Highly stable laser emission system and method for ozone profile detection

Abstract

The invention discloses a high-stability laser emission system and method for ozone profile detection, and the system comprises the steps: connecting a first laser and a reflector to construct a first light path, and installing a first micro-angle execution mechanism and a first micro-angle sensor to the reflector; connecting a second laser and a beam splitter to construct a second light path, and installing a second micro-angle execution mechanism and a second micro-angle sensor to the beam splitter; the first light path and the second light path are combined through the beam expander; when the reflector and the beam splitter need to be adjusted, the first micro-angle executing mechanism and the second micro-angle executing mechanism are respectively used for changing the angles of the reflector and the beam splitter according to a fuzzy control algorithm. According to the invention, automatic adjustment of a laser emission light path is realized through the high-precision light beam adjustment mechanism, the precision and repeatability of light path adjustment are improved, measurement differences caused by different environmental conditions and different operators during manual adjustment are avoided, and the system stability and the detection data reliability are further improved.

Description

Technical Field

[0001] The invention belongs to the field of atmosphere detection, and in particular relates to a high-stability laser emission system and method for ozone profile detection. Background Art

[0002] Air pollution is a major health issue and a bottleneck that restricts regional economic upgrading and social development. In some areas, atmospheric ozone pollution is rising and spreading rapidly, and in recent years, large-scale and long-term ozone pollution has occurred many times. Since the increase in ozone concentration not only has a direct destructive impact on the ecological environment and human health, but also accelerates the transformation and formation of pollutants such as PM2.5, thereby affecting the frequency and intensity of severe atmospheric pollution, ozone pollution control is one of the most important control factors for regional complex pollution.

[0003] At this stage, in order to curb the trend of increasing ozone pollution, it is urgent to find an effective way to control ozone pollution. However, there is still a lack of large-scale, high-precision detection methods for the current status of ozone pollution, and a lack of systematic evaluation. Differential absorption lidar is an effective means of high-precision ozone profile detection and can provide effective data support for ozone pollution research and control.

[0004] Differential absorption lidar generally has two working laser wavelengths, and the emission requires a series of optical path beam combining. During the transportation and emission process of the laser emission system, the emission optical path may be offset due to the influence of temperature and vibration, so that the emission light spot cannot be fully received by the receiving field of view, or even completely moves out of the receiving field of view, affecting the receiving efficiency of the lidar and reducing the system accuracy and detection capability. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a high-stability laser emission system and method for ozone profile detection. The laser emission optical path in the ozone profile detection laser radar is automatically adjusted through a high-precision beam adjustment mechanism, which improves the accuracy and repeatability of the optical path adjustment, avoids measurement differences caused by different environmental conditions and different operators during manual adjustment, and thus improves system stability and detection data reliability.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows: On the one hand, the present invention provides a high-stability laser emission system for ozone profile detection, comprising a first laser, a second laser, a reflector, a spectroscope, a first micro-angle actuator, a second micro-angle actuator, a first micro-angle sensor, a second micro-angle sensor, a driver, and a beam expander, wherein: The laser beam emitted by the first laser changes direction after passing through a reflector, passes through a beam splitter and a beam expander in sequence, and is emitted into the atmosphere, which is recorded as a first optical path; The laser beam emitted by the second laser changes direction after passing through a beam splitter, and then passes through a beam expander and is emitted into the atmosphere, which is recorded as a second optical path; The outgoing light beams of the first light path and the second light path are combined in the atmosphere; The first and second micro-angle actuators are used to change the angles of the reflector and the beam splitter according to the fuzzy control algorithm, and the first and second micro-angle sensors are used to measure the adjustment angles of the reflector and the beam splitter, respectively. The first and second micro-angle actuators and the first and second micro-angle sensors are respectively connected to the driver through signal lines. The driver receives the angle information measured in real time by the first and second micro-angle sensors and sends adjustment instructions based on the measured angle information, so that the first and second micro-angle actuators act according to the adjustment instructions.

[0007] Furthermore, the first laser and the second laser have different emission wavelengths, which are used to provide a differential wavelength pair for ozone profile detection.

[0008] Furthermore, the driver determines the initial positions of the two emitted laser light beams based on the echo signal intensity of the light beams combined in the atmosphere. If the echo signal intensity is at the maximum point of the echo signal, no adjustment is made; if not, the fuzzy control algorithm is called to change the angles of the reflector and the spectrometer through the first and second micro-angle actuators until the maximum point of the echo signal is reached.

