Laser detector, detection method and laser radar

Abstract

The invention provides a laser detector, a detection method and a laser radar. The laser detector comprises a plurality of light detection units, an input switch set, a control module and a received signal processing module. Each light detection unit in the plurality of light detection units selectively connects one of at least two different bias voltages through an input switch in the input switch set; the control module is used for controlling the input switch to select one of the at least two different bias voltages, so that the light detection unit is connected with the selected bias voltage; and the received signal processing module is used for processing the received incident light signals detected by the plurality of light detection units and providing output signals. The method can adapt to different scenes more flexibly.

Description

Technical Field

[0001] The present application relates to the field of laser radar, and in particular to a laser detector, a detection method and a laser radar. Background Art

[0002] Faced with the complex and ever-changing real-world vehicle driving environment, high-level autonomous driving functions have put forward higher requirements for the perception and detection capabilities of on-board LiDAR: including but not limited to longer detection distances, no blind spots in close-range detection distances, and differentiation of object reflectivity at different distances. Currently, LiDAR generally uses TOF (Time of Fight) technology. A pulsed laser is emitted in the direction of the target, and the reflected light that encounters the object will be received by the detector. By measuring the flight time of the light pulse between the radar and the target and the intensity and shape of the reflected echo, information on whether there is an object in the target direction, the distance from the object to the radar, and the reflectivity of the object's surface can be obtained.

[0003] Laser detectors are the core components of TOF solutions, which determine the detection efficiency, detection resolution and detection dynamic range of the photoelectric conversion link. Existing laser detectors still have room for improvement. Summary of the invention

[0004] The present application provides a laser detector, a detection method and a laser radar, which can improve the dynamic range of the radar and adapt to different scenarios more flexibly.

[0005] In a first aspect, the present application provides a laser detector, comprising a plurality of light detection units, an input switch set, a control module, and a received signal processing module;

[0006] Each of the plurality of light detection units is selectively connected to one of at least two different bias voltages through an input switch in the input switch set;

[0007] The control module is used to control the input switch to select one of the at least two different bias voltages, so that the light detection unit is connected to the selected bias voltage;

[0008] The received signal processing module is used to process the incident light signals detected by the multiple light detection units and provide output signals.

[0009] Optionally, at least two light detection units among the plurality of light detection units are connected to one of the at least two different bias voltages through a same input switch.

[0010] Optionally, the at least two light detection units are connected to another bias voltage of the at least two different bias voltages through different input switches respectively; or,

[0011] The at least two light detection units are selected from the at least two different bias voltages through the same input switch so as to be connected to the same bias voltage through the same input switch each time.

[0012] Optionally, the at least two light detection units are a first block among the multiple light detection units, and the first block includes light detection units located in a central area of ​​the multiple light detection units.

[0013] Optionally, each light detection unit in the first block is connected to the highest bias voltage among the at least two different bias voltages through the same input switch.

[0014] Optionally, the at least two light detection units are a second block among the multiple light detection units, and the second block includes light detection units located in an edge area of ​​the multiple light detection units.

[0015] Optionally, the at least two different bias voltages include a first bias voltage and a second bias voltage, wherein the second bias voltage is higher than the first bias voltage;

[0016] Each light detection unit in the second block is connected to the first bias voltage through the same input switch.

[0017] Optionally, the at least two different bias voltages include an extremely low bias voltage, so that the light detection unit connected to the extremely low bias voltage through the input switch is turned off.

[0018] Optionally, the control module is further used to connect the at least one light detection unit to the extremely low bias voltage when it is detected that the intensity of the light signal detected in at least one detection before at least one light detection unit located in the peripheral area of ​​the multiple light detection units is lower than a threshold.

[0019] Optionally, the control module is further configured to connect the light detection unit whose output signal-to-noise ratio is lower than a signal-to-noise ratio threshold to the extremely low bias voltage.

[0020] Optionally, the control module is further configured to connect at least part of the light detection units located outside the imaging area of ​​the emission light spot to the extremely low bias voltage.

[0021] Optionally, the at least two different bias voltages include a first bias voltage and a second bias voltage, and the second bias voltage is higher than the first bias voltage;

[0022] The control module is further used to connect at least part of the multiple light detection units to the second bias voltage during long-distance ranging, and / or, to connect at least part of the multiple light detection units to the first bias voltage during short-distance ranging.

[0023] Optionally, the at least two different bias voltages include a first bias voltage and a second bias voltage, and the second bias voltage is higher than the first bias voltage;

[0024] The control module is used to connect at least part of the multiple light detection units to the first bias voltage within a first preset time period in a detection window period of a detection, and to switch at least part of them to be connected to the second bias voltage within a second preset time period in the detection window period, wherein the second preset time period is after the first preset time period.

[0025] Optionally, the control module is further configured to select bias voltages to which the plurality of light detection units are respectively connected in the current detection according to an incident light signal detected at least once before.

[0026] Optionally, the control module is specifically used to reduce the bias voltage connected to at least some of the light detection units in this detection when saturation occurs in the incident light signal of at least the previous detection, and / or reduce the number of light detection units used for detection in this detection.

