲宽度约等于时间窗的宽度的整数倍。时间窗的宽度与脉冲宽度之间具有匹配关系。
例如，第二阈值可以为20％。
以第一激光脉冲信号为例，第一激光脉冲信号的脉冲宽度与第一时间窗的宽度的整数倍之间的差值小于或等于第二阈值。
即第一激光脉冲信号的脉冲宽度约等于第一时间窗的宽度的整数倍。
这样，处理单元430可以根据激光脉冲信号的脉冲宽度可以调整时间窗的宽度，以使两者匹配，或者，光电探测器420可以根据激光脉冲信号的脉冲宽度调整时间窗的宽度， 以使两者匹配。或者，处理单元430可以根据时间窗的宽度调整激光脉冲信号的脉冲宽度，以使两者匹配。或者，激光发射器可以根据时间窗的宽度调整激光脉冲信号的脉冲宽度，以使两者匹配。
本申请实施例的方案中，匹配脉冲宽度与时间窗的宽度，减少接收到的背景光噪声的占比，提高信噪比，有利于实现高精度探测。
通常来说，时间窗越长，则累积的背景光噪声越多。在脉冲宽度大于或等于时间窗的宽度的情况下，若脉冲宽度与时间窗的宽度不成整数倍，可能需要额外的时间窗来收集完整的反射信号。若脉冲宽度约等于时间窗的整数倍，则可以用最少的时间窗来收集完整的反射信号。例如，若脉冲宽度为1.5T，脉冲的总能量为3，T表示时间窗的宽度，当脉冲中心点位于0.6T时，在连续3个时间窗内的能量分布时0.3，2和0.7。若脉冲宽度为1T，则连续3个时间窗内的能量分布为0,1.8和1.2，需要的时间窗更少，累积的噪声越少，减少接收到的背景光噪声的占比，提高信噪比，从而提高探测精度。
进一步地，激光脉冲信号的脉冲宽度与时间窗的宽度之间的差值小于或等于第二阈值。
换言之，激光脉冲信号的脉冲宽度约等于时间窗的宽度。时间窗的宽度与脉冲宽度相当。
以第一激光脉冲信号为例，第一激光脉冲信号的脉冲宽度与第一时间窗的宽度之间的差值小于或等于第二阈值。
即第一激光脉冲信号的脉冲宽度约等于第一时间窗的宽度。
这样，在时间窗的宽度与脉冲宽度相当的情况下，可以采用较小的脉冲宽度，避免出现点云黏连的情况，保证了探测精度。同时，时间窗越长，则累积的背景光噪声越多，在时间窗的宽度与脉冲宽度相当的情况下，有利于接收到完整的反射信号，避免信号丢失，能够减少接收到的背景光噪声的占比，提高信噪比，从而提高探测精度。
采样序列用于目标探测。
根据采样序列确定探测结果，包括：根据采样序列中的信号值之间的比例确定探测结果。
换言之，采样序列中的信号值之间的比例用于目标探测。
例如，根据采样序列中的信号值之间的比例确定反射信号的位置。
以第一激光脉冲信号为例，第一光电探测器可以输出第一采样序列，第一采样序列中的信号值之间的比例可以用于目标探测。
示例性地，根据采样序列确定探测结果的处理过程可以由处理单元430执行。
在实际应用过程中，反射信号的脉冲宽度大于或等于发射的激光脉冲信号的脉冲宽度。光斑展宽程度用于描述两者之间差值。反射信号的有效脉冲宽度通常不会大于发射的激光脉冲信号的脉冲宽度的两倍，相应地，光斑展宽程度通常不会大于发射的激光脉冲信号的脉冲宽度。激光脉冲信号的脉冲宽度等于时间窗的宽度时，相应地，光斑展宽程度通常小于时间窗的宽度。
由于激光脉冲信号包括一个脉冲，激光脉冲信号的脉冲宽度等于时间窗的宽度，且时间窗的宽度大于光斑展宽程度，可以认为反射信号至多落在两个时间窗的范围内，或者说，采样序列中至多包括两个有效采样点。根据采样值的大小可以确定有效采样点。
可选地，在激光脉冲信号的脉冲宽度等于时间窗的宽度的情况下，当采样序列中只包括一个有效采样点时，反射信号的中间点为该有效采样点对应的时间窗的中点。有效采样点的信号值大于采样阈值。该采样阈值可以根据需要设置。
在激光脉冲信号的脉冲宽度等于时间窗的宽度的情况下，采样序列中只有一个有效采样点，说明该反射信号完全落在一个时间窗内，即有效采样点对应的时间窗内。
可选地，在激光脉冲信号的脉冲宽度等于时间窗的宽度的情况下，当采样序列中包括两个有效采样点时，在两个有效采样点的信号值不同时，反射信号的中间点落在信号值较大的有效采样点对应的时间窗内；在两个有效采样点的信号值相同时，反射信号的中间点为两个有效采样点对应的时间窗的分界点。
示例性地，在激光脉冲信号为矩形脉冲的情况下，反射信号的中间点Δt满足如下公式：
Figure PCTCN2022076593-appb-000007
