Methane concentration laser rapid scanning device and planar imaging method

Abstract

The application discloses a kind of methane concentration laser fast scanning device and plane imaging method, scanning device includes laser emission module, collimating optical unit, two-dimensional galvanometer scanning module, receiving optical module, photoelectric detection module, signal conditioning and data acquisition module, synchronous control module, angle feedback module, host computer processing module.Laser emission module emits detection laser and is scanned according to preset path by two-dimensional galvanometer scanning module;Detection laser irradiation to non-cooperative target surface after producing diffuse reflection echo, receiving optical module collects echo signal and is converted into electrical signal by photoelectric detection module;Host computer processing module calculates each scanning point methane path integral concentration according to laser absorption signal, galvanometer angle information and scanning time sequence, constructs methane concentration two-dimensional distribution image.The application can realize the plane imaging of methane concentration in scanning range, achieve remote, non-contact, visual detection to methane leakage position, concentration range and diffusion trend.

Description

Technical Field

[0001] This invention belongs to the field of gas leak telemetry imaging technology, specifically relating to a rapid laser scanning device for methane concentration and a planar imaging method. Background Technology

[0002] Methane is a typical flammable and explosive gas, widely found in coal mines, natural gas pipelines, gas stations, chemical plant areas, landfills, tank farms, and underground utility tunnels. When methane leaks and accumulates in a localized area, it can easily form an explosive gas mixture, posing a serious threat to human life and industrial production safety. Therefore, rapid, long-distance, non-contact detection and spatial location of methane leaks are of great significance.

[0003] Existing methane detection methods mainly include point sensor detection, open optical path detection, handheld telemetry detection, and patrol-type laser detection. Point sensors typically only reflect the gas concentration near the sensor's location, making it difficult to quickly obtain the spatial distribution of methane over a large area. While open optical path detection can achieve long-path detection, it usually requires fixed transmitters and receivers, limiting installation options. Handheld laser methane telemetry instruments can perform non-contact detection of distant targets, but they mostly rely on manual aiming and single-point measurement, and the detection results are usually represented as path integral concentration in a certain direction, making it difficult to form an intuitive two-dimensional concentration distribution image.

[0004] In addition, some gas imaging systems use infrared thermal imaging or scanning imaging to visualize gases, but the equipment costs are high and they are easily affected by environmental factors in complex backgrounds, weak leaks, small-scale leaks, or long-distance detection conditions. Summary of the Invention

[0005] The purpose of this invention is to provide a rapid laser scanning device and planar imaging method for methane concentration, which can realize planar imaging of methane concentration within the scanning range, and achieve long-distance, non-contact, and visual detection of methane leak location, concentration range and diffusion trend.

[0006] To achieve the above objectives, the present invention provides a rapid laser scanning device for methane concentration, comprising: A laser emission module is used to generate a tunable detection laser that matches the absorption spectrum of methane gas. The two-dimensional galvanometer scanning module is set in the output light path of the laser emission module. It is used to change the output angle of the detection laser in both horizontal and vertical directions, so that the detection laser can irradiate the non-cooperative target surface in the area of ​​the methane gas to be tested according to the preset scanning path. A receiving optical module is used to receive laser echoes returned by diffuse reflection from the surface of a non-cooperative target; The photoelectric detection module, connected to the receiving optical module, is used to convert the received laser echo into an electrical signal; The signal conditioning and data acquisition module, connected to the photoelectric detection module, is used to process electrical signals and acquire methane absorption characteristic signals. The synchronization control module is connected to the laser emission module, the two-dimensional galvanometer scanning module, and the signal conditioning and data acquisition module, respectively, and is used to realize the timing synchronization between the detection laser wavelength modulation, galvanometer scanning angle control, and methane absorption characteristic signal acquisition. The host computer processing module is connected to the signal conditioning and data acquisition module and the two-dimensional galvanometer scanning module, respectively. It is used to calculate the methane path integral concentration at the scanning point based on the acquired methane absorption characteristic signal and the angle information of the two-dimensional galvanometer scanning module, and generate a two-dimensional methane concentration distribution image.