[0027] Optionally, the control module is specifically configured to reduce a bias voltage of a light detection unit that has been saturated in at least one previous detection, or to shut down a light detection unit that has been saturated in at least one previous detection.

[0028] Optionally, the laser detector further comprises an output switch set, and each of the plurality of light detection units selectively connects one of at least two different output channels through an output switch in the output switch set;

[0029] The control module is further used to control the output switch to select one of the at least two different output channels, so that the light detection unit is connected to the selected output channel;

[0030] When the received signal processing module is used to process the incident light signals detected by the multiple light detection units and provide output signals, it is specifically used to process the incident light signals output by the at least two different output channels and provide output signals.

[0031] Optionally, the control module is used to control the output switch so that all light detection units connected to the same bias voltage are connected to the same output channel, and light detection units connected to different bias voltages are connected to different output channels.

[0032] Optionally, the control module is used to control the output switch so that at least part of the light detection units connected to one bias voltage and at least part of the light detection units connected to another bias voltage are connected to the same output channel;

[0033] and / or,

[0034] The control module is used to control the output switch so that part of the light detection units connected to the same bias voltage are connected to one of the output channels, and part of the light detection units are connected to the other output channel.

[0035] Optionally, the at least two different bias voltages include a first bias voltage and a second bias voltage, and the second bias voltage is higher than the first bias voltage; the at least two output channels include a first output channel and a second output channel;

[0036] For at least part of the multiple light detection units, the control module is used to control the input switch and the output switch in two adjacent detections so that at least part of them switches from connecting the first bias voltage and the first output channel to connecting the second bias voltage and the second output channel.

[0037] Optionally, the plurality of light detection units include SiPM or SPAD arrays.

[0038] Optionally, the laser detector further comprises a storage module for storing connection configuration information between the plurality of light detection units and the input switch set.

[0039] In a second aspect, the present application provides a detection method, applied to any of the above-mentioned laser detectors, comprising:

[0040] Controlling each input switch in the input switch set so that at least some of the plurality of light detection units are respectively connected to one of the at least two bias voltages;

[0041] an incident light signal detected by a light detection unit connected to a bias voltage;

[0042] The detected incident light signal is processed and an output signal is provided.

[0043] In a third aspect, the present application provides a laser radar, comprising a laser transmitter for emitting a laser beam, and any one of the laser detectors described.

[0044] In the embodiment of the present application, by providing an input switch set in the laser detector, each light detection unit selects and connects one of the bias voltages of at least two different bias voltages through the input switch in the input switch set, so that different light detection units in the multiple light detection units can be conveniently set to have different input bias voltages, wherein the light detection unit providing a higher bias voltage has a higher photoelectric conversion efficiency and a larger gain, and is suitable for weaker light measurement, such as an echo at a longer distance or an echo with a lower reflectivity; the light detection unit providing a lower bias voltage has a lower photoelectric conversion efficiency and a smaller gain, and is suitable for strong light measurement, such as an echo at a closer distance or an echo with a higher reflectivity; Moreover, each light detection unit can selectively connect one of at least two different bias voltages through the input switch concentrated in the input switch, so the bias voltage of each light detection unit can be flexibly set. Compared with the solution in which light detection units in different partitions are fixedly connected to different bias voltages, it can avoid the light detection units in the high bias partition from being saturated under the strong signal reflected at a close distance, thereby causing the loss of detection capability and generating additional power consumption. It can also avoid the problem of more light detection units in the low bias partition affecting the ability to detect weak signals at a long distance, and avoid the problem of limited dynamic range due to fewer light detection units in the low bias partition. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 is a schematic diagram of an embodiment of a laser detector in the present application;

[0046] Figure 2 is a schematic diagram of the relationship between a light detection unit and a switch in one embodiment of a laser detector in the present application;

[0047] Figure 3 is a schematic diagram of an embodiment of a laser detector in the present application;

[0048] Figure 4 It is a schematic diagram of the structure of a SiPM;

[0049] Figure 5 It is a schematic diagram of the structure of a SPAD array;

[0050] Figure 6 It is a schematic diagram of an embodiment of the positional relationship between the emission spot imaging and the overall phase of each light detection unit in the laser radar;

[0051] Fig. 7A is a schematic diagram of an embodiment of the positional relationship between the bias voltage and the second tolerance area of ​​the emission spot imaging in the laser radar;

[0052] Figure 7Bis a schematic diagram of another embodiment of the positional relationship between the imaging area of ​​the emission spot in the laser radar and the second tolerance area;

[0053] Figure 7C yes Fig. 7A A schematic diagram of the movement of the imaging area of ​​the emission spot in the laser radar shown;

[0054] Figure 8 is a schematic diagram of another embodiment of a laser detector of the present application;

[0055] Fig. 9 is a schematic diagram of another embodiment of a laser detector of the present application;

[0056] Fig.10 is a schematic diagram of an embodiment of the detection method of the present application;

[0057] Fig.11 It is a schematic diagram of an embodiment of a laser radar in an embodiment of the present application. DETAILED DESCRIPTION

[0058] The embodiments of the present application will be described in more detail below with reference to the accompanying drawings. Although the embodiments of the present application are shown in the accompanying drawings, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to make the present application more thorough and complete, and to fully convey the scope of the present application to those skilled in the art.

