Optical receiving sensor applied to laser radar, laser radar, and ranging method

Abstract

The application provides a light receiving sensor applied to a laser radar, the laser radar and a ranging method. The light receiving sensor performs grouping processing on each photosensitive element in the pixel, and combines the combination operation mode of OR operation and AND operation in the logic operation module, so that the dynamic change range of the FIR characteristic value is effectively increased, and the dynamic range of the ranging compensation is widened. Based on this, the compensation unit in the laser radar can realize accurate compensation for the first distance according to the FIR characteristic value with a larger dynamic change range, and improve the accuracy of the measured distance. In addition, based on the combination operation mode of OR operation and AND operation, the maximum value of the output value of the pixel is reduced, so that the number of connections between the logic operation module and the histogram accumulation module can be reduced, and the wiring difficulty and preparation cost during the integrated circuit layout design are reduced.

Description

Technical Field

[0001] This invention relates to the field of sensor technology, and in particular to a light receiving sensor, a lidar, and a ranging method for use in lidar. Background Technology

[0002] Time-of-flight (ToF) measurement is one of the existing ranging methods for lidar. It calculates the distance to the target object, R = C·t / 2, by recording the flight time t from laser emission to the detection of the reflected echo, where C is the speed of light. To obtain the flight time t, current technologies generally employ time-correlated single-photon counting (TCSPC). Specifically, the TCSPC circuit uses a pixel array composed of single-photon avalanche diodes (SPADs) as a receiving sensor to receive and count the number of photons. After multiple samplings, the photon count is accumulated over time intervals to generate a distance measurement result. Figure 1 The time series histogram is shown. The highest number of photons are detected in the time difference interval [Pdt, (P+1)dt], indicating that the probability of flight time t falling within this interval is highest. Therefore, flight time t can be determined using relevant data processing algorithms, and the distance R to the target object can then be calculated.

[0003] Typically, the waveform of the reflected echo detected by the optical receiving sensor of a lidar is consistent with the waveform of the laser pulse actually emitted by the laser; for example... Figure 1 The dashed lines shown exhibit a symmetrical Gaussian distribution. However, when the reflected echo energy is strong, the waveform of the reflected echo detected by the receiving sensor is an asymmetrical Gaussian waveform, for example... Figure 2 The dashed line illustrates this asymmetric phenomenon known as the photon pile-up effect. When pile-up occurs, the peak position of the detected reflected echo shifts to the left of the coordinate axis. If the Time-of-Flight (ToF) time is still calculated based on the peak position, it will be less than the actual laser flight time, ultimately leading to a measurement distance closer to the actual distance and a significant ranging error.

[0004] To reduce ranging errors caused by the pile-up phenomenon, existing technologies employ calibration to pre-establish the relationship between ranging error and reflected echo intensity. During actual measurement, the ranging error is calculated based on the measured reflected echo intensity and calibration data, and then compensated for to obtain an accurate measuring distance. The reflected echo intensity is characterized using a finite impulse response (FIR) characteristic value. Within the normal range of reflected echo intensity, the FIR characteristic value increases with increasing intensity. However, when the reflected echo intensity increases to a certain level, limited by factors such as the performance of the photosensitive element, the FIR characteristic value tends to a constant and no longer increases with further increases in reflected echo intensity. Therefore, it can no longer characterize changes in reflected echo intensity and cannot compensate for ranging errors.

[0005] Furthermore, due to the limitation of individual pixel size, the number of photosensitive elements contained in each pixel cannot be too large. In actual measurement processes, when the target object is close or a high-reflectivity target is encountered, the reflected echo intensity still exceeds the measurement dynamic range, meaning that the ranging error caused by pile-up cannot be accurately compensated using FIR eigenvalues. Clearly, the ranging error compensation methods employed in existing technologies have extremely limited applicability to reflected echo intensity and cannot meet the compensation needs for ranging errors caused by a wider range of reflected echo intensity.

[0006] Therefore, a new method for compensating for ranging errors is urgently needed to solve the above-mentioned technical problems. Summary of the Invention

[0007] The purpose of this invention is to provide an optical receiving sensor, a lidar, and a ranging method for use in lidar, in order to solve at least one of the following problems: how to increase the dynamic characterization range of FIR feature values, how to improve ranging accuracy, and how to reduce the wiring difficulty in integrated circuit layout design.

[0008] To solve the above-mentioned technical problems, the present invention provides a light receiving sensor for use in lidar, comprising: a pixel array and a TCSPC circuit;

[0009] The pixel array includes multiple pixels for receiving reflected echoes from laser light; and each pixel includes at least one set of photosensitive elements, and each set of photosensitive elements includes at least two photosensitive elements.

[0010] The TCSPC circuit includes a sampling module, a logic operation module, a histogram accumulation module, and a storage module. The sampling module samples data from each photosensitive element in each pixel at a preset sampling time and outputs the sampling result to the logic operation module. The logic operation module performs logical operations on the sampling results of all photosensitive elements within each pixel and outputs the operation result corresponding to the sampling time to the histogram accumulation module. The histogram accumulation module determines a time difference interval based on the sampling time and reads the stored data corresponding to the time difference interval from the storage module, adds the operation result to the stored data, and outputs the added data to the storage module. The storage module updates the stored data corresponding to the time difference interval with the added data.

[0011] The logical operation includes OR operation and AND operation; the result of the OR operation performed on each of the photosensitive elements belonging to the same group is used as the output value of the corresponding group; the result of the AND operation performed on the output values ​​of all groups belonging to the same pixel is used as the output value of the pixel; the operation result output by the logical operation module includes the output value of the pixel.

[0012] Optionally, in the light receiving sensor applied to LiDAR, the number of photosensitive elements in different groups within the same pixel is the same; or, the number of photosensitive elements in at least some groups is different.

[0013] Optionally, in the light receiving sensor applied to lidar, the pixel includes a plurality of photosensitive elements arranged in an array; wherein all photosensitive elements in the same row are grouped together; or, all photosensitive elements in the same column are grouped together; or, each group of photosensitive elements includes a plurality of photosensitive elements arranged in an array.

[0014] Optionally, in the light receiving sensor applied to lidar, the storage module includes multiple storage units; each storage unit corresponds to a time difference interval, and the storage unit is used to store the stored data corresponding to the time difference interval.

[0015] Optionally, in the aforementioned light receiving sensor applied to lidar, the pixel array, the sampling module, the logic operation module, the histogram accumulation module, and the storage module are integrated into the same chip; or,

[0016] At least some of the pixel array, the sampling module, the logic operation module, the histogram accumulation module, and the storage module are integrated in different chips.

