Differential absorption micro-pulse laser emission unit, control method and water vapor profile detection system

Abstract

The invention provides a differential absorption micro-pulse laser emission unit, a temperature and current control method, a pulse control method and a water vapor profile detection system. The differential absorption micro-pulse laser emission unit adopts a laser emission module, the constant temperature design of the laser emission module is realized through a high-precision temperature and current control module, and accurate compensation under tiny temperature fluctuation is carried out through current adjustment, so that the laser emission module generates high-precision online wavelength laser and offline wavelength laser, and the high-precision online wavelength laser and the high-precision offline wavelength laser are integrated. According to the water vapor profile detection system adopting the differential absorption micro-pulse laser emission unit, the vertical distribution characteristics of the water vapor content are obtained by detecting the scattered signal intensity of the pulse laser by the atmosphere at different heights, and the water vapor profile detection system has higher time and space resolution and better environmental adaptability and daytime detection performance.

Description

Technical Field

[0001] The present application relates to the technical field of water vapor detection, and in particular to a differential absorption micro-pulse laser emission unit, a temperature and current control method, a pulse control method, and a water vapor profile detection system. Background Art

[0002] Water vapor plays a crucial role in many atmospheric processes and is a major influencing factor in weather. It holds significant observational value for improving the accuracy of weather forecasts and climate simulations. Ground-based water vapor detection currently relies primarily on sensors, microwave radiometer inversion, ground-based GNSS inversion, sounding balloons, and Raman scattering lidar. Sensors and sounding balloons rely on in-situ detection and cannot provide real-time remote sensing of water vapor profiles. Microwave radiometers and ground-based GNSS rely on passive inversion and cannot provide high-precision water vapor profiles. Raman scattering lidar offers the ability to actively acquire water vapor profiles and offers high accuracy. However, Raman scattering lidars suffer from urgent shortcomings, such as high transmit power, bulk, and poor daytime detection, making them unsuitable for low-cost, compact nationwide deployment. Domestic differential absorption systems typically employ two lasers that switch between transmitting wavelengths. Temperature fluctuations can easily cause variations in the two transmitted wavelengths, impacting detection effectiveness. Summary of the Invention

[0003] The present application provides a differential absorption micro-pulse laser emitting unit, a temperature and current control method, a pulse control method, and a water vapor profile detection system. The differential absorption micro-pulse laser emitting unit utilizes a laser emitting module, which is designed to maintain a constant temperature through a high-precision temperature and current control module. Current regulation accurately compensates for small temperature fluctuations, allowing the laser emitting module to generate high-precision online and offline wavelength lasers. The water vapor profile detection system employing this differential absorption micro-pulse laser emitting unit detects the intensity of the pulsed laser's scattered signal at different atmospheric altitudes to determine the vertical distribution characteristics of water vapor content. This system exhibits higher temporal and spatial resolution, improved environmental adaptability, and greater daytime detection performance.

[0004] To achieve the above objectives, the present application provides, on one hand, a differential absorption micro-pulse laser emission unit, comprising a laser emission module, a temperature and current control module, and a pulse control module, wherein: A laser emission module, used for generating online wavelength laser and offline wavelength laser; A temperature and current control module, used to control the temperature and current of the laser emission module to generate online wavelength laser and offline wavelength laser; The pulse control module is used to control the laser emission module to generate micro-pulse laser output at a certain pulse repetition frequency.

[0005] Preferably, the laser emission module includes a power supply circuit unit, a driving circuit unit and a tunable laser unit, wherein: a power supply circuit unit, used for supplying power to the driving circuit unit; A tunable laser unit includes a laser diode and a grating. The laser diode continuously outputs narrow-linewidth, tunable laser light, and the grating performs wavelength fine-tuning and scanning. The driving circuit unit includes an analog voltage conversion circuit and a current stabilization circuit; the input end of the analog voltage conversion circuit is respectively connected to the power supply circuit, and is used to convert the DC voltage provided by the power supply circuit unit into an analog voltage; the input end of the current stabilization circuit is connected to the output end of the analog voltage conversion circuit and the temperature and current control module, and the output end of the current stabilization circuit is connected to the laser diode of the tunable laser unit, and is used to provide a stable current for the tunable laser unit.