[0059] The terms used in this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The singular forms of "a", "said" and "the" used in this application and the appended claims are also intended to include plural forms unless the context clearly indicates other meanings. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0060] It should be understood that although the terms "first", "second", "third", etc. may be used in this application to describe various information, this information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of this application, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0061] Laser radar is a radar system that emits laser beams to detect the position, speed and other characteristic quantities of the target. One of its working principles is to emit a laser beam to the target detection area, and then calculate the time difference between the received reflected echo and the emitted laser beam, which is the flight time of the laser beam. The laser radar calculates the distance, direction and other parameters of the object reflecting the echo based on the flight time, thereby detecting the external environment. Laser radar generally includes a transceiver module and a processing module. The laser transmitter in the transceiver module converts the electrical pulse into a light pulse and emits it, and then the light pulse reflected from the target is restored to an electrical pulse signal through the laser detector, and the processing module calculates relevant information based on the electrical pulse signal. Optionally, the laser radar may also include a scanning module (such as a MEMS galvanometer, a rotating mirror, a mechanical rotating platform, etc.) to change the emission direction of the emitted laser beam to achieve scanning of the laser beam within a certain field of view. In the example where the optical paths of the echo laser and the emitted laser are coaxial, the echo laser returns along the path of the scanning module-transceiver module and is received by the laser detector in the transceiver module.

[0062] like Figure 1 As shown, Figure 1 Schematic diagram of an embodiment of the laser detector in the present application. The laser detector 10 includes a plurality of light detection units 11 , an input switch set 12 , a control module 13 and a received signal processing module 14 .

[0063] In some examples, the light detection unit may include a single photon avalanche diode (SPAD) array, or a SPAD array or a silicon photomultiplier (SiPM), wherein the SiPM is a device composed of several spads. The single-point SPAD operates in Geiger mode with a large gain. Once triggered by a single photon, a large current signal is generated. Therefore, the photoelectric conversion efficiency is high, and the excitation of a single photon can be detected. It is suitable for weak light measurement, such as detecting echoes with low reflectivity at a long distance.

[0064] Each of the plurality of light detection units 11 selects and connects one of the at least two different bias voltages through an input switch in the input switch set 12. The control module is used to control the input switch to select one of the at least two different bias voltages so that the light detection unit is connected to the selected bias voltage. The received signal processing module 14 is used to process the incident light signals detected by the plurality of light detection units and provide an output signal.

[0065] It can be understood that the signal processing module can be built into the laser detector. Optionally, the signal processing module can also be arranged outside the laser detector to perform corresponding signal processing by connecting with the laser detector.

[0066] Specifically, at least one switch is provided between each light detection unit and each bias voltage of the at least two different bias voltages. Alternatively, in a specific implementation, each light detection unit is connected to a different bias voltage pin via an analog switch, and the bias voltage selected by the light detection unit is determined by turning on the analog switch. The at least two different bias voltages include a first bias voltage. In some examples, each of the plurality of light detection units 11 is connected to the first bias voltage via a different switch. For example, Figure 2 As shown, Figure 2 Schematic diagram of the relationship between the light detection unit and the switch in one embodiment of the laser detector in the present application. The multiple light detection units 11 include a first light detection unit 111 and a second light detection unit 112. The first light detection unit 111 is connected to the first bias voltage through the switch 121, and the second light detection unit 112 is connected to the first bias voltage through the switch 124. The first light detection unit 111 is connected to the second bias voltage through the switch 122, and the second light detection unit 112 is connected to the second bias voltage through the switch 124. The received signal processing module 14 is used to process the incident light signal detected by the first light detection unit 111 and the second light detection unit 112 and provide an output signal.

[0067] In some examples, at least two of the plurality of light detection units are connected to one of the at least two different bias voltages through the same input switch. In practical applications, there is a high probability that some of the plurality of light detection units need to be connected to the same bias voltage in various situations. Connecting these light detection units to the same bias voltage through only one switch can simplify the switch layout and improve the control efficiency.

[0068] Alternatively, as another optional method, this part of the detection units can also be connected to a configurable branch, and the configurable branch has connections to each detection unit and each bias switch. The bias voltage is switched by the configurable branch, so that the bias states of multiple detection units can be configured in batches by switching one switch, thereby improving control efficiency.

[0069] For example, Figure 3 As shown, Figure 3It is a schematic diagram of an embodiment of the laser detector in the present application. The multiple light detection units include a first block 113, wherein the first block includes at least two light detection units. The first block 113 is connected to the first bias voltage through a switch 125, so that when the switch 125 is turned on, all the light detection units in the first block 113 are simultaneously connected to the first bias voltage. Optionally, the first block 113 is also connected to the second bias voltage through a switch 126, so that when the switch 126 is turned on, all the light detection units in the first block 113 are simultaneously connected to the second bias voltage. Alternatively, different light detection units in the first block 113 can be connected to the second bias voltage through different switches, respectively, so as to control whether the light detection unit is connected to the second bias voltage individually by turning on and off the switch between each light detection unit and the second bias voltage. For example, in addition to the first bias voltage and the second bias voltage, at least one other bias voltage is provided, and each light detection unit in the first block is simultaneously connected to the first bias voltage through the same switch, but can freely choose to connect to the second bias voltage or other bias voltages through different switches.