[0017] Based on the same inventive concept, the present invention also provides a lidar, including a light transmitter, a light receiving sensor applied to the lidar, and a data processor;

[0018] The optical emitter is used to emit laser light toward the target being measured;

[0019] The optical receiving sensor is used to receive and process the reflected echo formed by the laser beam reflected by the target being measured;

[0020] The data processor is used to obtain the flight time of the laser based on the stored data corresponding to different time difference intervals in the storage module of the optical receiving sensor, and to calculate the first distance of the measured target based on the flight time; and,

[0021] The data processor further includes a compensation unit; the compensation unit is used to obtain the light intensity characteristic value of the reflected echo according to the stored data corresponding to different time difference intervals in the storage module; and to obtain at least the distance compensation value of the target under test according to the light intensity characteristic value; the data processor is also used to compensate the first distance according to the distance compensation value and form a second distance of the target under test as the measurement distance output by the data processor.

[0022] Optionally, in the lidar, the compensation unit is used to calculate the maximum value after filtering for the stored data corresponding to different time difference intervals in the storage module using the finite impulse response filtering formula, and use it as the FIR feature value; and the light intensity feature value includes the FIR feature value;

[0023] Furthermore, within a preset light intensity range, as the light intensity changes from low to high, the FIR feature value first increases with the increase of the light intensity, and then decreases with the increase of the light intensity.

[0024] Optionally, in the lidar, the compensation unit stores a data relationship table between the distance compensation value and the light intensity of the reflected echo, and a data relationship table between the light intensity of the reflected echo and the light intensity characteristic value; and the compensation unit is used to determine the distance compensation value based at least on the light intensity characteristic value and the data relationship table.

[0025] Optionally, in the lidar, the compensation unit is further configured to acquire an auxiliary light intensity feature value, and determine the light intensity of the reflected echo based on the auxiliary light intensity feature value, the light intensity feature value, and a data relationship table between the light intensity of the reflected echo and the light intensity feature value; and determine the distance compensation value based on the light intensity of the reflected echo and a data relationship table between the distance compensation value and the light intensity of the reflected echo.

[0026] The stored data includes the number of photons, and the light intensity-assisted feature value includes the maximum number of photons stored in all storage units of the storage module.

[0027] Based on the same inventive concept, the present invention also provides a ranging method, comprising:

[0028] A light emitter is used to emit a laser towards the target being measured;

[0029] A light receiving sensor is used to receive and process the reflected echo formed by the laser beam reflected from the target being measured.

[0030] The data processor uses the stored data corresponding to different time difference intervals in the storage module of the optical receiving sensor to obtain the flight time of the laser, and calculates the first distance of the target under test based on the flight time.

[0031] The compensation unit in the data processor obtains the light intensity characteristic value of the reflected echo based on the stored data corresponding to different time difference intervals in the storage module; and at least obtains the distance compensation value of the target under test based on the light intensity characteristic value.

[0032] The data processor compensates for the first distance according to the distance compensation value and forms a second distance of the measured target, which is used as the measured distance output by the data processor.

[0033] In summary, this invention provides a light receiving sensor, a lidar, and a ranging method for use in lidar. Compared to existing technologies, the light receiving sensor effectively increases the dynamic range of FIR feature values ​​by performing grouping processing on each photosensitive element within the pixel and combining OR and SUM operations within the logic operation module, thus broadening the dynamic range of ranging compensation. Based on this, the compensation unit in the lidar can achieve accurate compensation for the first distance based on the FIR feature values ​​with a wider dynamic range, improving the accuracy of distance measurement. Furthermore, based on the combined OR and SUM operations, the maximum value of the pixel's output value is reduced, thereby reducing the number of connections between the logic operation module and the histogram accumulation module, reducing the wiring difficulty and manufacturing cost in integrated circuit layout design. Attached Figure Description

[0034] Those skilled in the art will understand that the accompanying drawings are provided to better understand the invention and do not constitute any limitation on the scope of the invention.

[0035] Figure 1 It is a schematic diagram of a histogram of a symmetrical Gaussian waveform in the prior art.

[0036] Figure 2 It is a schematic diagram of a histogram of an asymmetric Gaussian waveform in the prior art.

[0037] Figure 3 This is a schematic diagram of the structural relationship of the light receiving sensor in an embodiment of the present invention.

[0038] Figure 4 This is a pixel diagram showing each row as a group in an embodiment of the present invention.

[0039] Figure 5 This is a pixel diagram showing that each column is a group in an embodiment of the present invention.

[0040] Figure 6 This is a schematic diagram of pixels with different numbers of photosensitive elements in each group in an embodiment of the present invention.

[0041] Figure 7 This is a schematic diagram of pixels arranged in an array as a group in an embodiment of the present invention.

[0042] Figure 8 This is a schematic diagram of pixels in some groups with different numbers of photosensitive elements and some groups with the same number of photosensitive elements, as described in an embodiment of the present invention.

[0043] Figure 9 This is a schematic diagram of the output values ​​of each photosensitive element within a single pixel sampled in five time difference intervals under the condition of weak light intensity in an embodiment of the present invention.

[0044] Figure 10 This is a schematic diagram of the output values ​​of each photosensitive element within a single pixel sampled in five time-difference intervals under the condition of strong light intensity in an embodiment of the present invention.

[0045] Figure 11 This is a schematic diagram of the output values ​​of each photosensitive element within a single pixel sampled in five time-difference intervals under the condition of very strong light intensity in an embodiment of the present invention.

[0046] Figure 12 This is a schematic diagram comparing the relationship curves between the FIR feature values ​​and the reflected echo intensity obtained by the prior art and the present invention in an embodiment of the present invention.

[0047] Figure 13 This is a flowchart of the ranging method in an embodiment of the present invention.

[0048] And, in the attached image:

[0049] 1 - pixel array; 10 - pixel; 100 - photosensitive element;

[0050] 2-TCSPC circuit; 20-Sampling module; 21-Logic operation module; 22-Histogram accumulation module; 23-Storage module;

[0051] G1 - Group 1; G2 - Group 2; G3 - Group 3; G4 - Group 4; G5 - Group 5; G6 - Group 6. Detailed Implementation

[0052] To make the objectives, advantages, and features of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the drawings are all in a very simplified form and are not drawn to scale, and are only used to facilitate and clearly illustrate the objectives of the embodiments of the present invention. Furthermore, the structures shown in the drawings are often part of the actual structures. In particular, different figures may emphasize different aspects and sometimes use different scales. It should also be understood that, unless specifically stated or indicated, the terms "first," "second," "third," etc., in the specification are only used to distinguish the various components, elements, steps, etc., in the specification, and are not used to indicate the logical or sequential relationships between the various components, elements, steps, etc.

