A laser gas remote imaging system and detection method based on micro-mirror scanning

Abstract

The application discloses a laser gas remote imaging system and detection method based on micro-mirror scanning, which comprises a laser transceiving optical unit, a semiconductor laser and a sighting laser are combined by a combiner, and the combined laser is collimated by a collimating system and then reaches a MEMS micro-mirror; the MEMS micro-mirror deflects the laser beam to a target detection area by a corresponding angle; a photodetector array is used for receiving a back light signal of the detection laser; a signal processing and control unit calculates concentration information of a target gas in the target detection area according to the back light signal after photoelectric conversion; a visual imaging unit is used for shooting a visual image of the detection area; an information fusion unit is used for fusing the calculated gas concentration of the target detection area into the visual image, and sending the fused visual image to a signal output display unit for visual display of the gas concentration.

Description

Technical Field

[0001] This invention belongs to the field of laser gas telemetry technology, and particularly relates to a laser gas telemetry imaging system and detection method based on micro-mirror scanning. Background Technology

[0002] Currently, laser gas telemetry based on Tunable Laser Absorption Spectroscopy (TDLAS) is one of the main methods for detecting hazardous gas leaks. However, traditional laser telemetry instruments have small emitted laser spots, meaning they can only detect gas leaks along the path of the scanned spot. This makes aiming difficult, prone to missed detections, and fails to meet the early warning requirements for safe production. Furthermore, laser gas detection can only reflect the magnitude of the gas leak and cannot visualize the gas cloud.

[0003] In existing technologies, some methods enlarge the detection spot of the emitted laser, while others collimate the point spot of the emitted laser into a linear spot using an optical system. While these modifications make the laser telemetry system easier to aim and reduce missed detections, they also shorten the detection distance and decrease sensitivity due to the dispersion of the emitted laser energy. Other methods use a pan-tilt unit to scan the laser telemetry system, which offers a large detection range and long detection distance, but the pan-tilt unit's belt has a limited lifespan, requiring frequent replacement and resulting in high maintenance costs. Still others employ a dual-mechanical galvanometer laser scanning system, using mechanical galvanometers to perform a comprehensive scan of the detection area. While this solves the problem of expanding the detection range, the use of mechanical galvanometers makes the system not only structurally complex and large, but also difficult to integrate, and results in low control accuracy and poor synchronization.

[0004] Therefore, there is an urgent need for a laser gas telemetry imaging system that integrates a wide detection range and a long detection distance to make up for the deficiencies of existing detection methods and technologies. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention proposes a laser gas telemetry imaging system and detection method based on micro-mirror scanning.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] In a first aspect, the present invention provides a laser gas telemetry imaging system based on micro-mirror scanning, comprising:

[0008] The system includes a laser transceiver optical unit, a signal processing and control unit, a visualization and imaging unit, an information fusion unit, a signal output and display unit, and a power supply unit for providing power to each unit.

[0009] The laser transceiver optical unit includes a semiconductor laser, a targeting laser, a beam combiner, a collimation system, a MEMS micro mirror, a receiving lens, and a photodetector array. The detection laser emitted by the semiconductor laser and the targeting laser emitted by the targeting laser are combined by the beam combiner and then collimated by the collimation system onto the MEMS micro mirror.

[0010] The MEMS micromirror has two axes, X and Y, with two electrodes on each axis. The MEMS micromirror is connected to the signal processing and control unit and the power supply unit, respectively. The signal processing and control unit controls the power supply unit to provide the MEMS micromirror with the voltage corresponding to the required deflection angle, so as to control the MEMS micromirror to reflect the laser beam to the target detection area.

[0011] The photodetector array is used to receive the return light signal of the detection laser that passes through the target detection area, is absorbed by the target gas, is reflected back by the background reflector, and is focused by the receiving lens. After photoelectric conversion, the signal is transmitted to the signal processing and control unit.

[0012] The signal processing and control unit calculates the concentration information of the target gas in the target detection area based on the backlight signal after photoelectric conversion;

[0013] The visualization imaging unit is used to capture a visualization image of the detection area;

[0014] The information fusion unit is connected to the signal processing and control unit, the visualization imaging unit, and the signal output display unit. It is used to fuse the calculated gas concentration of the target detection area into the visualization image and send the fused visualization image to the signal output display unit for gas concentration visualization display.

[0015] Secondly, the present invention provides a detection method based on the aforementioned laser gas telemetry imaging system based on micro-mirror scanning, comprising the following steps:

[0016] (1) The signal processing and control unit controls the semiconductor laser and the aiming laser to emit light, and controls the visualization imaging unit to start capturing a visualization image;

[0017] (2) The signal processing and control unit controls the power supply unit to provide corresponding voltage values ​​to the four electrodes X1, X2, Y1 and Y2 of the X and Y axes of the MEMS micro mirror, so that it scans the target detection area in a quasi-static mode or a uniform speed scanning mode according to a pre-set path.

[0018] (3) The signal processing and control unit synchronously starts the corresponding dot matrix acquisition of the light signal in the photodetector array according to the voltage values ​​of the four electrodes of the MEMS micro mirror. The signal after photoelectric conversion is transmitted to the signal processing and control unit for calculation and processing to obtain the gas concentration value. The scanning angle of the MEMS micro mirror is synchronized with the acquisition of the corresponding photodetector array.

[0019] (4) When the calculated gas concentration value is greater than the preset alarm threshold, the signal processing and control unit adjusts the voltage values ​​of the four electrodes X1, X2, Y1 and Y2 of the MEMS micro mirror on the X and Y axes, so that the MEMS micro mirror performs a re-inspection near the alarm position according to the preset re-inspection number and re-inspection path to confirm whether the alarm is a real leak alarm.

