A multi-wavelength raman lidar quality control system

Abstract

The utility model relates to a kind of multi-wavelength Raman laser radar quality control system, including control device and with the emission light path modulation device, receiving light path modulation device and data acquisition device of control device connection, emission light path modulation device includes detection light path, front light splitting module, optical switch, emission monitoring module;Receiving light path modulation device includes four quadrant module, telescope, detection light source module for calibrating and calibrating detection center wavelength range sequentially arranged in telescope, pinhole diaphragm, collimation module, detection attenuation module, detection filter module, rear light splitting module, the CCD light source detection module being oppositely arranged with rear light splitting module, detector and multichannel spectral detection module;Data acquisition device is connected with detector.This system realizes full-link hardware state monitoring, guarantees emission, receiving system closed loop real-time calibration, without external standardization equipment, integration is high, reduces manual intervention frequency, reduces operation and maintenance complexity and investment cost.

Description

Technical Field

[0001] This utility model relates to a lidar control system, and more particularly to a multi-wavelength Raman lidar quality control system. Background Technology

[0002] Atmospheric lidar systems play a crucial role in environmental monitoring, meteorological research, and air quality assessment. The quality of their data directly impacts the reliability of monitoring results and the scientific basis of decision-making. Therefore, quality control is a critical step in ensuring system performance and data accuracy. LiDAR quality control can reduce data drift caused by equipment aging, environmental changes, or hardware deviations. Through quality control processes, long-term stable and high-performance operation of the equipment is ensured, data accuracy is guaranteed, and inversion errors are reduced. Traditional quality control methods suffer from single monitoring modules, cumbersome operation, low integration, and reliance on manual on-site debugging and testing. They cannot monitor system operation in real time, nor can they provide early feedback on abnormal equipment status for proactive risk management and prevention. They are insufficient to meet the long-term, stable, reliable, and continuous observation requirements of radar. For example, Chinese patent CN2018211266286 discloses a spatiotemporal multiplexing single-channel lidar, which uses a half-wave plate rotated by a driving component to adjust the polarization direction of the measurement light emitted by the laser. This allows the polarization direction of the measurement light to remain unchanged or rotate 180 degrees. The polarization direction of the probe light emitted from the emission system into the area to be measured is parallel to and perpendicular to the polarization direction of the measurement light in time to measure the polarization channel gain ratio. However, this method requires tooling setup for debugging and testing, has limited detection function indicators, low monitoring dimensions, and insufficient integration. Utility Model Content

[0003] To address the aforementioned problems, this utility model provides a multi-wavelength Raman lidar quality control system, the specific technical solution of which is as follows: A multi-wavelength Raman lidar quality control system includes: The emission optical path modulation device includes a pre-splitting module for splitting the laser emitted by the laser into a detection optical path for atmospheric detection and a monitoring optical path for monitoring the performance of the laser, an optical switch located behind the detection optical path for controlling the beam switching, a reflector disposed opposite to the optical switch for realizing beam deflection, and an emission monitoring module for monitoring the monitoring optical path. The receiving optical path modulation device includes, in sequence, a four-quadrant module for evaluating beam pointing deviation, a telescope, a detection light source module disposed within the telescope for calibrating and setting the detection center wavelength range, a pinhole aperture, a collimation module, a detection attenuation module, a detection filter module, a post-splitting module, a CCD light source detection module disposed opposite to the post-splitting module, a detector, and a multi-channel spectral detection module. A data acquisition device, connected to the detector, is used to convert the data detected by the detector into photoelectric signals; and The control device is connected to the transmitting optical path modulation device, the receiving optical path modulation device, and the data acquisition device, respectively.

[0004] Preferably, the emission monitoring module includes an energy detection unit, a divergence angle detection unit, a pointing detection unit, and a center wavelength detection unit.

[0005] Preferably, the four-quadrant module includes: a base with a circular detection cavity and an optical aperture communicating with the detection cavity; four fan-shaped cover plates arranged in a ring array on the top of the detection cavity; and a flipping assembly disposed on the base and connected to the fan-shaped cover plates for opening the fan-shaped cover plates.

