Calibration method and system of gas detection laser radar

Abstract

The invention discloses a calibration method and system for a gas detection laser radar, and relates to the technical field of laser radars. The method comprises the following steps: acquiring first echo signal intensity and second echo signal intensity of a to-be-processed laser radar; wherein the first echo signal intensity is detected by using auxiliary calibration equipment and the to-be-processed laser radar, and a receiving and transmitting optical path of the auxiliary calibration equipment meets a preset receiving and transmitting view field condition; based on the first echo signal intensity and the second echo signal intensity, a preset calibration algorithm is used to obtain a target calibration parameter; based on the target calibration parameter, determining a laser radar system efficiency influence value by using a preset influence value algorithm; and based on the laser radar system efficiency influence value, carrying out calibration processing on the to-be-processed laser radar to obtain the calibrated laser radar.

Description

Technical Field

[0001] The present application relates to the field of laser radar technology, specifically to technical fields such as gas concentration detection technology and gas concentration detection laser radar technology, and especially to a calibration method and system for a gas detection laser radar. Background Art

[0002] Generally, in order to ensure the detection accuracy and precision of the gas detection laser radar, the laser radar needs to be calibrated before use. In the related art, a horizontal detection method is used to obtain the variation of the laser radar system efficiency with distance to achieve the calibration of the gas detection laser radar.

[0003] However, this method has two major drawbacks. First, the detection process requires a very open experimental site. Second, the horizontally uniform atmosphere is the ideal condition, and there are large errors in the actual detection process. Summary of the invention

[0004] The present application provides a gas detection laser radar calibration method and system, which can solve the problem of poor accuracy of gas detection laser radar calibration. The technical solution is as follows: In a first aspect, a calibration method for a gas detection laser radar is provided, the method comprising: Obtaining the first echo signal strength and the second echo signal strength of the laser radar to be processed; wherein the first echo signal strength is detected by using an auxiliary calibration device and the laser radar to be processed, and the light transmitting and receiving path of the auxiliary calibration device meets the preset transmitting and receiving field of view condition; the interval between the detection time of the first echo signal strength and the detection time of the second echo signal strength is less than a preset time threshold, and the distance between the detection position of the first echo signal strength and the detection position of the second echo signal strength is less than a preset distance threshold; Based on the first echo signal strength and the second echo signal strength, using a preset calibration algorithm, obtaining a target calibration parameter; Based on the target calibration parameters, a preset influence value algorithm is used to determine the influence value of the laser radar system efficiency; Based on the laser radar system efficiency impact value, the laser radar to be processed is calibrated to obtain a calibrated laser radar.

[0005] In a possible implementation, the obtaining the first echo signal strength of the laser radar to be processed includes: The laser radar to be processed emits a first laser to the auxiliary calibration device; The auxiliary calibration device performs a first detection process on the atmosphere based on the first laser to obtain the first echo signal intensity.

[0006] The first echo signal strength of the laser radar to be processed is obtained from the auxiliary calibration device.

[0007] In a possible implementation, the auxiliary calibration device includes a beam integration module, an echo receiving module, and a signal processing module. The auxiliary calibration device performs a first detection process on the atmosphere based on the first laser to obtain the first echo signal strength, including: The beam integration module receives the first laser emitted by the laser radar to be processed; The beam integration module adjusts the received first laser to obtain an adjusted first echo light, and sends the first echo light to the echo receiving module; The echo receiving module converts the received first echo light to obtain a first electrical signal, and sends the first electrical signal to the signal processing module; The signal processing module performs calculation processing on the first electrical signal to obtain the first echo signal strength.

[0008] In a possible implementation, obtaining the second echo signal strength of the laser radar to be processed includes: The laser radar to be processed emits a second laser vertically upward; The laser radar to be processed performs a second detection process on the atmosphere based on the second laser to obtain the second echo signal intensity; The second echo signal strength is obtained from the laser radar to be processed.

[0009] In a possible implementation, the laser radar to be processed includes a light-receiving and light-emitting circuit module, an optoelectronic processing module, and a data processing module. The laser radar to be processed performs a second detection process on the atmosphere based on the second laser to obtain the second echo signal strength, including: The light receiving and transmitting circuit module receives a second echo light returned based on the second laser; The light receiving and transmitting circuit module sends the second echo light to the photoelectric processing module; The optoelectronic processing module converts the second echo light to obtain the second electrical signal, and sends the second electrical signal to the data processing module; The optoelectronic processing module performs calculation processing on the second electrical signal to obtain the second echo signal strength.

[0010] In a possible implementation, the first echo signal strength includes a first echo signal strength at a first position and a first echo signal strength at a second position, the second echo signal strength includes a second echo signal strength at the first position and a second echo signal strength at the second position, and obtaining a target calibration parameter based on the first echo signal strength and the second echo signal strength by using a preset calibration algorithm includes: Based on the first echo signal strength at the first position and the first echo signal strength at the second position, and the second echo signal strength at the first position and the second echo signal strength at the second position, a calibration parameter is calculated using a preset calibration algorithm; The calibration parameters are used as target calibration parameters.

[0011] In a possible implementation, the target calibration parameters include target calibration parameters of at least two wavelengths, and determining the laser radar system efficiency influence value based on the target calibration parameters and using a preset influence value algorithm includes: Obtaining a target calibration parameter for the first wavelength and a target calibration parameter for the second wavelength; Based on the target calibration parameters of the first wavelength and the target calibration parameters of the second wavelength, the efficiency impact value of the laser radar system is calculated using a preset impact value algorithm.

[0012] In one possible implementation, the preset receiving and transmitting field of view conditions may include that the receiving diameter of the receiving field of view is larger than the transmitting spot diameter of the transmitting field of view, and the receiving field of view angle is larger than the sum of the transmitting field of view angle and a preset coefficient, and the preset coefficient is determined based on the angle between the optical axis of the receiving field of view and the optical axis of the transmitting field of view.

[0013] In a second aspect, a calibration system for a gas detection laser radar is provided, the calibration system comprising: an auxiliary calibration device, a laser radar to be processed, and a data processing device; the data processing device is respectively connected to the auxiliary calibration device and the laser radar to be processed in communication; The auxiliary calibration device is used to detect and obtain the first echo signal strength based on the received laser sent by the laser radar to be processed; The laser radar to be processed is used to detect and obtain the second echo signal strength; The data processing device is used to execute the calibration method of the gas detection laser radar according to the aspects described above and any possible implementation manner.

[0014] In a possible implementation, the auxiliary calibration device includes a beam integration module, an echo receiving module, and a signal processing module; The beam integration module is used to control the center of the emission spot of the emission field of view to coincide with the center of the receiving field of view; The echo receiving module is used to control the receiving field of view angle and the transmitting field of view angle to meet the preset field of view angle condition, and the receiving field of view diameter and the transmitting field of view diameter to meet the preset length condition; The signal processing module is used to calculate and store the first echo signal strength.

[0015] In a third aspect, a computer-readable storage medium is provided, wherein at least one instruction is stored in the storage medium, and the at least one instruction is loaded and executed by a processor to implement the method of the above-mentioned aspect and any possible implementation manner.

[0016] In a fourth aspect, an electronic device is provided, including: at least one processor; and a memory communicatively connected to the at least one processor; wherein, The memory stores instructions that can be executed by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to perform the method of any possible implementation manner and the aspects described above.