[0020] (5) When a real leak alarm is confirmed, the signal processing and control unit sends the gas concentration to the information fusion unit; the information fusion unit draws the corresponding area of ​​the visualization image into images of different colors or different gray levels according to the gas concentration, so as to intuitively present the shape and size of the leaking gas cloud; the information fusion unit sends the drawn image to the signal output display unit for alarm and display;

[0021] (6) After the prescribed re-inspection is completed, the signal processing and control unit controls the MEMS micro-mirror to continue scanning along the original path;

[0022] (7) If the alarm is confirmed to be false, the signal processing and control unit discards the alarm and controls the micromirror to continue scanning along the original path.

[0023] (8) When the system is powered off, the signal processing and control unit controls the power supply of the laser and the MEMS micro mirror to be turned off, so that the laser is powered off and the position of the MEMS micro mirror returns to zero, and then the power supply of other parts of the system is turned off.

[0024] Based on the above, before performing detection, the laser gas telemetry imaging system based on micro-mirror scanning also calibrates the image of the visualization imaging unit, the scanning angle of the MEMS micro-mirror, and the photodetector array:

[0025] The visualization imaging unit divides the visualization image into multiple detection areas according to the scanning angle of the MEMS micro-mirror and the photodetector array;

[0026] The signal processing and control unit controls the semiconductor laser and the aiming laser to emit light, and simultaneously controls the MEMS micro-mirror to scan, recording and storing the correspondence between the voltages of the four electrodes X1, X2, Y1 and Y2 of the MEMS micro-mirror on the X and Y axes and the corresponding areas of the photodetector array and the visualization image.

[0027] Based on the above, the MEMS micro-mirror is placed at the center of the receiving lens, and a hole is drilled at the center of the receiving lens;

[0028] A reflector is provided between the collimation system and the MEMS micro-mirror;

[0029] The detection laser emitted by the semiconductor laser and the aiming laser emitted by the aiming laser are combined by the beam combiner, then collimated by the collimation system and emitted by the reflector, and finally onto the MEMS micro-mirror. The MEMS micro-mirror reflects the combined laser beam from the center of the aperture of the receiving lens to the target detection area.

[0030] Based on the above, the MEMS micro-mirror is placed at the edge of the receiving lens to reflect the laser beam to the target detection area.

[0031] Based on the above, the scan path is set as follows:

[0032] According to the detection area divided by the visualization imaging unit, the circular spot of the detection laser scans continuously from the initial position along the positive X-axis direction - negative Y-axis direction - negative X-axis direction - positive Y-axis direction, from the outer layer to the center, point by point, to the center of the visualization imaging unit, and then scans from the center of the visualization imaging unit along the opposite path to the initial position of the set scanning path.

[0033] When scanning according to the set scanning path, the method for controlling the voltage of the four electrodes of the MEMS micro-mirror includes:

[0034] Achieve X-axis scanning:

[0035] The signal processing and control unit controls the power supply unit to fix the voltage values ​​of the two electrodes Y1 and Y2 of the MEMS micro mirror Y-axis, and provides corresponding voltage values ​​to the two electrodes X1 and X2 of the MEMS micro mirror X-axis.

[0036] To achieve Y-axis scanning:

[0037] The signal processing and control unit controls the power supply unit to fix the voltage values ​​of the two electrodes X1 and X2 on the X-axis of the MEMS micro mirror, and provides corresponding voltage values ​​to the two electrodes Y1 and Y2 on the Y-axis of the MEMS micro mirror.

[0038] Based on the above, the scan path is set as follows:

[0039] According to the detection area divided by the visualization imaging unit, the circular spot of the detection laser scans from the initial position along the Y direction from top to bottom to the bottom of the Y direction, then moves to the right once along the X direction, then scans from bottom to top along the Y direction to the top of the Y direction, then moves to the right once along the X direction, and so on, until the last detection area of ​​the visualization imaging unit, and then returns to the initial position of the scanning path along the opposite path.

[0040] When scanning according to the set scanning path, the method for controlling the voltage of the four electrodes of the MEMS micro-mirror includes:

[0041] Achieve X-axis scanning:

[0042] The signal processing and control unit controls the power supply unit to fix the voltage values ​​of the two electrodes Y1 and Y2 of the MEMS micro mirror Y-axis, and provides corresponding voltage values ​​to the two electrodes X1 and X2 of the MEMS micro mirror X-axis.

[0043] To achieve Y-axis scanning:

[0044] The signal processing and control unit controls the power supply unit to fix the voltage values ​​of the two electrodes X1 and X2 on the X-axis of the MEMS micro mirror, and provides corresponding voltage values ​​to the two electrodes Y1 and Y2 on the Y-axis of the MEMS micro mirror.

[0045] Based on the above, the mirror size of the MEMS micro-mirror is φ1~φ10mm, and the deflection angle is ±1°~±10°;

[0046] The photodetector array is a 10×10 photodetector array.

[0047] Based on the above, the laser gas telemetry imaging system based on micro-mirror scanning also includes a positioning unit for acquiring the location information of the detection device and a target recognition module for identifying the target detection area.

[0048] The positioning unit determines whether it has entered the detection area based on the obtained detection device location information. If it has entered the detection area, the target recognition module is activated to identify the target detection area and obtain the azimuth information of the target to be detected in the target detection area.

[0049] This invention has outstanding substantive features and significant progress compared to the prior art, specifically:

[0050] 1. This invention integrates GPS positioning technology, image classification technology, micromirror scanning technology, tunable laser absorption spectroscopy (TDLAS) technology, and imaging technology to propose a laser gas telemetry imaging system based on micromirror scanning. It also proposes an optical path system and detection control method based on micromirror, which solves the problem that existing detection systems cannot simultaneously meet the monitoring and early warning requirements of wide detection range, long detection distance, high sensitivity, and visualization.