[0006] Preferably, the detection light source module includes: a first motor; a light source turntable, with a plurality of light source holes arranged in a circular array; and LED beads disposed within the light source holes; wherein at least one of the light source holes is used for light transmission, and the others are used for light shielding or for installing LED beads of different wavelengths.

[0007] Preferably, the detection attenuation module includes: an attenuation housing with an attenuation cavity and an attenuation through hole communicating with the attenuation cavity; a second motor disposed in the attenuation cavity; an attenuation turntable with a plurality of attenuation holes arranged in a ring array; and attenuation plates disposed on the attenuation holes; wherein at least one of the attenuation holes is used for light transmission, and the rest are used for mounting attenuation plates with different attenuation values.

[0008] Preferably, the detection filter module includes: a third motor; a filter turntable, with a plurality of filter holes arranged in a ring array; and filters disposed within the filter holes; wherein at least one of the filter holes is used for light transmission, and the rest are used for mounting filters of different wavelengths.

[0009] Preferably, the detector includes a PMT, an APD, and a bias adjustment unit.

[0010] Compared with the prior art, the present invention has the following beneficial effects: The multi-wavelength Raman lidar quality control system provided by the present invention achieves full-link hardware status monitoring by integrating the transmitting optical path modulation device, the transmitting optical path modulation device, the data acquisition device and the control device, ensuring closed-loop real-time calibration of the transmitting and receiving systems, eliminating the need for external standardized equipment, and having a high degree of integration, reducing the frequency of manual intervention, and lowering the complexity of operation and maintenance and investment costs. Attached Figure Description

[0011] Figure 1 This is a structural diagram of the application; Figure 2 This is a schematic diagram of the front beam splitter module; Figure 3 This is a structural diagram of a four-quadrant module; Figure 4 This is a schematic diagram of the detection light source module; Figure 5 This is a schematic diagram of the attenuation detection module; Figure 6 This is a schematic diagram of the structure of the detection attenuation module after the attenuation housing is hidden; Figure 7 This is a schematic diagram of the detection filter module; Figure 8 This is a schematic diagram of a motor driving the receiver to rotate. Detailed Implementation

[0012] The present invention will now be further described with reference to the accompanying drawings.

[0013] like Figures 1 to 7 As shown, a multi-wavelength Raman lidar quality control system includes a transmitting optical path modulation device, a receiving optical path modulation device, a data acquisition device, and a control device. The transmitting optical path modulation device includes a pre-splitter module for splitting the laser emitted by the laser into a detection optical path for atmospheric detection and a monitoring optical path for monitoring laser performance; an optical switch located behind the detection optical path for controlling the beam switching; a reflector opposite the optical switch for beam deflection; and a transmitting monitoring module for monitoring the monitoring optical path. The receiving optical path modulation device includes, in sequence, a four-quadrant module for evaluating beam pointing deviation; a telescope; a detection light source module located inside the telescope for calibrating and standardizing the detection center wavelength range; a pinhole aperture; a collimation module; a detection attenuation module; a detection filter module; a post-splitter module; a CCD light source detection module opposite the post-splitter module; a detector; and a multi-channel spectral detection module. The data acquisition device is connected to the detector and is used to perform photoelectric signal conversion on the data detected by the detector. The control device is connected to the transmitting optical path modulation device, the receiving optical path modulation device, and the data acquisition device.

[0014] The laser is a multi-wavelength laser, which can be a solid-state laser or a semiconductor laser. The wavelength range covers ultraviolet to near-infrared. It usually emits multiple wavelengths. Pulsed lasers are characterized by high energy and narrow linewidth.

[0015] The optical switch uses a motor-controlled light blocker to terminate beam emission; its structure is as follows: Figure 8 As shown, by controlling the appropriate rotation angle with a motor, the laser spot that needs to be blocked is located at the center of the receiver, thus turning off the light.