[0070] As an optional implementation, the first block 113 may also be connected to the first bias voltage or the second bias voltage through a single-pole double-throw switch or a gate driver.

[0071] Optionally, the first block includes a light detection unit located in the central area of ​​the plurality of light detection units. Optionally, the first bias voltage is the highest bias voltage of the at least two different bias voltages. Since the central area of ​​the plurality of light detection units needs to better receive weak signals reflected from a long distance, the switching efficiency of the switch and the detection capability of weak signals can be improved by connecting the first block located in the central area to a high bias voltage through the same switch.

[0072] Alternatively, optionally, the first block includes at least two light detection units located in the edge area of ​​the multiple light detection units. Optionally, the second bias voltage is higher than the first bias voltage; each light detection unit in the first block is connected to the first bias voltage through the same input switch. Generally, in order not to affect the ability to detect weak signals at a long distance, in one detection, only the light detection units in the edge area are usually connected to a low bias voltage to detect strong signals. Therefore, by connecting the first block located in the edge area to a low bias voltage through the same switch, the switching efficiency of the switch can be improved and the weakening of the detection ability of weak signals can be reduced.

[0073] In some examples, the at least two different bias voltages include an extremely low bias voltage, so that the light detection unit connected to the extremely low bias voltage through the input switch is turned off. For example, when it is detected that some of the light detection units among the multiple light detection units meet a preset condition, the control module is used to connect the part of the light detection units to the extremely low bias voltage, so that the part of the light detection units hardly responds to the light signal in this detection, thereby achieving the effect of turning off the output of the part of the light detection units. For example, when the control module detects multiple times in a row that the intensity of the light signal detected by at least one light detection unit in the peripheral area of ​​the multiple light detection units in at least one previous detection is lower than a threshold, the at least one light detection unit is connected to the extremely low bias voltage in this detection.

[0074] It can be understood that if the unit of the photon detection unit is a single-point SPAD, the intensity of the light signal received by the photon detection unit can be confirmed based on the detection rate or trigger rate of the SPAD.

[0075] As another optional implementation, each of the light detection units may further include a plurality of single-point SPADs. In this case, the light detection unit may have a built-in signal detection circuit, and the intensity threshold of the light signal may be confirmed according to the signal detection circuit.

[0076] Among them, as another optional implementation, each light detection unit may also include multiple single-point SPADs. In this case, the intensity of the light signal received by each light detection unit may also be determined according to the number of triggered multiple single-point SPADs in each light detection unit.

[0077] Alternatively, the self-test mode may be entered autonomously periodically or in response to a trigger. In the self-test mode, each light detection unit is detected to see whether it meets the preset conditions. In the self-test mode, the control module may scan the output signal-to-noise ratio of each light detection unit, and when a light detection unit whose output signal-to-noise ratio is lower than a signal-to-noise ratio threshold is detected, the light detection unit is confirmed to meet the preset conditions. For example, the correlation between the detection signal of each light detection unit and the laser emission is checked respectively, and when the correlation is lower than the coherence threshold, it is determined that the output signal-to-noise ratio of the light detection unit is lower than the signal-to-noise ratio threshold.

[0078] Alternatively, in the self-test mode, the control module can scan the signal intensity of each light detection unit, and when a light detection unit with an intensity lower than the intensity threshold is detected, it is confirmed that the light detection unit meets the preset condition. Alternatively, the control module can connect the outputs of the light detection units row by row or one by one to an output channel, determine the distribution position of the effective light detection unit by determining the maximum output amplitude position, and then confirm the remaining light detection units other than the effective light detection unit as meeting the preset condition. Alternatively, the control module determines the distribution position of the effective light detection unit by judging the focal area of ​​the receiving field of view of the laser radar on the overall phase plane of each light detection unit through the optical imaging area, and then confirms the remaining light detection units other than the effective light detection unit as meeting the preset condition.

[0079] In a specific example, the multiple light detection units include a first block and a second block, wherein the first block includes at least two light detection units located in the central area of ​​the multiple light detection units, and the second block includes at least two light detection units located in the edge area of ​​the multiple light detection units. All the light detection units in the first block are connected to the first bias voltage through the same switch, and are connected to each other bias voltage, such as the second bias voltage and the third bias voltage, through different switches or through the same switch respectively. All the light detection units in the second block are connected to the second bias voltage through the same switch, and are connected to each other bias voltage, such as the first bias voltage and the third bias voltage, through different switches or through the same switch respectively. Optionally, all the light detection units of the multiple light detection units are allocated to the first block or the second block, or, in addition to the light detection units in the first block and the second block, the multiple light detection units also include other light detection units.