[0051] 2. The laser gas telemetry system provided by this invention achieves real-time monitoring over a large detection range by adjusting the deflection angles of the micromirror in the X and Y axes. It features a wide detection range, long detection distance, high sensitivity, and long lifespan, making it particularly suitable for installation in natural gas transmission and distribution stations for dynamic 24-hour real-time monitoring, reducing labor costs, increasing detection frequency, and improving safety. Furthermore, combined with a visualization imaging system, it can intuitively display the concentration and image of gas masses.

[0052] 3. This invention can achieve line scanning laser telemetry by adjusting the X-axis deflection and fixing the Y-axis direction. It can be used in conjunction with drones, cars, electric vehicles, etc. to achieve laser gas inspection, and conduct long-distance, large-area telemetry inspection of transmission and distribution pipelines and emergency rescue, effectively detect toxic and harmful gas leaks, and ensure the safety of inspection personnel.

[0053] 4. This invention uses piezoelectric or electrostatic MEMS micromirrors, which are small in size and can be integrated into the optical path system. The optical path structure is simple, does not block effective light, and has a long detection distance. The scanning of the micromirror is controlled by controlling the voltage of the electrodes of the micromirror. The two-dimensional adjustment has high synchronization, high control accuracy, and the control system is simple. The micromirror can realize quasi-static scanning mode and uniform speed scanning mode, which can be adapted to different application occasions.

[0054] 5. This invention can measure different gases, such as ethane and acetylene, by changing the laser with different center wavelengths. Attached Figure Description

[0055] To more clearly illustrate the technical solutions in the embodiments or related technologies of this application, the accompanying drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0056] Figure 1 This is a structural block diagram of the system of the present invention.

[0057] Figure 2This is a schematic diagram of the optical path between the photodetector array and the visualization imaging unit in this invention.

[0058] Figure 3 This is a 10*10 array diagram of the photodetector array and a 10*10 array partitioning diagram of the visualization imaging unit in this invention.

[0059] Figure 4 This is a 5x5 array diagram of the photodetector array and a 10x10 array partition diagram of the visualization imaging unit in this invention.

[0060] Figure 5 This is a schematic diagram of the scanning optical path of the micro-mirror in Example 3.

[0061] Figure 6 This is a schematic diagram of the scanning optical path of the micro-mirror in Example 4.

[0062] Figure 7 This is the surface scanning route diagram in Example 5.

[0063] Figure 8 This is the surface scanning route diagram in Example 6.

[0064] Figure 9 This is the line scan route diagram in Example 7.

[0065] Figure 10 This is the inspection scanning route map in Example 7. Detailed Implementation

[0066] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0067] Example 1

[0068] This embodiment provides a laser gas telemetry imaging system based on micro-mirror scanning, such as... Figure 1 As shown, it includes:

[0069] The system includes a laser transceiver optical unit, a signal processing and control unit, a visualization and imaging unit, an information fusion unit, a signal output and display unit, and a power supply unit for providing power to each unit.

[0070] The laser transceiver optical unit includes a semiconductor laser, a targeting laser, a beam combiner, a collimation system, a MEMS micro mirror, a receiving lens, and a photodetector array. The detection laser emitted by the semiconductor laser and the targeting laser emitted by the targeting laser are combined by the beam combiner and then collimated by the collimation system onto the MEMS micro mirror.

[0071] The MEMS micromirror is a micromirror that uses the piezoelectric or electrostatic effect principle and has two axes, X and Y, with two electrodes on each axis. The MEMS micromirror is connected to the signal processing and control unit and the power supply unit respectively. The signal processing and control unit controls the power supply unit to provide the MEMS micromirror with the voltage corresponding to the required deflection angle, so as to control the MEMS micromirror to reflect the laser beam to the target detection area.

[0072] The photodetector array is used to receive the return light signal of the detection laser that passes through the target detection area, is absorbed by the target gas, is reflected back by the background reflector, and is focused by the receiving lens. After photoelectric conversion, the signal is transmitted to the signal processing and control unit.

[0073] The signal processing and control unit calculates the concentration information of the target gas in the target detection area based on the backlight signal after photoelectric conversion;

[0074] The visualization imaging unit is used to capture a visualization image of the detection area;

[0075] The information fusion unit is connected to the signal processing and control unit, the visualization imaging unit, and the signal output display unit. It is used to fuse the calculated gas concentration of the target detection area into the visualization image and send the fused visualization image to the signal output display unit for gas concentration visualization display.

[0076] Example 2

[0077] This embodiment provides a detection method for the laser gas telemetry imaging system based on micro-mirror scanning as described in Embodiment 1, including the following steps:

[0078] (1) Before detection, the image of the visualization imaging unit, the scanning angle of the MEMS micro-mirror, and the photodetector array are calibrated:

[0079] The visualization imaging unit divides the visualization image into multiple detection areas according to the scanning angle of the MEMS micro-mirror and the photodetector array;

[0080] The signal processing and control unit controls the semiconductor laser and the aiming laser to emit light, and simultaneously controls the MEMS micro-mirror to scan, recording and storing the correspondence between the voltages of the four electrodes X1, X2, Y1 and Y2 of the MEMS micro-mirror on the X and Y axes and the corresponding areas of the photodetector array and the visualization image.

[0081] (2) The signal processing and control unit controls the semiconductor laser and the aiming laser to emit light, and controls the visualization imaging unit to start capturing visualization images.

[0082] (3) The signal processing and control unit controls the power supply unit to provide corresponding voltage values ​​to the four electrodes X1, X2, Y1 and Y2 of the X and Y axes of the MEMS micro mirror, so that it scans the target detection area in a quasi-static mode or a uniform speed scanning mode according to a pre-set path.

[0083] (4) The signal processing and control unit synchronously starts the corresponding dot matrix acquisition and reception of the optical signal in the photodetector array according to the voltage values ​​of the four electrodes of the MEMS micro mirror. The signal after photoelectric conversion is transmitted to the signal processing and control unit for calculation and processing to obtain the gas concentration value. The scanning angle of the MEMS micro mirror is synchronized with the acquisition of the corresponding photodetector array.