其中，t 1表示两个有效采样点中的第一个有效采样点对应的时间窗的结束时刻，Δt window表示时间窗的宽度，K表示根据两个有效采样点的信号值之间的比例确定的结果，即根据第一个有效采样点的信号值与第二个有效采样点的信号值之间的比例确定的结果。第一个有效采样点指的是在时间上位于其他有效采样点之前的有效采样点。反射信号的中间点Δt也可以理解为反射信号的中间点与激光脉冲信号的起始点之间的时间间隔。
示例性地，K可以为信号值之间的比例，即第一个有效采样点的信号值和第二个有效采样点的信号值之间的比例。
示例性地，K可以为通过arctan函数对信号值之间的比例进行调整后得到的结果。在信噪比较低的情况下，第二个有效采样点的值可能出现极小值，导致信号值之间的比例出现极值，影响测距结果的稳定性。在本申请实施例中，在信噪比较低的情况下，采用arctan函数对信号值之间的比例进行调整，减少对极值对测距结果的影响，提高计算结果的准确性，保证探测精度。
图7示出了本申请实施例提供的一种反射信号、时间窗和采样序列之间的对应关系。下面结合图7对根据采样序列确定探测结果的处理过程进行说明。其中，激光脉冲信号包括1个矩形脉冲，脉冲宽度等于时间窗的宽度。
图7中示出了5个时间窗对应的采样值，即5个时间窗对应的信号值sp1，sp2，sp3，sp4和sp5。虚线矩形用于指示一次电荷累积的过程，其中，该矩形的宽度表示累积时间，即时间窗的宽度，矩形的高度表示信号值，可以用于指示累积的电荷量。如图7所示，部分采样值较高，说明光电探测器接收到了反射信号，即图7中的反射脉冲。
如图7所示，sp2和sp3这两个采样值高于其余三个采样值，说明在sp2和sp3对应的时间窗内接收了反射信号。
可选地，采样序列是经过去除直流(direct current，DC)成分后得到的。
例如，在图5所示的光电探测器中，可以去除放大器的输出结果中的背景光噪声的DC成分，以得到采样序列。
或者，根据采样序列确定探测结果包括：去除采样序列的采样值中的DC成分，根据处理后的采样序列中的信号值之间的比例确定探测结果。
例如，在图5所示的光电探测器中，放大器的输出结果可以作为采样序列，去除该采 样序列的采样值中的背景光噪声的DC成分。
背景光噪声引入的直流成分与目标探测的实际结果无关，在本申请实施例中，去除背景光噪声引入的直流成分，能够避免该直流成分影响探测结果。
根据sp2＜sp3，可以确定反射脉冲的位置处于sp2对应的时间窗的末端至sp3对应的时间窗的中点之间。
需要说明的是，图7中仅以反射脉冲的位置为反射脉冲的中间点为例进行说明，不对本申请实施例的方案构成限定。例如，反射脉冲的位置还可以为反射脉冲的上升沿，或者，反射脉冲的下降沿等。
进一步地，可以根据sp2和sp3之间的比例确定反射脉冲的位置。
反射脉冲的中间点Δt满足如下公式：
Figure PCTCN2022076593-appb-000008
其中，t sp2表示sp2对应的时间窗的结束时刻，即第一个有效采样点对应的时间窗的结束时刻，Δt window表示时间窗的宽度，K表示根据信号值之间的比例确定的结果，即根据sp2和sp3之间的比例确定的结果。
示例性地，K满足如下公式：
Figure PCTCN2022076593-appb-000009
或者，K满足如下公式：
Figure PCTCN2022076593-appb-000010
在信噪比较低的情况下，sp3可能出现极小值，导致信号值之间的比例出现极值，影响测距结果的稳定性。在本申请实施例中，在信噪比较低的情况下，采用arctan函数对信号值之间的比例进行调整，减少对极值对测距结果的影响，提高计算结果的准确性，保证探测精度。
进一步地，还可以根据arctan的特性进行非线性的校正，以得到校正后的K的值。
由于arctan函数是非线性函数，而测距结果和信号值之间的比例线性相关。因此，在本申请实施例中，还可以根据arctan的曲线进行非线性的校正，减少arctan函数的非线性对测距结果带来的影响。
需要说明的是，上述过程仅以激光脉冲信号为矩形脉冲为例进行说明，在实际应用中，还可以采用其他形状的脉冲，例如，高斯脉冲、抛物线脉冲等。
具体地，反射信号的位置满足如下公式：
Figure PCTCN2022076593-appb-000011
其中，f(K)可以根据脉冲的形状进行调整，本申请实施例对脉冲的形状不做限定。
根据仿真分析，通过设计合理的结构，本申请实施例的探测方案可以获得厘米级的探测精度。
根据本申请实施例的方案，利用采样序列中的信号值之间的比例进行目标探测，无需对脉冲波形进行精确测量，能够以较低的采样率和较长的脉冲宽度实现高精度探测。
可选地，激光脉冲信号包括多个脉冲。