[0017] The beneficial effects of the technical solution provided by this application include at least: It can be seen from the above technical scheme that the embodiment of the present application can obtain the first echo signal strength and the second echo signal strength of the laser radar to be processed, wherein the first echo signal strength is detected by using an auxiliary calibration device and the laser radar to be processed, and the light transmitting and receiving path of the auxiliary calibration device meets the preset transmitting and receiving field of view condition; the interval between the detection time of the first echo signal strength and the detection time of the second echo signal strength is less than the preset time threshold, and the distance between the detection position of the first echo signal strength and the detection position of the second echo signal strength is less than the preset distance threshold, and then based on the first echo signal strength and the second echo signal strength, a preset calibration algorithm can be used to obtain the target calibration parameters. Based on the target calibration parameters, a preset influence value algorithm is used to determine the system efficiency influence value of the laser radar to be processed. Based on the system efficiency influence value of the laser radar to be processed, a calibrated laser radar is obtained. Since the target calibration parameters of the laser radar can be determined by detecting the first echo signal strength of the laser radar to be processed using an auxiliary calibration device and the second echo signal strength of the laser radar to be processed itself, the accuracy of the calibration parameters can be improved, and the inversion result of the gas concentration can be better corrected, that is, a higher-precision system efficiency influence value is obtained, and the inversion accuracy of the gas concentration is improved, thereby ensuring the detection accuracy and reliability of the gas detection laser radar.

[0018] It should be understood that the content described in this section is not intended to identify the key or important features of the embodiments of the present application, nor is it intended to limit the scope of the present application. Other features of the present application will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0020] Figure 1 It is a flow chart of a calibration method for a gas detection laser radar provided by an embodiment of the present application; Figure 2 It is a schematic diagram of the architecture of a calibration system for a gas detection laser radar provided by an embodiment of the present application; Figure 3 It is a schematic diagram of the process of a calibration method for a gas detection laser radar provided by an embodiment of the present application; Figure 4 It is a schematic diagram of an application scenario of a calibration method for a gas detection laser radar provided by an embodiment of the present application; Figure 5 It is a schematic diagram of the receiving and transmitting field of view of an auxiliary calibration device of a calibration method for a gas detection laser radar provided in one embodiment of the present application; Figure 6 It is a schematic diagram of the structure of an auxiliary calibration device of a calibration method for a gas detection laser radar provided in an embodiment of the present application; Figure 7 It is a schematic diagram of the structure of another auxiliary calibration device for the calibration method of the gas detection laser radar provided in another embodiment of the present application. DETAILED DESCRIPTION

[0021] The following is a description of exemplary embodiments of the present application in conjunction with the accompanying drawings, including various details of the embodiments of the present application to facilitate understanding, which should be considered as merely exemplary. Therefore, it should be recognized by those of ordinary skill in the art that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present application. Similarly, for the sake of clarity and conciseness, the description of well-known functions and structures is omitted in the following description.

[0022] Obviously, the described embodiments are only part of the embodiments of the present application, but not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0023] It should be noted that the hardware observation equipment terminal involved in the embodiments of the present application may include but is not limited to equipment in meteorological observation stations such as receivers, integrated processors, remote control equipment, and basic measurement boxes.

[0024] In addition, the term "and / or" in this article is only a description of the association relationship between the associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0025] Gas detection lidar, or gas component concentration detection lidar, refers to a lidar that emits pulsed light into the atmosphere and measures the gas composition by collecting the backscattered light of atmospheric molecules and aerosols to the pulsed light. Atmospheric molecules include nitrogen, oxygen, carbon dioxide, water vapor, ozone, etc. Aerosols include dust, fine particles, etc. Atmospheric molecules and aerosols will absorb and scatter pulsed lasers. Assume that the pulse energy emitted by the lidar is , then the height received by the laser radar is The thickness is The backscattered pulse echo signal intensity As shown in formula (1): in, The efficiency of the LiDAR system includes factors such as the matching degree of the transmitting and receiving fields of view, the transmitting efficiency, the receiving efficiency, and the photoelectric conversion efficiency. is Planck's constant, is the speed of light, is the laser wavelength, is the atmospheric backscattering coefficient, is the atmospheric extinction coefficient, is the pulse energy emitted by the laser radar, To detect the height, It is the detection distance resolution (obtaining an echo signal value every this distance).

[0026] Here, the atmospheric backscatter coefficient It represents the backscattering ability of the atmosphere to light, which is related to the total concentration of atmospheric molecules, aerosol concentration, and laser wavelength. Generally, the gas to be measured accounts for a small proportion of the total atmospheric molecules, and its concentration change has little effect on the total concentration of atmospheric molecules. Therefore, the impact on the atmospheric backscattering coefficient can be basically ignored, and the backscattering coefficient does not change with the concentration of the gas to be measured. However, there is a characteristic absorption effect in gas. When the wavelength of the laser pulse is in the characteristic absorption section of the gas to be measured, the gas to be measured has a strong absorption ability for the laser, and the effect of the concentration of the gas to be measured on the atmospheric extinction coefficient cannot be ignored. The absorption cross section is usually used. To express the absorption capacity of a unit gas to laser. Generally, the greater the gas concentration, the stronger the absorption capacity. Therefore, the atmospheric extinction coefficient at any wavelength can be expressed as formula (2): in, is the extinction coefficient after removing the gas to be measured, The wavelength of the gas to be measured The absorption cross section at is the concentration of the gas to be measured. Therefore, formula (1) can be rewritten as formula (3) In the process of gas concentration detection, the laser radar usually emits one or more groups of laser pulses with different wavelengths into the atmosphere. Here, we can take the emission of a group of laser pulses with different wavelengths as an example. Assume that the emission wavelength and pulse energy are , , , , we can get Where , The echo signal strength at wavelength is expressed as formula (4) and formula (5): Here, we can simplify formulas (4) and (5) and combine them with The echo signal strength at different wavelengths can be calculated. Among them, A can represent the influence of echo signal intensity on the inverted gas concentration, B can represent the influence of lidar system efficiency on the inverted gas concentration, that is, the system efficiency impact value, and C can represent the influence of atmospheric composition (except the gas to be measured) on the inverted gas concentration. Among them, the inversion accuracy can be improved by correcting item B, that is, determining the change of system efficiency with distance .

[0027] Generally, the transmission efficiency, receiving efficiency, and photoelectric conversion efficiency do not change with distance, and the change in system efficiency is caused by the change in the matching degree of the transmitting and receiving fields of view. When the receiving field of view can always cover the transmitting field of view, the system efficiency does not change. However, the laser radar optical path mainly has two forms: coaxial transmission and reception and off-axis transmission and reception. On the one hand, in order to ensure the transmission efficiency, the coaxial transceiver laser radar generally adopts the form of central hole. Specifically, the light is emitted from the internal "hole", reflected by the atmosphere, and then received by the external "ring". The optical receiving position is equivalent to the external "ring" type receiving lens, and the optical transmitting position is equivalent to the internal "hole" type transmitting lens. The receiving position cannot cover the transmitting position. Therefore, even if the receiving field of view angle is greater than the transmitting field of view angle, the receiving field of view cannot cover the transmitting field of view within the entire detection range, which causes the system efficiency to change with the change of distance. On the other hand, in the off-axis transceiver structure, the receiving field of view cannot cover the transmitting field of view within the entire detection range, causing the system efficiency to change with the change of distance.

[0028] In traditional gas detection lidar, horizontal detection is usually used to determine the change in system efficiency with distance. Specifically, a mechanical or optical mechanism can be used to transmit the detection beam horizontally, and the atmosphere in this direction is assumed to be uniform, and the backscatter coefficient and extinction coefficient are all constants. The change in system efficiency can be derived from the echo signal strength in formula (1).