[0084] Figure 2 A schematic diagram of the optical path between the photodetector array and the visualization imaging unit is shown. Figure 3 The diagram shows a 10x10 array of the photodetector array and a 10x10 array partitioning diagram of the visualization imaging unit. Figure 4 The diagram shows a 5x5 array of the photodetector array and a 10x10 array of the visualization imaging unit. In step (4), if the visualization imaging unit is a 10x10 array and the photodetector array is also a 10x10 array, then according to... Figures 2-4 It can be seen that when visual imaging unit 1 is detected, the photodetector array is the 100th photodetector that can receive the signal; when visual imaging unit 2 is detected, the photodetector array is the 99th photodetector that can receive the signal; and when visual imaging unit 100 is detected, the photodetector array is the 1st photodetector that can receive the signal.

[0085] If the visualization imaging unit is a 10*10 array and the photodetector array is a 5*5 array, then according to Figures 2-4 It can be seen that when visual imaging units 1, 2, 11, and 12 are detected, the photodetector array is the 25th photodetector that can receive signals; when visual imaging units 3, 4, 13, and 14 are detected, the photodetector array is the 24th photodetector that can receive signals; and when visual imaging units 89, 90, 99, and 100 are detected, the photodetector array is the 1st photodetector that can receive signals.

[0086] (5) When the calculated gas concentration value is greater than the preset alarm threshold, the signal processing and control unit adjusts the voltage values ​​of the four electrodes X1, X2, Y1 and Y2 of the MEMS micro mirror on the X and Y axes, so that the MEMS micro mirror performs a re-inspection near the alarm position according to the preset re-inspection number and re-inspection path, to confirm whether the alarm is a real leak alarm.

[0087] (6) When a genuine leak alarm is confirmed, the signal processing and control unit sends the gas concentration to the information fusion unit; the information fusion unit renders the corresponding area of ​​the visualization image as an image of different colors or different gray levels according to the gas concentration, thereby intuitively presenting the shape and size of the leaking gas cloud; the information fusion unit sends the rendered image to the signal output display unit for alarm and display. Furthermore, the gas concentration information can also be transmitted to other devices.

[0088] (7) After the prescribed re-inspection is completed, the signal processing and control unit controls the micromirror to continue scanning along the original path.

[0089] (8) If the alarm is confirmed to be false, the signal processing and control unit discards the alarm and controls the micromirror to continue scanning along the original path.

[0090] (9) When the system is powered off, the signal processing and control unit controls the power supply of the laser and the MEMS micro mirror to be turned off, so that the laser is powered off and the position of the MEMS micro mirror returns to zero, and then the power supply of other parts of the system is turned off.

[0091] In this embodiment, the semiconductor laser is a mainstream semiconductor laser. The photodetector array is a detector array that responds to the detection laser. The receiving lens is coated with an anti-reflection film for the measurement band to improve transmittance and increase the measurement distance. The secondary focusing system includes a secondary focusing lens and a filter. The secondary focusing lens is used to refocus the light gathered by the receiving lens for easier reception by the photodetector array. The filter is a narrowband interference filter that is transparent to the measurement band. The aiming laser is a visible light laser, which, after being combined with the detection laser by a beam combiner, is collimated by the collimating system onto the MEMS micromirror, and then reflected by the MEMS micromirror to the detection area to indicate the detection position of the detection laser.

[0092] The laser control unit connects the signal processing and control unit, the semiconductor laser, and the aiming laser. The laser control unit includes a current drive unit and a temperature control unit. After determining the laser's drive current, it adjusts the temperature of the internal TEC (thermal control unit) of the laser in real time to ensure that the laser's output wavelength is always locked at the absorption peak of the target gas. The laser drive signal output from the signal processing and control unit adjusts the laser. After being converted from a digital to a digital output (DA) signal, the drive signal is transmitted to the laser control unit to drive the semiconductor laser to emit light. Simultaneously, the temperature control unit in the laser control unit adjusts the TEC of the semiconductor laser in real time to keep the laser's output wavelength stable at the gas absorption peak.

[0093] The signal processing and control unit is connected to the MEMS micromirror, laser control unit, photodetector array, signal output unit, and power supply unit. The MEMS micromirror is connected to the power supply unit; the signal processing and control unit controls the power supply unit to provide the corresponding voltage value to the MEMS micromirror, thereby controlling the deflection angle of the MEMS micromirror and ensuring the detection laser scans along a preset path. Based on the voltage values ​​of the four electrodes of the MEMS micromirror, the signal processing and control unit initiates signal acquisition and processing at a specific point in the photodetector array. The scanning angle of the MEMS micromirror is synchronized with the acquisition by the corresponding photodetector array.

[0094] When a target gas leak is detected in the detection area, the detection laser passes through the target gas, is reflected by the background reflectors, and the reflected light signal, absorbed by the target gas, is received by a photodetector array. After photoelectric conversion, it is transmitted to the signal processing and control unit. This signal is amplified and filtered, and the first harmonic f and second harmonic 2f are demodulated to calculate the concentration of the target gas. When the concentration exceeds a set alarm threshold, the signal processing and control unit adjusts the voltage values ​​of the four electrodes X1, X2, Y1, and Y2 on the X and Y axes of the MEMS micromirror. This causes the MEMS micromirror to re-examine the vicinity of the alarm location according to a pre-set number of re-examinations and a re-examination path, determining whether the alarm is a genuine leak alarm. The number of re-examinations and the re-examination path are pre-set in the signal processing and control unit. Specifically, the number of re-examinations can be 2 or N, and the re-examination path is a 3*3 or 4*4 area scan near the alarm point.

[0095] When there are few photodetector arrays, each array can be acquired simultaneously without time-division acquisition. Starting the acquisition of a specific point in the photodetector array based on the scanning angle of the MEMS micromirror is to reduce system computing resources, which is particularly suitable for situations with a large number of photodetector arrays.