[0006] Preferably, the temperature and current control module includes a temperature monitoring unit, a temperature control unit, a PID temperature unit, a current monitoring unit, a current control unit and a PID current unit, wherein: A temperature monitoring unit, used to monitor the temperature of the laser emission module in real time; A PID temperature unit is used to determine the target opening of the cooling plate or heating plate inside the PID temperature unit according to the monitoring value of the temperature monitoring unit and the initial temperature distance value, so as to achieve temperature control accuracy; A temperature control unit, comprising a cooling plate or a heating plate, for adjusting the current temperature parameters of the laser emission module and performing cooling and heating control on the laser emission module in real time according to the PID temperature unit; A current monitoring unit, used to monitor the power supply current of the laser emission module driving circuit board in real time; A PID current unit is used to determine a duty cycle of a PWM (pulse width modulation) module of the PID current unit based on the monitoring value of the current monitoring unit and the initial current distance value, and based on the temperature interpolation value returned by the PID temperature unit, so as to achieve current control accuracy; The current control unit is used to adjust the current parameters of the laser emission module and control the power supply current of the laser emission module driving circuit board in real time according to the PID current unit.

[0007] Preferably, the pulse control module includes a timing control unit, a parallel / serial conversion module, a high-speed serial differential output module, and an output interface plug-in, wherein: A timing control unit, used to control the pulse width, duty cycle and pulse repetition frequency of the transmitted pulse; A parallel / serial conversion module, used to convert parallel control signals into serial signals; A high-speed serial differential output module, configured to output the high-speed serial differential signal output by the parallel / serial conversion module; The output interface plug-in is used for signal connection of the laser emission module driving circuit unit.

[0008] Another aspect of the present application further provides a method for controlling temperature and current of the differential absorption micropulse laser emitting unit, comprising: Step S101, real-time monitoring of the temperature of the laser emission module; Step S102, cooling and heating control of the laser emission module; Step S103, determining the target opening of the cooling plate or heating plate inside the PID temperature unit according to the monitoring value of the temperature monitoring unit and the initial temperature distance value, so as to achieve temperature control accuracy; Step S104, real-time monitoring of the power supply current of the driving circuit board of the laser emission module; Step S105, controlling the power supply current of the driving circuit of the laser emission module in real time according to the PID current unit; Step S106 , based on the monitoring value of the current monitoring unit and the initial current distance value, and at the same time, based on the temperature difference value returned by the PID temperature unit.

[0009] Preferably, the temperature difference control range is between -55°C and 125°C.

[0010] A third aspect of the present invention provides a pulse control method for a differential absorption micropulse laser emitting unit, comprising: Step S201, controlling the pulse width, duty cycle and pulse repetition frequency of the transmit pulse; Step S202, converting the parallel control signal into a serial signal; Step S203, outputting a high-speed serial differential signal; Step S204: connecting the laser emission module drive circuit.

[0011] A fourth aspect of the present invention provides a differential absorption micropulse lidar water vapor profile detection system, comprising the above-mentioned differential absorption micropulse lidar transmitting unit, a receiver module, an integrated transceiver optical cavity module, a signal processing module, and a display module, wherein: The receiver module performs photoelectric conversion to receive the return optical signal on the detection path; The integrated transceiver optical cavity module is used for amplifying the transmitting optical path and detecting the receiving optical path; The signal processing module is used to generate synchronization signals and control signals, and perform joint calculations of online wavelength laser and offline wavelength laser on the collected signals; The display module is used to display the water vapor content results on the detection path.

[0012] Preferably, the integrated transceiver optical cavity module comprises a collimating lens, a plano-convex cylindrical lens, a 45° reflector, a beam expander, a window and an integrated casting, wherein: A collimating lens, used to convert the light beam emitted by the laser emission module into a parallel light beam; Plano-convex cylindrical lens, which can be adjusted to focus a parallel beam of light to a single point; 45° reflector, used to change the optical path of the returning laser beam; Beam expander, used to amplify the transmitted and received beams; A window, used to protect the internal optical path of the transceiver integrated optical cavity module; An integrated casting is used for fixing and mounting the lens, the beam expander and the window.

[0013] Preferably, the integrated casting includes a fine-tuning structure for adjusting the positions of the collimating lens, the plano-convex cylindrical lens, and the 45° reflector.

[0014] The differential absorption micro-pulse lidar water vapor profile detection system of this application obtains the vertical distribution characteristics of water vapor content by detecting the scattered signal intensity of the pulsed laser by the atmosphere at different altitudes. It has higher time and spatial resolution, better environmental adaptability and daytime detection performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a flow chart of a method for controlling temperature and current of a differential absorption micropulse laser emitting unit according to an embodiment of the present application; Figure 2 1 is a flow chart of a pulse control method of a differential absorption micro-pulse laser emitting unit according to an embodiment of the present application; Figure 3 1 is a schematic diagram of the pulse control process of the differential absorption micro-pulse laser emitting unit according to an embodiment of the present application; Figure 4 is a schematic diagram of a water vapor profile detection system of a differential absorption micro-pulse lidar according to an embodiment of the present application; Figure 5 This is a schematic diagram of the integrated detection process of the differential absorption lidar water vapor profile detection system according to an embodiment of the present application; Figure 6 This is a schematic diagram of the laser emission process of the differential absorption lidar water vapor profile detection system according to an embodiment of the present application; Figure 7 This is a schematic diagram of the signal receiving process of the differential absorption lidar water vapor profile detection system according to an embodiment of the present application; Figure 8 It is a schematic diagram of the signal processing flow of the differential absorption lidar water vapor profile detection system according to an embodiment of the present application. DETAILED DESCRIPTION

[0016] To make the purpose, technical solutions, and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative efforts shall fall within the scope of protection of this application.