[0007] As a further aspect of the present invention: the preset scanning path is any one or more combinations of row-by-row raster scanning, column-by-column raster scanning, spiral scanning, key area encryption scanning, partition scanning, and adaptive scanning.

[0008] As a further aspect of the present invention, the scanning device further includes a ranging module for acquiring distance information between the scanning device and the surface of the non-cooperative target.

[0009] As a further aspect of the present invention: the scanning device is installed in any one of the following ways: fixed monitoring bracket, mobile inspection platform, robot platform, vehicle platform, or drone platform, for performing fixed, mobile, or aerial inspection-type planar scanning imaging of methane concentration in the target area.

[0010] As a further aspect of the present invention: the laser emitting module includes a tunable laser, a laser driving circuit, a temperature control unit, and a collimating optical unit; The tunable laser is connected to the collimating optical unit. The laser wavelength emitted by the tunable laser is adjusted by the laser driving circuit and the temperature control unit. The output wavelength of the tunable laser matches the near-infrared absorption spectrum of methane gas.

[0011] As a further aspect of the present invention: the receiving optical module includes an aperture structure for sequentially receiving laser echoes, a receiving lens, and a narrowband filter; Among them, narrowband filters are used to suppress ambient stray light; The aperture structure is used to limit the receiving field of view and reduce echo interference from non-target areas.

[0012] As a further aspect of the present invention: the signal conditioning and data acquisition module includes a preamplifier circuit, a filter circuit, a lock-in amplifier or harmonic demodulation unit, and an analog-to-digital converter unit, which are used to amplify, filter, demodulate, and acquire the electrical signal in sequence to obtain the methane absorption signal.

[0013] As a further aspect of the present invention: the two-dimensional galvanometer scanning module includes a horizontal scanning galvanometer, a vertical scanning galvanometer, a galvanometer driving unit, and an angle feedback unit; Among them, the galvanometer driving unit is connected to control the placement angle of the horizontal scanning galvanometer and the vertical scanning galvanometer; The angle feedback unit is used to acquire the angle information of the horizontal scanning galvanometer and the vertical scanning galvanometer in real time, and send the angle information to the host computer processing module.

[0014] As a further aspect of the present invention: the host computer processing module includes a concentration inversion unit, a scanning point positioning unit, and an image reconstruction unit; Among them, the concentration inversion unit is used to calculate the methane path integral concentration based on the harmonic signal calculated from the laser echo signal or the methane absorption characteristic signal; The scanning point positioning unit is used to determine the scanning position of the detection laser on the target plane based on the angle information of the two-dimensional galvanometer scanning module; The image reconstruction unit is used to map the methane path integral concentration at each scan point to a two-dimensional pixel matrix.

[0015] To achieve the above-mentioned objectives, the present invention also provides a planar imaging method based on the above-mentioned methane concentration laser rapid scanning device, comprising the following steps: S1. Control the laser emission module to generate a tunable detection laser that matches the methane absorption spectrum, and modulate the wavelength of the detection laser. S2. The detection laser is deflected in both the horizontal and vertical directions by the two-dimensional galvanometer scanning module, so that the detection laser sequentially irradiates the non-cooperative target surface in the methane gas region to be tested according to the preset scanning path. S3. Receive the laser echo returned by diffuse reflection from the surface of the non-cooperative target, and transmit the laser echo to the photoelectric detection module to convert it into an electrical signal; S4. Amplify, filter, demodulate, and acquire data of the electrical signal to obtain the methane absorption characteristic signal related to methane absorption; S5. Synchronously record the horizontal and vertical angle information and methane absorption characteristic signal in the two-dimensional galvanometer scanning module at each sampling moment; S6. Calculate the methane path integral concentration corresponding to each scan point based on the methane absorption characteristic signal; S7. Based on the angle information in the two-dimensional galvanometer scanning module, establish the mapping relationship between the scanning angle and the pixel position on the surface of the non-cooperative target, and map the methane path integral concentration of each scanning point to the two-dimensional image matrix. S8. Interpolate the two-dimensional image matrix to generate a two-dimensional methane concentration distribution image, mark the areas with high methane concentration distribution and determine the gas leakage area.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention combines non-cooperative target laser telemetry with two-dimensional galvanometer scanning, eliminating the need to deploy reflectors, reflective sheets, or cooperative targets in the area to be measured. It can utilize existing surfaces such as walls, floors, pipes, and equipment casings as diffuse reflection targets, making it highly adaptable to different locations.