[0053] Please see Figures 3 to 8 This embodiment provides a light receiving sensor for use in lidar, including: a pixel array 1 and a TCSPC circuit 2; the pixel array 1 includes a plurality of pixels 10 for receiving reflected echoes from lasers; and each pixel 10 includes at least one group of photosensitive elements 100, and each group of photosensitive elements 100 includes at least two photosensitive elements 100; the TCSPC circuit 2 includes a sampling module 20, a logic operation module 21, a histogram accumulation module 22, and a storage module 23; the sampling module 20 is used to sample data from each photosensitive element 100 in each pixel 10 at a preset sampling time, and output the sampling result to the logic operation module 21; the logic operation module 21 is at least used to perform logical operations on the sampling results of all photosensitive elements 100 in each pixel 10, and output the corresponding sampling result. The calculation result at the sampling time is sent to the histogram accumulation module 22; the histogram accumulation module 22 is used to determine the time difference interval according to the sampling time, and read the stored data corresponding to the time difference interval in the storage module 23, so as to add the calculation result to the stored data, and output the added data to the storage module 23; the storage module 23 is at least used to update the stored data corresponding to the time difference interval with the added data; wherein, the logical operation includes OR operation and SUM operation; the result of the OR operation performed by each photosensitive element 100 belonging to the same group is used as the output value of the corresponding group; the result of the SUM operation performed by the output values ​​of all groups belonging to the same pixel 10 is used as the output value of the pixel 10; the calculation result output by the logical operation module 21 includes the output value of the pixel 10.

[0054] As can be seen, based on the grouping configuration of pixel 10 in this embodiment and the combined application of OR and AND operations in the logic operation module 21, not only can the dynamic range of FIR feature values ​​be increased, the dynamic range of distance compensation be broadened, and the accuracy of distance measurement be improved, but the maximum value of the output value of pixel 10 can also be reduced, which is conducive to reducing the number of connections between the logic operation module 21 and the histogram accumulation module 22, thereby reducing the wiring difficulty and manufacturing cost in integrated circuit layout design.

[0055] The optical receiving sensor for use in lidar provided in this embodiment is described in detail below with reference to the accompanying drawings.

[0056] Please see Figure 3 The optical receiving sensor used in the lidar includes a pixel array 1 and a TCSPC circuit 2. The pixel array 1 receives the reflected echo formed by the laser light reflected from the target object, and after photoelectric conversion by each pixel 100, generates multiple electrical signals which are output to the TCSPC circuit 2. The TCSPC circuit 2 processes the electrical signals and generates data carrying distance information of the target object.

[0057] For details, please refer to Figures 3 to 8 The pixel array 1 includes a plurality of pixels 10 arranged in an array, and each pixel 10 includes a plurality of photosensitive elements 100. Preferably, the photosensitive element 100 includes a SPAD. When a single photon is incident on the SPAD, photogenerated carriers are excited in the SPAD, triggering avalanche discharge through collision. The electrical signal output by the SPAD jumps from a low level to a high level, outputting a valid detection pulse. The number of photons received by the pixel 10 can then be counted by sampling and detection by the TCSPC circuit 2. To ensure that the SPAD can repeatedly receive photons to generate pulses, a quenching circuit needs to pull down the bias voltage to extinguish the avalanche, causing the SPAD to reset to a low level. Therefore, after successfully detecting a photon-triggered avalanche effect, the SPAD must wait for a period of time to recover to its initial state where it can detect the next photon again. During this period, the SPAD cannot respond to new photon signals; this time is called the dead time. Based on this, when the intensity of the reflected echo light is very strong, all the photosensitive elements 100 in the pixel 10 will trigger the avalanche effect. As a result, the photons that arrive at the pixel 10 during the dead time cannot be detected and counted, thus causing the pile-up phenomenon.

[0058] Therefore, in the distance compensation scheme for the pile-up phenomenon, to improve the measurement dynamic range, this embodiment groups the photosensitive elements 100 within each pixel 10. Each pixel 10 includes at least one group of photosensitive elements 100, and each group includes at least two photosensitive elements 100. This embodiment does not limit the specific number of photosensitive elements 100 within each group, nor does it limit the relationship between the number of photosensitive elements 100 between different groups. That is, within the same pixel 10, the number of photosensitive elements 100 in different groups may be the same or different, or some groups may have the same number of photosensitive elements 100, while others may have different numbers. Furthermore, this embodiment does not limit the grouping rules. Preferably, all photosensitive elements 100 in the same row are grouped together; or, all photosensitive elements 100 in the same column are grouped together; or, each group of photosensitive elements 100 includes multiple photosensitive elements 100 arranged in an array. For example, each pixel 10 includes (R×m) rows × (C×n) columns of photosensitive elements 100, and R rows × C columns of photosensitive elements 100 form a group, so they can be divided into m×n groups; where R, C, m and n are positive integers.

[0059] For example, such as Figure 4 As shown, the pixel 10 includes 3×3 photosensitive elements 100. The pixel 10 is divided into three groups: the first group G1 includes all the photosensitive elements 100 in the first row; the second group G2 includes all the photosensitive elements 100 in the second row; and the third group G3 includes all the photosensitive elements 100 in the third row. That is, Figure 4 The pixels 10 shown are grouped by row, and the number of photosensitive elements 100 in each group is the same. For example... Figure 5 As shown, the pixel 10 includes 3×3 photosensitive elements 100. The pixel 10 is divided into three groups: the first group G1 includes all the photosensitive elements 100 in the first column; the second group G2 includes all the photosensitive elements 100 in the second column; and the third group G3 includes all the photosensitive elements 100 in the third column. That is, Figure 5 The pixels 10 shown are grouped by column, and the number of photosensitive elements 100 in each group is the same. For example... Figure 6 As shown, the pixel 10 includes 3×3 photosensitive elements 100. The pixel 10 is divided into three groups: the first group G1 includes all the photosensitive elements 100 in the first column; the second group G2 includes all the photosensitive elements 100 in the second column and the photosensitive elements 100 located in the third row of the third column; and the third group G3 includes the photosensitive elements 100 located in the first row of the third column and the second row of the third column. Based on this, Figure 6The number of photosensitive elements 100 in the first group G1 is 3, the number of photosensitive elements 100 in the second group G2 is 4, and the number of photosensitive elements 100 in the third group G3 is 2; that is, the number of photosensitive elements 100 is different between the groups.

[0060] Another example, such as Figure 7 As shown, the pixel 10 includes 6×6 photosensitive elements 100. The pixel 10 is divided into six groups, and each group includes 3×2 photosensitive elements 100. The first group G1 includes the photosensitive elements 100 located in the 1st row, 1st column, 1st row, 2nd column, 2nd row, 2nd column, 3rd row, 1st column, and 3rd row, 2nd column; the second group G2 includes the photosensitive elements 100 located in the 1st row, 3rd column, 1st row, 4th column, 2nd row, 3rd row, 4th column, 3rd row, 3rd column, and 4th row; the third group G3 includes the photosensitive elements 100 located in the 1st row, 5th column, 1st row, 6th column, 2nd row, 5th column, 2nd row, 6th column, 3rd row, 5th column, and 3rd row, 6th column. The fourth group G4 includes the photosensitive element 100 located in the 4th row, 1st column, 4th row, 2nd column, 5th row, 1st column, 5th row, 2nd column, 6th row, 1st column, and 6th row, 2nd column; the fifth group G5 includes the photosensitive element 100 located in the 4th row, 3rd column, 4th row, 4th column, 5th row, 3rd column, 5th row, 4th column, 6th row, 3rd column, and 6th row, 4th column; the sixth group G6 includes the photosensitive element 100 located in the 4th row, 5th column, 5th row, 6th column, 6th row, 5th column, and 6th row, 6th column.