换言之，激光脉冲信号为多个脉冲组成的调制脉冲，即利用调制脉冲替代单个脉冲完成目标探测。
示例性地，第一激光脉冲信号包括多个脉冲。
在本申请实施例中，激光脉冲信号包括多个脉冲，可以通过脉冲能量累积提高信噪比，降低外界干扰。同时，由于激光发射器发射的能量是固定的，通过发射由多个脉冲组成的调制脉冲，能够将能量分散到不同的脉冲中去，多个脉冲可以分摊过高的峰值功率，避免接收机(例如，光电探测器)饱和时的探测结果失真。
进一步地，该多个脉冲的脉冲宽度与时间窗的宽度的整数倍之间的差值小于或等于第二阈值。
换言之，该多个脉冲的脉冲宽度约等于时间窗的宽度的整数倍。
示例性地，第一激光脉冲信号的脉冲宽度与第一时间窗的宽度的整数倍之间的差值小于或等于第二阈值。
进一步地，该多个脉冲的脉冲宽度与时间窗的宽度之间的差值小于或等于第二阈值。
换言之，该多个脉冲的脉冲宽度约等于时间窗的宽度。
示例性地，第一激光脉冲信号的脉冲宽度与第一时间窗的宽度之间的差值小于或等于第二阈值。
进一步地，该多个脉冲之间的脉冲间隔约等于时间窗的宽度的整数倍。
示例性地，第一激光脉冲信号的多个脉冲之间的脉冲间隔约等于第一时间窗的宽度的整数倍。
进一步地，该多个脉冲之间的脉冲间隔约等于时间窗的宽度。
示例性地，第一激光脉冲信号的多个脉冲之间的脉冲间隔约等于第一时间窗的宽度。
这样，数据处理过程较为简单，有利于提高处理效率。
图8示出了本申请实施例提出的一种激光脉冲信号的波形示意图。如图8所示，该激光脉冲信号中包括三个矩形脉冲。Δw表示脉冲宽度，Δs表示脉冲间隔。
可选地，在激光脉冲信号的脉冲宽度等于时间窗的宽度，激光脉冲信号的脉冲间隔等于时间窗的宽度的情况下，采样序列包括第一子序列和第二子序列，第一子序列包括采样序列中的位于奇数位置的信号值，第二子序列包括采样序列中的位于偶数位置的信号值。第一子序列中的信号值和第二子序列中的信号值之间的比例用于目标探测。
换言之，若将采样序列中的信号值按照次序排列，第一子序列包括序号为奇数的信号值，第二子序列包括序号为偶数的信号值。第一子序列也可以称为奇采样序列。第二子序列也可以称为偶采样序列。
可选地，探测装置400还可以包括奇偶校验电路，奇偶校验电路用于输出第一子序列和第二子序列。
奇偶校验电路可以位于光电探测器420中。或者，奇偶校验电路也可以位于处理单元430中。或者，奇偶校验电路也可以独立于光电探测器420以及处理单元430。
可选地，奇偶校验电路包括校验开关、第一模数转换器和第二模数转换器。校验开关可以用于控制光电探测器周期性地与第一模数转换器和第二模数转换器交替相连，校验开关的切换周期为时间窗的宽度的2倍。
也就是说，校验开关每隔一个时间窗切换一次，若当前时间窗与第一模数转换器相连， 则下个时间窗与第二模数转换器相连。在该情况下，若光电探测器输出的信号值依次排序，则序号为奇数的信号值和序号为偶数的信号值分别被不同的模数转换器采样，例如，序号为奇数的信号值进入第一模数转换器，得到奇采样序列，序号为偶数的信号值可以进入第二模数转换器，得到偶采样序列。
例如，如图9所示，奇偶校验电路包括校验开关S1、第一模数转换器ADC_o和第二模数转换器ADC_e，校验开关S1用于控制光电探测器420与第一模数转换器ADC_o和第二模数转换器ADC_e交替相连。校验开关S1的切换周期为时间窗的宽度的2倍。若光电探测器输出的信号值依次排序，则序号为奇数的信号值和序号为偶数的信号值分别被不同的模数转换器采样，例如，序号为奇数的信号值进入ADC_o，得到奇采样序列，序号为偶数的信号值可以进入ADC_e，得到偶采样序列。
应理解，以上仅以奇偶校验电路独立于光电探测器420为例进行说明，不对本申请实施例的方案构成限定。例如，奇偶校验电路还可以位于光电探测器420内部，奇偶校验电路可以与图5所示的放大器的输出相连，光电探测器420可以输出两路结果，分别作为第一采样序列和第二采样序列。
下面以图8所示的激光脉冲波形对反射信号的位置的具体计算过程进行说明。为了便于理解和说明，下面以激光脉冲波形的脉冲宽度等于时间窗的宽度等于激光脉冲波形的脉冲间隔为例进行说明。
若反射信号的起始时刻等于时间窗的宽度的奇数倍，则奇采样序列中会出现脉冲信号，而偶采样序列中没有脉冲信号。反射信号的起始时刻等于时间窗的宽度的奇数倍，可以理解为，反射信号的起始时刻与第一个时间窗的起始时刻之间的时间间隔等于时间窗的宽度的奇数倍。若反射信号的起始时刻等于时间窗宽度的偶数倍，则奇采样序列中没有脉冲信号，偶采样序列中出现脉冲信号。反射信号的起始时刻等于时间窗的宽度的偶数倍，可以理解为，反射信号的起始时刻与第一个时间窗的起始时刻之间的时间间隔等于时间窗的宽度的偶数倍。