[0017] On the one hand, the present application provides a differential absorption micro-pulse laser emission unit, including a laser emission module 10, a temperature and current control module 11, and a pulse control module 12, wherein: the laser emission module 10 is used to generate online wavelength laser and offline wavelength laser; the temperature and current control module 11 is used to control the temperature and current of the laser emission module 10 to generate the online wavelength laser and the offline wavelength laser; the pulse control module 12 is used to control the laser emission module 10 to generate micro-pulse laser output at a certain pulse repetition frequency.

[0018] In one embodiment of the present application, the laser emission module 10 includes a power supply circuit unit, a driving circuit unit and a tunable laser unit, wherein: the power supply circuit unit is used to supply power to the driving circuit unit; the tunable laser unit includes a laser diode and a grating, the laser diode continuously outputs narrow-linewidth, tunable laser, and the grating performs wavelength fine-tuning and scanning; the driving circuit unit includes an analog voltage conversion circuit and a current stabilization circuit, the input ends of the analog voltage conversion circuit are respectively connected to the power supply circuit, and are used to convert the DC voltage provided by the power supply circuit unit into an analog voltage, the input end of the current stabilization circuit is connected to the output end of the analog voltage conversion circuit and the temperature and current control module, and the output end of the current stabilization circuit is connected to the laser diode of the tunable laser unit, and is used to provide a stable current for the tunable laser unit.

[0019] In a preferred embodiment, the temperature and current control module 11 includes a temperature monitoring unit, a temperature control unit, a PID temperature unit, a current monitoring unit, a current control unit and a PID current unit, wherein: the temperature monitoring unit is used to monitor the temperature of the laser emitting module 10 in real time; the PID temperature unit is used to determine the target opening of the cooling plate or heating plate inside the PID temperature unit according to the monitoring value of the temperature monitoring unit and the initial temperature distance value, so as to achieve temperature control accuracy; the temperature control unit includes a cooling plate or a heating plate, which is used to adjust the current temperature parameter of the laser emitting module and perform cooling and heating control on the laser emitting module in real time according to the PID temperature unit; the current monitoring unit is used to monitor the power supply current of the laser emitting module 10 driving circuit board in real time; the PID current unit is used to determine the PWM (pulse width modulation) module duty cycle of the PID current unit according to the monitoring value of the current monitoring unit and the initial current distance value, and at the same time, according to the temperature interpolation returned by the PID temperature unit, so as to achieve current control accuracy; the current control unit is used to adjust the current parameter of the laser emitting module 10 and control the power supply current of the laser emitting module driving circuit board in real time according to the PID current unit.

[0020] The pulse control module 12 includes a timing control unit, a parallel / serial conversion module, a high-speed serial differential output module, and an output interface plug-in, wherein: the timing control unit is used to control the pulse width, duty cycle and pulse repetition frequency of the emission pulse; the parallel / serial conversion module is used to convert the parallel control signal into a serial signal; the high-speed serial differential output module is used to output the high-speed serial differential signal output by the parallel / serial conversion module; the output interface plug-in is used to connect the laser emission module to the driving circuit unit for signal connection.

[0021] Another aspect of the application, such as Figure 1 As shown, a temperature and current control method of a differential absorption micro-pulse laser emitting unit is also provided, including: Step S101, real-time monitoring of the temperature of the laser emission module; Step S102, cooling and heating control of the laser emission module; Step S103, determining the target opening of the cooling plate or heating plate inside the PID temperature unit according to the monitoring value of the temperature monitoring unit and the initial temperature distance value, so as to achieve temperature control accuracy; Step S104, real-time monitoring of the power supply current of the driving circuit board of the laser emission module; Step S105, controlling the power supply current of the driving circuit of the laser emission module in real time according to the PID current unit; Step S106 , based on the monitoring value of the current monitoring unit and the initial current distance value, and at the same time, based on the temperature difference value returned by the PID temperature unit.

[0022] In specific operation, step S101 monitors the temperature of the laser emitting module in real time. The temperature monitoring unit uses a DS18B20 sensor to monitor the laser emitting module's temperature in real time, with a test temperature range of -55°C to 125°C. Using a 12-bit register for reading, the test accuracy reaches 0.0625°C, and the maximum conversion time is approximately 745ms.