[0029] However, this method has two major drawbacks. First, the detection process requires an extremely open experimental site, with a horizontal distance of more than two kilometers; second, the ideal condition is that the atmosphere is uniform in the horizontal direction, which results in large errors in the actual detection process.

[0030] Therefore, there is an urgent need for a gas detection lidar calibration method that can accurately determine the change in system efficiency with distance, thereby ensuring the accuracy and reliability of the gas detection lidar calibration.

[0031] Please refer to Figure 1 , which shows a flow chart of a calibration method for a gas detection laser radar provided by an embodiment of the present application. The calibration method for the gas detection laser radar may specifically include: Step 101, obtaining the first echo signal strength and the second echo signal strength of the laser radar to be processed; wherein the first echo signal strength is detected by using an auxiliary calibration device and the laser radar to be processed, and the light transmitting and receiving path of the auxiliary calibration device meets the preset transmitting and receiving field of view condition; the interval between the detection time of the first echo signal strength and the detection time of the second echo signal strength is less than a preset time threshold, and the distance between the detection position of the first echo signal strength and the detection position of the second echo signal strength is less than a preset distance threshold.

[0032] Step 102: Based on the first echo signal strength and the second echo signal strength, a preset calibration algorithm is used to obtain target calibration parameters.

[0033] Step 103: Based on the target calibration parameters, a preset influence value algorithm is used to determine the influence value of the laser radar system efficiency.

[0034] Step 104: Based on the laser radar system efficiency impact value, calibrate the laser radar to be processed to obtain a calibrated laser radar.

[0035] It should be noted that the target calibration parameter may be the variation of the laser radar system efficiency with distance. The system efficiency impact value may be the influence of the laser radar system efficiency on the inverted measured gas concentration, that is, the influence value of the laser radar system efficiency on the inverted measured gas concentration.

[0036] It should be noted that the laser radar to be processed may be a gas detection laser radar to be calibrated. The gas detection laser radar may include a laser radar for detecting different gases in the atmosphere.

[0037] It should be noted that the first echo signal strength may include echo signal strengths at at least two wavelengths. The second echo signal strength may also include echo signal strengths at at least two wavelengths.

[0038] It should be noted that the first echo signal strength may be detected by using the auxiliary calibration device and the laser radar to be processed. The second echo signal strength may be directly detected by using the laser radar to be processed.

[0039] It is understandable that, before detection processing, the device operating parameters of the laser radar to be processed and its corresponding auxiliary calibration device can be pre-configured according to the requirements of the actual detection scene.

[0040] It should be noted that the preset time threshold and the preset distance threshold can be determined according to the actual application scenario. For example, the preset time threshold can be 3 minutes, and the preset distance threshold can be 3 meters. Here, based on the fact that the interval between the detection time of the first echo signal strength and the detection time of the second echo signal strength is less than the preset time threshold, and the distance between the detection position of the first echo signal strength and the detection position of the second echo signal strength is less than the preset distance threshold, it can be ensured that the atmospheric extinction coefficient and the backscattering coefficient involved in the first echo signal strength and the second echo signal strength are the same value.

[0041] In this way, the target calibration parameters of the laser radar can be determined based on the first echo signal strength of the laser radar to be processed detected by the auxiliary calibration equipment and the second echo signal strength detected by the laser radar itself. This can improve the accuracy of the calibration parameters and better correct the inversion results of the gas concentration, that is, obtain a higher-precision system efficiency impact value, improve the inversion accuracy of the gas concentration, and thus ensure the detection accuracy and reliability of the gas detection laser radar.

[0042] Optionally, in a possible implementation of this embodiment, in step 101, first, the laser radar to be processed may emit a first laser to the auxiliary calibration device. Secondly, the auxiliary calibration device performs a first detection process on the atmosphere based on the first laser to obtain the first echo signal strength. Thirdly, the first echo signal strength of the laser radar to be processed is obtained from the auxiliary calibration device.

[0043] In this implementation, the auxiliary calibration device may include a beam integration module, an echo receiving module, and a signal processing module.

[0044] In a specific implementation process of this implementation, first, the beam integration module receives the first laser emitted by the laser radar to be processed. Secondly, the beam integration module adjusts the received first laser to obtain the adjusted first echo light, and sends the first echo light to the echo receiving module. Thirdly, the echo receiving module converts the received first echo light to obtain a first electrical signal, and sends the first electrical signal to the signal processing module. Thirdly, the signal processing module calculates the first electrical signal to obtain the first echo signal strength.

[0045] Exemplarily, first, the gas detection laser radar to be calibrated can emit a first laser to the auxiliary calibration device. The first laser can be called incident light. The incident light is sent vertically to the high-altitude atmosphere through the beam integration module. After the detection light is extinct and backscattered by the atmosphere, echo light is generated. The echo light enters the echo receiving module after passing through the beam integration module. In the echo receiving module, the echo light signal can be converted into an electrical signal and sent to the signal processing module. The signal processing module can calculate the first echo signal strength that changes with height, and can detect, store, and process the received electrical signal.

[0046] In this implementation, the beam integration module can control the center of the emission spot of the emission field of view to coincide with the center of the receiving field of view. The echo receiving module can control the receiving field of view angle and the transmitting field of view angle to meet the preset field of view angle condition, and the receiving field of view diameter and the transmitting field of view diameter to meet the preset length condition.

[0047] Preferably, the preset field of view angle condition may include that the receiving field of view angle is greater than the sum of the transmitting field of view angle and twice the angle between the receiving and transmitting optical axes, and the angle between the receiving and transmitting optical axes may be 500 microradians (urad). Here, twice the angle between the receiving and transmitting optical axes may be a preset coefficient. The preset length condition may include that the receiving diameter of the receiving field of view is greater than the emission spot diameter of the transmitting field of view.

[0048] Here, the beam integration system can be used to achieve the coincidence of the center of the emission spot with the center of the effective receiving area, and the echo receiving system can be used to achieve the emission spot diameter of the emission field of view. The effective receiving diameter of the receiving field of view Should meet , receiving field of view Should be larger than the launch field of view ,satisfy , is the angle between the receiving and transmitting optical axes, It is 500urad so that the receiving field of view can cover the transmitting field of view.

[0049] In this way, by utilizing auxiliary calibration equipment that meets the preset receiving and transmitting field of view conditions, the laser emitted by the laser radar to be processed can be adjusted to obtain an electrical signal of light whose receiving field of view can cover the transmitting field of view, thereby obtaining a more accurate first echo signal strength, so as to further improve the reliability of subsequent calibration.

[0050] Optionally, in a possible implementation of this embodiment, in step 101, first, the laser radar to be processed emits a second laser vertically upward. Secondly, the laser radar to be processed performs a second detection process on the atmosphere based on the second laser to obtain the second echo signal strength. Thirdly, the second echo signal strength is obtained from the laser radar to be processed.

[0051] In this implementation, the laser radar to be processed may include a light transmitting and receiving circuit module, an optoelectronic processing module and a data processing module.

[0052] Here, the light transmitting and receiving circuit module, the optoelectronic processing module and the data processing module may be arranged inside the laser radar to be processed.

[0053] In a specific implementation process of this implementation, first, the light receiving and transmitting circuit module receives the second echo light returned based on the second laser. Secondly, the light receiving and transmitting circuit module sends the second echo light to the photoelectric processing module. Thirdly, the photoelectric processing module converts the second echo light to obtain the second electrical signal, and sends the second electrical signal to the data processing module. Thirdly, the photoelectric processing module calculates and processes the second electrical signal to obtain the second echo signal strength.

[0054] Here, the direction in which the laser radar to be processed emits the laser pulse is vertically upward, so that the deviation between the emission optical axis and the vertical direction can be further reduced.