例如，激光脉冲信号的脉冲宽度等于时间窗的宽度T，激光脉冲信号的三个脉冲的发射的起始时间点为0，2T和4T，若目标的时延为5T，则反射信号的三个脉冲的起始时刻分别为5T，7T和9T，第5个采样点、第7个采样点和第9个采样点中会出现脉冲信号，即奇采样序列中会出现脉冲信号。若目标的时延为4T，则反射信号的三个脉冲的起始时刻分别为4T，6T和8T，第4个采样点、第6个采样点和第8个采样点中会出现脉冲信号，即偶采样序列中会出现脉冲信号。
若反射信号的起始时刻不是时间窗的宽度的整数倍，则奇采样序列和偶采样序列中均会出现脉冲信号。根据奇采样序列的信号值和偶采样序列的信号值的对比，可以确定反射信号的位置。具体包括以下步骤：
(1)对采样信号的信号值进行阈值检测，确定采样信号中是否存在反射信号。
或者说，确定采样信号中是否存在有效采样点。
示例性地，阈值检测可以为恒虚警检测(constant false-alarm rate,CFAR)。例如，若信号值大于或等于阈值，则认定存在反射信号。
根据奇采样序列中的信号值和偶采样序列中的信号值完成阈值检测，是否存在反射信号。
图10示出了一种根据奇偶采样序列确定反射信号的处理流程的示意图。例如，如图10所示，奇采样序列中的信号值大于阈值，可以认定奇采样序列中存在反射信号。
(2)根据阈值检测的结果进行粗定位。目标的粗定位精度在一个时间窗的宽度内。
例如，通过CFAR检测之后，在奇采样序列中确定第7、9、11个采样点中存在反射信号，也即在第7、9、11个采样点对应的时间窗内接收到了脉冲。目标的位置可以根据反射信号的中间点确定，通过峰值查找等算法，确定反射信号的中间点则落在中间的采样点对应的时间窗内。应理解，此处仅以目标的位置根据反射信号的中间点确定为例进行说明。例如，目标的位置还可以根据反射信号的起始点确定，或者，目标的位置还可以根据反射信号的结束点确定，本申请实施例对此不做限定。
(3)完成奇采样序列和偶采样序列目标位置的匹配，根据奇采样序列和偶采样序列的信号值计算得到目标的位置。
例如，在奇采样序列中确定第7、9、11个采样点中存在反射信号，则偶采样序列中第8、10、12个采样点和第6、8、10个采样点中的一组采样点中也存在反射信号。完成奇采样序列和偶采样序列目标位置的匹配，可以为，基于奇采样序列的检测结果确定偶采样序列中存在反射信号的采样点为第8、10、12个采样点还是第6、8、10个采样点。
例如，如图10所示，奇采样序列中的信号值的平均值为v1，偶采样序列中的信号值的平均值为v2。根据v1和v2之间的比例即可确定K，进而确定目标的位置。
示例性地，K满足如下公式：
Figure PCTCN2022076593-appb-000012
参考前文中单脉冲的公式即可确定目标的位置。
应理解，本申请实施例中仅以奇偶校验为例进行说明，在实际应用中，可以根据激光脉冲信号的调制格式确定校验方法以完成校验，例如，在激光脉冲信号的脉冲间隔为时间窗的宽度的2倍及以上的整数倍，且脉冲宽度等于时间窗的宽度的情况下，可以采用多点联合检验的方式完成校验。
此外，在一些探测场景中，可能存在多机干扰或多目标干扰的问题。
多机干扰是由多个探测装置对同一目标进行测量，导致回波信号比发射的激光脉冲信号多一个或多个脉冲，且存在脉冲交叠的问题。
多目标干扰指的是当目标距离较近时，利用调制脉冲探测目标时引发的回波交叠的问题。如图11所示，空间中存在目标1和目标2，发射的激光脉冲信号包括3个脉冲。图11的横坐标表示时间或者距离，纵坐标表示功率或幅度。在正确探测的情况下，如图11的(a)所示，可以接收到6个脉冲。但如果目标1和目标2的距离较近，如图11的(b)所示，仅接收到4个脉冲，说明接收到的回波信号可能出现脉冲交叠，无法完成目标探测。例如，目标1可以为磨砂玻璃，目标2可以为磨砂玻璃后距离较近的物体。
本申请实施例提出对同一目标采用不同调制格式的激光脉冲信号进行探测，以消除多机干扰问题以及多目标干扰问题。
为了便于描述，后文中以第一激光脉冲信号和第二激光脉冲信号作为不同调制格式的激光脉冲信号的示例，不对本申请实施例的方案构成限定。在实际应用中，可以发射更多不同调制格式的激光脉冲信号，本申请实施例对此不做限定。