[0080] In some examples, the binning can be implemented by silicon photomultiplier (SiPM) binning. Figure 4 As shown, Figure 4It is a schematic diagram of the structure of a SiPM. SiPM 40 is composed of multiple single-point SPAD micro-units 41 connected in parallel under the input of the same bias voltage V1 to generate an output signal O1. The output signal O1 is a synthetic signal triggered by multiple SPADs, which characterizes the relationship between the number of SPADs triggered by the SiPM phase surface and time. Therefore, SiPM is also called MPPC (Multi-Pixel Photon Counter). The output of SiPM directly reflects the light intensity information of the detected light signal. The bias voltage V1 can be achieved by connecting the SiPM to the first bias voltage through switch 125, or by connecting the switch 126 to the second bias voltage. In some examples, one block of the multiple light detection units can be implemented by part of the SiPM, and the part is connected to the first bias voltage through a switch, and the part is connected in parallel to generate an output. The SiPM can also be divided into different blocks, each of which is connected to different bias voltages through different switches, and each block is connected in parallel to generate an output, and different blocks generate different outputs. Optionally, the bias application method of the SiPM can be applied from the cathode or the anode.

[0081] In some examples, the blocking can be achieved by combining the outputs of an off-the-shelf SPAD array into blocks. Figure 5 As shown, Figure 5 is a schematic diagram of the structure of a SPAD array. The SPAD array 50 is an array composed of single-point SPADs 51. Under the same bias voltage V2 input, each single-point SPAD has an independent output O2 and can only respond to single-photon triggering. Figure 5 As shown, all outputs O2 of the SPAD array can be combined to realize SiPM, as a block in the multiple light detection units, the bias voltage V2 can be realized by connecting the SPAD array to the first bias voltage through switch 125, or connected to the second bias voltage through switch 126. Or the output of the existing SPAD array is divided into at least two blocks, where the outputs of different blocks are respectively combined to realize SiPM respectively, and respectively serve as different blocks in the multiple light detection units. Each block is connected to different bias voltages through different switches.

[0082] SiPM has high photoelectric conversion efficiency and single-photon gain, but at the same time reduces the receiving dynamic range. The number of SPADs in SiPM determines the maximum number of photons that can be triggered, that is, the receiving dynamic range. The number of SPADs in SiPM is usually within 4000, and the dynamic range does not exceed 80dB. In order to ensure the ranging capability of long-distance or low-reflective objects, this 80dB dynamic range will be used to cover 80dB of weaker light in the 160dB dynamic range of reflected light. This means that in many cases where the reflected light is strong, SiPM will enter a saturated state.

[0083] When SiPM enters the saturation state, it will bring a series of problems. The first is the decline in ranging performance. Once SiPM is saturated, it will lose its detection capability and gradually recover its detection capability within the saturation recovery time. This means that when encountering strong echo light, it will experience a sudden drop in detection capability and a recovery process. Especially for the coaxial optical path lidar architecture, there is a leading reflected echo light because the stray optical path cannot be avoided. If the leading reflected echo light causes the SiPM to enter saturation, it will cause a close-range ranging blind spot. Secondly, the reflectivity is difficult to distinguish. If reflected light of different intensities can saturate the SiPM, then it is difficult to distinguish the two intensities of reflected light in terms of intensity. The closer the distance, the more difficult it is to distinguish the reflectivity.

[0084] In order to prevent SiPM from entering saturation state in close range detection, an additional small energy emission is usually introduced in addition to the maximum power emission. Fewer emitted photons will mean fewer reflected echo photons, which can prevent SiPM from entering saturation state. This enables SiPM to have detection capabilities at close range. However, the additional small energy emission consumes energy and takes up time, making the transmit and receive timing design more complicated, and also making the laser emission circuit design more complicated and expensive.

[0085] In the embodiment of the present application, by providing an input switch set in the laser detector, each light detection unit selects and connects one of the bias voltages of at least two different bias voltages through the input switch in the input switch set, and different light detection units in the multiple light detection units can be conveniently set to have different input bias voltages, wherein the light detection unit providing a higher bias voltage has a higher photoelectric conversion efficiency and a larger gain, which is suitable for weaker light measurement, such as echoes at a longer distance or echoes with a lower reflectivity; the light detection unit providing a lower bias voltage has a lower photoelectric conversion efficiency and a smaller gain, which is suitable for strong light measurement, such as echoes at a closer distance or echoes with a higher reflectivity. In this way, by setting different light detection units with different bias voltages, different detection efficiencies can be taken into account and a higher detection dynamic range can be achieved; it also means that under the same laser emission power, the laser detector in the present application can achieve a longer detection distance and a higher optical signal-to-noise ratio detection capability. In addition, the intensity of light can be better identified and distinguished, thereby better realizing the distinction of reflectivity, especially the distinction of reflectivity at a close distance. There is no need to introduce the low-energy emission in the traditional short-range ranging solution, which can save the energy consumption of single-point ranging, simplify the transmission and reception timing design, and simplify the laser emission circuit design.