[0016] Three optical switches are connected to the motor control system to control the switching light state of lasers of different wavelengths, and to conduct system performance quality control tests.

[0017] The reflector deflects multi-wavelength emitted beams into the atmosphere and is used to adjust the parallelism between the respective emitted optical axes and the telescope's optical axis to achieve the highest coupling efficiency for optical signal reception. It can be used with an automatic adjustment frame for automatic adjustment of the optical path signal.

[0018] like Figure 2 As shown, the front beam splitting module includes a dichroic mirror, a beam splitter, an energy meter, and a spectrometer. These are existing, mature modules. The dichroic mirror and beam splitter split the laser beam according to wavelength type and a certain energy ratio. The wavelength classification and beam splitting ratio depend on the specific radar system. Multi-wavelength beam splitting and corresponding beam splitting module design are carried out according to the specific emitted laser wavelength distribution.

[0019] The emission monitoring module includes an energy detection unit, a divergence angle detection unit, a pointing detection unit, and a center wavelength detection unit. The pre-splitter module separates a portion of the emitted wavelength into a weaker energy beam at a certain ratio to detect indicators such as laser energy, divergence angle, pointing, and center wavelength, thereby evaluating the performance status of the emission source.

[0020] like Figure 3 As shown, the four-quadrant module 101 includes a base 201, four sector-shaped cover plates 202, and a flipping assembly. The base 201 has a circular detection cavity inside, and a light hole 208 communicating with the detection cavity is provided on the side of the base 201. The four sector-shaped cover plates 202 are arranged in a circular array on the top of the detection cavity. The flipping assembly is mounted on the base 201 and connected to the sector-shaped cover plates 202 for opening the sector-shaped cover plates 202. The flipping assembly includes a flipping motor 205, a rotating disk 204, and a connecting rod 203. The flipping motor 205 is fixed to the outer circular surface of the base 201, and four motors are provided. The rotating disk 204 is fixed to the motor shaft of the flipping motor 205 and connected to the connecting rod 203. The connecting rod 203 is L-shaped and is also connected to the sector-shaped cover plates 202.

[0021] Four sector-shaped covers 202 divide the circular receiving area, forming the basic structure of the four-quadrant module 101. The opening and closing of the sector-shaped covers 202 is achieved by rotating a flip motor 205, thereby controlling the signal receiving status of each quadrant area. The flip motor 205 is mounted on the base 201 via a motor fixing component 206, and the base 201 is connected to the telescope 106 via a base 201 fixing component, thus maintaining the relative fixation of each quadrant position. The aperture 208 is a channel reserved for the light source device. The controller controls the flip motor 205 via serial communication to complete the opening and closing of a single quadrant cover.

[0022] The laser beam emitted by the laser can obtain independent signals in four directions through the control of the four-quadrant module 101. Through consistency calculation, the consistency of the light path direction can be confirmed. When the four-quadrant calculation value exceeds the threshold, the automatic adjustment process is started. After each quadrant plate starts collecting independent data, the reflector group and its corresponding direction are fine-tuned according to their respective deviation amplitude. The above operation is repeated until the four quadrants meet the threshold requirements.

[0023] The four-quadrant module 101 is used to automatically acquire signal data in the four quadrants and evaluate optical path pointing deviation.