[0096] Once a leak is confirmed, the signal processing and control unit sends the gas concentration data to the information fusion unit. The information fusion unit then fuses the gas concentration data with the visualized image, processes the image, and renders the corresponding area of ​​the image as a different color (color) or different grayscale image based on the gas concentration, thus visually presenting the shape and size of the leaking gas cloud.

[0097] If a false alarm is detected, the concentration is discarded, and the signal processing system controls the deflection angle of the micromirror so that the detection laser continues to scan along the original path.

[0098] Preferably, in order to improve detection efficiency, the laser gas telemetry imaging system based on micro-mirror scanning further includes a target recognition module for identifying the target detection area;

[0099] Based on the target recognition results of the target recognition module on the visualized image, a target detection area can be set, thereby pre-limiting the scanning path. By identifying gas storage equipment such as gas pipelines as key target detection areas, the system focuses on scanning pipeline areas where gas leaks may occur. Gas pipeline identification methods include, but are not limited to, image classification methods such as target recognition and target segmentation. The information fusion unit sends the location information of the key target detection area to the signal processing and control unit. The signal processing and control unit controls the voltage of the MEMS micromirror, causing the semiconductor laser to illuminate the corresponding position in the key target detection area for detection, thus improving detection efficiency.

[0100] Preferably, the laser gas telemetry imaging system based on micro-mirror scanning further includes a positioning unit for acquiring the location information of the detection device; the positioning unit confirms whether it has entered the detection area based on the acquired location information of the detection device; if it has entered the detection area, the target recognition module is activated to identify the target detection area and acquire the azimuth information of the target to be detected in the target detection area.

[0101] Example 3

[0102] For large-scale methane gas leak monitoring, a DFB laser with a center wavelength of 1653.7nm or a quantum cascade laser with a center wavelength of 3260.2nm is selected as the light source. The photodetector array is either an InGaAs detector array or a mercury cadmium telluride detector array. For area scanning, an area array detector is used; for linear scanning, a linear array detector is used. The receiving lens is an aspherical lens coated with an anti-reflection film around 1653.7nm or 3260.2nm. The anti-reflection film improves the transmittance of the receiving lens to the measurement laser, increasing the telemetry distance. The filter is a narrowband interference filter around 1653.7nm or 3260.2nm. The aiming laser is a 532nm green laser. The detection laser and the aiming laser are combined by a beam combiner, collimated by a laser collimation system, and then projected onto a reflector. The reflector then projects the laser onto a micromirror, which reflects the light and projects it into the monitoring area. After the detection laser passes through the target gas, it is reflected by the background reflectors. The photodetector or photodetector array receives the reflected light signal after it is absorbed by the target gas. After photoelectric conversion, it is transmitted to the signal processing and control unit, which amplifies and filters the signal to calculate the concentration information of the target gas in the target area.

[0103] Preferably, the MEMS micro-mirror is a piezoelectric or electrostatic MEMS micro-mirror with a mirror size of φ1~φ10mm, a deflection angle of ±1°~±10°, and a gold-plated film on the mirror, achieving a reflectivity of over 90% for lasers in the 1653.7nm or 3260.2nm bands.

[0104] The signal processing and control unit controls the power supply unit to provide the voltage corresponding to the required deflection angle to the MEMS micromirror, controlling the laser beam to detect different positions. For example, if a detection distance of 100 meters is required, and the detection range is an area 10 meters long and 10 meters wide, the deflection angle range of the MEMS micromirror is approximately ±1.35°. The detection spot output by the collimator is a circular spot with a diameter of 100 cm at 100 meters, so the MEMS micromirror deflects by approximately 0.3° each time.

[0105] A 10×10 array of photodetectors was selected.

[0106] An optical path system for MEMS micromirror scanning:

[0107] like Figure 5 As shown, the MEMS micro-mirror is placed at the center of the receiving lens, and a hole is drilled at the center of the receiving lens;

[0108] A reflector is provided between the collimation system and the MEMS micro-mirror. The detection laser emitted by the semiconductor laser and the aiming laser emitted by the aiming laser are combined by the beam combiner and then collimated by the collimation system and emitted by the reflector in sequence to the MEMS micro-mirror. The MEMS micro-mirror reflects the combined laser beam from the center of the aperture of the receiving lens to the target detection area.

[0109] When the MEMS micromirror is at zero position, the laser emission direction is the optical axis direction of the receiving lens.

[0110] In this embodiment, the MEMS micro-mirror is placed at the center of the receiving lens, and the laser beam can be emitted from the center of the receiving lens. It has a compact structure, high sensitivity, and long detection distance.

[0111] Example 4

[0112] For large-scale methane gas leak monitoring, a DFB laser with a center wavelength of 1653.7nm or a quantum cascade laser with a center wavelength of 3260.2nm is selected as the light source. The photodetector array is either an InGaAs detector array or a mercury cadmium telluride detector array. For area scanning, an area array detector is used; for linear scanning, a linear array detector is used. The receiving lens is an aspherical lens coated with an anti-reflection film near 1653.7nm or 3260.2nm. The anti-reflection film improves the transmittance of the receiving lens to the measurement laser, increasing the telemetry distance. The filter is a narrowband interference filter near 1653.7nm or 3260.2nm. The aiming laser is a 532nm green laser. The detection laser and the aiming laser are combined by a beam combiner, collimated by a laser collimation system, and then projected onto a micromirror. After reflection by the micromirror, the light is projected onto the monitoring area. After the detection laser passes through the target gas, it is reflected by the background reflectors. The photodetector or photodetector array receives the reflected light signal after it is absorbed by the target gas. After photoelectric conversion, it is transmitted to the signal processing and control unit, which amplifies and filters the signal to calculate the concentration information of the target gas in the target area.