[0061] Another example, such as Figure 8As shown, the pixel 10 includes 6×6 photosensitive elements 100. The pixel 10 is divided into six groups, with some groups having a different number of photosensitive elements 100, and others having the same number. The first group G1 includes 3×3 photosensitive elements 100, located in the following rows: row 1, column 1; row 1, column 2; row 1, column 3; row 2, column 1; row 2, column 2; row 2, column 3; row 3, column 1; row 3, column 2; and row 3, column 3. The second group G2 includes 3×1 photosensitive elements 100, located in the following rows: row 4, column 1; row 4, column 2; and row 4, column 3. The third group G3 includes 3×2 photosensitive elements 100, located in the following rows: row 1, column 5; row 1, column 6; row 2, column 5; row 2, column 6; row 3, column 5; and row 3, column 6. The fourth group G4 includes 3×1 photosensitive elements 100, located in the 4th row, 1st column, 5th row, 1st column, and 6th row, 1st column, respectively; the fifth group G5 includes 3×3 photosensitive elements 100, located in the 4th row, 2nd column, 4th row, 3rd column, 4th row, 4th column, 5th row, 2nd column, 5th row, 3rd column, 5th row, 4th column, 6th row, 2nd column, 6th row, 3rd column, and 6th row, 4th column, respectively; the sixth group G6 includes 3×2 photosensitive elements 100, located in the 4th row, 5th column, 4th row, 6th column, 5th row, 5th row, 6th column, 6th row, 5th column, and 6th row, 6th column, respectively. The first group G1 and the fifth group G5 each contain the same number of photosensitive elements 100, which is 9; the second group G2 and the fourth group G4 each contain the same number of photosensitive elements 100, which is 3; and the third group G3 and the sixth group G6 each contain the same number of photosensitive elements 100, which is 6.

[0062] It should be noted that the above grouping method is only an example, and in actual applications, grouping can be carried out according to actual needs.

[0063] Please continue reading. Figure 3 In this embodiment, each pixel 10 is adapted to one TCSPC circuit 2, or a macro pixel composed of multiple pixels 10 is adapted to one TCSPC circuit 2. Preferably, the TCSPC circuit 2 includes a sampling module 20, a logic operation module 21, a histogram accumulation module 22, and a storage module 23.

[0064] The sampling module 20 is connected to the pixel array 1 and the logic operation module 21. The sampling module 20 is used to sample data from each photosensitive element 100 in each pixel 10 at a preset sampling time, and output the sampling results to the logic operation module 21. The logic operation module 21 is used to perform logical operations on the sampling results of all photosensitive elements 100 within each pixel 10.

[0065] Specifically, the sampling module 20 is connected to one or more pixels 10 in the pixel array 1 to perform digital time sampling on all photosensitive elements 100 in the connected pixels 10. That is, taking the laser pulse emitted by the light emitter as the zero point of timing, sampling is performed once every time difference interval, and the current sampling time is recorded in digital form. When the photosensitive element 100 detects a photon, the sampling output result of the current sampling moment is high level; recorded as 1, otherwise it is low level; recorded as 0. Preferably, when the photosensitive element 100 is a SPAD, digital time sampling is usually implemented by a time-to-digital converter (TDC). It should be noted that the preset sampling time includes the time after the light emitter performs each laser emission (i.e., a single light emission), every time difference interval dt.

[0066] For example, please refer to Figure 9 The sampling module 20 is connected to a single pixel 10, and the pixel 10 includes 3×3 photosensitive elements 100. After the light emitter performs a single illumination, timing begins, and the sampling module 20 performs a sampling once every time interval dt. When in the Kth time interval [dt(K-1), dtK], the sampling module 20 detects that all photosensitive elements 100 in the first column output 1, and all other photosensitive elements 100 output 0. In other words, within the Kth time interval [dt(K-1), dtK], all photosensitive elements 100 in the first column receive photons, while the other photosensitive elements 100 do not receive photons; therefore, it can be considered that the pixel 10 receives 3 photons within the Kth time interval [dt(K-1), dtK]. Similarly, in the (K+1)th time difference interval [dtK, dt(K+1)], pixel 10 receives 2 photons; in the (K+2)th time difference interval [dt(K+1), dt(K+2)], pixel 10 receives 2 photons; in the (K+3)th time difference interval [dt(K+2), dt(K+3)], pixel 10 receives 1 photon; and in the (K+4)th time difference interval [dt(K+3), dt(K+4)], pixel 10 receives 1 photon. Here, K is a positive integer.

[0067] It should be further explained that the applicant's research found that the ranging error caused by the pile-up phenomenon is closely related to the intensity of the reflected echo. Therefore, in order to reduce the impact of the pile-up phenomenon on the measurement distance error, it is necessary to calibrate the relationship between the ranging error and the intensity of the reflected echo through actual measurements. This allows the ranging error, i.e., the distance compensation value, to be determined based on the intensity of the reflected echo during radar operation, and then used to compensate for the lidar's measurement value, thereby obtaining a more accurate measurement distance. Based on this, the data representation of the reflected echo intensity directly affects the ranging compensation effect. Preferably, the data representation of the reflected echo intensity is obtained by performing finite impulse response (FIR) filtering on the original histogram data.

[0068] Specifically, the FIR filter formula is as follows:

[0069] ;

[0070] Where y[n] is the output value after FIR filtering; This refers to the impulse response coefficient; n is the number of the storage unit bin corresponding to each time difference interval dt in the histogram, and n is an integer greater than or equal to k. The input values ​​are the number of photons corresponding to each storage unit bin[n], bin[n-1], ..., bin[nk] in the histogram, respectively, and k is a non-negative integer.

[0071] The FIR filtering formula is essentially a convolution operation on the signal in the time domain. The width of the convolution window is generally chosen to be consistent with the pulse width of the emitted laser pulse. For example, if the emitted laser pulse width is 5 time intervals dt, then k in the FIR filtering formula is 4. Assuming that all impulse response coefficients are 1, then y[n] is equivalent to the sum of the number of photons in bin n to bin[n-4]. Therefore, after performing the FIR filtering formula operation on the stored histogram data with a sliding window length of 5 (i.e., k=4), a new filtered array will be obtained, in which the largest output value is... Used to represent the intensity of the reflected echo light. In this embodiment, the maximum value of the array obtained after FIR filtering is simply referred to as the FIR eigenvalue.