[0024] The telescope is a total reflection Cassegrain telescope system, which, along with the pinhole aperture and collimation module, is the receiving system of the radar equipment, used for receiving and transmitting echo signals; The pinhole aperture controls the telescope's receiving field of view, keeping it within 0-1 mrad. Collimation module; used for collimating the received beam and controlling the spot size of the beam to better match the subsequent beam splitting channel; Lens contamination detection module: This module mainly installs an LED bead and a receiving PIN tube on the fan blade of the optical path calibration fixture to detect the contamination on the lens surface so that it can be cleaned and maintained in a timely manner. like Figure 4 As shown, the detection light source module includes a first motor 31, a light source turntable 32, and LED beads 33. The light source turntable 32 is mounted on the motor shaft of the first motor 31. The light source turntable 32 has six light source holes 321 arranged in a ring array. The LED beads 33 are fixed in the light source holes 321. One light source hole 321 is used for light transmission, and the others are used for light shielding or for installing LED beads 33 of different wavelengths. The transmission center spectrum of the subsequent channel is tested by rotating the LED beads of the corresponding wavelengths, which is used to calibrate and standardize the detection center wavelength range of the system. The detection light source module consists of a series of LEDs or other small light sources with different center wavelengths. This type of light source has the characteristics of low cost and variety, but it has a large beam divergence angle, resulting in a short transmission distance, making it unsuitable for direct detection. By placing the detection light source module above the aperture stop of the telescope and using the same aperture stop and collimating lens as the telescope to control the numerical aperture of the light source and the collimation effect of the transmitted beam, the problems of large divergence angle, low collimation and short transmission distance of the detection light source group can be solved, so as to better serve the subsequent system quality control index detection.

[0025] like Figure 5 and Figure 6As shown, the detection attenuation module includes an attenuation housing 41, a second motor 42, an attenuation turntable 43, and attenuation plates 44. The attenuation housing 41 has an attenuation cavity 411 and an attenuation through hole 412 communicating with the attenuation cavity 411. The second motor 42 is fixed inside the attenuation cavity 411 and connected to the attenuation turntable 43. The attenuation turntable 43 has six attenuation holes 431 arranged in a ring array. There are five attenuation plates 44 with different attenuation values, which are respectively installed on the five attenuation holes 431. One of the attenuation holes 431 is used for light transmission. By rotating the attenuation plates 44, the attenuation plates 44 with different OD values ​​are positioned at the center of the channel to attenuate the received optical signal, and the corresponding data are collected to test the linearity of the system.

[0026] like Figure 7 As shown, the detection filter module includes a third motor 51, a filter turntable 52, and filters 53. The third motor 51 is connected to the filter turntable 52, which has six filter holes 521 arranged in a ring array. Five filters 53 are provided, each with a different filtering wavelength, and are installed in one of the five filter holes 521. The remaining filter hole 521 is used for light transmission. The filters 53 are narrowband filters that match the different center wavelengths of the subsequent receiving channels. By rotating the filters, the filters with different center wavelengths are positioned at the center of the channel to filter the received optical signal, and corresponding data are collected to test the crosstalk of the system channels.

[0027] like Figure 1 As shown, the subsequent beam splitting module includes multiple beam splitters, polarizers, and polarizers to receive signals from different wavelengths and polarization channels, detect channel optical axis offset, channel crosstalk, polarization ratio, and channel center spectrum detection. The channel contains three CCD spot detection modules, one polarization state modulation module, and one multi-channel spectral detection module. The detection light source module, detection attenuation module, detection filter module, and polarization modulation module are all controlled by motors to switch between different functions.

[0028] The CCD light source detection module is mainly placed in the subsequent light transmission channel. It separates a portion of the background light through a beam splitter to detect the position and shape of the light spot received by the telescope. It is used to detect and evaluate the coaxiality deviation of the optomechanical system and can be selectively deployed and monitored according to the actual situation. The polarization adjustment module includes a half-wave plate and a rotary control motor module, which are used to modulate and match the polarization state direction of the subsequent polarization channel and to perform opposite actions, and are used to test the gain ratio of the subsequent polarization channel. Dichroic mirrors are used to split echo signals of different wavelengths for subsequent reception by various channels. Beam splitters are used to split light in each channel according to a certain energy ratio, and the separated light signals are then used for corresponding spectrum and spot position detection. Polarizers are used to transmit and reflect light in directions with different polarization states. The detector is used to receive weak light signals and can be a PMT, APD, etc. The post-splitting module is used in the spectral system of lidar to realize multi-functional atmospheric environmental parameter detection. It can be a multi-channel system such as aerosol polarization channel, Raman channel, water vapor channel, and temperature channel. The corresponding spectral channel scheme is determined according to the radar function. The multi-channel spectral detection module mainly includes a spectrometer with multiple detection channels. It can be an integrated multi-spectral instrument or a multi-channel single spectrometer. The detection wavelength range covers ultraviolet to near-infrared, and the detection wavelength resolution is about 0.1-0.5nm.