可选地，激光发射器410可以包括第一激光发射器和第二激光发射器，光电探测装置420可以包括第一光电探测装置和第二光电探测装置。第一激光发射器用于发射第一激光脉冲信号(激光脉冲信号的一例)；第一光电探测器可以用于在一个或多个第一时间窗(时间窗的一例)内分别累积响应于第一回波信号(回波信号的一例)产生的电荷，根据一个或多个第一时间窗内分别累积的电荷得到第一采样序列(采样序列的一例)，第一回波信号包括第一激光脉冲信号的反射信号。第二激光发射器用于发射第二激光脉冲信号(激光脉冲信号的一例)；第二光电探测器可以用于在一个或多个第二时间窗(时间窗的一例)内分别累积响应于第二回波信号(回波信号的一例)产生的电荷，根据一个或多个第二时间窗内分别累积的电荷得到第二采样序列(采样序列的一例)，第二回波信号包括第二激光脉冲信号的反射信号，第一采样序列或第二采样序列用于目标探测。第二激光脉冲信号的脉冲宽度或脉冲间隔与第一激光脉冲信号不同。
换言之，采用多个不同调制格式的激光脉冲信号，例如，第一激光脉冲信号和第二激光脉冲信号，对同一目标分别进行测量。
需要说明的是，第一激光发射器与第二激光发射器可以是同一个激光发射器，也可以为不同的激光发射器，本申请实施例对此不做限定。第一光电探测器和第二光电探测器可以是同一个光电探测器，也可以是不同的光电探测器，本申请实施例对此不做限定。
第二激光脉冲信号的脉冲宽度或脉冲间隔与第一激光脉冲信号不同，可以理解为，第二激光脉冲信号与第一激光脉冲信号在脉冲宽度和脉冲间隔中的至少一项上存在区别。
如前所示，激光脉冲信号的脉冲宽度与时间窗匹配。在第一激光脉冲信号的脉冲宽度与第二激光脉冲信号的脉冲宽度不同的情况下，第一时间窗的宽度与第二时间窗的宽度也不同。
需要说明的是，本申请实施例中的“第一激光脉冲信号”和“第二激光脉冲信号”中的“第一”和“第二”仅用于限定两个激光脉冲信号为不同的激光脉冲信号，不具有其他限定作用。前文中关于“激光脉冲信号”的具体描述均适用于“第二激光脉冲信号”，关于“时间窗”的具体描述均适用于“第二时间窗”，关于“回波信号”的具体描述均适用于“第二回波信号”，关于“采样序列”的具体描述均适用于“第二采样序列”，关于“激光发射器”的具体描述均适用于“第二激光发射器”，关于“光电探测器”的具体描述均适用于“第二光电探测器”，只要将相应内容进行替换即可，为了避免重复，此处不再重复相关内容。
示例性地，第二激光发射器可以根据第一回波信号确定发射第二激光脉冲信号。
也就是说，激光发射器可以根据回波信号确定是否进行下一次的目标探测，即是否发送下一次的激光脉冲信号。
例如，激光发射器可以在第一回波信号发生脉冲交叠的情况下，发射第二激光脉冲信号。
可替换地，第二激光脉冲信号是否发射与第一回波信号无关。也就是说，激光发射器也可以直接发送第一激光脉冲信号和第二激光脉冲信号。
根据本申请实施例的方案，采用多个不同调制格式的激光脉冲信号，例如，第一激光脉冲信号和第二激光脉冲信号，对同一目标分别进行测量。其他探测装置发射激光脉冲信号通常不是调制脉冲，即通常只包括一个脉冲。本申请实施例的方案采用多个不同调制格式的激光脉冲信号，即使受到其他探测装置发射的激光脉冲信号的干扰，也只有一个调制 格式的激光脉冲信号的探测结果会被干扰，其他调制格式的激光脉冲信号的探测结果不会受到影响，因此，采用多个不同调制格式的激光脉冲信号能够有效避免多机干扰问题。
同时，采用多个不同调制格式的激光脉冲信号进行目标探测，有利于消除脉冲自交叠的问题。具体地，可以通过调整调制格式，使得至少存在一个调制格式，使得激光脉冲信号对应的回波信号不会出现脉冲自交叠的问题。
可选地，第二激光脉冲信号的脉冲间隔大于第一激光脉冲信号的脉冲持续时间。
例如，第一激光脉冲信号的脉冲持续时间为τ K，则第二激光脉冲信号的脉冲间隔大于τ K。
下面结合图12对第一激光信号和第二激光信号进行举例说明。
假设第一激光脉冲信号包括3个脉冲，脉冲宽度和脉冲间隔分别为8ns和8ns，相应地，光电探测器的时间窗的宽度可以为8ns。第二激光脉冲信号包括3个脉冲，脉冲宽度和脉冲间隔分别为7ns和42ns，光电探测器的时间窗的宽度为7ns。利用第一激光脉冲信号和第二激光脉冲信号完成目标探测。
如图12的(a)所示，第一回波信号中仅检测到4个脉冲，则说明出现了脉冲自交叠，两个目标之间的距离必然小于第一脉冲信号的脉冲持续时间8*5＝40ns。第二激光脉冲信号的脉冲宽度为42ns，第二回波信号如图12的(b)所示，不会再出现交叠。根据第二回波信号可以得到目标位置，完成目标探测。应理解，图12仅为示例，图12中的具体数值不对本申请实施例构成限定。
