Highly stable laser emission system and method for ozone profile sounding

Abstract

The application discloses a high-stability laser emission system and method for ozone profile detection, and the system comprises the following steps: connecting a first laser, a mirror to build a first light path, and installing a first micro-angle actuator and a first micro-angle sensor to the mirror; connecting a second laser, a beam splitter to build a second light path, and installing a second micro-angle actuator and a second micro-angle sensor to the beam splitter; the first light path and the second light path are combined through an expander; when the mirror and the beam splitter need to be adjusted, the first micro-angle actuator and the second micro-angle actuator are used to change the angles of the mirror and the beam splitter respectively according to a fuzzy control algorithm. The application realizes automatic adjustment of a laser emission light path through a high-precision light beam adjustment mechanism, improves the precision and repeatability of light path adjustment, avoids measurement differences caused by different environmental conditions and different operators during manual adjustment, and further improves the system stability and the reliability of detection data.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of atmospheric detection, and particularly relates to a high-stability laser emission system and method for ozone profile detection. BACKGROUND

[0002] Atmospheric pollution is a major problem related to health and is a bottleneck problem limiting regional economic upgrading and social development. In some areas, atmospheric ozone pollution is showing a rapid upward and spreading trend, and in recent years, there have been many long-range ozone pollution processes. The increase in ozone concentration not only directly damages the ecological environment and human health, but also accelerates the transformation of PM2.5 and other pollutants, thereby affecting the frequency and intensity of atmospheric heavy pollution processes. Therefore, ozone pollution control is one of the most important control elements of regional composite pollution.

[0003] At the present stage, 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 means for the current characteristics of ozone pollution, and there is a lack of systematic evaluation. Differential absorption laser radar is an effective means of high-precision ozone profile detection, which can provide effective data support for ozone pollution research and control.

[0004] Differential absorption laser radar generally has two working laser wavelengths, and the emission needs to go through a series of optical path combination. During transportation and emission, the laser emission system may be affected by temperature and vibration, which may cause the emission light path to deviate, so that the emission spot cannot be completely received by the receiving field of view, or even completely moves out of the receiving field of view, affecting the receiving efficiency of the laser radar and reducing the system precision and detection capability. SUMMARY

[0005] To solve the above technical problems, the present application provides a high-stability laser emission system and method for ozone profile detection. Through a high-precision beam adjustment mechanism, the laser emission light path in the ozone profile detection laser radar is automatically adjusted, the precision and repeatability of the light path adjustment are improved, the measurement differences caused by different environmental conditions and different operators during manual adjustment are avoided, and the system stability and detection data reliability are improved.

[0006] To achieve the above purpose, the technical solution adopted by the present application is as follows:

[0007] On the one hand, the present application provides a high-stability laser emission system for ozone profile detection, comprising a first laser, a second laser, a reflecting mirror, 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,

[0008] The laser beam emitted by the first laser changes direction after the mirror, and then changes direction after the beam splitter and the beam expander, and is emitted into the atmosphere, which is recorded as a first light path;

[0009] The laser beam emitted by the second laser changes direction after the beam splitter, and then changes direction after the beam expander and is emitted into the atmosphere, which is recorded as a second light path;

[0010] The outgoing beams of the first light path and the second light path are combined in the atmosphere;

[0011] The first and second micro-angle actuators are used to change the angles of the mirror 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 mirror and the beam splitter;

[0012] The first and second micro-angle actuators, the first and second micro-angle sensors are connected to the driver through signal lines, the driver receives the angle information measured by the first and second micro-angle sensors in real time and sends adjustment instructions according to the measured angle information, so that the first and second micro-angle actuators act according to the adjustment instructions.

[0013] Further, the first laser and the second laser emit different wavelengths, which are used to provide differential wavelength pairs for ozone profile detection.

[0014] Further, the driver judges the initial positions of the two emitted laser beams according to the echo signal strength of the combined light beams in the atmosphere, and if the echo signal strength is at the maximum echo signal point, no adjustment is made; if not, the fuzzy control algorithm is called to change the angles of the mirror and the beam splitter through the first and second micro-angle actuators until the maximum echo signal point is reached.