[0029] The data acquisition device receives, collects, and stores the echo signal data fed back from each channel of the subsequent beam splitting system in real time, and processes the transmitted data to meet the application requirements of radar data product display.

[0030] The control device completes hardware monitoring information collection, quality control judgment, and module modulation drive control, realizing closed-loop control of the entire monitoring, feedback and quality control chain.

[0031] All motors are connected to the control device via motor controllers.

[0032] A multi-wavelength laser is used as the light source. The output laser is divided into two paths according to a preset energy ratio by the pre-splitting module: (1) Main emission beam (strong light path): used for atmospheric detection. After interacting with aerosols, molecules and other substances in the atmosphere, it generates an echo signal and then inverts the atmospheric parameters; (2) Monitoring beam (weak light path): used to monitor the laser performance indicators in real time, including the changes in parameters such as laser energy, divergence angle, beam direction and center wavelength.

[0033] Three optical switches, labeled Optical Switch 1, Optical Switch 2, and Optical Switch 3, are configured at the rear end of the main emission optical path. Precise switching control of the optical switches is achieved through a motor control system: In the on state, the system operates normally, and the laser beam is emitted normally for atmospheric detection; in the off state, it has multiple functions: (1) collecting background light signals to assess the daytime background baseline level and abnormal phenomena; (2) in quality control testing, it is used to separate optical and electrical interference and accurately assess the stability of the device. Real-time monitoring of laser performance and rapid diagnosis of system anomalies are realized. At the same time, through flexible optical switch control, the technical difficulties of background noise subtraction and interference separation in traditional systems are effectively solved.

[0034] The receiving optical path modulation device primarily controls the beam pointing deviation, optomechanical system optical axis deviation, subsequent channel center spectrum, channel crosstalk, system linearity, and polarization gain ratio during long-term radar operation, ensuring the system operates within a reasonable linear range. An internal lens contamination detection module monitors long-term contamination of the telescope's internal lenses for timely cleaning and maintenance. Among these: (1) Quality control of beam pointing deviation: The echo signal of the four quadrants of the incident surface is collected by the optical path calibration fixture on the telescope. The four fan blades are opened and closed in sequence by the motor control to collect data. The beam pointing is tested and controlled by the consistency of the data in the four quadrants. When working normally, the four fan blades of the optical path calibration fixture are in the unfolded state. (2) Optical axis deviation quality control of the optomechanical system: When the system is in normal working condition, after the optomechanical system is calibrated, each channel passes through the echo and background light signals normally. After the partially separated light signals pass through the CCD spot detection module, a clear and complete spot located at the center of the CCD detection surface can be observed. The deviation of the optical axis of the optomechanical system can be calculated and evaluated by the spot position deviation in order to evaluate the stability of the optomechanical system.

[0035] (3) Quality control of the center spectrum of the subsequent channel: The detection light source module placed above the aperture stop of the telescope rotates its own structure by motor control. When the fan blade area of ​​the structure is blank, the system is in normal working state. When it rotates to the position of LED beads of different wavelengths, the corresponding spectrum can be detected through the subsequent separated channel. The spectral line of the center wavelength is displayed through the multi-channel spectral detection module to monitor the range of the center spectrum of the echo signal of the subsequent spectral system, which is used to calibrate and standardize the spectral status of the system's detected echo signal. (4) System linearity quality control: By rotating the attenuator array structure, attenuators with different OD values ​​are placed at the center of the channel to attenuate the received optical signal, and corresponding data are collected to test the system linearity. (5) Channel crosstalk quality control: The filter group structure is rotated by motor control. The structure consists of 6 fan blades, one of which is light-transmitting. When the system is in the light-transmitting position, it is in normal working state. When it is in different filter positions, it is in test state. By rotating the filter group structure, the filters of different center wavelengths are aligned with the center spectrum of the channel to be tested. Two sets of data are collected before and after the filter is added. The crosstalk of the channel is calculated by the correlation between the two sets of data, which is used to test the crosstalk of the system channel. (6) Polarization gain quality control: By rotating the half-wave plate through the polarization modulation module, the polarization direction of the signal is parallel or perpendicular to the polarization direction detected by the channel, thereby obtaining the signal amplitude under the two states, and obtaining the gain ratio value through relevant calculations.