[0086] Moreover, each light detection unit can selectively connect one of at least two different bias voltages through the input switch concentrated in the input switch, so the bias voltage of each light detection unit can be flexibly set. Compared with the solution in which light detection units in different partitions are fixedly connected to different bias voltages, it can avoid the light detection units in high bias partitions from being saturated under strong signals reflected at close range (including leading signals during high-power transmission in coaxial systems), thereby causing loss of detection capability and generating additional power consumption. It can also avoid the problem of more light detection units in low bias partitions affecting the ability to detect weak signals at long distances, and avoid the problem of limited dynamic range due to fewer light detection units in low bias partitions.

[0087] In some examples, the multiple light detection units include a third block in addition to the first block and the second block. The setting of the third block can be similar to the first block and the second block, that is, all the light detection units in the block are connected to one of the bias voltages through the same switch, and are connected to each of the other bias voltages through different switches or through the same switch.

[0088] In some examples, the plurality of light detection units include other light detection units in addition to the first block and the second block, and at least part of the other light detection units are connected to the same bias voltage through different switches. Optionally, at least part of the other light detection units are located between the first block and the second block.

[0089] In some examples, the shape, arrangement and number of each light detection unit are adapted to the optomechanical system of the laser radar to obtain all the reflected energy that can be received by the receiving aperture of the laser radar. However, in order to reduce the transmission crosstalk between different channels of the laser radar, the receiving field divergence angle of the optomechanical system is designed to be larger than the divergence angle of the emission spot, so that the image of the emission spot on the overall phase plane of each light detection unit is smaller than the size of the overall phase plane. Figure 6 As shown, Figure 6 6 is a schematic diagram of an embodiment of the positional relationship between the emission light spot imaging and the overall phase plane of each light detection unit in the laser radar. In some examples, the design of the overall phase plane 600 of each light detection unit will leave enough margin for the tolerance between the assembly and the structure, forming a first tolerance area 601 to ensure that the imaging of the emission light spot can be received by the overall phase plane 600. The first tolerance area 601 is generally annularly surrounding the imaging area 602 of the emission light spot.

[0090] However, in a laser radar with a moving scanning component, an additional walk-off tolerance is introduced to form a second tolerance area 603. This is because the flight time of the reflected echoes at different distances is different, and the imaging area 602 of the emission spot is offset due to the scanning motion. Therefore, the design of the overall phase plane 600 of each light detection unit also needs to reserve a walk-off tolerance. The shape and position of the second tolerance area 603 are related to the movement mode of the moving scanning component and the shape of the imaging area of ​​the emission spot. In some examples, such as Fig. 7A As shown, Fig. 7A FIG. 6 is a schematic diagram of an embodiment of the positional relationship between the bias voltage of the emission spot imaging and the second tolerance area in the laser radar. In the overall phase plane 600 of each light detection unit, the imaging area 602 of the emission spot is rectangular, and the second tolerance area 603 is strip-shaped and is located on the adjacent side of the imaging area 602 of the emission spot. Figure 7B As shown, Figure 7B 602 is a schematic diagram of another embodiment of the positional relationship between the imaging area of ​​the emission light spot and the second tolerance area in the laser radar. The imaging area 602 of the emission light spot is circular, and the second tolerance area 603 is crescent-shaped and is located on one side adjacent to the imaging area 602 of the emission light spot.

[0091] like Figure 7C As shown, Figure 7C yes Fig. 7A Schematic diagram of the movement of the imaging area of ​​the emission spot in the laser radar shown. During the displacement process of the imaging area 602 of the emission spot, the imaging area 602 of the emission spot gradually moves toward the second tolerance area 603, so that at least part of the light detection units originally located in the second tolerance area 603 become located in the imaging area 602, and the light detection units moved out of the imaging area 602 become located in the second tolerance area 603.

[0092] Optionally, each light detection unit located in the second tolerance area 603 is connected to at least one bias voltage through different switches, and the same light detection unit is connected to different bias voltages through different switches. The control module is also used to control each light detection unit in the second tolerance area 603 to change to different bias voltages as the imaging area of ​​the emission light spot moves. For example, since the second tolerance area 603 does not receive a valid signal, resulting in a low signal-to-noise ratio, the control module controls the light detection signal in the second tolerance area 603 to be connected to an extremely low bias voltage to be in a closed state; as the imaging area of ​​the emission light spot moves, the control module is used to switch the light detection unit moved from the second tolerance area 603 into the imaging area of ​​the emission light spot from being connected to an extremely low bias voltage to being connected to another bias voltage, and to switch the light detection unit moved from the imaging area of ​​the emission light spot into the second tolerance area 603 from the bias voltage originally connected to being connected to an extremely low bias voltage.

[0093] Optionally, the second block described above may be a light detection unit located in the first tolerance area 601, and connected to an extremely low bias voltage through the same switch. Optionally, the second block described above may be located in the peripheral area of ​​the imaging area 602 of the emission light spot, and connected to a lower bias voltage of the at least two different bias voltages through the same switch, and when a strong signal needs to be detected, the control module controls the switch so that the second block is connected to the lower bias voltage. Optionally, the first block described above may be located in the central area of ​​the imaging area 602 of the emission light spot, and connected to a higher or highest bias voltage of the at least two different bias voltages through the same switch, and when a weak signal needs to be detected, the control module controls the switch so that the first block is connected to the higher or highest bias voltage.