[0072] However, the existing technology calculates the number of photons by summing the number of photons captured by all photosensitive elements 100 within the pixel 10; that is, all photosensitive elements 100 within the same pixel 10 perform an AND operation. Based on this, during the stage when the intensity of the reflected echo is relatively weak, the FIR feature value increases with the increase of the intensity of the reflected echo. However, when the intensity of the reflected echo increases to a certain extent, due to the influence of the dead time, the FIR feature value will tend to a constant and no longer change.

[0073] For example, according to existing statistical methods of summation, such as Figure 9 The number of photons acquired by pixel 10 within five time intervals dt after a single illumination is 3, 2, 2, 1, and 1, respectively. Assuming the impulse response coefficient is always 1, this illumination will increase the FIR eigenvalue by 9. As the intensity of the reflected echo gradually increases, the probability of photosensitive element 100 detecting photons increases, thus making it more likely that each photosensitive element 100 will output 1 within the initial time interval of the convolution window. Figure 10 As shown, when the intensity of the reflected echo increases, the number of photons acquired within the initial time difference interval increases. Therefore, the number of photons acquired within the five time difference intervals dt after one illumination are 5, 3, 1, 0, and 0 respectively. It can be considered that this illumination will increase the FIR eigenvalue by 9. For example... Figure 11 As shown, when the intensity of the reflected echo light is further enhanced, more photons are acquired within the initial time difference interval. Therefore, the number of photons acquired within the five time difference intervals dt after one illumination are 9, 0, 0, 0, and 0, respectively. It can be considered that this illumination will increase the FIR eigenvalue by 9. Clearly, according to... Figures 9 to 11 It is evident that under three distinctly different light intensities, the FIR eigenvalue increases by 9 in all cases, and does not increase with increasing light intensity. Clearly, existing statistical methods, when operating at a certain light intensity, cannot continue to characterize the changes in the reflected echo's light intensity, thus failing to distinguish the light intensity level during measurement and failing to compensate for the LiDAR's measured values, severely impacting the accuracy of ranging.

[0074] Therefore, to improve the dynamic range of FIR feature values, the logic operation module 21 provided in this embodiment uses a combination of OR and AND operations to perform photon count statistics. Specifically, in the configuration environment where the photosensitive elements 100 within the pixel 10 are grouped, each photosensitive element 100 belonging to the same group performs an OR operation, and the result of the OR operation is used as the output value of the corresponding group. Furthermore, the output values ​​of all groups belonging to the same pixel 10 are subjected to an AND operation, and the result of the AND operation is used as the output value of the pixel 10. In short, within the same pixel 10, the photosensitive elements 100 in each group first perform an OR operation, and then perform an AND operation on the results of each group to obtain the output value of the pixel 10; that is, the number of photons of the pixel 10 sampled within a certain time interval after a single illumination. It should be noted that when the pixel 10 includes only one group of photosensitive elements 100, the result of the OR operation performed by each photosensitive element 100 belonging to the same group is directly used as the output value of the pixel 10.

[0075] For example, such as Figure 4As shown, the pixel 10 includes 3×3 photosensitive elements 100, and each row of photosensitive elements 100 forms a group, for a total of 3 groups. Assuming that, for... Figure 4 The pixel 10 shown is formed within 5 time intervals dt after a single lighting cycle. Figure 9 The diagram shows the output values ​​of the photosensitive element 100. In the Kth time difference interval [dt(K-1), dtK], the output value of the three photosensitive elements 100 in the first group after performing an OR operation is 1; the output value of the three photosensitive elements 100 in the second group after performing an OR operation is 1; the output value of the three photosensitive elements 100 in the third group after performing an OR operation is 1. Therefore, after performing a summation operation on these three groups of output values, the number of photons of pixel 10 in the Kth time difference interval [dt(K-1), dtK] is 3; that is, the output value of pixel 10 is 3. Similarly, in the remaining four time difference intervals, the output values ​​of pixel 10 are 2, 2, 1, and 1, respectively. Therefore, this lighting will increase the FIR feature value by 9.

[0076] Assuming, for Figure 4 The pixel 10 shown is formed within 5 time intervals dt after a single lighting cycle. Figure 10 The diagram shows the output values ​​of the photosensitive element 100. It can be understood that when the intensity of the reflected echo increases, within the Kth time difference interval [dt(K-1), dtK], the output value of the three photosensitive elements 100 in the first group after performing an OR operation is 1; the output value of the three photosensitive elements 100 in the second group after performing an OR operation is 1; and the output value of the three photosensitive elements 100 in the third group after performing an OR operation is 1. Therefore, after performing a sum operation on these three groups of output values, the number of photons in the Kth time difference interval [dt(K-1), dtK] of pixel 10 can be obtained as 3; that is, the output value of pixel 10 is 3. Similarly, in the remaining four time difference intervals, the output values ​​of pixel 10 are 3, 1, 0, and 0, respectively. Therefore, this illumination will increase the FIR feature value by 7. Compared to the prior art that simply relies on sum operations to count photons, in this embodiment, after the intensity of the reflected echo increases, the FIR feature value does not remain unchanged at 9, but changes to 7.

[0077] Similarly, assuming that for Figure 4 The pixel 10 shown is formed within 5 time intervals dt after a single lighting cycle. Figure 11The diagram shows the output values ​​of the photosensitive element 100. It can be understood that when the intensity of the reflected echo light is further enhanced, the output values ​​of the pixel 10 corresponding to the five time intervals dt after a single illumination are 3, 0, 0, 0, 0 respectively. Therefore, this illumination will increase the FIR feature value by 3. Compared to the simple summation operation in the prior art, after the intensity of the reflected echo light is further enhanced, the FIR feature value in this embodiment does not remain unchanged at 9, but changes to 3.

[0078] For further details, please refer to Figure 12 To verify that the FIR feature values ​​obtained by the light receiving sensor provided in this embodiment have a wider range of variation with the light intensity of the reflected echo, the applicant, under the same light intensity variation, used the sum operation method in the prior art and the combined operation method of OR and sum operation used in this embodiment to obtain FIR feature values ​​for the same pixel 10, and formed respectively Figure 12 The graph shows two curves. The green curve represents the change in FIR characteristic value obtained using existing technology as the intensity of the reflected echo increases. The red curve represents the change in FIR characteristic value obtained using the optical receiving sensor described in this embodiment as the intensity of the reflected echo increases. Clearly, in the curve comparison graph, when the intensity of the reflected echo reaches E, the FIR characteristic value in the existing technology has reached its maximum value and will no longer change with increasing light intensity. However, the FIR characteristic value obtained by the optical receiving sensor provided in this embodiment has changed from its maximum value to a value below the maximum value when the intensity of the reflected echo reaches E. Furthermore, as the light intensity further increases, the FIR characteristic value obtained by the optical receiving sensor provided in this embodiment will change for a certain period; that is, the FIR characteristic value gradually decreases and eventually tends to a constant.