[0017] This invention uses a two-dimensional galvanometer to control a detection laser to rapidly scan within a target area, extending traditional single-point laser methane telemetry to planar scanning detection, and is able to obtain two-dimensional spatial distribution information of methane concentration within the target area.

[0018] This invention establishes a mapping relationship between scanning angle and image pixels by synchronously recording the angle information of a two-dimensional galvanometer and the methane absorption characteristic signal, thereby realizing the image reconstruction of the methane path integral concentration. It can intuitively display the leak location, diffusion range, and high concentration area.

[0019] This invention employs tunable laser absorption spectroscopy or wavelength modulation spectroscopy technology, which can improve the sensitivity and anti-interference ability of methane detection, and is suitable for long-distance, non-contact detection scenarios.

[0020] This invention can be used in conjunction with fixed supports, inspection robots, vehicle-mounted platforms or drone platforms, and is applicable to various methane leak monitoring scenarios such as coal mine roadways, gas pipeline corridors, chemical plants, natural gas facilities, and underground spaces. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structural principle of the methane concentration laser rapid scanning device of the present invention.

[0022] Figure 2 This is a schematic diagram of the area scanning detection of the methane concentration laser rapid scanning device of the present invention when it is installed on a fixed bracket.

[0023] Figure 3 This is a schematic diagram of area scanning detection when the methane concentration laser rapid scanning device of the present invention is installed on a UAV platform.

[0024] In the diagram: 1. Laser emission module, 2. Collimating optical unit, 3. Two-dimensional galvanometer scanning module, 4. Non-cooperative target surface, 5. Methane gas region to be measured, 6. Receiving optical module, 7. Photoelectric detection module, 8. Signal conditioning and data acquisition module, 9. Synchronization control module, 10. Host computer processing module, 11. Ranging module. 31. Horizontal scanning galvanometer; 32. Vertical scanning galvanometer. Detailed Implementation

[0025] The invention will now be further described with reference to the accompanying drawings.

[0026] like Figure 1 As shown, a rapid laser scanning device for methane concentration includes: Laser emission module 1 is used to generate a tunable detection laser that matches the absorption spectrum of methane gas; Furthermore, the laser emitting module 1 includes a tunable laser, a laser driving circuit, a temperature control unit, and a collimating optical unit 2; The tunable laser is connected to the collimating optical unit 2. The laser wavelength emitted by the tunable laser is adjusted by the laser driving circuit and the temperature control unit. The output wavelength of the tunable laser matches the near-infrared absorption spectrum of methane gas, and the absorption detection sensitivity is enhanced by wavelength modulation.

[0027] The two-dimensional galvanometer scanning module 3 is set on the output light path of the laser emission module 1. It is used to change the output angle of the detection laser in both horizontal and vertical directions, so that the detection laser irradiates the non-cooperative target surface 4 in the methane gas region 5 to be tested according to the preset scanning path. Non-cooperative targets refer to natural or artificial surfaces within the test area that are not specifically equipped with reflectors, reflectors, or cooperative targets. These include walls, floors, surrounding rock of tunnels, pipe walls, equipment casings, building structures, mine structures, or other background surfaces capable of generating diffuse reflection echoes. The detection laser passes through methane gas in the test space and then illuminates the non-cooperative target surface 4, subsequently generating a diffuse reflection echo. If methane gas is present in the laser propagation path, the laser echo carries information related to the methane absorption intensity.