[0113] Preferably, the MEMS micromirror is a piezoelectric or electrostatic MEMS micromirror with a mirror size of φ1~φ10mm and a deflection angle of ±1°~±10°.

[0114] The signal processing and control unit controls the power supply unit to provide the voltage corresponding to the required deflection angle to the MEMS micromirror, controlling the laser beam to detect different positions. For example, if a detection distance of 100 meters is required, and the detection range is an area 10 meters long and 10 meters wide, the deflection angle range of the MEMS micromirror is approximately ±1.35°. The detection spot output by the collimator is a circular spot with a diameter of 100 cm at 100 meters, so the MEMS micromirror deflects by approximately 0.3° each time.

[0115] A 10×10 array of photodetectors was selected.

[0116] An optical path system for MEMS micromirror scanning:

[0117] like Figure 6 As shown, no reflector is placed between the collimation system and the MEMS micromirror. The MEMS micromirror is placed at the edge of the receiving lens, and no hole is needed in the center of the receiving lens. The zero point of the MEMS micromirror is a horizontal position rotated counterclockwise by 45°. The laser collimation system illuminates the surface of the micromirror vertically upwards with a laser beam. When the MEMS micromirror is at its zero point, the laser emission direction is along the optical axis of the receiving lens. In this embodiment, the MEMS micromirror is placed at the edge of the receiving lens, no hole is needed in the center of the receiving lens, and a reflector is eliminated, resulting in a simple structure and flexible design.

[0118] Example 5

[0119] Based on the laser gas telemetry imaging system based on micro-mirror scanning described in Embodiments 3 and 4, this embodiment provides an implementation scheme for a set scanning path of the detection method of the present invention.

[0120] like Figure 7 As shown, the scan path is set as follows:

[0121] According to the detection area divided by the visualization imaging unit, the circular spot of the detection laser scans continuously from the initial position along the positive X-axis direction - negative Y-axis direction - negative X-axis direction - positive Y-axis direction, from the outer layer to the center, point by point, to the center of the visualization imaging unit, and then scans from the center of the visualization imaging unit along the opposite path to the initial position of the set scanning path.

[0122] When scanning according to the set scanning path, the method for controlling the voltage of the four electrodes of the MEMS micro-mirror includes:

[0123] Achieve X-axis scanning:

[0124] The signal processing and control unit controls the power supply unit to fix the voltage values ​​of the two electrodes Y1 and Y2 of the MEMS micro mirror Y-axis, and provides corresponding voltage values ​​to the two electrodes X1 and X2 of the MEMS micro mirror X-axis.

[0125] To achieve Y-axis scanning:

[0126] The signal processing and control unit controls the power supply unit to fix the voltage values ​​of the two electrodes X1 and X2 on the X-axis of the MEMS micro mirror, and provides corresponding voltage values ​​to the two electrodes Y1 and Y2 on the Y-axis of the MEMS micro mirror.

[0127] Specifically, such as Figure 3 or Figure 4 As shown, the visualization imaging unit is divided into 10×10 (numbers 1-100) detection areas, forming 5 layers of detection areas. The small circles represent the circular spots of the detection laser. The method for controlling the MEMS micromirror to achieve a scanning path along the positive X-axis direction - negative Y-axis direction - negative X-axis direction - positive Y-axis direction is as follows:

[0128] 1) The signal processing and control unit controls the power supply unit to fix the voltage values ​​of the two electrodes Y1 and Y2 of the MEMS micro mirror Y-axis, and provides corresponding voltage values ​​to the two electrodes X1 and X2 of the MEMS micro mirror X-axis, scanning along the positive X-axis direction to reach the last detection area in the positive X-axis direction of the detection area of ​​the layer.

[0129] 2) The signal processing and control unit controls the power supply unit to fix the voltage values ​​of the two electrodes X1 and X2 of the MEMS micro mirror X-axis, and provides corresponding voltage values ​​to the two electrodes Y1 and Y2 of the MEMS micro mirror Y-axis, and scans the last detection area in the reverse Y-axis direction of the detection area of ​​the layer to the detection area of ​​the layer.

[0130] 3) The signal processing and control unit controls the power supply unit to fix the voltage values ​​of the two electrodes Y1 and Y2 of the MEMS micro mirror Y-axis, and provides corresponding voltage values ​​to the two electrodes X1 and X2 of the MEMS micro mirror X-axis, scanning along the reverse X-axis direction to reach the last detection area in the reverse X-axis direction of the detection area of ​​the layer.

[0131] 4) The signal processing and control unit controls the power supply unit to fix the voltage values ​​of the two electrodes X1 and X2 of the MEMS micro mirror X-axis, and provides corresponding voltage values ​​to the two electrodes Y1 and Y2 of the MEMS micro mirror Y-axis, and scans the second to last detection area in the positive Y-axis direction of the detection area of ​​the layer.

[0132] Example 6

[0133] Based on the laser gas telemetry imaging system based on micro-mirror scanning described in Embodiments 3 and 4, this embodiment provides another implementation scheme for the set scanning path of the detection method of the present invention.

[0134] like Figure 8 As shown, the scan path is set as follows:

[0135] According to the detection area divided by the visualization imaging unit, the circular spot of the detection laser scans from the initial position along the Y direction from top to bottom to the bottom of the Y direction, then moves to the right once along the X direction, then scans from bottom to top along the Y direction to the top of the Y direction, then moves to the right once along the X direction, and so on, until the last detection area of ​​the visualization imaging unit, and then returns to the initial position of the scanning path along the opposite path.

[0136] When scanning according to the set scanning path, the method for controlling the voltage of the four electrodes of the MEMS micro-mirror includes:

[0137] Achieve X-axis scanning:

[0138] The signal processing and control unit controls the power supply unit to fix the voltage values ​​of the two electrodes Y1 and Y2 of the MEMS micro mirror Y-axis, and provides corresponding voltage values ​​to the two electrodes X1 and X2 of the MEMS micro mirror X-axis.