[0055] It should be noted that the specific implementation process provided in this implementation can be combined with the various specific implementation processes provided in the aforementioned implementation to implement the calibration method of the gas detection laser radar of this embodiment. For a detailed description, please refer to the relevant content in the aforementioned implementation, which will not be repeated here.

[0056] Optionally, in a possible implementation of this embodiment, the first echo signal strength may include the first echo signal strength at the first position and the first echo signal strength at the second position, and the second echo signal strength may include the second echo signal strength at the first position and the second echo signal strength at the second position. In step 102, based on the first echo signal strength at the first position and the first echo signal strength at the second position, and the second echo signal strength at the first position and the second echo signal strength at the second position, a preset calibration algorithm may be used to calculate calibration parameters, and the calibration parameters may be used as target calibration parameters.

[0057] In this implementation, the first position may represent the laser detection height The second position can represent the laser detection height Plus the detection distance resolution corresponding to the acquisition cycle location.

[0058] In a specific implementation process of the implementation mode, first, the ratio of the first echo signal strength at the first position to the first echo signal strength at the second position can be calculated to obtain a first ratio. Secondly, the ratio of the second echo signal strength at the first position to the second echo signal strength at the second position is calculated to obtain a second ratio. Thirdly, the ratio of the first ratio to the second ratio is calculated to obtain a calibration parameter, that is, a target calibration parameter.

[0059] Here, the target calibration parameter may be the variation of the system efficiency of the laser radar to be calibrated with height.

[0060] It can be understood that, here, the first echo signal strength and the second echo signal strength of lasers with different wavelengths can be detected. Here, the target calibration parameters can include calibration parameters of lasers with different wavelengths.

[0061] In this way, more accurate and effective target calibration parameters can be calculated by more accurately calculating the first echo signal strength at the first position and the first echo signal strength at the second position, as well as the second echo signal strength at the first position and the second echo signal strength at the second position.

[0062] It should be noted that the specific implementation process provided in this implementation can be combined with the various specific implementation processes provided in the aforementioned implementation to implement the calibration method of the gas detection laser radar of this embodiment. For a detailed description, please refer to the relevant content in the aforementioned implementation, which will not be repeated here.

[0063] Optionally, in a possible implementation of this embodiment, the target calibration parameters include target calibration parameters of at least two wavelengths. In step 103, first, the target calibration parameters of the first wavelength and the target calibration parameters of the second wavelength are obtained. Secondly, based on the target calibration parameters of the first wavelength and the target calibration parameters of the second wavelength, the efficiency impact value of the laser radar system can be calculated using a preset impact value algorithm.

[0064] In this implementation, the target calibration parameters of different wavelengths may be target calibration parameters corresponding to lasers of different wavelengths. The target calibration parameters of the first wavelength may be target calibration parameters corresponding to the laser of the first wavelength. The target calibration parameters of the second wavelength may be target calibration parameters corresponding to the laser of the second wavelength.

[0065] In a specific implementation process of this implementation method, the preset influence value algorithm can be shown as formula (8). Specifically, the influence value of the laser radar system efficiency can be calculated based on the target calibration parameters of the first wavelength and the target calibration parameters of the second wavelength using formula (8).

[0066] Here, the system efficiency impact value of the laser radar to be processed can represent the impact of the laser radar system efficiency on the inverted gas concentration to be measured.

[0067] It can be understood that the calculated laser radar system efficiency impact value can be used as the system efficiency impact value of the laser radar to be processed to complete the calibration processing of the laser radar to be processed.

[0068] In this way, the efficiency impact value of the laser radar system can be calculated through the target calibration parameters corresponding to any two wavelengths and the preset impact value algorithm, which can improve the accuracy of the efficiency impact value of the laser radar system.

[0069] It should be noted that the specific implementation process provided in this implementation can be combined with the various specific implementation processes provided in the aforementioned implementation to implement the calibration method of the gas detection laser radar of this embodiment. For a detailed description, please refer to the relevant content in the aforementioned implementation, which will not be repeated here.

[0070] Optionally, in a possible implementation of this embodiment, the preset transmitting and receiving field of view conditions may include that the receiving diameter of the receiving field of view is larger than the transmitting spot diameter of the transmitting field of view, and the receiving field of view angle is larger than the sum of the transmitting field of view angle and a preset coefficient, and the preset coefficient is determined based on the angle between the optical axis of the receiving field of view and the optical axis of the transmitting field of view.

[0071] In this implementation, the preset receiving and transmitting field of view condition may include a preset field of view angle condition and a preset length condition. The preset coefficient may be twice the angle between the receiving and transmitting optical axes.

[0072] Preferably, the preset field of view angle condition may include that the receiving field of view angle is greater than the sum of the transmitting field of view angle and twice the angle between the receiving and transmitting optical axes, and the angle between the receiving and transmitting optical axes may be 500urad. The preset length condition may include that the receiving diameter of the receiving field of view is greater than the transmitting spot diameter of the transmitting field of view.

[0073] Here, the receiving diameter of the receiving field of view may be an effective receiving diameter of the receiving field of view.

[0074] In this implementation, the preset transmitting and receiving field of view condition may also include that the center of the transmitting light spot of the transmitting field of view coincides with the center of the receiving field of view.

[0075] Here, the center of the receiving field of view may be the center of an effective receiving area of ​​the receiving field of view.

[0076] It is understandable that the beam integration module of the auxiliary calibration device can control the emission spot center of the emission field of view to coincide with the center of the receiving field of view. The echo receiving module of the auxiliary calibration device can control the receiving field of view angle and the emission field of view angle to meet the preset field of view angle condition, and the receiving field of view diameter and the emission field of view diameter to meet the preset length condition.

[0077] In this way, it can be ensured that the light transmitting and receiving paths of the auxiliary calibration equipment can meet the preset transmitting and receiving field of view conditions, and that the receiving field of view of the auxiliary calibration equipment can cover the transmitting field of view. Furthermore, more accurate target calibration parameters can be determined by utilizing the first echo signal strength calculated based on the auxiliary calibration equipment.

[0078] It should be noted that the specific implementation process provided in this implementation can be combined with the various specific implementation processes provided in the aforementioned implementation to implement the calibration method of the gas detection laser radar of this embodiment. For a detailed description, please refer to the relevant content in the aforementioned implementation, which will not be repeated here.

[0079] Figure 2 FIG. 1 shows a schematic diagram of the architecture of a calibration system for a gas detection laser radar provided by an embodiment of the present application. Figure 2 shown.

[0080] In this embodiment, the calibration system of the gas detection laser radar may include an auxiliary calibration device, a laser radar to be processed, and a data processing device. The data processing device is respectively connected to the auxiliary calibration device and the laser radar to be processed. The auxiliary calibration device is used to detect and obtain the first echo signal strength based on the laser sent by the laser radar to be processed. The laser radar to be processed is used to detect and obtain the second echo signal strength. The data processing device is used to perform the calibration method of the gas detection laser radar as described in the above embodiment.

[0081] Optionally, in a possible implementation of this embodiment, the auxiliary calibration device may include a beam integration module, an echo receiving module, and a signal processing module.

[0082] Preferably, the beam integration module can be used to control the center of the emission light spot of the emission field of view to coincide with the center of the receiving field of view.

[0083] The echo receiving module can be used to control the receiving field of view angle and the transmitting field of view angle to meet the preset field of view angle condition, and the receiving field of view diameter and the transmitting field of view diameter to meet the preset length condition.

[0084] The signal processing module may be configured to calculate and store the first echo signal strength.

[0085] Preferably, the preset transmitting and receiving field of view condition may include a preset field of view angle condition and a preset length condition.