[0028] Furthermore, the two-dimensional galvanometer scanning module 3 includes a horizontal scanning galvanometer 31, a vertical scanning galvanometer 32, a galvanometer driving unit, and an angle feedback unit; The galvanometer driving unit controls the placement angles of the horizontal scanning galvanometer 31 and the vertical scanning galvanometer 32. The angle feedback unit is used to acquire the angle information of the horizontal scanning galvanometer 31 and the vertical scanning galvanometer 32 in real time, and send the angle information to the host computer processing module 10.

[0029] The preset scanning path is any one or more combinations of row-by-row raster scanning, column-by-column raster scanning, spiral scanning, key area encryption scanning, partition scanning, and adaptive scanning.

[0030] The receiving optical module 6 is used to receive the laser echo returned by diffuse reflection from the non-cooperative target surface 4; Furthermore, the receiving optical module 6 includes an aperture structure for sequentially receiving laser echoes, a receiving lens, and a narrowband filter; Among them, narrowband filters are used to suppress ambient stray light; The aperture structure is used to limit the receiving field of view and reduce echo interference from non-target areas.

[0031] The photoelectric detection module 7 is connected to the receiving optical module 6 and is used to convert the received laser echo into an electrical signal; The signal conditioning and data acquisition module 8 is connected to the photoelectric detection module 7 and is used to process the electrical signal and acquire the methane absorption characteristic signal. Furthermore, the signal conditioning and data acquisition module 8 includes a preamplifier circuit, a filter circuit, a lock-in amplifier or harmonic demodulation unit, and an analog-to-digital converter unit, which are used to amplify, filter, demodulate, and acquire the electrical signal in sequence to obtain the methane absorption signal.

[0032] The synchronization control module 9 is connected to the laser emission module 1, the two-dimensional galvanometer scanning module 3 and the signal conditioning and data acquisition module 8 respectively, and is used to realize the timing synchronization between the detection laser wavelength modulation, galvanometer scanning angle control and methane absorption characteristic signal acquisition. The host computer processing module 10 is connected to the signal conditioning and data acquisition module 8 and the two-dimensional galvanometer scanning module 3, respectively. It is used to calculate the methane path integral concentration at the scanning point based on the acquired methane absorption characteristic signal and the angle information of the two-dimensional galvanometer scanning module 3, and generate a two-dimensional methane concentration distribution image. Furthermore, the scanning device also includes a ranging module 11 for acquiring distance information between the scanning device and the non-cooperative target surface 4.

[0033] Furthermore, the host computer processing module 10 includes a concentration inversion unit, a scanning point positioning unit, and an image reconstruction unit; Among them, the concentration inversion unit calculates the methane path integral concentration based on the harmonic signal calculated from the laser echo signal or the methane absorption characteristic signal; The scanning point positioning unit is used to determine the scanning position of the detection laser on the target plane based on the angle information of the two-dimensional galvanometer scanning module 3; The image reconstruction unit is used to map the methane path integral concentration at each scan point to a two-dimensional pixel matrix.

[0034] Furthermore, the scanning device can be installed using any of the following methods: fixed monitoring bracket, mobile inspection platform, robot platform, vehicle-mounted platform, or drone platform, for fixed, mobile, or aerial inspection of methane concentration planar scanning imaging of the target area.