如前所示，在实际应用中，还可以发射更多不同调制格式的激光脉冲信号，能够有效避免干扰。
可选地，调制格式的数量小于或等于设定阈值。例如，设定阈值可以为5。
激光脉冲信号的调制格式过多，即发送了过多的激光脉冲信号，导致探测频率降低，若探测结果的生成周期不变，则探测结果中的点的数量减少。例如，探测结果表示为点云图像，探测频率降低会导致点云图像分辨率降低。本申请实施例中限定了激光脉冲信号的调制格式，即限定了激光脉冲信号对同一目标的探测次数，能够保证探测频率，从而保证探测结果的分辨率。
在本申请实施例中，通过激光脉冲信号的波形之间的正交性消除多目标场景下调制脉冲自交叠导致的探测误差，提升了系统探测鲁棒性。具体地，两个调制格式不同的激光脉冲信号，其中一个激光脉冲信号(即第二激光脉冲信号)的脉冲间隔大于另一个激光脉冲信号(即第一激光脉冲信号)，这样可以保证在两个目标的场景下最多只有一个激光脉冲信号对应的回波信号受到自交叠的影响。也就是说，若两个目标距离较近导致第一激光脉冲对应的第一回波信号中出现脉冲自交叠，第二激光脉冲信号的脉冲间隔大于第一激光脉冲信号的脉冲持续时间，第二激光脉冲对应的第二回波信号必然不会出现脉冲自交叠，即第二激光脉冲信号可以消除脉冲自交叠的问题。
图13示出了本申请实施例提供的探测方法1300。图13所示的方法可以由图3所示的激光雷达300或图4所示的探测装置400执行，具体描述可以参考探测装置400中的描述，为了避免不必要的重复，下面在介绍探测方法1300时适当省略重复的描述。
方法1300包括步骤S1310至步骤S1320。下面对步骤S1310至步骤S1320进行详细介绍。
S1310，发射第一激光脉冲信号。
示例性地，步骤S1310可以由探测装置400中的激光发射器410执行。
S1320，在一个或多个第一时间窗内分别累积响应于第一回波信号产生的电荷，根据一个或多个第一时间窗内分别累积的电荷得到第一采样序列，第一回波信号包括第一激光脉冲信号的反射信号，第一采样序列用于目标探测。
示例性地，步骤S1320可以由探测装置400中的光电探测器420执行。
可选地，第一激光脉冲信号的脉冲宽度与第一时间窗的宽度的整数倍之间的差值小于或等于第二阈值。
可选地，第一激光脉冲信号的脉冲宽度与第一时间窗的宽度之间的差值小于或等于第二阈值。
可选地，第一采样序列中的信号值之间的比例用于目标探测。
可选地，第一激光脉冲信号包括多个脉冲。
可选地，方法1300还包括步骤S1330和步骤S1340。
S1330，发射第二激光脉冲信号，第二激光脉冲信号的脉冲间隔或脉冲宽度与第一激光脉冲信号不同。
示例性地，步骤S1330可以由探测装置400中的激光发射器410执行。
S1340，在一个或多个第二时间窗内分别累积响应于第二回波信号产生的电荷，根据一个或多个第二时间窗内分别累积的电荷得到第二采样序列，第二回波信号包括第二激光脉冲信号的反射信号，第二采样序列或第一采样序列用于目标探测。
示例性地，步骤S1340可以由探测装置400中的光电探测器420执行。
可选地，第二激光信号的脉冲间隔大于第一激光信号的脉冲波形的持续时间。
根据本申请实施例的方案，采用基于“光生电荷累积-读出”的循环的方式实现光电检测，提供了足够的光电转换增益，在该情况下，可以采用光电二极管作为光电转换元件，能够达到较高的量子效率，有利于降低背景光散粒噪声的影响，提高信噪比，进而提高探测性能。示例性地，本申请实施例中采用基于浮置扩散放大原理的光电二极管作为光电探测器，例如，利用电容收集光电二极管中的光生电荷，读取电容压降以得到采样序列，完成光电检测。光电二极管具有较高的量子效率，能够有效降低背景光散粒噪声的影响，提高信噪比，进而提高探测性能。换言之，本申请实施例采用电荷累积的形式完成光电检测能够实现高QE、高增益以及低噪声。
本申请实施例还提供了一种激光雷达，所述激光雷达包括前文所述的探测装置。
进一步地，激光雷达还包括处理单元，所述处理单元与探测装置连接。
可选地，处理单元用于发送第一控制信息，第一控制信息用于指示第一激光脉冲信号的波形。
可选地，处理单元用于发送第二控制信息，第二控制信息用于指示第一时间窗的宽度。
可选地，处理单元用于根据采样序列确定探测结果。
应理解，本申请实施例中的处理器可以为CPU，该处理器还可以是其他通用处理器、数字信号处理器(digital signal processor，DSP)、ASIC、FPGA或者其他可编程逻辑器件、分立门或者晶体管逻辑器件、分立硬件组件等。通用处理器可以是微处理器或者该处理器也可以是任何常规的处理器等。