[0079] Therefore, combining Figure 12 It is known that in the existing technical solution, when the intensity of the reflected echo light reaches approximately 10... 9 At the order of magnitude 10, the FIR eigenvalues ​​approach their maximum value and no longer change with increasing light intensity. However, in the optical receiving sensor provided in this embodiment, the FIR eigenvalues ​​are such that the light intensity of the reflected echo reaches 10... 12 It only tends to a constant when it reaches an order of magnitude. Among these, the light intensity is at 10... 9 Quantity up to 10 12When the light intensity changes within a certain range, the FIR feature values ​​obtained by existing technologies do not change, thus failing to characterize the changes in light intensity. However, the FIR feature values ​​obtained in this embodiment decrease as the light intensity increases; that is, they continue to change with the light intensity. Clearly, based on the grouping configuration of pixel 10 described in this embodiment and the combined application of OR and AND operations within the logic operation module 21, the dynamic range of FIR feature values ​​is increased, which is beneficial for increasing the dynamic range of distance compensation and improving the accuracy of distance measurement.

[0080] Furthermore, when one TCSPC circuit is connected to multiple pixels 10, the logic operation module 21 also includes other arithmetic units to calculate the output value of each pixel 10.

[0081] Please continue reading. Figure 3 The logic operation module 21 outputs the operation result corresponding to the sampling time to the histogram accumulation module 22. The operation result output by the logic operation module 21 includes the output value of pixel 10. The histogram accumulation module 22 determines the time difference interval based on the sampling time and reads the stored data corresponding to the time difference interval from the storage module 23, adds the operation result to the stored data, and outputs the added data to the storage module 23.

[0082] In other words, the histogram accumulation module 22 acts as an accumulator, used to accumulate the number of photons within the same time difference interval after each illumination and sampling detection process, and the result is stored in the storage unit corresponding to the time difference interval within the storage module 23. Based on this, after all illumination and sampling detections are completed, the histogram can be obtained by retrieving the data stored in the storage unit corresponding to each time difference interval within the storage module 23.

[0083] For example, Figure 3 , Figure 4 and Figure 9 As shown, assuming that one pixel 10 is connected to one TCSPC circuit 2, and the pixel 10 adopts... Figure 4The rows shown are grouped together. After a single illumination, within the Kth time difference interval [dt(K-1), dtK], the sampling module 20 collects the output values ​​of all photosensitive elements 100 within pixel 10 and inputs them to the logic operation module 21. After performing the operation, the logic operation module 21 calculates the photon count of pixel 10 to be 3, which is used as the output value of pixel 10. Then, the output value of pixel 10 is input to the histogram accumulation module 22. The histogram accumulation module 22 first determines the specific time difference interval [dt(K-1), dtK], and then retrieves the cumulative photon count in the storage unit binK corresponding to the Kth time difference interval [dt(K-1), dtK] from the storage module 23; that is, the cumulative photon count from previous illuminations. Subsequently, the histogram accumulation module 22 performs a summation operation between the retrieved cumulative photon count and the current output value of pixel 10; that is, the retrieved cumulative photon count is increased by 3 to obtain the new cumulative photon count for the Kth time difference interval [dt(K-1), dtK]. Finally, the histogram accumulation module 22 inputs the new accumulated photon count to the storage module 23, and the storage module 23 updates and stores the new accumulated photon count in the storage unit binK.

[0084] Similarly, the stored data in storage unit bin(K+1) corresponding to the (K+1)th time difference interval [dtK, dt(K+1)] is incremented by 2; the stored data in storage unit bin(K+2) corresponding to the (K+2)th time difference interval [dt(K+1), dt(K+2)] is incremented by 2; the stored data in storage unit bin(K+3) corresponding to the (K+3)th time difference interval [dt(K+2), dt(K+3)] is incremented by 1; and the stored data in storage unit bin(K+4) corresponding to the (K+4)th time difference interval [dt(K+3), dt(K+4)] is incremented by 1. Based on this, the accumulation of stored data in storage units corresponding to other time difference intervals follows the same process. Furthermore, the above is only an explanation of the accumulation and update of stored data in storage units corresponding to each time difference interval after one illumination; the data processing and storage after each illumination follow the same process.

[0085] It should be further noted that the storage module 23 includes multiple storage units. Each storage unit corresponds to one of the time difference intervals, and the storage unit is used to store the storage data corresponding to the time difference interval.

[0086] Furthermore, the optical receiving sensor for lidar provided in this embodiment also reduces the wiring difficulty in integrated circuit layout design. Specifically, with Figure 4 and Figure 11As an example, pixel 10 includes 3×3 photosensitive elements 100, with each row of photosensitive elements 100 forming a group, for a total of 3 groups. Within the Kth time difference interval [dt(K-1), dtK], the sampling module 20 collects the output value of all photosensitive elements 100 within pixel 10, which is 1. Therefore, after the logic operation module 21 performs the operation, the output value of pixel 10 is 3. Furthermore, under the combined operations of OR and AND, the maximum output value of a single pixel 10 can only be 3; that is, the maximum output value is equal to the number of groups within pixel 10. Therefore, expressing the value 3 only requires a 2-bit width, and thus only 2 connections are needed between the logic operation module 21 and the histogram accumulation module 22. If, according to the summation method in the existing technology, for this lighting, the output values ​​of all 9 photosensitive elements 100 within the Kth time difference interval [dt(K-1), dtK] are 1, then the output value of pixel 10 is 9, and the maximum output value of pixel 10 is 9; that is, the total number of photosensitive elements 100 within pixel 10. Since expressing the value 9 requires at least 4 bits of width, only 4 connections are needed between the logic operation module 21 and the histogram accumulation module 22.

[0087] Therefore, based on the pixel 10 and the logic operation module 21 provided in this embodiment, the number of connections between the logic operation module 21 and the histogram accumulation module 22 is reduced by half. Due to limitations such as physical size and production cost, the size of the pixel 10 is usually small, especially when all the above modules are integrated on the same semiconductor, the size of the pixel 10 is usually on the order of micrometers. Therefore, reducing the number of connections between the logic operation module 21 and the histogram accumulation module 22 can effectively reduce the wiring difficulty in integrated circuit layout design.