[0035] A planar imaging method based on the above-mentioned methane concentration laser rapid scanning device includes the following steps: S1. System initialization: Set the operating temperature, drive current, modulation frequency, modulation amplitude, sampling frequency, scanning range, scanning resolution, and scanning path of the scanning device. Control the laser emission module 1 to generate a tunable detection laser that matches the methane absorption spectrum and perform wavelength modulation on the detection laser. That is, the laser drive current is superimposed with a low-frequency scanning sawtooth wave and a high-frequency sinusoidal modulation signal. The laser signal is then modulated and emitted to the space to be measured. S2. The synchronous control module 9 drives the two-dimensional galvanometer scanning module 3 to control the detection laser to deflect in both the horizontal and vertical directions, so that the detection laser sequentially irradiates the non-cooperative target surface 4 in the methane gas region 5 to be tested according to the preset scanning path; the range of the region to be scanned is set to M×N pixels, where M is the number of measurement points in the horizontal direction and N is the number of measurement points in the vertical direction. The scanning path can be row-by-row grid scanning, column-by-column grid scanning, spiral scanning, key area densification scanning or adaptive scanning. S3. The detection laser passes through the gas region to be tested during propagation and irradiates the non-cooperative target surface 4. The non-cooperative target surface 4 diffusely reflects the detection laser. The receiving optical module 6 receives the laser echo returned by the diffuse reflection from the non-cooperative target surface 4 and transmits the laser echo to the photoelectric detection module 7 to convert it into an electrical signal. S4, Signal Conditioning and Data Acquisition Module 8 amplifies, filters, demodulates and acquires data from electrical signals to obtain methane absorption characteristic signals; S5. Synchronously record the horizontal and vertical angle information and methane absorption characteristic signal in the two-dimensional galvanometer scanning module 3 corresponding to each sampling moment; S6. Calculate the methane path integral concentration corresponding to each scan point based on the methane absorption characteristic signal; Specifically, the methane absorption characteristic signal is fed into a lock-in amplifier, and the first harmonic (1f) component and the second harmonic (2f) component are demodulated simultaneously. The 2f signal is baseline corrected. In the wavelength region where there is no methane absorption within the modulation period, the average value of the 2f signal is used as the baseline. The baseline is subtracted from the entire 2f waveform to obtain the corrected second harmonic signal. The methane absorption intensity is characterized by the second harmonic and the peak value of the second harmonic, and the methane path integral concentration is calculated. S7. Based on the angle information in the two-dimensional galvanometer scanning module 3, establish the mapping relationship between the scanning angle and the 4-pixel position of the non-cooperative target surface, and map the methane path integral concentration of each scanning point to the two-dimensional image matrix to obtain two-dimensional M×N concentration data points. S8. Linear or bilinear interpolation based on Delaunay triangulation is used to interpolate the two-dimensional M×N concentration data point matrix, reconstructing the sparse concentration data into a continuously distributed two-dimensional methane concentration distribution image. Then, a Gaussian smoothing filter is used for spatial filtering to suppress scanning noise and interpolation artifacts. Based on the two-dimensional methane concentration distribution image, areas with high methane concentration are marked. Finally, morphological closing operations are used to connect adjacent abnormal regions and fill holes, followed by connected component marking to determine the gas leak area.

[0036] like Figure 2 As shown, the scanning device of the present invention is installed on a fixed bracket on one side of the area to be measured, facing the pipeline valve area, the tunnel wall, the equipment area, or the gas facility area.

[0037] During operation, the host computer processing module 10 sets the scanning range and scanning resolution; the synchronous control module 9 controls the tunable laser emission module 1 to output the detection laser and makes the laser wavelength periodically scan through the methane absorption spectrum; the detection laser is shaped by the collimating optical unit 2 and then incident on the two-dimensional galvanometer scanning module 3; the two-dimensional galvanometer scanning module 3 consists of a horizontal scanning galvanometer 31 and a vertical scanning galvanometer 32, which can be set to scan once every 5°, and the detection laser forms a two-dimensional scanning grid in the area to be measured by the angle deflection in two directions.

[0038] After the detection laser passes through the space under test, it illuminates a non-cooperative target surface 4, such as a wall, floor, pipe exterior, or equipment casing. If methane gas is present in the laser propagation path, the detection laser experiences absorption attenuation near the methane absorption lines. The non-cooperative target surface 4 diffusely reflects the detection laser, and some of the diffusely reflected light returns along the receiving optical path. The receiving lens collects this diffusely reflected echo, and after suppressing ambient light with a narrow-band filter, it is focused onto the photoelectric detection module 7.