[0009] In another aspect, the present invention provides a highly stable laser emission method for ozone profile detection, the method comprising: Step 1, connect the first laser and the reflector to construct the first optical path, and install the first micro-angle actuator and the first micro-angle sensor to the reflector; connect the second laser and the beam splitter to construct the second optical path, and install the second micro-angle actuator and the second micro-angle sensor to the beam splitter; the first optical path and the second optical path are combined through the beam expander, and the first and second micro-angle actuators, the first and second micro-angle sensors are respectively connected to the driver through signal lines; Step 2: The first laser and the second laser emit light beams simultaneously, and the driver receives the angle information measured in real time by the first and second micro-angle sensors, and determines whether the reflector and the beam splitter need to be adjusted according to the echo signal intensity of the light beams combined in the atmosphere; when adjustment is required, the first and second micro-angle actuators are respectively used to change the angles of the reflector and the beam splitter according to the fuzzy control algorithm.

[0010] Furthermore, the fuzzy control algorithm in step 2 includes first changing the angles of the first and second micro-angle actuators through the driver to enter the large-range adjustment stage, and judging whether to enter the extremely small-range adjustment stage in real time according to the echo signal strength. If the echo signal strength is greater than the preset background signal threshold Sback , then it enters the extremely small range adjustment stage, and changes the angles of the first and second micro-angle actuators through the driver again, and determines in real time whether the signal reaches the strongest point. If it reaches it, the adjustment ends.

[0011] Furthermore, the large-range adjustment stage includes variable-step spiral adjustment.

[0012] Furthermore, the extremely small range adjustment stage includes taking the end point of the large range adjustment stage as the starting point, keeping the x-axis or y-axis coordinate unchanged, and advancing in the y-axis or x-axis direction at a fixed step size. If the motion trajectory passes through a process in which the echo signal intensity first increases to a first maximum value and then decreases, then returning to the point where the first maximum value of the motion trajectory is located, recorded as the y-axis or x-axis coordinate of the maximum echo signal intensity; changing the direction of movement, keeping the y-axis or x-axis coordinate unchanged, and advancing in the x-axis or y-axis direction at a fixed step size. When the motion trajectory again experiences a process in which the echo signal intensity first increases to a second maximum value and then decreases, then returning to the point where the second maximum value of the motion trajectory is located, recorded as the x-axis or y-axis coordinate of the maximum echo signal intensity.

[0013] The beneficial effects of the present invention are: Based on the fuzzy control algorithm of echo signal intensity, the laser emission optical path is automatically adjusted by automatically adjusting the micro-angle actuator in the optical path, which improves the accuracy and repeatability of the optical path adjustment and enhances the stability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a structural block diagram of a high-stability laser emission system for ozone profile detection according to the present invention; Figure 2 This is the flow chart of the fuzzy control algorithm for echo signal strength; Figure 3 Schematic diagram of the echo signal strength fuzzy control algorithm adjustment process.

[0015] Reference numerals: 1. First laser, 2. Second laser, 3. Reflector, 4. Spectrometer, 5. First micro-angle actuator, 6. Second micro-angle actuator, 7. First micro-angle sensor, 8. Second micro-angle sensor, 9. Driver, 10. Beam expander. DETAILED DESCRIPTION

[0016] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0017] like Figure 1As shown, it is a block diagram of the structure of the high-stability laser emission system for ozone profile detection of the present invention. The first laser 1 and the second laser 2 are lasers of two wavelengths of ozone differential absorption laser radar respectively. The emission wavelength of the first laser 1 is 310nm, and ozone absorption at this wavelength is relatively strong; the emission wavelength of the second laser 2 is 355nm, and ozone absorption at this wavelength is relatively weak. The two wavelength lasers together provide the differential wavelength pair required for ozone profile detection. The laser beam emitted by the first laser 1 changes direction after passing through the reflector 3, and is emitted into the atmosphere after passing through the beam splitter 4 and the beam expander 10 in sequence. The laser beam emitted by the second laser 2 changes direction after passing through the beam splitter 4, and is emitted into the atmosphere after passing through the beam expander 10, thereby, the beams emitted by the two lasers are combined in the atmosphere. The first and second micro-angle actuators 5 and 6 are the realization mechanisms of the beam pointing adjustment mechanism, which are mainly used to change the angles of the reflector 3 and the beam splitter 4 and limit their movement in other degrees of freedom. The first and second micro-angle sensors 7 and 8 are the measuring devices of the adjustment mechanism. The first and second micro-angle actuators 5, 6, the first and second micro-angle sensors 7, 8 and the driver 9 are connected through a signal line. The driver 9 can receive the angle information measured in real time by the first and second micro-angle sensors 7, 8 and send adjustment instructions based on the measured angle information, so that the first and second micro-angle actuators 5, 6 act according to the adjustment instructions to realize closed-loop control of the system.