[0088] Furthermore, this embodiment does not limit the hardware distribution of the various components in the optical receiving sensor applied to LiDAR, and the specific hardware distribution can be determined according to the design needs of different products. For example, the pixel array 1, the sampling module 20, the logic operation module 21, the histogram accumulation module 22, and the storage module 23 are all integrated into the same chip. Alternatively, at least some of the pixel array 1, the sampling module 20, the logic operation module 21, the histogram accumulation module 22, and the storage module 23 are integrated into different chips. For example, the pixel array 1 and the sampling module 20 are integrated into the same chip, while the logic operation module 21, the histogram accumulation module 22, and the storage module 23 are integrated into another chip. Yet another example is that the pixel array 1, the sampling module 20, the logic operation module 21, the histogram accumulation module 22, and the storage module 23 are located in different chips; that is, they all exist independently as discrete devices.

[0089] In summary, the optical receiving sensor for LiDAR provided in this embodiment effectively increases the dynamic range of FIR feature values ​​by performing grouping processing on each photosensitive element 100 within the pixel 10 and combining it with the OR and SUM operations within the logic operation module 21. This facilitates widening the dynamic range of ranging compensation and improving the accuracy of distance measurement. Simultaneously, based on the combined OR and SUM operations, the maximum output value of the pixel 10 is reduced, thereby reducing the number of connections between the logic operation module 21 and the histogram accumulation module 22. This reduces the wiring difficulty in integrated circuit layout design and lowers manufacturing costs.

[0090] Based on the same concept, this embodiment also provides a lidar. Please refer to [link / reference]. Figure 3 The lidar includes a light emitter, a light receiving sensor as described above, and a data processor. The light emitter emits a laser beam toward the target; the light receiving sensor receives and processes the reflected echo formed by the laser beam reflected from the target; and the data processor obtains the flight time of the laser beam based on stored data corresponding to different time difference intervals in the storage module of the light receiving sensor, and calculates a first distance to the target based on the flight time.

[0091] Specifically, the light emitter includes a laser and a transmitting mirror assembly. The laser emitted by the laser is modulated by the transmitting mirror assembly and propagates towards the target. The light receiving sensor samples the photon count for each illumination by the light emitter across multiple time intervals, ultimately accumulating a histogram after multiple illuminations. The data processor retrieves the histogram data from the light receiving sensor and calculates the time of flight of the laser, as well as a first distance to the target based on the time of flight. This first distance is a measurement value before distance compensation is performed.

[0092] Furthermore, the data processor also includes a compensation unit. The compensation unit is used to compensate and correct the first distance to obtain a more accurate second distance, which is the final measured distance output by the data processor. Specifically, the compensation unit first obtains the light intensity characteristic value of the reflected echo based on the stored data corresponding to different time difference intervals in the storage module 23. In other words, it first retrieves the stored data of each storage unit in the storage module 23; that is, histogram data. Then, it uses the FIR filtering formula to obtain FIR characteristic values ​​as light intensity characteristic values, thereby characterizing the light intensity change of the reflected echo. Finally, it uses a lookup table method to obtain the distance compensation value of the measured target based on the FIR characteristic values. The lookup table method is based on a pre-calibrated data relationship table between the distance compensation value and the light intensity of the reflected echo.

[0093] Therefore, in practical applications, extensive field calibration is required to obtain a data relationship table between the distance compensation value and the intensity of the reflected echo, and a data relationship table between the intensity of the reflected echo and the intensity characteristic value. These two data relationship tables can be combined into one table or separated into two tables. The data relationship tables are stored within the compensation unit so that the required distance compensation value for the current measurement can be retrieved based on the obtained FIR characteristic value. Furthermore, the compensation unit sums the obtained distance compensation value with the first distance to compensate for the difference in the first distance, thereby obtaining the second distance of the measured target; that is, the final measurement distance output by the lidar.

[0094] Furthermore, in the process of obtaining the distance compensation value from the table, other reference factors also need to be considered. Please refer to [link / reference]. Figure 12 Within a preset light intensity range before the FIR eigenvalues ​​tend to a constant, as the light intensity changes from low to high, the FIR eigenvalues ​​acquired by the light receiving sensor provided in this embodiment first increase with the increase of light intensity, and then decrease with the increase of light intensity. This is evident in the monotonically increasing and monotonically decreasing portions of the FIR eigenvalue variation; that is, Figure 12Within a specific interval W, there exist cases where the FIR feature values ​​are the same, but the light intensities differ. Therefore, to ensure that the FIR feature values ​​can accurately represent the light intensity of the corresponding reflected echo, it is necessary to further determine whether the light intensity is in a monotonically increasing or monotonically decreasing phase by combining auxiliary light intensity feature values. Preferably, the auxiliary light intensity feature values ​​include, but are not limited to, the maximum number of photons stored in all storage units of the storage module 23. It can be understood that when the FIR feature values ​​are the same under two different light intensities, the larger maximum number of photons stored in the storage unit necessarily corresponds to the light intensity in a monotonically decreasing phase, while the smaller one corresponds to the light intensity in a monotonically increasing phase. This allows for the differentiation of the specific light intensity represented by the FIR feature values, thereby accurately obtaining the corresponding distance compensation value.

[0095] Based on the same concept, such as Figure 13 As shown, this embodiment also provides a ranging method. Preferably, the ranging method utilizes the aforementioned lidar.

[0096] Please see Figures 3 to 13 The ranging method includes:

[0097] Step 1 S10: Use a light emitter to emit a laser towards the target being tested.

[0098] Step 2 S20: Use a light receiving sensor to receive and process the reflected echo formed by the laser reflected by the target being measured.

[0099] The data sampling and processing process of each pixel 10 by the TCSPC circuit 2 in the light receiving sensor can be referred to the relevant description of the light receiving sensor applied to LiDAR described above, and will not be repeated in this embodiment.

[0100] Step 3 S30: The data processor obtains the flight time of the laser based on the stored data corresponding to different time difference intervals in the storage module 23 of the optical receiving sensor, and calculates the first distance of the target under test based on the flight time.

[0101] In short, the flight time t is obtained by extracting histogram data, and then the first distance R of the target is calculated using the formula R=C·t / 2, where C is the speed of light.

[0102] Step 4S40: The compensation unit in the data processor obtains the light intensity characteristic value of the reflected echo based on the stored data corresponding to different time difference intervals in the storage module 23; and at least obtains the distance compensation value of the target under test based on the light intensity characteristic value.

[0103] That is, firstly, the FIR feature value and the light intensity auxiliary feature value are obtained using histogram data; then, the specific light intensity of the reflected echo is determined based on the FIR feature value and the light intensity auxiliary feature value; finally, the distance compensation value is obtained using a lookup table method based on the light intensity. Specifically, the process of obtaining the distance compensation value using the lookup table method includes: firstly, determining the light intensity of the reflected echo based on the light intensity auxiliary feature value, the light intensity feature value, and a data relationship table between the light intensity of the reflected echo and the light intensity feature value; then, determining the distance compensation value based on the data relationship table between the light intensity of the reflected echo and the distance compensation value.