[0094] In the present application, the control module may have multiple switching strategies for controlling the switches connected to each light detection unit. For example, in an example where the second bias voltage is higher than the first bias voltage, the control module is used to connect at least part of the multiple light detection units to the second bias voltage respectively during long-distance ranging, and / or, is also used to connect at least part of the multiple light detection units to the first bias voltage respectively during short-distance ranging. There are multiple methods for the control module to determine whether the current detection is long-distance ranging or short-distance ranging, such as determining based on the scene where the user is located, determining based on auxiliary information from the vehicle-mounted system, and determining based on at least one previous echo time, which is not limited here.

[0095] For another example, in an example where the second bias voltage is higher than the first bias voltage, the control module is used to connect at least part of the multiple light detection units to the first bias voltage within a first preset time period in a detection window period of a detection, and is used to switch the at least part to be connected to the second bias voltage within a second preset time period in the detection window period, wherein the second preset time period is located after the first preset time period. In an example where more bias voltages are provided, the control module may increase the bias voltage level of at least part of the multiple light detection units after a fixed flight time in the detection window period of a detection. Alternatively, the control module may be used to gradually increase the bias voltage connected to at least part of the light detection units in several adjacent detections, so as to better adapt to changes in the full-distance dynamic range to achieve a gradual change process of the receiving dynamic range, and better adapt to changes in the full-distance dynamic range.

[0096] In some examples, the control module can be used to select the bias voltages to which the multiple light detection units are respectively connected in this detection according to the incident light signal of at least the previous detection. For example, when saturation occurs in the incident light signal of at least the previous detection, the control module is used to reduce the bias voltage connected to at least some of the light detection units in this detection, and / or reduce the number of light detection units used for detection in this detection, so that the saturation pulse width and the saturation pulse width recovery time can be shortened. Optionally, the control module can reduce the bias voltage connected to all light detection units by one level, or turn off some of the light detection units in a fixed number and / or fixed position. Optionally, the control module can also determine the light detection unit that appeared saturated in the previous detection, and reduce the bias voltage of the light detection unit that appeared saturated in at least the previous detection, or directly turn off the light detection unit that appeared saturated, for example, by connecting it to an extremely low bias voltage to achieve the shutdown.

[0097] In the above examples, each light detection unit selectively connects one of at least two different bias voltages through an input switch in the input switch set. Figure 8 As shown, Figure 8 is a schematic diagram of another embodiment of the laser detector of the present application. Figure 1The difference between the laser detector shown in the figure is that the laser detector also includes an output switch set 15, and each of the multiple light detection units 11 selects and connects an output channel in at least one output channel through an output switch in the output switch set 15. The control module is used to control the output switch to select an output channel in the at least one output channel, so that the light detection unit is connected to the selected output channel or disconnected from the at least one output channel. When the received signal processing module is used to process the incident light signals detected by the multiple light detection units and provide output signals, it is specifically used to receive the incident light signals detected by the multiple light detection units through the at least one output channel, process the incident light signals and provide output signals.

[0098] Optionally, the number of output channels may be only one, and an output switch is provided between each light detection unit and the output channel. Optionally, the number of output channels may be at least two, and each light detection unit is connected to a different output channel through a different switch, and the control module is connected to the output channel by turning on the switch corresponding to the output channel to be selected. Fig. 9 As shown, Fig. 9 is a schematic diagram of another embodiment of the laser detector of the present application. Figure 2 The difference from the illustrated embodiment is that the first light detection unit 111 is also connected to the first output channel through a switch 151, and the second light detection unit 112 is connected to the first output channel through a switch 152. The first light detection unit 111 is connected to the second output channel through a switch 153, and the second light detection unit 112 is connected to the second output channel through a switch 154. The received signal processing module 14 is used to process the signals from the first output channel and the second output channel respectively and provide output signals.

[0099] In the above example of selectively connecting the light detection unit to the extremely low bias voltage, the light detection unit can also be disconnected from all output channels so that the signal of the light detection unit does not participate in the output. Alternatively, the light detection unit to be turned off can be directly disconnected from all output channels without changing the input switch connected to the part of the light detection unit to connect to the extremely low bias voltage.

[0100] Optionally, the control module can control all the light detection units connected to the same bias voltage to select the same output channel for output. Optionally, the control module can control some of the light detection units connected to the same bias voltage to select the first output channel for output and some of the light detection units to select the second output channel for output. Optionally, the control module can control some or all of the light detection units connected to the first bias voltage and some or all of the light detection units connected to the second bias voltage to select the same output channel for output.

[0101] In a specific example, the at least two different bias voltages include a first bias voltage and a second bias voltage, the second bias voltage being higher than the first bias voltage; the at least two output channels include a first output channel and a second output channel. For at least part of the plurality of light detection units, the control module is used to control the input switch and the output switch in two adjacent detections so that the at least part switches from connecting the first bias voltage and the first output channel to connecting the second bias voltage and the second output channel.