[0039] The electrical signal output by the photodetector is amplified, filtered, and demodulated using harmonics to obtain the methane absorption characteristic signal. Simultaneously, the synchronous control module 9 records the horizontal and vertical angle information from the two-dimensional galvanometer scanning module 3 while acquiring the methane absorption characteristic signal. The host computer processing module 10 calculates the methane path integral concentration corresponding to each angle position based on a pre-calibrated concentration inversion model and maps it to the corresponding pixel position on the non-cooperative target surface 4, generating a two-dimensional methane concentration distribution image.

[0040] When the methane path integral concentration in a certain region of the image exceeds a preset threshold, the host computer processing module 10 performs connected component analysis on that region to determine the center location, area, concentration peak, and diffusion direction of the abnormal region. By comparing consecutive frame images, it can also be determined whether the leak area has expanded, moved, or dissipated.

[0041] like Figure 3As shown, the scanning device of this invention is installed on a drone platform. Before the drone takes off, the operator imports a map of the target inspection area through a ground control terminal and plans the drone's three-dimensional flight path based on the terrain, facility distribution, and safety requirements. The ground control terminal sets the scanning angle range, scanning resolution, flight speed, and detection distance.

[0042] During the inspection, the drone flies along a preset route. The two-dimensional galvanometer scanning module 3 in the device controls the detection laser to perform planar scanning in the area in front of or below the flight direction. When the detection laser illuminates non-cooperative targets such as the ground, pipelines, equipment casings, or building surfaces, it generates diffuse reflection echoes. The scanning device receives the echo signals and calculates the methane path integral concentration in real time. Combining the drone's pose information, the two-dimensional galvanometer angle information, and the scanning timing information, it generates a two-dimensional image or a stitched image of the methane concentration distributed along the flight path.

[0043] When an area with abnormal methane concentration is detected, the system can send the abnormal location, concentration peak, and image results to the ground control terminal, and can control the drone to hover, return to base, or repeat the scan of the abnormal area to improve the reliability of leak location.

Claims

1. A rapid laser scanning device for methane concentration, characterized in that, include: A laser emission module (1) is used to generate a tunable detection laser that matches the absorption spectrum of methane gas; The two-dimensional galvanometer scanning module (3) is set on the output light path of the laser emission module (1) and is used to change the output angle of the detection laser in both horizontal and vertical directions so that the detection laser irradiates the non-cooperative target surface (4) in the methane gas region (5) to be tested according to the preset scanning path. A receiving optical module (6) is used to receive laser echoes returned by diffuse reflection from the surface (4) of a non-cooperative target; The photoelectric detection module (7) is connected to the receiving optical module (6) and is used to convert the received laser echo into an electrical signal; The signal conditioning and data acquisition module (8) is connected to the photoelectric detection module (7) and is used to process the electrical signal and acquire the methane absorption characteristic signal. The synchronization control module (9) is connected to the laser emission module (1), the two-dimensional galvanometer scanning module (3), and the signal conditioning and data acquisition module (8) respectively, and is used to realize the timing synchronization between the detection laser wavelength modulation, galvanometer scanning angle control and methane absorption characteristic signal acquisition; The host computer processing module (10) is connected to the signal conditioning and data acquisition module (8) and the two-dimensional galvanometer scanning module (3) respectively. It is used to calculate the methane path integral concentration at the scanning point based on the acquired methane absorption characteristic signal and the angle information of the two-dimensional galvanometer scanning module (3), and generate a two-dimensional methane concentration distribution image.

2. The methane concentration laser rapid scanning device according to claim 1, characterized in that, The preset scanning path is any one or more combinations of row-by-row raster scanning, column-by-column raster scanning, spiral scanning, key area encryption scanning, partition scanning, and adaptive scanning.

3. The methane concentration laser rapid scanning device according to claim 1, characterized in that, The scanning device also includes a ranging module (11) for acquiring distance information from the scanning device to the non-cooperative target surface (4).