[0086] Preferably, the preset field of view angle condition may include that the receiving field of view angle is greater than the sum of the transmitting field of view angle and a preset coefficient, and the preset coefficient may be 2 times the angle between the receiving and transmitting optical axes. For example, the angle between the receiving and transmitting optical axes may be 500urad. The preset length condition may include that the receiving diameter of the receiving field of view is greater than the emission spot diameter of the transmitting field of view.

[0087] In this embodiment, a set of echo signal data can be obtained by utilizing the auxiliary calibration equipment of the calibration system, and the echo signal data can be differentially processed with the echo signal data of the gas detection lidar to be calibrated by using the data processing equipment to obtain a more accurate change in the efficiency of the gas detection lidar system to be calibrated with distance, thereby improving the influence of the lidar system efficiency on the inverted gas concentration to be measured, thereby inverting more accurate gas concentration data.

[0088] In order to better illustrate the calibration method of the gas detection lidar in the present application, the calibration method of the gas detection lidar is described in detail in combination with the calibration system and application scenarios of the gas detection lidar.

[0089] Figure 3 A schematic diagram showing the process of a calibration method for a gas detection laser radar provided by another embodiment of the present application is shown as follows: Figure 3 In this embodiment, the calibration method of the gas detection laser radar can be specifically implemented as follows: Step 301: The gas detection laser radar to be calibrated emits a first laser to an auxiliary calibration device.

[0090] In this embodiment, before calibration, first, the operating parameters of the gas detection laser radar to be calibrated can be determined. The operating parameters may include laser wavelength, energy, spot size, field of view, etc. Secondly, according to the operating parameters of the gas detection laser radar to be calibrated, the specifications of the components in the auxiliary calibration equipment are adjusted so that the receiving field of view of the auxiliary calibration equipment can cover the transmitting field of view and complete the echo signal detection work.

[0091] Step 302: The beam integration module of the auxiliary calibration device receives the first laser, and adjusts the received first laser to obtain an adjusted first echo light, and sends the first echo light to the echo receiving module of the auxiliary calibration device.

[0092] Step 303: The echo receiving module of the auxiliary calibration device converts and processes the received first echo light of the gas detection laser radar to be calibrated to obtain a first electrical signal, and sends the first electrical signal of the gas detection laser radar to be calibrated to the signal processing module of the auxiliary calibration device.

[0093] Step 304: The signal processing module of the auxiliary calibration device performs calculation processing on the first electrical signal of the gas detection laser radar to be calibrated to obtain the first echo signal strength.

[0094] Step 305: The gas detection laser radar to be calibrated emits a second laser vertically upward to perform a second detection process on the atmosphere based on the second laser of the gas detection laser radar to be calibrated to obtain a second echo signal intensity.

[0095] In this embodiment, the auxiliary calibration device may include a beam integration module, an echo receiving module and a signal processing module. The auxiliary calibration device may be an auxiliary calibration device.

[0096] In this embodiment, the gas detection laser radar to be calibrated transmits pulses in a vertically upward direction, so that the deviation between the emission optical axis and the vertical direction can be reduced as much as possible.

[0097] Figure 4 A schematic diagram showing an application scenario of a calibration method for a gas detection laser radar provided by another embodiment of the present application is shown. Figure 4 As shown. The application scenario includes a gas detection lidar to be calibrated and an auxiliary calibration device. The auxiliary calibration device includes a beam integration module, an echo receiving module, and a signal processing module.

[0098] In this embodiment, for example, Figure 4 As shown, first, the gas detection laser radar to be calibrated emits a first laser to the auxiliary calibration device. The first laser can be called incident light. After the incident light passes through the beam integration module, the detection light is vertically sent to the high-altitude atmosphere. After the detection light is extinct and backscattered by the atmosphere, an echo light is generated. The echo light enters the echo receiving module after passing through the beam integration module. In the echo receiving module, the echo light signal can be converted into an electrical signal and transmitted to the signal processing module for calculation, detection, storage and other processing, and the first echo signal intensity that varies with height can be calculated. Here, before detection, the signal processing modules of the gas detection laser radar to be calibrated and the auxiliary calibration equipment can be time synchronized.

[0099] Secondly, the auxiliary calibration equipment of the laser radar can be removed, and the gas detection laser radar to be calibrated can be used to directly emit a second laser in the vertical direction. The light-receiving and light-emitting circuit module, optoelectronic processing module and data processing module of the gas detection laser radar to be calibrated can be used to calculate another set of echo signal intensities that vary with height.

[0100] Here, the gas detection laser radar to be calibrated and the auxiliary calibration equipment are close in test position and test time, the test time interval can be less than 3 minutes, and the distance between the test positions can be less than 3 meters. Therefore, in the two sets of first echo signal intensity and second echo signal intensity, the atmospheric extinction coefficient and backscattering coefficient at different heights can be considered to be the same value. According to formula (1), the following formulas (10) and (11) can be obtained: in, is the first echo signal strength, is the second echo signal strength, To calculate the system efficiency using auxiliary calibration equipment, is the system efficiency of the gas detection lidar to be calibrated, is the pulse energy emitted by the gas detection lidar to be calibrated, To assist in calibrating the loss of the light transmission and receiving circuits of the equipment. is Planck's constant, is the speed of light, is the laser wavelength, is the atmospheric backscattering coefficient, is the atmospheric extinction coefficient, To detect the height, is the detection distance resolution.

[0101] Understandably, Determined by the acquisition time interval of the signal collector. For example, the acquisition time interval is 50 nanoseconds (ns), which corresponds to a distance of 15 meters (m) at the speed of light. There is light return during detection, and the corresponding detection distance resolution is 7.5m. The signal collector can be set in the signal processing module of the gas detection laser radar to be calibrated. At the same time, the signal collector can also be set in the signal processing module of the auxiliary calibration equipment.

[0102] Furthermore, formulas (10) and (11) can be simplified and combined with The number of echo photons at The echo signal strength at , we can get formula (12): Here, since the receiving field of view of the auxiliary calibration device can cover the transmitting field of view, the system efficiency parameters under the auxiliary calibration device are is a constant and does not change with altitude. Thus, the change of the system efficiency of the gas detection lidar to be calibrated with altitude can be obtained, that is, the target calibration parameter , which can be expressed as formula (13): in, is the first echo signal strength in The echo signal strength of the position, that is, the first echo signal strength of the first position, is the first echo signal strength in The echo signal strength at the position, that is, the first echo signal strength at the second position, is the second echo signal strength The echo signal strength of the position, that is, the second echo signal strength of the first position, is the second echo signal strength The echo signal strength at the second position, that is, the second echo signal strength at the second position.

[0103] Step 306: The data processing device obtains the first echo signal strength and the second echo signal strength.

[0104] Step 307: The data processing device calculates the target calibration parameters based on the first echo signal strength and the second echo signal strength of the gas detection laser radar to be calibrated using a preset calibration algorithm.

[0105] In this embodiment, the data processing device calculates the target calibration parameter based on the first echo signal strength and the second echo signal strength of the gas detection laser radar to be calibrated using a preset calibration algorithm as shown in formula (13). .

[0106] It can be understood that, first, the first echo signal strength and the second echo signal strength of the lasers of multiple wavelengths can be obtained. Secondly, based on the first echo signal strength and the second echo signal strength of each wavelength laser, the target calibration parameters of each wavelength laser are calculated using the preset calibration algorithm shown in formula (13).

[0107] Step 308: The data processing device calculates the influence value of the laser radar system efficiency based on the target calibration parameters of the gas detection laser radar to be calibrated and using a preset influence value algorithm.