还应理解，本申请实施例中的存储器可以是易失性存储器或非易失性存储器，或可包括易失性和非易失性存储器两者。其中，非易失性存储器可以是只读存储器(read-only memory，ROM)、可编程只读存储器(programmable ROM，PROM)、可擦除可编程只读存储器(erasable PROM，EPROM)、电可擦除可编程只读存储器(electrically EPROM，EEPROM)或闪存。易失性存储器可以是随机存取存储器(random access memory，RAM)，其用作外部高速缓存。通过示例性但不是限制性说明，许多形式的RAM可用，例如静态随机存取存储器(static RAM，SRAM)、动态随机存取存储器(DRAM)、同步动态随机存取存储器(synchronous DRAM，SDRAM)、双倍数据速率同步动态随机存取存储器(double data rate SDRAM，DDR SDRAM)、增强型同步动态随机存取存储器(enhanced SDRAM，ESDRAM)、同步连接动态随机存取存储器(synchlink DRAM，SLDRAM)和直接内存总线随机存取存储器(direct rambus RAM，DR RAM)。
上述实施例，可以全部或部分地通过软件、硬件、固件或其他任意组合来实现。当使用软件实现时，上述实施例可以全部或部分地以计算机程序产品的形式实现。所述计算机程序产品包括一个或多个计算机指令或计算机程序。在计算机上加载或执行所述计算机指令或计算机程序时，全部或部分地产生按照本申请实施例所述的流程或功能。所述计算机可以为通用计算机、专用计算机、计算机网络、或者其他可编程装置。所述计算机指令可以存储在计算机可读存储介质中，或者从一个计算机可读存储介质向另一个计算机可读存储介质传输，例如，所述计算机指令可以从一个网站站点、计算机、服务器或数据中心通过有线(例如红外、无线、微波等)方式向另一个网站站点、计算机、服务器或数据中心进行传输。所述计算机可读存储介质可以是计算机能够存取的任何可用介质或者是包含一个或多个可用介质集合的服务器、数据中心等数据存储设备。所述可用介质可以是磁性介质(例如，软盘、硬盘、磁带)、光介质(例如，DVD)、或者半导体介质。半导体介质可以是固态硬盘。
应理解，本文中术语“和/或”，仅仅是一种描述关联对象的关联关系，表示可以存在三种关系，例如，A和/或B，可以表示：单独存在A，同时存在A和B，单独存在B这三种情况，其中A,B可以是单数或者复数。另外，本文中字符“/”，一般表示前后关联对象是一种“或”的关系，但也可能表示的是一种“和/或”的关系，具体可参考前后文进行理解。
本申请中，“至少一个”是指一个或者多个，“多个”是指两个或两个以上。“以下至少一项(个)”或其类似表达，是指的这些项中的任意组合，包括单项(个)或复数项(个)的任意组合。例如，a,b,或c中的至少一项(个)，可以表示：a,b,c,a-b,a-c,b-c,或a-b-c，其中a,b,c可以是单个，也可以是多个。
应理解，在本申请的各种实施例中，上述各过程的序号的大小并不意味着执行顺序的先后，各过程的执行顺序应以其功能和内在逻辑确定，而不应对本申请实施例的实施过程构成任何限定。
在本申请所提供的几个实施例中，应该理解到，所揭露的系统、装置和方法，可以通过其它的方式实现。例如，以上所描述的装置实施例仅仅是示意性的，例如，所述单元的划分，仅仅为一种逻辑功能划分，实际实现时可以有另外的划分方式，例如多个单元或组件可以结合或者可以集成到另一个系统，或一些特征可以忽略，或不执行。另一点，所显 示或讨论的相互之间的耦合或直接耦合或通信连接可以是通过一些接口，装置或单元的间接耦合或通信连接，可以是电性，机械或其它的形式。
所述作为分离部件说明的单元可以是或者也可以不是物理上分开的，作为单元显示的部件可以是或者也可以不是物理单元，即可以位于一个地方，或者也可以分布到多个网络单元上。可以根据实际的需要选择其中的部分或者全部单元来实现本实施例方案的目的。
另外，在本申请各个实施例中的各功能单元可以集成在一个处理单元中，也可以是各个单元单独物理存在，也可以两个或两个以上单元集成在一个单元中。