[0015] On the other hand, the present application provides a high-stability laser emission method for ozone profile detection, which comprises:

[0016] Step 1, connect the first laser and the mirror to build the first light path, and install the first micro-angle actuator and the first micro-angle sensor to the mirror; connect the second laser and the beam splitter to build the second light path, and install the second micro-angle actuator and the second micro-angle sensor to the beam splitter; the first light path and the second light path are combined through the beam expander, and the first and second micro-angle actuators, the first and second micro-angle sensors are connected to the driver through signal lines;

[0017] Step 2, the first laser and the second laser emit beams simultaneously, the driver receives the angle information measured by the first and second micro-angle sensors in real time, and whether the mirror and the beam splitter need to be adjusted is determined according to the echo signal strength of the combined beams in the atmosphere; when adjustment is needed, the first and second micro-angle actuators are used to change the angles of the mirror and the beam splitter according to the fuzzy control algorithm.

[0018] Further, the fuzzy control algorithm in step 2 includes first changing the angles of the first and second micro-angle actuators by the driver to enter the large-range adjustment stage, and determining whether the extremely small-range adjustment stage can be entered in real time according to the echo signal strength. back If the echo signal strength is greater than the preset background signal threshold S , then the extremely small-range adjustment stage is entered, the angles of the first and second micro-angle actuators are changed again by the driver, and it is determined in real time whether the strongest signal point is reached. If the strongest signal point is reached, the adjustment is completed.

[0019] Further, the large-range adjustment stage includes variable step spiral adjustment.

[0020] Further, 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 by a fixed step size. If the motion trajectory experiences a process in which the echo signal strength first increases to a first maximum value and then decreases, the first maximum value point of the motion trajectory is returned, which is recorded as the y-axis or x-axis coordinate of the maximum echo signal strength. The motion direction is changed, the y-axis or x-axis coordinate is kept unchanged, and the motion advances in the x-axis or y-axis direction by a fixed step size. When the motion trajectory again experiences a process in which the echo signal strength first increases to a second maximum value and then decreases, the second maximum value point of the motion trajectory is returned, which is recorded as the x-axis or y-axis coordinate of the maximum echo signal strength.

[0021] The beneficial effects of the present application are:

[0022] Based on the echo signal strength fuzzy control algorithm, the laser emission path is automatically adjusted by automatically adjusting the micro-angle actuators in the optical path, the accuracy and repeatability of the optical path adjustment are improved, and the system stability is enhanced. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 The structure block diagram of the high-stability laser emission system for ozone profile detection according to the present application;

[0024] Figure 2 The flowchart of the echo signal strength fuzzy control algorithm;

[0025] Figure 3 The adjustment process schematic diagram of the echo signal strength fuzzy control algorithm.

[0026] Figure label:

[0027] 1. First laser, 2. Second laser, 3. Reflector, 4. Beam splitter, 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 Implementation

[0028] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0029] like Figure 1 The diagram shows the structural block diagram of the high-stability laser emission system for ozone profile detection according to the present invention. The first laser 1 and the second laser 2 are lasers of two wavelengths for the ozone differential absorption lidar. The first laser 1 emits a wavelength of 310 nm, which has strong ozone absorption; the second laser 2 emits a wavelength of 355 nm, which has weak ozone absorption. These two wavelengths 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 then passes through the beam splitter 4 and the beam expander 10 before being emitted into the atmosphere. The laser beam emitted by the second laser 2 changes direction after passing through the beam splitter 4, and then passes through the beam expander 10 before being emitted into the atmosphere. Thus, the beams emitted by the two lasers are combined in the atmosphere. The first and second micro-angle actuators 5 and 6 are the implementation mechanisms for the beam pointing adjustment mechanism, mainly used to change the angles of the reflector 3 and the beam splitter 4 and restrict their movement in other degrees of freedom. The first and second micro-angle sensors 7 and 8 are the measuring devices for the adjustment mechanism. The first and second micro-angle actuators 5 and 6, the first and second micro-angle sensors 7 and 8, and the driver 9 are connected by signal lines. The driver 9 can receive the angle information measured in real time by the first and second micro-angle sensors 7 and 8 and send adjustment commands based on the measured angle information, so that the first and second micro-angle actuators 5 and 6 can act according to the adjustment commands, thereby realizing the closed-loop control of the system.