[0102] Optionally, the laser detector in the present application further includes a storage module for storing connection configuration information between the plurality of light detection units and the input switch set. Specifically, the storage module may include a non-volatile storage medium and a digital communication configuration interface to configure and store output control configuration information of each light detection unit or each block.

[0103] The present application also provides a detection method, which is applied to any of the above-mentioned laser detectors. Fig.10 As shown, Fig.10 1 is a schematic diagram of an embodiment of a detection method of the present application. The method 1000 includes:

[0104] Step S1001 : controlling each input switch in the input switch set so that at least part of the plurality of light detection units are respectively connected to one of the at least two bias voltages.

[0105] Step S1002: an incident light signal is detected by a light detection unit connected to a bias voltage.

[0106] Step S1003: Process the detected incident light signal and provide an output signal.

[0107] The present application also provides a laser radar, such as Fig.11 As shown, Fig.11is a schematic diagram of an embodiment of a laser radar in an embodiment of the present application. The laser radar 1 includes a laser emitter 2 for emitting a laser beam, and the laser detector 10 described above. It can be understood that, as an optional embodiment, the laser radar may also include a scanning component, wherein the scanning component may be, for example, a galvanometer, a rotating mirror, a mechanical rotating platform, etc. The present application does not limit whether the laser radar includes a scanning component.

[0108] The embodiments of the present application have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or improvements to the technology in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A laser detector, characterized in that: It includes a plurality of light detection units, an input switch set, a control module and a receiving signal processing module; Each of the plurality of light detection units is selectively connected to one of at least two different bias voltages through an input switch in the input switch set; The control module is used to control the input switch to select one of the at least two different bias voltages, so that the light detection unit is connected to the selected bias voltage; The received signal processing module is used to process the incident light signals detected by the multiple light detection units and provide output signals.

2. The laser detector according to claim 1, characterized in that: At least two of the plurality of light detection units are connected to one of the at least two different bias voltages through a same input switch.

3. The laser detector according to claim 2, characterized in that: The at least two light detection units are respectively connected to another bias voltage of the at least two different bias voltages through different input switches; or, The at least two light detection units are selected from the at least two different bias voltages through the same input switch so as to be connected to the same bias voltage through the same input switch each time.

4. The laser detector according to claim 2, characterized in that: The at least two light detection units are a first block among the plurality of light detection units, and the first block includes light detection units located in a central area of ​​the plurality of light detection units.

5. The laser detector according to claim 4, characterized in that: Each photodetection unit in the first block is connected to a highest bias voltage among the at least two different bias voltages through a same input switch.

6. The laser detector according to claim 2, characterized in that: The at least two light detection units are a second block among the plurality of light detection units, and the second block includes light detection units located in edge areas of the plurality of light detection units.

7. The laser detector according to claim 6, characterized in that: The at least two different bias voltages include a first bias voltage and a second bias voltage, wherein the second bias voltage is higher than the first bias voltage; Each light detection unit in the second block is connected to the first bias voltage through the same input switch.

8. The laser detector according to any one of claims 1 to 7, characterized in that: The at least two different bias voltages include a very low bias voltage, so that the light detection unit connected to the very low bias voltage through the input switch is turned off.

9. The laser detector according to claim 8, characterized in that: The control module is further configured to connect the at least one light detection unit to the extremely low bias voltage when it is detected that the intensity of the light signal detected in at least one detection before at least one light detection unit located in the peripheral area of ​​the plurality of light detection units is lower than a threshold.

10. The laser detector according to claim 8, characterized in that: The control module is further configured to connect the light detection unit, whose output signal-to-noise ratio is lower than a signal-to-noise ratio threshold, to the extremely low bias voltage.

11. The laser detector according to claim 8, characterized in that: The control module is further configured to connect at least a portion of the light detection units located outside the imaging region of the emission light spot to the extremely low bias voltage.

12. The laser detector according to any one of claims 1 to 7, characterized in that: The at least two different bias voltages include a first bias voltage and a second bias voltage, wherein the second bias voltage is higher than the first bias voltage; The control module is further used to connect at least part of the multiple light detection units to the second bias voltage during long-distance ranging, and / or, to connect at least part of the multiple light detection units to the first bias voltage during short-distance ranging.

13. The laser detector according to any one of claims 1 to 7, characterized in that: The at least two different bias voltages include a first bias voltage and a second bias voltage, wherein the second bias voltage is higher than the first bias voltage; The control module is used to connect at least part of the multiple light detection units to the first bias voltage within a first preset time period in a detection window period of a detection, and to switch at least part of them to be connected to the second bias voltage within a second preset time period in the detection window period, wherein the second preset time period is after the first preset time period.

14. A detection method, applied to the laser detector according to any one of claims 1 to 13, characterized in that: include: Controlling each input switch in the input switch set so that at least some of the plurality of light detection units are respectively connected to one of the at least two bias voltages; an incident light signal detected by a light detection unit connected to a bias voltage; The detected incident light signal is processed and an output signal is provided.

15. A laser radar, characterized in that: include: A laser transmitter for emitting a laser beam, and a laser detector as claimed in any one of claims 1 to 13.

Images