以上所述，仅为本申请的具体实施方式，但本申请的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本申请揭露的技术范围内，可轻易想到变化或替换，都应涵盖在本申请的保护范围之内。因此，本申请的保护范围应以所述权利要求的保护范围为准。

Claims (20)

  1. 一种探测装置，其特征在于，包括：
    第一激光发射器，用于发射第一激光脉冲信号；
    第一光电探测器，用于在一个或多个第一时间窗内分别累积响应于第一回波信号产生的电荷，根据所述一个或多个第一时间窗内分别累积的电荷得到第一采样序列，所述第一回波信号包括所述第一激光脉冲信号的反射信号，所述第一采样序列用于目标探测。
  2. 根据权利要求1所述的探测装置，其特征在于，所述第一光电探测器的电荷导出时间小于所述第一时间窗的宽度。
  3. 根据权利要求2所述的探测装置，其特征在于，所述电荷导出时间和所述第一时间窗的宽度之间的比值小于或等于第一阈值。
  4. 根据权利要求1至3中任一项所述的探测装置，其特征在于，所述第一光电探测器包括互补性金属氧化物半导体CMOS或电荷耦合器件CCD。
  5. 根据权利要求1至4中任一项所述的探测装置，其特征在于，所述第一激光脉冲信号的脉冲宽度与所述第一时间窗的宽度的整数倍之间的差值小于或等于第二阈值。
  6. 根据权利要求5所述的探测装置，其特征在于，所述第一激光脉冲信号的脉冲宽度与所述第一时间窗的宽度之间的差值小于或等于所述第二阈值。
  7. 根据权利要求1至6中任一项所述的探测装置，其特征在于，所述第一采样序列中的信号值之间的比例用于目标探测。
  8. 根据权利要求1至7中任一项所述的探测装置，其特征在于，所述第一激光脉冲信号包括多个脉冲。
  9. 根据权利要求8所述的探测装置，其特征在于，还包括：
    第二激光发射器，用于：发射第二激光脉冲信号，所述第二激光脉冲信号的脉冲间隔或脉冲宽度与所述第一激光脉冲信号不同；
    第二光电探测器，用于：在一个或多个第二时间窗内分别累积响应于第二回波信号产生的电荷，根据所述一个或多个第二时间窗内分别累积的电荷得到第二采样序列，所述第二回波信号包括所述第二激光脉冲信号的反射信号，所述第二采样序列或所述第一采样序列用于目标探测。
  10. 根据权利要求9所述的探测装置，其特征在于，所述第二激光脉冲信号的脉冲间隔大于所述第一激光脉冲信号的脉冲波形的持续时间。
  11. 一种探测方法，其特征在于，包括：
    发射第一激光脉冲信号；
    在一个或多个第一时间窗内分别累积响应于第一回波信号产生的电荷，根据所述一个或多个第一时间窗内分别累积的电荷得到第一采样序列，所述第一回波信号包括所述第一激光脉冲信号的反射信号，所述第一采样序列用于目标探测。
  12. 根据权利要求11所述的方法，其特征在于，所述第一激光脉冲信号的脉冲宽度与所述第一时间窗的宽度的整数倍之间的差值小于或等于第二阈值。
  13. 根据权利要求12所述的方法，其特征在于，所述第一激光脉冲信号的脉冲宽度 与所述第一时间窗的宽度之间的差值小于或等于所述第二阈值。
  14. 根据权利要求11至13中任一项所述的方法，其特征在于，所述第一采样序列中的信号值之间的比例用于目标探测。
  15. 根据权利要求14所述的方法，其特征在于，所述第一激光脉冲信号包括多个脉冲。
  16. 根据权利要求15所述的方法，其特征在于，所述方法还包括：
    发射第二激光脉冲信号，所述第二激光脉冲信号的脉冲间隔或脉冲宽度与所述第一激光脉冲信号不同；
    在一个或多个第二时间窗内分别累积响应于第二回波信号产生的电荷，根据所述一个或多个第二时间窗内分别累积的电荷得到第二采样序列，所述第二回波信号包括所述第二激光脉冲信号的反射信号，所述第二采样序列或所述第一采样序列用于目标探测。
  17. 根据权利要求16所述的方法，其特征在于，所述第二激光信号的脉冲间隔大于所述第一激光信号的脉冲波形的持续时间。
  18. 一种激光雷达，其特征在于，所述激光雷达包括如权利要求1至10中任一项所述的探测装置。
  19. 一种终端，其特征在于，所述终端包括如权利要求18所述的激光雷达。
  20. 根据权利要求19所述的终端，其特征在于，所述终端为车辆、无人机或机器人。
PCT/CN2022/076593 2022-02-17 2022-02-17 探测装置及探测方法 WO2023155093A1 (zh)

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