[0104] Preferably, step three (30) and step four (S40) can be executed simultaneously or in separate steps. This embodiment does not limit their specific order.

[0105] Step 5S50: The data processor compensates the first distance according to the distance compensation value, and forms a second distance of the measured target, which is used as the measured distance output by the data processor. The specific compensation process can be referred to the relevant description in the above-mentioned lidar documentation, and will not be repeated in this embodiment.

[0106] In summary, this embodiment provides a light receiving sensor, a lidar, and a ranging method for use in lidar. The light receiving sensor, by performing grouping processing on each photosensitive element 100 within the pixel 10 and combining this with OR and SUM operations within the logic operation module 21, effectively increases the dynamic range of FIR feature values, thus broadening the dynamic range of ranging compensation. Based on this, the compensation unit in the lidar can achieve accurate compensation for the first distance based on the FIR feature values ​​with a wider dynamic range, improving the accuracy of distance measurement. Furthermore, based on the combined OR and SUM operations, the maximum value of the output value of the pixel 10 is reduced, thereby reducing the number of connections between the logic operation module 21 and the histogram accumulation module 22, reducing the wiring difficulty and manufacturing cost in integrated circuit layout design.

[0107] Furthermore, it should be understood that although the present invention has been disclosed above with reference to preferred embodiments, these embodiments are not intended to limit the present invention. For any person skilled in the art, many possible variations and modifications can be made to the technical solutions of the present invention based on the disclosed technical content, or equivalent embodiments can be modified accordingly, without departing from the scope of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention, without departing from the content of the present invention, shall still fall within the scope of protection of the present invention.

Claims

1. A light receiving sensor for use in lidar, characterized in that, include: Pixel array and TCSPC circuit; The pixel array includes multiple pixels for receiving reflected echoes from laser light; and each pixel includes at least one set of photosensitive elements, and each set of photosensitive elements includes at least two photosensitive elements. The TCSPC circuit includes a sampling module, a logic operation module, a histogram accumulation module, and a storage module; the sampling module is used to sample data from each photosensitive element in each pixel at a preset sampling time and output the sampling result to the logic operation module. The logic operation module is at least used to perform logic operations on the sampling results of all the photosensitive elements in each pixel, and output the operation results corresponding to the sampling time to the histogram accumulation module; The histogram accumulation module is used to determine the time difference interval based on the sampling time, and read the stored data corresponding to the time difference interval from the storage module, so as to add the calculation result to the stored data and output the added data to the storage module; the storage module is at least used to update the stored data corresponding to the time difference interval with the added data; The logical operation includes OR operation and AND operation; the result of the OR operation performed on each of the photosensitive elements belonging to the same group is used as the output value of the corresponding group; the result of the AND operation performed on the output values ​​of all groups belonging to the same pixel is used as the output value of the pixel. The calculation result output by the logic operation module includes the output value of the pixel.

2. The optical receiving sensor for lidar according to claim 1, characterized in that, Within the same pixel, the number of photosensitive elements in different groups is the same; or, at least some groups have different numbers of photosensitive elements.

3. The optical receiving sensor for lidar according to claim 1 or 2, characterized in that, The pixel includes a plurality of photosensitive elements arranged in an array; wherein all photosensitive elements in the same row are grouped together; or, all photosensitive elements in the same column are grouped together; or, each group of photosensitive elements includes a plurality of photosensitive elements arranged in an array.

4. The optical receiving sensor for lidar according to claim 1, characterized in that, The storage module includes multiple storage units; each storage unit corresponds to a time difference interval, and the storage unit is used to store the storage data corresponding to the time difference interval.

5. The optical receiving sensor for lidar according to claim 1, characterized in that, The pixel array, the sampling module, the logic operation module, the histogram accumulation module, and the storage module are integrated into the same chip; or... At least some of the pixel array, the sampling module, the logic operation module, the histogram accumulation module, and the storage module are integrated in different chips.

6. A lidar, characterized in that, Includes an optical transmitter, an optical receiving sensor for use in lidar as described in any one of claims 1 to 5, and a data processor; The optical emitter is used to emit laser light toward the target being measured; The optical receiving sensor is used to receive and process the reflected echo formed by the laser beam reflected by the target being measured; The data processor is used to obtain the flight time of the laser based on the stored data corresponding to different time difference intervals in the storage module of the optical receiving sensor, and to calculate the first distance of the measured target based on the flight time; and, The data processor further includes a compensation unit; the compensation unit is used to obtain the light intensity characteristic value of the reflected echo based on the stored data corresponding to different time difference intervals in the storage module. In addition, the data processor is configured to obtain at least the distance compensation value of the target under test based on the light intensity characteristic value; the data processor is also configured to compensate the first distance based on the distance compensation value and form a second distance of the target under test as the measurement distance output by the data processor.

7. The lidar according to claim 6, characterized in that, The compensation unit is used to calculate the maximum value after filtering for the stored data corresponding to different time difference intervals in the storage module using the finite impulse response filtering formula, which is used as the FIR feature value; and the light intensity feature value includes the FIR feature value. Furthermore, within a preset light intensity range, as the light intensity changes from low to high, the FIR feature value first increases with the increase of the light intensity, and then decreases with the increase of the light intensity.

8. The lidar according to claim 6, characterized in that, The compensation unit stores a data relationship table between the distance compensation value and the light intensity of the reflected echo, and a data relationship table between the light intensity of the reflected echo and the light intensity characteristic value; and the compensation unit is used to determine the distance compensation value based at least on the light intensity characteristic value and the data relationship table.

9. The lidar according to claim 8, characterized in that, The compensation unit is also used to acquire light intensity auxiliary feature values, and to determine the light intensity of the reflected echo according to the light intensity auxiliary feature values, the light intensity feature values, and a data relationship table between the light intensity of the reflected echo and the light intensity feature values; and to determine the distance compensation value according to the light intensity of the reflected echo and a data relationship table between the distance compensation value and the light intensity of the reflected echo. The stored data includes the number of photons, and the light intensity-assisted feature value includes the maximum number of photons stored in all storage units of the storage module.

10. A distance measurement method, characterized in that, Using a lidar as described in any one of claims 6 to 9, wherein the ranging method comprises: A light emitter is used to emit a laser towards the target being measured; A light receiving sensor is used to receive and process the reflected echo formed by the laser beam reflected from the target being measured. The data processor uses the stored data corresponding to different time difference intervals in the storage module of the optical receiving sensor to obtain the flight time of the laser, and calculates the first distance of the target under test based on the flight time. The compensation unit in the data processor obtains the light intensity characteristic value of the reflected echo based on the stored data corresponding to different time difference intervals in the storage module; and at least obtains the distance compensation value of the target under test based on the light intensity characteristic value. The data processor compensates for the first distance according to the distance compensation value and forms a second distance of the measured target, which is used as the measured distance output by the data processor.

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