[0018] like Figure 2 As shown, based on the above structure, the present invention adopts the fuzzy control algorithm of echo signal intensity to realize the stable adjustment of laser emission. First, the driver 9 judges the initial positions of the two emitted laser beams according to the echo signal intensity of the beam combined in the atmosphere. If the echo signal intensity is at the maximum point of the echo signal, it means that the emission light path is in the best position and no adjustment is required. If not, the fuzzy control algorithm is called to change the angles of the first and second micro-angle actuators 5 and 6 through the driver 9, thereby adjusting the pointing directions of the two emission light beams and starting a large-scale adjustment. In addition, it is judged in real time according to the echo signal intensity whether it is possible to enter a very small range adjustment. If the echo signal intensity is greater than the preset background signal threshold S back , it enters the extremely small range adjustment, and changes the angles of the first and second micro-angle actuators 5 and 6 through the driver 9 again, thereby adjusting the direction of the emitted light beam, and judging in real time whether it has reached the strongest signal point. If it has reached it, the adjustment is completed. During the real-time adjustment process, the driver 9 receives the angle information measured in real time by the first and second micro-angle sensors 7 and 8 and sends adjustment instructions based on the measured angle information.

[0019] like Figure 3 As shown, the adjustment process is further explained in a graphical manner. The adjustment process can be divided into two parts: large-range adjustment and very small-range adjustment, and the x-axis and y-axis coordinates are the divergence angle μrad.

[0020] 1. Large-range adjustment: Assuming that point O(0,0) is the initial point, the range of the fuzzy control algorithm during large-range adjustment is (5,110). Within this range, variable step-length spiral adjustment is performed. The step-length is determined by the fuzzy control algorithm. The adjustment process is: Figure 3 The motion trajectory from point O to point A; 2. The very small range adjustment process is described in detail as follows: When the very small range adjustment is performed, the value range of the fuzzy control algorithm is (0,5). Assuming that point O1 is the strongest point of the input signal, when the large range adjustment is completed and runs to point A, it is found that the echo signal strength is greater than the preset background signal threshold S back , enter the extremely small range adjustment area. At this time, the ordinate y of point A remains unchanged at first, and point A continues to move forward in the east direction at a fixed step length of 1 (that is, x increases by 1 in a single step). As shown in the figure, if the value of the echo signal strength continues to increase during the x-axis advance, then continue to move forward along the x-axis in this direction until the echo signal strength begins to decrease. Assuming that point O1 in the figure is the point with the strongest signal, when passing through point O1 to point B, it is found that the echo signal strength decreases, then the movement direction is changed, and it returns to the previous step position O1, and the x value of the previous step position is determined to be the x coordinate of the point with the strongest signal. By default, The adjustment of the x-axis is finished; the y-axis adjustment starts from the current point with the strongest x-axis signal. Assuming that the current position is at point O1, keep the x-axis coordinate unchanged, move forward to point C in a fixed step of 1 step toward the north. After judging that the echo signal strength value at point C is greater than the echo signal strength value at point O1, change the direction and move in the opposite direction. During the movement, it is found that the echo signal strength value has been increasing until it moves to point D. It is found that the echo signal strength value is less than the previous position value, and returns to the previous position, and defaults to the previous position as the position of the strongest y-axis signal point, and determines this point as the strongest signal point. The entire extremely small range adjustment range path should be: A→O1→B→O1→C→O1→D.

[0021] Based on the fuzzy control algorithm of echo signal intensity, the laser emission optical path is automatically adjusted by automatically adjusting the micro-angle actuator in the optical path, which improves the accuracy and repeatability of the optical path adjustment, avoids the measurement differences caused by different environmental conditions and different operators during manual adjustment, and thus improves the system stability and detection data reliability.