4. The methane concentration laser rapid scanning device according to claim 1, characterized in that, The scanning device can be installed using any of the following methods: fixed monitoring bracket, mobile inspection platform, robot platform, vehicle-mounted platform, or drone platform. It is used to perform fixed, mobile, or aerial inspection-type planar scanning imaging of methane concentration in the target area.

5. The methane concentration laser rapid scanning device according to claim 1, characterized in that, The laser emitting module (1) includes a tunable laser, a laser driving circuit, a temperature control unit, and a collimating optical unit (2). The tunable laser is connected to the collimating optical unit (2). The laser wavelength emitted by the tunable laser is adjusted by the laser driving circuit and the temperature control unit. The output wavelength of the tunable laser matches the near-infrared absorption spectrum of methane gas.

6. The methane concentration laser rapid scanning device according to claim 1, characterized in that, The receiving optical module (6) includes an aperture structure for sequentially receiving laser echoes, a receiving lens, and a narrowband filter; Among them, narrowband filters are used to suppress ambient stray light; The aperture structure is used to limit the receiving field of view and reduce echo interference from non-target areas.

7. The methane concentration laser rapid scanning device according to claim 1, characterized in that, The signal conditioning and data acquisition module (8) includes a preamplifier circuit, a filter circuit, a lock-in amplifier or harmonic demodulation unit and an analog-to-digital converter unit, which are used to amplify, filter, demodulate and acquire electrical signals in sequence to obtain methane absorption signals.

8. The methane concentration laser rapid scanning device according to claim 1, characterized in that, The two-dimensional galvanometer scanning module (3) includes a horizontal scanning galvanometer (31), a vertical scanning galvanometer (32), a galvanometer driving unit, and an angle feedback unit; Among them, the galvanometer driving unit is connected to control the placement angle of the horizontal scanning galvanometer (31) and the vertical scanning galvanometer; The angle feedback unit is used to acquire the angle information of the horizontal scanning galvanometer (31) and the vertical scanning galvanometer in real time, and send the angle information to the host computer processing module (10).

9. A rapid laser scanning device for methane concentration according to claim 8, characterized in that, The host computer processing module (10) includes a concentration inversion unit, a scanning point positioning unit, and an image reconstruction unit; Among them, the concentration inversion unit is used to calculate the methane path integral concentration based on the harmonic signal calculated from the laser echo signal or the methane absorption characteristic signal; The scanning point positioning unit is used to determine the scanning position of the detection laser on the target plane based on the angle information of the two-dimensional galvanometer scanning module (3); The image reconstruction unit is used to map the methane path integral concentration at each scan point to a two-dimensional pixel matrix.

10. A planar imaging method based on the methane concentration laser rapid scanning device according to any one of claims 1-9, characterized in that, Includes the following steps: S1. Control the laser emission module (1) to generate a tunable detection laser that matches the methane absorption spectrum and modulate the wavelength of the detection laser; S2. The detection laser is deflected in both horizontal and vertical directions by the two-dimensional galvanometer scanning module (3), so that the detection laser sequentially irradiates the non-cooperative target surface (4) in the methane gas region (5) to be tested according to the preset scanning path. S3. Receive the laser echo returned by diffuse reflection from the non-cooperative target surface (4) and transmit the laser echo to the photoelectric detection module (7) to convert it into an electrical signal; S4. Amplify, filter, demodulate, and acquire data of the electrical signal to obtain the methane absorption characteristic signal; S5. Synchronously record the horizontal and vertical angle information and methane absorption characteristic signal in the two-dimensional galvanometer scanning module (3) corresponding to each sampling moment; S6. Calculate the methane path integral concentration corresponding to each scan point based on the methane absorption characteristic signal; S7. Based on the angle information in the two-dimensional galvanometer scanning module (3), establish the mapping relationship between the scanning angle and the pixel position of the non-cooperative target surface (4), and map the methane path integral concentration of each scanning point to the two-dimensional image matrix. S8. Interpolate the two-dimensional image matrix to generate a two-dimensional methane concentration distribution image, mark the areas with high methane concentration distribution and determine the gas leakage area.

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