[0030] like Figure 2 As shown, based on the above structure, this invention employs an echo signal intensity fuzzy control algorithm to achieve stable adjustment of laser emission. First, the driver 9 determines the initial position of the two emitted laser beams based on the echo signal intensity of the beams combined in the atmosphere. If the echo signal intensity is at the maximum point, it indicates that the emitted optical path is in the optimal position and no adjustment is needed. Otherwise, the fuzzy control algorithm is invoked, and the driver 9 changes the angles of the first and second micro-angle actuators 5 and 6, thereby adjusting the direction of the two emitted beams and initiating a large-range adjustment. The system also continuously monitors the echo signal intensity to determine whether it can enter a minimal adjustment range. If the echo signal intensity is greater than a preset background signal threshold S... backIf the signal is too strong, the driver 9 will adjust the angle of the first and second micro-angle actuators 5 and 6 again, thereby adjusting the direction of the emitted beam and judging in real time whether the strongest signal point has been reached. If it has, the adjustment ends. During the real-time adjustment, the driver 9 receives the angle information measured in real time by the first and second micro-angle sensors 7 and 8 and sends the adjustment command based on the measured angle information.

[0031] like Figure 3 As shown in the figure, the adjustment process is further illustrated. The adjustment process can be divided into two parts: large-range adjustment and small-range adjustment, with the x-axis and y-axis coordinates being the divergence angle μrad.

[0032] 1. Large-range adjustment: Assuming 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 spiral adjustment is performed, with the step size determined by the fuzzy control algorithm. The adjustment process is as follows: Figure 3 The trajectory of movement from point O to point A;

[0033] 2. The minimal range adjustment process is described in detail below: During minimal range adjustment, the fuzzy control algorithm's value range is (0,5). Assuming point O1 is the strongest input signal point, when the large range adjustment ends and the algorithm reaches point A, it is determined that the echo signal strength is greater than the preset background signal threshold S. back The system enters a very small adjustment range. At this point, the ordinate (y) of point A remains unchanged initially. Point A continues to move eastward with a fixed step size of 1 (i.e., x increases by 1 per step), as shown in the figure. If the echo signal strength continuously increases during the x-axis movement, the system continues to move forward along the x-axis in this direction until the echo signal strength begins to decrease. Assuming point O1 is the strongest signal point in the figure, when the system moves past O1 to point B and finds the echo signal strength decreasing, the system changes direction, returns to the previous position O1, and determines the x-coordinate of the previous position as the strongest signal point. The x-axis adjustment is complete. Starting from the current point of strongest x-axis signal, adjust the y-axis. Assuming the current position is at point O1, keep the x-axis coordinate unchanged and move northward in a fixed step of 1 step to point C. If the echo signal strength at point C is found to be greater than that at point O1, change direction and move in the opposite direction. During this movement, the echo signal strength is observed to continuously increase until reaching point D. If the echo signal strength is found to be less than the previous position, return to the previous position, and assume that the previous position is the strongest y-axis signal point. The entire minimal adjustment range path should be: A→O1→B→O1→C→O1→D.

[0034] The echo signal intensity fuzzy control algorithm is used to automatically adjust the micro-angle actuator in the light path to realize automatic adjustment of the laser emission light path, improve the accuracy and repeatability of the light path adjustment, avoid measurement differences caused by different environmental conditions and different operators during manual adjustment, and further improve the system stability and detection data reliability.