[0022] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A highly stable laser emission system for ozone profile detection, characterized in that: It includes a first laser, a second laser, a reflector, a beam splitter, a first micro-angle actuator, a second micro-angle actuator, a first micro-angle sensor, a second micro-angle sensor, a driver, and a beam expander, wherein: The laser beam emitted by the first laser changes direction after passing through the reflector, passes through the beam splitter and the beam expander in sequence, and is emitted into the atmosphere, which is recorded as the first optical path; The laser beam emitted by the second laser changes direction after passing through a beam splitter, and then passes through a beam expander and is emitted into the atmosphere, which is recorded as a second optical path; The outgoing light beams of the first light path and the second light path are combined in the atmosphere; The first and second micro-angle actuators are used to change the angles of the reflector and the beam splitter according to the fuzzy control algorithm, and the first and second micro-angle sensors are used to measure the adjustment angles of the reflector and the beam splitter, respectively. The first and second micro-angle actuators and the first and second micro-angle sensors are respectively connected to the driver through signal lines. The driver receives the angle information measured in real time by the first and second micro-angle sensors and sends adjustment instructions based on the measured angle information, so that the first and second micro-angle actuators act according to the adjustment instructions.

2. A highly stable laser emission system for ozone profile detection according to claim 1, characterized in that: The first laser and the second laser have different emission wavelengths and are used to provide a differential wavelength pair for ozone profile detection.

3. A highly stable laser emission system for ozone profile detection according to claim 1, characterized in that: The driver determines the initial positions of the two emitted laser light beams based on the echo signal intensity of the light beams combined in the atmosphere. If the echo signal intensity is at the maximum point of the echo signal, no adjustment is made; if not, the fuzzy control algorithm is called to change the angles of the reflector and the spectrometer through the first and second micro-angle actuators until the maximum point of the echo signal is reached.

4. A highly stable laser emission method for ozone profile detection, characterized in that: The method comprises: Step 1, connect the first laser and the reflector to construct the first optical path, and install the first micro-angle actuator and the first micro-angle sensor to the reflector; connect the second laser and the beam splitter to construct the second optical path, and install the second micro-angle actuator and the second micro-angle sensor to the beam splitter; the first optical path and the second optical path are combined through the beam expander, and the first and second micro-angle actuators, the first and second micro-angle sensors are respectively connected to the driver through signal lines; Step 2: The first laser and the second laser emit light beams simultaneously, and the driver receives the angle information measured in real time by the first and second micro-angle sensors, and determines whether the reflector and the beam splitter need to be adjusted according to the echo signal intensity of the light beams combined in the atmosphere; when adjustment is required, the first and second micro-angle actuators are respectively used to change the angles of the reflector and the beam splitter according to the fuzzy control algorithm.

5. A highly stable laser emission method for ozone profile detection according to claim 4, characterized in that: The fuzzy control algorithm in step 2 includes first changing the angles of the first and second micro-angle actuators through the driver to enter the large-range adjustment stage, and judging whether to enter the extremely small-range adjustment stage in real time according to the echo signal strength. If the echo signal strength is greater than the preset background signal threshold S back , then it enters the extremely small range adjustment stage, and changes the angles of the first and second micro-angle actuators through the driver again, and determines in real time whether the signal reaches the strongest point. If it reaches it, the adjustment ends.

6. A highly stable laser emission method for ozone profile detection according to claim 5, characterized in that: The wide range adjustment stage includes variable step length spiral adjustment.

7. A highly stable laser emission method for ozone profile detection according to claim 5, characterized in that: The extremely small range adjustment stage includes: taking the end point of the large range adjustment stage as the starting point, keeping the x-axis or y-axis coordinate unchanged, and advancing in the y-axis or x-axis direction at a fixed step size. If the motion trajectory goes through a process in which the echo signal intensity first increases to a first maximum value and then decreases, then returning to the point where the first maximum value of the motion trajectory is located, recorded as the y-axis or x-axis coordinate of the maximum echo signal intensity; changing the direction of movement, keeping the y-axis or x-axis coordinate unchanged, and advancing in the x-axis or y-axis direction at a fixed step size. When the motion trajectory again goes through a process in which the echo signal intensity first increases to a second maximum value and then decreases, then returning to the point where the second maximum value of the motion trajectory is located, recorded as the x-axis or y-axis coordinate of the maximum echo signal intensity.

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