[0108] In this embodiment, the target calibration parameters may include target calibration parameters of different wavelengths. For example, the target calibration parameters of the gas detection laser radar to be calibrated may include target calibration parameters of a first wavelength and target calibration parameters of a second wavelength.

[0109] Here, the target calibration parameters of the first wavelength and the target calibration parameters of the second wavelength can be obtained, and the influence value of the laser radar system efficiency can be calculated using the preset influence value algorithm shown in formula (8).

[0110] Step 309: Use the laser radar system efficiency impact value as the system efficiency impact value of the gas detection laser radar to be calibrated to obtain the gas detection laser radar after calibration.

[0111] In this embodiment, the light transmission and light transmission path of the auxiliary calibration device should meet the preset transmission and reception field of view conditions. The preset transmission and reception field of view conditions may include that the transmission spot diameter of the transmission field of view is smaller than the receiving diameter of the receiving field of view, the transmission spot center of the transmission field of view coincides with the center of the receiving field of view, and the receiving field of view angle is greater than the sum of the transmission field of view angle and the preset coefficient. The preset coefficient of the gas detection laser radar to be calibrated is determined based on the angle between the optical axis of the receiving field of view and the optical axis of the transmission field of view.

[0112] In this embodiment, illustratively, Figure 5 A schematic diagram of the receiving and transmitting field of view of an auxiliary calibration device of a gas detection laser radar calibration method provided in another embodiment of the present application is shown. Figure 5 The light receiving and transmitting path of the auxiliary calibration equipment can meet the following two conditions, namely the preset receiving and transmitting field conditions: 1. The diameter of the transmitting light spot in the transmitting field Receiving diameter and receiving field of view Should meet , and the center points coincide; 2. Receiving field of view Should be larger than the launch field of view ,satisfy , is the angle between the receiving and transmitting optical axes, Smaller, for example, It can be 500urad. In this way, the purpose of the receiving field of view of the auxiliary calibration device covering the transmitting field of view can be achieved.

[0113] In addition, it can be understood that the auxiliary calibration device can be implemented using a variety of structures.

[0114] For example, Figure 6 A schematic diagram showing the structure of an auxiliary calibration device for a calibration method of a gas detection laser radar provided in another embodiment of the present application is shown. Figure 6 As shown. The laser radar 1 to be calibrated can be a gas detection laser radar to be calibrated. The emission pulse direction of the laser radar 1 to be calibrated is vertically upward to reduce the deviation of the emission optical axis from the vertical direction. The beam integration system 3 can be a beam integration module of the auxiliary calibration device, the echo receiving system 4 can be an echo receiving module of the auxiliary calibration device, and the echo receiving system 5 can be a signal processing module 5 of the auxiliary calibration device. The beam integration system 3 can include a light-transmitting pinhole 31, a spectroscope 32, and an extinction chamber 33. The echo receiving system 4 can include a receiving lens group 41, a filter 42, and a photoelectric converter 43.

[0115] Here, the transmission-reflection ratio of the spectroscope 32 can be 1:1. The horizontal laser is incident on the spectroscope 32 at an angle of 45°, and the relative position is adjusted so that the center of the light spot coincides with the center of the spectroscope 32. Part of the reflection becomes the detection light and is vertically injected into the atmosphere, and part of the transmitted light enters the extinction chamber 34 and is absorbed. At the same time, the echo light can be transmitted and reflected through the spectroscope 32, and the reflected part eventually reaches the extinction chamber 33 and is absorbed, and the transmitted part is converged and received by the echo receiving system 4. In addition to the installation position and the transmission-reflection ratio, the spectroscope 32 has a certain area size and does not block the receiving field of view. The extinction chamber 33 can absorb the laser energy to prevent the laser from reflecting again. The signal processing system 5 is time synchronized with the gas detection laser radar 1 to be calibrated, and detects and records the electrical signal generated by the echo light to obtain the echo signal intensity.

[0116] Preferably, the receiving lens group 41 mainly functions to shape the receiving field of view. The echo light is converged onto the photoelectric converter through the receiving lens group 41. In order to better meet the purpose of the receiving field of view covering the transmitting field of view, the optical center of the receiving lens group coincides with the center of the spectroscope 32 in the vertical direction, and the receiving diameter of the receiving field of view is greater than the transmitting spot diameter of the transmitting field of view, and the receiving field of view angle is greater than the sum of the transmitting field of view angle and twice the angle between the receiving and transmitting optical axes. The angle between the receiving and transmitting optical axes can be smaller, for example, the angle between the receiving and transmitting optical axes can be 500urad. The filter 42 can be a narrow-band filter to filter out background light other than the laser wavelength. It can use a filter with a bandwidth of less than 1nm and an optical density of one hundred thousandth. The photoelectric converter 43 can be a vacuum photomultiplier tube to convert and amplify weak optical signals into electrical signals for detection and recording.

[0117] Here, if Figure 6As shown, during the processing of the auxiliary calibration equipment, the incident light of the laser radar 1 to be marked reaches the spectroscope 32 through the light-transmitting hole 31, and the spectroscope 32 is a semi-transparent and semi-reflective mirror. Part of the incident light is reflected by the spectroscope 32 to the extinction chamber 33, and is absorbed. After part of the incident light is transmitted through the spectroscope 32, it is vertically shot into the atmosphere, which can be called detection light. After the detection light is extinct and backscattered by the atmosphere, echo light is generated. The echo light passes through the spectroscope 32 again, is partially reflected to the echo receiving system 4, and is partially transmitted to the light-transmitting hole 31. The aperture area of ​​the light-transmitting hole 31 is relatively small compared to the light-transmitting hole 31, and has a strong absorption effect on the laser of this wavelength, so the influence of the transmitted light can be ignored. The echo receiving system 4 is composed of a receiving lens group 41, a filter 42, and a photoelectric converter 43. The receiving lens group 41 controls the size of the receiving field angle and the receiving field diameter through optical processing, the filter 42 uses a narrowband filter to filter the background light, and the photoelectric converter 43 can be a high-sensitivity photomultiplier tube, and the photoelectric converter 43 is used for the conversion of optical signals to electrical signals. The electrical signal is input to the signal processing system 5 for the collection and storage of the electrical signal. Here, the beam integration system 3 can be used to achieve the coincidence of the center of the emission spot and the center of the effective receiving area, and the echo receiving system 4 can be used to achieve that the receiving diameter of the receiving field is greater than the emission spot diameter of the emission field, and the receiving field angle is greater than the sum of the emission field angle and twice the angle between the receiving and emitting optical axes, and the angle between the receiving and emitting optical axes can be 500urad, so that the receiving field can cover the emitting field. Thus, when the system efficiency of the auxiliary calibration equipment is constant, a set of echo signal intensity information that varies with height is obtained, that is, the first echo signal intensity information.

[0118] For another example, Figure 7 A schematic diagram showing the structure of another auxiliary calibration device of a gas detection laser radar calibration method provided by another embodiment of the present application is shown as follows: Figure 7 As shown. The laser radar 1 to be calibrated can be a gas detection laser radar to be calibrated. The emission pulse direction of the laser radar 1 to be calibrated is vertically upward to reduce the deviation of the emission optical axis from the vertical direction. The beam integration system 3 can be a beam integration module of the auxiliary calibration device, the echo receiving system 4 can be an echo receiving module of the auxiliary calibration device, and the echo receiving system 5 can be a signal processing module 5 of the auxiliary calibration device. The beam integration system 3 can include a reflector 35, a spectroscope 32, an extinction chamber 33, and an extinction chamber 34. The echo receiving system 4 can include a receiving lens group 41, a filter 42, and a photoelectric converter 43.