[0139] To achieve Y-axis scanning:

[0140] The signal processing and control unit controls the power supply unit to fix the voltage values ​​of the two electrodes X1 and X2 on the X-axis of the MEMS micro mirror, and provides corresponding voltage values ​​to the two electrodes Y1 and Y2 on the Y-axis of the MEMS micro mirror.

[0141] Specifically, such as Figure 3 or Figure 4 As shown, the visualization imaging unit is divided into 10×10 (number 1-100) detection areas, and the small circles represent the circular spots of the detection laser.

[0142] When scanning according to the scanning path set in this embodiment, the control steps for the voltage of the four electrodes of the MEMS micro-mirror are as follows:

[0143] 1) The signal processing and control unit controls the power supply unit to provide corresponding voltage values ​​to the two electrodes Y1 and Y2 of the MEMS micro mirror on the Y axis, and fixes the voltage values ​​of the two electrodes X1 and X2 on the X axis. First, the Y axis direction is scanned, and after reaching the last detection area in the current Y axis direction, the voltages Y1 and Y2 are fixed.

[0144] 2) The signal processing and control unit controls the power supply unit to provide corresponding voltage values ​​to the two electrodes X1 and X2 of the MEMS micro mirror along the X-axis, so that after moving once in the X-axis direction, the voltages of X1 and X2 are fixed.

[0145] 3) Repeat steps 1) and 2) in a loop until the last detection area of ​​the visualization imaging unit is scanned;

[0146] 4) Then, from the last detection area of ​​the visualization imaging unit, scan along the opposite path in the manner of 1), 2), 3) to the initial position of the set scanning path.

[0147] Example 7

[0148] For long-distance pipeline inspection, the MEMS micromirror can be configured for linear scanning, enabling large-area inspections by leveraging the linear movement of drones, cars, or electric vehicles. The scanning path diagram is shown below. Figure 9 As shown, from left to right, then from right to left. The diagram illustrates the vehicle-mounted inspection process. Figure 10 As shown, a line-scanning spot covers the pipeline, and the pipeline is scanned by the linear movement of the car.

[0149] The scan path is set as follows:

[0150] According to the detection area divided by the visualization imaging unit, the circular spot of the detection laser moves from the initial position along the X direction, first from left to right, and then from right to left back to the initial position;

[0151] The control steps for the four electrode voltages of the MEMS micromirror during scanning according to the set scanning path are as follows:

[0152] 1) The signal processing and control unit controls the power supply unit to provide corresponding voltage values ​​to the two electrodes X1 and X2 of the MEMS micro mirror on the X-axis, and fixes the voltage of the two electrodes Y1 and Y2 on the Y-axis to achieve scanning in the X-axis direction. After reaching the edge of the detection area in the X-axis direction, it returns to the initial position of the X-axis in the opposite direction.

[0153] 2) Repeat in sequence.

[0154] The scanning path in this embodiment is based on the linear motion of a motor vehicle or electric vehicle, and a large-area long pipeline scanning is achieved through the principle of linear motion forming a surface.

[0155] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A laser gas telemetry imaging system based on micro-mirror scanning, characterized in that, include: The system includes a laser transceiver optical unit, a signal processing and control unit, a visualization and imaging unit, an information fusion unit, a signal output and display unit, and a power supply unit for providing power to each unit. The laser transceiver optical unit includes a semiconductor laser, a targeting laser, a beam combiner, a collimation system, a MEMS micro mirror, a receiving lens, and a photodetector array. The detection laser emitted by the semiconductor laser and the targeting laser emitted by the targeting laser are combined by the beam combiner and then collimated by the collimation system onto the MEMS micro mirror. The MEMS micromirror has two axes, X and Y, with two electrodes on each axis. The MEMS micromirror is connected to the signal processing and control unit and the power supply unit, respectively. The signal processing and control unit controls the power supply unit to provide the MEMS micromirror with the voltage corresponding to the required deflection angle, so as to control the MEMS micromirror to reflect the laser beam to the target detection area. The photodetector array is used to receive the return light signal of the detection laser that passes through the target detection area, is absorbed by the target gas, is reflected back by the background reflector, and is focused by the receiving lens. After photoelectric conversion, the signal is transmitted to the signal processing and control unit. The signal processing and control unit calculates the concentration information of the target gas in the target detection area based on the backlight signal after photoelectric conversion; The visualization imaging unit is used to capture a visualization image of the detection area; The information fusion unit is connected to the signal processing and control unit, the visualization imaging unit, and the signal output display unit. It is used to fuse the calculated gas concentration of the target detection area into the visualization image and send the fused visualization image to the signal output display unit for gas concentration visualization display.

2. A detection method based on the laser gas telemetry imaging system based on micro-mirror scanning as described in claim 1, characterized in that, Includes the following steps: (1) The signal processing and control unit controls the semiconductor laser and the aiming laser to emit light, and controls the visualization imaging unit to start capturing a visualization image; (2) The signal processing and control unit controls the power supply unit to provide corresponding voltage values ​​to the four electrodes X1, X2, Y1 and Y2 of the X and Y axes of the MEMS micro mirror, so that it scans the target detection area in a quasi-static mode or a uniform speed scanning mode according to a pre-set path. (3) The signal processing and control unit synchronously starts the corresponding dot matrix acquisition of the light signal in the photodetector array according to the voltage values ​​of the four electrodes of the MEMS micro mirror. The signal after photoelectric conversion is transmitted to the signal processing and control unit for calculation and processing to obtain the gas concentration value. The scanning angle of the MEMS micro mirror is synchronized with the acquisition of the corresponding photodetector array. (4) When the calculated gas concentration value is greater than the preset alarm threshold, the signal processing and control unit adjusts the voltage values ​​of the four electrodes X1, X2, Y1 and Y2 of the MEMS micro mirror on the X and Y axes, so that the MEMS micro mirror performs a re-inspection near the alarm position according to the preset re-inspection number and re-inspection path to confirm whether the alarm is a real leak alarm. (5) When a real leak alarm is confirmed, the signal processing and control unit sends the gas concentration to the information fusion unit; the information fusion unit draws the corresponding area of ​​the visualization image into images of different colors or different gray levels according to the gas concentration, so as to intuitively present the shape and size of the leaking gas cloud; the information fusion unit sends the drawn image to the signal output display unit for alarm and display; (6) After the prescribed re-inspection is completed, the signal processing and control unit controls the MEMS micro-mirror to continue scanning along the original path; (7) If the alarm is confirmed to be false, the signal processing and control unit discards the alarm and controls the micromirror to continue scanning along the original path. (8) When the system is powered off, the signal processing and control unit controls the power supply of the laser and the MEMS micro mirror to be turned off, so that the laser is powered off and the position of the MEMS micro mirror returns to zero, and then the power supply of other parts of the system is turned off.