[0035] The above-described specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above-described specific embodiments are merely examples of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A high-stability laser transmitter system for ozone profile sounding, characterized in that, The device comprises a first laser, a second laser, a mirror, 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 mirror, and is emitted into the atmosphere after passing through the beam splitter and the beam expander in sequence, which is recorded as a first light path; The laser beam emitted by the second laser changes direction after passing through the beam splitter, and is emitted into the atmosphere after passing through the beam expander, which is recorded as a second light path; The outgoing 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 mirror and the beam splitter according to a fuzzy control algorithm, and the first and second micro-angle sensors are used to measure the adjustment angles of the mirror and the beam splitter; The first and second micro-angle actuators, the first and second micro-angle sensors, and the driver are connected through signal lines, the driver receives the real-time measurement angles of the first and second micro-angle sensors, generates and sends adjustment instructions according to the measurement angles according to the fuzzy control algorithm, and makes the first and second micro-angle actuators act according to the adjustment instructions; the fuzzy control algorithm comprises: First, the angle of the first and second micro-angle actuators is changed by the driver to enter a large-range adjustment stage, and whether it can enter a minimum-range adjustment stage is determined in real time according to the echo signal strength back If the echo signal strength is greater than a preset background signal threshold S , the minimum-range adjustment stage is entered, and the angle of the first and second micro-angle actuators is changed again by the driver, and whether the strongest signal point is reached is determined in real time, and if so, the adjustment is completed.

2. A highly stable laser transmitter system for ozone profile sounding according to claim 1, characterized in that, The first laser and the second laser emit different wavelengths, which are used to provide differential wavelength pairs for ozone profile detection.

3. A highly stable laser transmitter system for ozone profile sounding according to claim 1, characterized in that, The driver judges the initial positions of the two emitted laser beams according to the echo signal intensity of the combined light beam in the atmosphere, and 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 mirror and the beam splitter through the first and second micro-angle actuators until the maximum point of the echo signal is reached.

4. A method for high stability laser emission for ozone profile sounding, applied to the system of any of claims 1-3, characterized in that, The method comprises: Step 1, connecting the first laser and the mirror to construct the first light path, and installing the first micro-angle actuator and the first micro-angle sensor to the mirror; connecting the second laser and the beam splitter to construct the second light path, and installing the second micro-angle actuator and the second micro-angle sensor to the beam splitter; the first light path and the second light path are combined through the beam expander, and the first and second micro-angle actuators, the first and second micro-angle sensors, and the driver are connected through signal lines; Step 2, the first laser and the second laser emit beams simultaneously, the driver receives the angle information measured by the first and second micro-angle sensors in real time, and whether the mirror and the beam splitter need to be adjusted is determined according to the echo signal strength of the combined beams in the atmosphere; when adjustment is needed, the first and second micro-angle actuators are respectively used to change the angles of the mirror and the beam splitter according to a fuzzy control algorithm, the fuzzy control algorithm comprises the following steps: first, the angles of the first and second micro-angle actuators are changed by the driver to enter a large-range adjustment stage, whether the smallest-range adjustment stage can be entered is determined in real time according to the echo signal strength, if the echo signal strength is greater than a preset background signal threshold S back , then the smallest-range adjustment stage is entered, the angles of the first and second micro-angle actuators are changed again by the driver, and whether the strongest signal point is reached is determined in real time, if the strongest signal point is reached, the adjustment is completed.

5. A method for high stability laser emission for ozone profile sounding according to claim 4, characterized in that, The large-range adjustment stage comprises variable-step spiral adjustment.

6. A method for high stability laser emission for ozone profile sounding according to claim 4, characterized in that, The minimum-range adjustment stage comprises, 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 by a fixed step, if the motion trajectory experiences a process that the echo signal intensity first increases to a first maximum value and then decreases, returning to the point where the first maximum value of the echo signal intensity is located, which is recorded as the y-axis or x-axis coordinate of the maximum value of the echo signal intensity; changing the motion direction, keeping the y-axis or x-axis coordinate unchanged, and advancing in the x-axis or y-axis direction by a fixed step, when the motion trajectory again experiences a process that the echo signal intensity first increases to a second maximum value and then decreases, returning to the point where the second maximum value of the motion trajectory is located, which is recorded as the x-axis or y-axis coordinate of the maximum value of the echo signal intensity.

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