[0119] Here, the extinction chamber 34 can be used to absorb the laser energy and prevent the laser from being reflected again. In order to ensure that the laser is efficiently converted from the vertical direction to the horizontal direction, the reflector 35 can be installed at a 45° horizontal tilt, and the relative position can be adjusted so that the center of the reflector 35 coincides with the center of the light spot, and a high reflectivity film can be evaporated on the surface. In addition, in order to reduce the intensity of the echo light reflected by the beam splitter 32 and reflected back to the laser radar by the reflector 35 again, the reflector 35 can be reduced in area while ensuring the vertical-horizontal conversion efficiency.

[0120] It is understood that the configuration and use of other components may be different. Figure 6 The settings and uses of the corresponding components of the auxiliary calibration equipment shown are the same, and reference may be made to the aforementioned related contents, which will not be elaborated here.

[0121] Here, if Figure 7 As shown, during the processing of the auxiliary calibration equipment, the laser radar 1 to be calibrated emits laser light vertically upward, which is called incident light and enters the beam integration system 3. The incident light hits the reflector 35, which is installed at an angle of 45° and can convert the vertical laser light into the horizontal laser light. The surface of the reflector 35 is coated with a high reflectivity film, so that the reflectivity can reach more than 95%. The spectroscope 32 partially transmits and reflects the light. When the incident light reaches the spectroscope 32, part of the light will pass through the spectroscope 32 to the extinction chamber 34 and be absorbed, and will not participate in the subsequent detection process; part of the light will be reflected by the spectroscope 32 to form a vertical upward detection light. After the detection light is extinct and backscattered by atmospheric molecules, echo light is generated. Part of the echo light passes through the spectroscope 32 to the echo receiving system 4; part of the echo light is reflected by the spectroscope 32 and reaches the extinction chamber 33 and is absorbed. Here, the presence of the reflector 35 may affect the propagation path of part of the echo light to the extinction chamber 33, but this effect can be ignored by reducing the size of the reflector 35. The receiving lens group 41 of the echo receiving system 4 controls the receiving field angle and the size of the receiving diameter through optical processing, the filter 42 uses a narrow-band filter to filter the background light, and the photoelectric converter 43 uses a high-sensitivity photomultiplier tube to convert the optical signal to the electrical signal. The electrical signal is input to the signal processing system 5 for calculation and storage of the electrical signal.

[0122] Understandably, Figure 6 and Figure 7The difference between the auxiliary calibration settings in the figure is that the structure of the beam integration system 3 is different, and the functions realized by the auxiliary calibration device are the same. The beam integration system 3 can realize the coincidence of the center of the emission spot and the center of the effective receiving area, and the echo receiving system 4 can satisfy that the receiving diameter of the receiving field of view is greater than the emission spot diameter of the transmitting field of view, the receiving field of view angle is greater than the sum of the transmitting field of view angle and twice the angle between the receiving and transmitting optical axes, and the angle between the receiving and transmitting optical axes can be 500urad, so that the receiving field of view can cover the transmitting field of view. Therefore, when the system efficiency corresponding to the auxiliary calibration device is constant, a set of echo signal strength information that varies with height is obtained, that is, the first echo signal strength information.

[0123] It can be understood that, here, other existing devices that can realize the same function of the auxiliary calibration device in this embodiment can also be used, and the specific structure of the auxiliary calibration device is not specifically limited here.

[0124] In this embodiment, a set of echo signal data can be obtained by utilizing an auxiliary calibration device, and this data is differentially processed with the echo signal data of the gas detection lidar to be calibrated to obtain a more accurate change in the efficiency of the gas detection lidar system to be calibrated with distance, thereby improving the influence of the lidar system efficiency on the inverted gas concentration to be measured, thereby inverting more accurate gas concentration data.

[0125] In this embodiment, for example, an ozone laser radar can be selected as the gas detection laser radar to be calibrated, taking the laser with an emission wavelength of 289 nanometers (nm) and 316 nm as an example. Among them, the single pulse energy, spot diameter, field of view angle, angle between the optical axis and the vertical direction and other working parameters are shown in the following table.

[0126] Single pulse energy / mJ Spot diameter / cm Field of view / mrad Optical axis angle / mrad 289nm 12 2 0.15 0.1 316nm 14 1.5 0.1 0.1 Here, as Figure 7Taking the auxiliary calibration device shown as an example, the working parameters of the corresponding auxiliary calibration device are set based on the working parameters of the ozone laser radar, wherein the reflector 35 should be larger than the spot size, and the lens diameter can be selected as 3 cm. The surface of the reflector 35 is coated with a high-reflection film to ensure that the reflection efficiency of the light in the 285nm~320nm band is higher than 95% when the incident angle is 45°. Adjust the relative position so that the center of the reflector 35 coincides with the center of the spot. The spectroscope 32 uses a lens with a transmission-reflection ratio of 1:1 in the 285nm~320nm band and 45° incidence. The lens diameter is 10 cm, and the center positions of the reflector 35 and the spectroscope 32 in the horizontal direction can coincide when installed. The surfaces of the extinction chambers 33 and 34 in the direction of light incidence can be treated with anti-reflection, and light absorbers are used inside for optical absorption. The receiving lens group 41 coincides with the center position of the spectroscope 32 in the vertical direction, and the effective diameter is 8 cm. Considering the optical axis deviation and installation error, it is configured according to the field of view angle of 1 mrad. The specifications of the filter 42 are selected as 289nm±0.25nm, 316±0.25nm, OD5, OD5 can be expressed as a transmittance lower than 10 to the negative fifth power in the non-selected wavelength band. The photoelectric converter 43 can select a vacuum photomultiplier tube, and the multiplication wavelength covers the 285nm~320nm band. The signal processing module 5 can include a signal acquisition unit, that is, a signal collector, a time synchronization unit, a data storage unit, a power supply unit, a control processing unit, etc.

[0127] Here, first, the filter 42 can be set to a filter of 289nm±0.25nm, and the ozone laser radar and the signal processing module of the auxiliary calibration equipment can be synchronized in time. The reflector 35 has a light opening of 30 cm to 50 cm on the laser radar, and the relative position of the ozone laser radar and the auxiliary calibration equipment is adjusted so that the center of the reflector 35 coincides with the center of the light spot. Specifically, the position can be checked using a light spot analyzer.

[0128] Secondly, after the position adjustment is completed, the echo signal strength at a wavelength of 289nm is detected using the auxiliary calibration equipment. , and then immediately remove the auxiliary calibration equipment and use the ozone lidar to be calibrated to detect the echo signal intensity at a wavelength of 289nm After replacing the filter with the specification of 316±0.25nm, the same method was used to measure the wavelength of 316nm. and According to formula (13), the variation of the system efficiency of the ozone lidar to be calibrated at 289nm wavelength and 316nm wavelength with distance, that is, the target calibration parameter, is calculated as shown in the following formulas (14) and (15): in, is the target calibration parameter at 289nm wavelength, At a wavelength of 289 nm The first echo signal strength at the location, At a wavelength of 289 nm The first echo signal strength at the location, At a wavelength of 289 nm The second echo signal strength at the location, At a wavelength of 289 nm The second echo signal strength at the location, The target calibration parameters for the 316nm wavelength are: At a wavelength of 289 nm The first echo signal strength at the location, At a wavelength of 316 nm The first echo signal strength at the location, At a wavelength of 316 nm The second echo signal strength at the location, At a wavelength of 316 nm The second echo signal strength at the location, To detect the height, is the detection distance resolution.