3. The detection method of the laser gas telemetry imaging system based on micro-mirror scanning according to claim 2, characterized in that, Before detection, the laser gas telemetry imaging system based on micro-mirror scanning also calibrates the image of the visualization imaging unit, the scanning angle of the MEMS micro-mirror, and the photodetector array. The visualization imaging unit divides the visualization image into multiple detection areas according to the scanning angle of the MEMS micro-mirror and the photodetector array; The signal processing and control unit controls the semiconductor laser and the aiming laser to emit light, and simultaneously controls the MEMS micro-mirror to scan, recording and storing the correspondence between the voltages of the four electrodes X1, X2, Y1 and Y2 of the MEMS micro-mirror on the X and Y axes and the corresponding areas of the photodetector array and the visualization image.

4. The detection method of the laser gas telemetry imaging system based on micro-mirror scanning according to claim 3, characterized in that, The MEMS micro-mirror is placed at the center of the receiving lens, and a hole is drilled at the center of the receiving lens; A reflector is provided between the collimation system and the MEMS micro-mirror; The detection laser emitted by the semiconductor laser and the aiming laser emitted by the aiming laser are combined by the beam combiner, then collimated by the collimation system and emitted by the reflector, and finally onto the MEMS micro-mirror. The MEMS micro-mirror reflects the combined laser beam from the center of the aperture of the receiving lens to the target detection area.

5. The detection method of the laser gas telemetry imaging system based on micro-mirror scanning according to claim 3, characterized in that, The MEMS micro-mirror is placed at the edge of the receiving lens to reflect the laser beam to the target detection area.

6. The detection method of the laser gas telemetry imaging system based on micro-mirror scanning according to claim 4 or 5, characterized in that, The scan path is set as follows: According to the detection area divided by the visualization imaging unit, the circular spot of the detection laser scans continuously from the initial position along the positive X-axis direction - negative Y-axis direction - negative X-axis direction - positive Y-axis direction, from the outer layer to the center, point by point, to the center of the visualization imaging unit, and then scans from the center of the visualization imaging unit along the opposite path to the initial position of the set scanning path. When scanning according to the set scanning path, the method for controlling the voltage of the four electrodes of the MEMS micro-mirror includes: Achieve X-axis scanning: The signal processing and control unit controls the power supply unit to fix the voltage values ​​of the two electrodes Y1 and Y2 of the MEMS micro mirror Y-axis, and provides corresponding voltage values ​​to the two electrodes X1 and X2 of the MEMS micro mirror X-axis. To achieve Y-axis scanning: The signal processing and control unit controls the power supply unit to fix the voltage values ​​of the two electrodes X1 and X2 on the X-axis of the MEMS micro mirror, and provides corresponding voltage values ​​to the two electrodes Y1 and Y2 on the Y-axis of the MEMS micro mirror.

7. The detection method of the laser gas telemetry imaging system based on micro-mirror scanning according to claim 4 or 5, characterized in that, The scan path is set as follows: According to the detection area divided by the visualization imaging unit, the circular spot of the detection laser scans from the initial position along the Y direction from top to bottom to the bottom of the Y direction, then moves to the right once along the X direction, then scans from bottom to top along the Y direction to the top of the Y direction, then moves to the right once along the X direction, and so on, until the last detection area of ​​the visualization imaging unit, and then returns to the initial position of the scanning path along the opposite path. When scanning according to the set scanning path, the method for controlling the voltage of the four electrodes of the MEMS micro-mirror includes: Achieve X-axis scanning: The signal processing and control unit controls the power supply unit to fix the voltage values ​​of the two electrodes Y1 and Y2 of the MEMS micro mirror Y-axis, and provides corresponding voltage values ​​to the two electrodes X1 and X2 of the MEMS micro mirror X-axis. To achieve Y-axis scanning: The signal processing and control unit controls the power supply unit to fix the voltage values ​​of the two electrodes X1 and X2 on the X-axis of the MEMS micro mirror, and provides corresponding voltage values ​​to the two electrodes Y1 and Y2 on the Y-axis of the MEMS micro mirror.

8. The detection method of the laser gas telemetry imaging system based on micro-mirror scanning according to any one of claims 3-5, characterized in that, The mirror surface size of the MEMS micro-mirror is φ1~φ10mm, and the deflection angle is ±1°~±10°; The photodetector array is a 10×10 photodetector array.

9. The scanning method of the laser gas telemetry imaging system based on micro-mirror scanning according to any one of claims 2-5, characterized in that: The laser gas telemetry imaging system based on micro-mirror scanning also includes a positioning unit for acquiring the location information of the detection equipment and a target recognition module for identifying the target detection area. The positioning unit determines whether it has entered the detection area based on the obtained detection device location information. If it has entered the detection area, the target recognition module is activated to identify the target detection area and obtain the azimuth information of the target to be detected in the target detection area.

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