[0036] The technical principles of this utility model have been described above with reference to specific embodiments. These descriptions are merely for explaining the principles of this utility model and should not be construed as limiting the scope of protection of this utility model in any way. Based on this explanation, those skilled in the art can readily conceive of other specific embodiments of this utility model without inventive effort, and these embodiments will all fall within the protection scope of the claims of this utility model.

Claims

1. A multi-wavelength Raman lidar quality control system, characterized in that, include: The emission optical path modulation device includes a pre-splitting module for splitting the laser emitted by the laser into a detection optical path for atmospheric detection and a monitoring optical path for monitoring the performance of the laser, an optical switch located behind the detection optical path for controlling the beam switching, a reflector disposed opposite to the optical switch for realizing beam deflection, and an emission monitoring module for monitoring the monitoring optical path. The receiving optical path modulation device includes, in sequence, a four-quadrant module for evaluating beam pointing deviation, a telescope, a detection light source module disposed within the telescope for calibrating and setting the detection center wavelength range, a pinhole aperture, a collimation module, a detection attenuation module, a detection filter module, a post-splitting module, a CCD light source detection module disposed opposite to the post-splitting module, a detector, and a multi-channel spectral detection module. A data acquisition device, connected to the detector, is used to convert the data detected by the detector into photoelectric signals; as well as The control device is connected to the transmitting optical path modulation device, the receiving optical path modulation device, and the data acquisition device, respectively.

2. The multi-wavelength Raman lidar quality control system according to claim 1, characterized in that, The launch monitoring module includes an energy detection unit, a divergence angle detection unit, a pointing detection unit, and a center wavelength detection unit.

3. The multi-wavelength Raman lidar quality control system according to claim 1, characterized in that, The four-quadrant module includes: The base has a circular detection cavity inside and an optical aperture communicating with the detection cavity; Four fan-shaped cover plates are arranged in a ring array on the top of the detection cavity; A flip-up assembly is disposed on the base and connected to the fan-shaped cover plate for opening the fan-shaped cover plate.

4. The multi-wavelength Raman lidar quality control system according to claim 1, characterized in that, The detection light source module includes: First motor; A rotating light source disk, with a circular array of several light source holes; and LED beads are disposed inside the light source hole; Among them, at least one of the light source holes is used for light transmission, and the rest are used for light shielding or for installing LED beads of different wavelengths.

5. The multi-wavelength Raman lidar quality control system according to claim 1, characterized in that, The detection attenuation module includes: The attenuation housing is provided with an attenuation cavity and an attenuation through hole communicating with the attenuation cavity; The second motor is located within the attenuation cavity; Attenuation disk, the ring array has several attenuation holes; and An attenuator is disposed on the attenuation hole; At least one of the attenuation holes is used for light transmission, while the rest are used to install attenuation plates with different attenuation values.

6. The multi-wavelength Raman lidar quality control system according to claim 1, characterized in that, The detection filter module includes: Third motor; A filter turntable, with a ring array of filter holes; and A filter is disposed within the filter aperture; At least one of the filter holes is used for light transmission, while the rest are used to install filters of different wavelengths.

7. The multi-wavelength Raman lidar quality control system according to claim 1, characterized in that, The detector includes a PMT, an APD, and a bias adjustment unit.

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