[0129] Thirdly, based on the change in system efficiency with distance at 289nm and 316nm wavelengths of the ozone lidar to be calibrated, the influence of the lidar system efficiency on the inverted concentration of the gas to be measured, i.e., the system efficiency influence value, can be calculated using the preset influence value algorithm shown in the above formula (8).

[0130] Finally, the system efficiency impact value is used as the influence of the laser radar system efficiency of the ozone laser radar on the inversion of the concentration of the gas to be measured, and the ozone laser radar after calibration is obtained.

[0131] In this embodiment, the scheme in this example is adopted to obtain the change in system efficiency by differentially processing the two types of echo signal intensities obtained by the gas detection lidar to be calibrated and the auxiliary equipment, thereby solving the problem that existing horizontal detection schemes require a larger test site, and there is no need to assume that the atmosphere is uniform over a longer distance range, thereby reducing the test error of the detection results.

[0132] In addition, by adopting the solution in this example, the difference between the two types of echo signal intensities obtained by the gas detection lidar to be calibrated and the auxiliary equipment can be processed to obtain the change in system efficiency, which not only simplifies the test site but also improves the convenience of calibration.

[0133] In addition, by adopting the solution in this example, a more accurate change in system efficiency can be obtained, thereby better correcting the inversion result and improving the inversion accuracy of gas concentration.

[0134] It should be noted that, for the above-mentioned embodiments, for the sake of simplicity, they are all expressed as a series of action combinations, but those skilled in the art should be aware that the present application is not limited by the described order of actions, because according to the present application, certain steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily required by the present application.

[0135] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0136] In the technical solution of the present application, the user personal information involved, such as the collection, storage, use, processing, transmission, provision and disclosure of the user's image and attribute data, as well as the collection, storage, use, processing, transmission, provision and disclosure of meteorological information, weather detection-related data, atmospheric detection-related data, etc., all comply with the relevant laws and regulations and do not violate public order and good morals.

[0137] According to an embodiment of the present application, the present application also provides an electronic device, a readable storage medium and a computer program product for executing the calibration method of the gas detection lidar in the aforementioned embodiment.

[0138] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps recorded in this disclosure can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution disclosed in this application can be achieved, and this document is not limited here.

[0139] The above specific implementations do not constitute a limitation on the protection scope of this application. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions and improvements made within the spirit and principles of this application should be included in the protection scope of this application.

Claims

1. A gas detection laser radar calibration method, characterized in that: The method comprises: Obtaining the first echo signal strength and the second echo signal strength of the laser radar to be processed; wherein the first echo signal strength is detected by using an auxiliary calibration device and the laser radar to be processed, and the light transmitting and receiving path of the auxiliary calibration device meets the preset transmitting and receiving field of view condition; the interval between the detection time of the first echo signal strength and the detection time of the second echo signal strength is less than a preset time threshold, and the distance between the detection position of the first echo signal strength and the detection position of the second echo signal strength is less than a preset distance threshold; Based on the first echo signal strength and the second echo signal strength, using a preset calibration algorithm, obtaining a target calibration parameter; Based on the target calibration parameters, a preset influence value algorithm is used to determine the influence value of the laser radar system efficiency; Based on the laser radar system efficiency impact value, the laser radar to be processed is calibrated to obtain a calibrated laser radar.

2. The method according to claim 1, characterized in that The obtaining of the first echo signal strength of the laser radar to be processed includes: The laser radar to be processed emits a first laser to the auxiliary calibration device; The auxiliary calibration device performs a first detection process on the atmosphere based on the first laser to obtain the first echo signal strength; The first echo signal strength of the laser radar to be processed is obtained from the auxiliary calibration device.

3. The method according to claim 2, characterized in that The auxiliary calibration device includes a beam integration module, an echo receiving module, and a signal processing module. The auxiliary calibration device performs a first detection process on the atmosphere based on the first laser to obtain the first echo signal strength, including: The beam integration module receives the first laser emitted by the laser radar to be processed; The beam integration module adjusts the received first laser to obtain an adjusted first echo light, and sends the first echo light to the echo receiving module; The echo receiving module converts the received first echo light to obtain a first electrical signal, and sends the first electrical signal to the signal processing module; The signal processing module performs calculation processing on the first electrical signal to obtain the first echo signal strength.

4. The method according to claim 1, characterized in that: Get the second echo signal strength of the laser radar to be processed, including: The laser radar to be processed emits a second laser vertically upward; The laser radar to be processed performs a second detection process on the atmosphere based on the second laser to obtain the second echo signal intensity; The second echo signal strength is obtained from the laser radar to be processed.

5. The method according to claim 4, characterized in that The laser radar to be processed includes a light-receiving and light-emitting circuit module, an optoelectronic processing module and a data processing module. The laser radar to be processed performs a second detection process on the atmosphere based on the second laser to obtain the second echo signal strength, including: The light receiving and transmitting circuit module receives a second echo light returned based on the second laser; The light receiving and transmitting circuit module sends the second echo light to the photoelectric processing module; The photoelectric processing module converts the second echo light to obtain a second electrical signal, and sends the second electrical signal to the data processing module; The optoelectronic processing module performs calculation processing on the second electrical signal to obtain the second echo signal strength.

6. The method according to any one of claims 1 to 5, characterized in that The first echo signal strength includes a first echo signal strength at a first position and a first echo signal strength at a second position, the second echo signal strength includes a second echo signal strength at the first position and a second echo signal strength at the second position, and obtaining a target calibration parameter based on the first echo signal strength and the second echo signal strength using a preset calibration algorithm includes: Based on the first echo signal strength at the first position and the first echo signal strength at the second position, and the second echo signal strength at the first position and the second echo signal strength at the second position, a calibration parameter is calculated using a preset calibration algorithm; The calibration parameters are used as target calibration parameters.

7. The method according to any one of claims 1 to 5, characterized in that The target calibration parameters include target calibration parameters of at least two wavelengths, and determining the laser radar system efficiency influence value based on the target calibration parameters and using a preset influence value algorithm includes: Obtaining a target calibration parameter for the first wavelength and a target calibration parameter for the second wavelength; Based on the target calibration parameters of the first wavelength and the target calibration parameters of the second wavelength, the efficiency impact value of the laser radar system is calculated using a preset impact value algorithm.

8. The method according to claim 1, characterized in that The preset receiving and transmitting field of view conditions include that the receiving diameter of the receiving field of view is greater than the transmitting spot diameter of the transmitting field of view, and the receiving field of view angle is greater than the sum of the transmitting field of view angle and a preset coefficient, and the preset coefficient is determined based on the angle between the optical axis of the receiving field of view and the optical axis of the transmitting field of view.

9. A gas detection laser radar calibration system, characterized in that: The calibration system comprises: an auxiliary calibration device, a laser radar to be processed, and a data processing device; the data processing device is respectively connected to the auxiliary calibration device and the laser radar to be processed in communication; The auxiliary calibration device is used to detect and obtain the first echo signal strength based on the received laser sent by the laser radar to be processed; The laser radar to be processed is used to detect and obtain the second echo signal strength; The data processing device is used to execute the calibration method of the gas detection laser radar as described in any one of claims 1-8.

10. The system according to claim 9, characterized in that The auxiliary calibration equipment includes a beam integration module, an echo receiving module, and a signal processing module; The beam integration module is used to control the center of the emission spot of the emission field of view to coincide with the center of the receiving field of view; The echo receiving module is used to control the receiving field of view angle and the transmitting field of view angle to meet the preset field of view angle condition, and the receiving field of view diameter and the transmitting field of view diameter to meet the preset length condition; The signal processing module is used to calculate and store the first echo signal strength.

Images