[0023] Step S102, cooling and heating control of the laser emission module. The temperature control unit controls the cooling or heating of the laser emission module according to the real-time output signal of the PID temperature unit. When the cooling control signal is received, the circuit current is controlled according to the coarse adjustment value and the fine adjustment value, thereby controlling the cooling power. Semiconductor refrigeration chips are selected for cooling control to achieve cooling power of watts, and the temperature difference control range covers -55℃~125℃. When the heating control signal is received, the circuit current is controlled according to the coarse adjustment value and the fine adjustment value, thereby controlling the heating power. MOSFET power tubes are selected for heating control, which have low driving power and fast switching speed. The switching time is between 10~100ns, the operating frequency can reach 100kHz, and the thermal stability is excellent. The maximum heating power can reach hundreds of watts, and the temperature difference control range covers -55℃~125℃.

[0024] Step S103, based on the monitoring value of the temperature monitoring unit and the initial temperature distance value, determine the target opening of the cooling plate or heating plate inside the PID temperature unit to achieve temperature control accuracy. You can first set a required normal working reference temperature, collect the real-time temperature of the laser emission module through the temperature monitoring unit to make a judgment, and then calculate the current instantaneous temperature with the set working reference temperature to make a judgment on coarse adjustment or fine adjustment; accumulate the cooling or heating time, calculate the rate of change of temperature drop or temperature rise over time, and judge the rate of change of temperature drop or temperature rise. When the rate of change of temperature rise is greater than When the temperature rise rate is less than At the same time, the real-time temperature interpolation is output to the PID current unit.

[0025] Step S104: Real-time monitoring of the power supply current of the laser emission module driver circuit board. A differential current sensor is used to perform real-time monitoring of the current range of 0-160A, with a response time as low as 2.5us.

[0026] Step S105: Real-time current control of the laser emission module driver circuit is performed based on the PID current unit. The current control unit's power supply is connected in parallel between the positive and negative electrodes, and current output is controlled via a rectifier circuit. The rectifier circuit's output is connected to the pulse control module's timing control unit, which adjusts the input signal to the pulse control module's timing control unit based on the PID current unit.

[0027] In step S106, based on the monitored value of the current monitoring unit and the initial current distance value, and also based on the temperature difference value returned by the PID temperature unit, the PID current unit performs a combined calculation based on the temperature difference value and the current distance value returned by the PID temperature unit to quickly determine the PWM module duty cycle of the PID current unit, achieving current control accuracy to the microsecond level. Considering that sudden temperature changes can cause temperature control delays of up to milliseconds, which can also have a significant impact on the laser emission module, the PID current unit performs a combined calculation based on the temperature difference value and the current distance value returned by the PID temperature unit. This allows for accurate current control, with control precision reaching the microsecond level.

[0028] like Figure 2 As shown, the pulse control method of the differential absorption micro-pulse laser emitting unit includes: Step S201, controlling the pulse width, duty cycle and pulse repetition frequency of the transmit pulse; Step S202, converting the parallel control signal into a serial signal; Step S203, outputting a high-speed serial differential signal; Step S204: connecting the laser emission module drive circuit.

[0029] In specific operations, the process includes the following steps: Step S201, control the pulse width, duty cycle and pulse repetition frequency of the transmitted pulse. The signal processing module synchronization circuit is used as the control signal, and the pulse control module realizes the pulse energy modulation of outputting 10uJ at a repetition frequency of 8.2kHz. Figure 3 As shown, the timing control unit is triggered according to the synchronization signal of the signal processing module. The timing control unit transmits calibration pulses (T0) and detection pulses (T1, T1, ..., TN) in a repetition period. The timing control unit realizes the pulse timing used to control the laser emission module to generate a repetition frequency of 8.2kHz according to the set pulse width value, duty cycle value and pulse repetition frequency, and the duty cycle reaches 65%.

[0030] Step S202: Convert the parallel control signal into a serial signal. The parallel / serial conversion module arranges the transmit calibration pulse (T0) and the detection pulses (T1, T1, ..., TN) in a time sequence, converts them into a series of electrical signal switches, and sends them to the high-speed serial differential output module.

[0031] Step S203: Output high-speed serial differential signal. The high-speed serial differential output module performs serial differential output to the laser emission module drive circuit according to the input signal of the parallel / serial conversion module.

[0032] Step S204: Connect the laser emission module drive circuit. The output interface unit adopts a CML interface, and the input and output are matched, which reduces peripheral devices, is suitable for working in high frequency bands, and provides a small signal swing.

[0033] A fourth aspect of the present invention, as Figure 4 As shown, a differential absorption micro-pulse laser radar water vapor profile detection system is provided, including a differential absorption micro-pulse laser radar transmitting unit 10, a receiver module 20, an integrated transceiver optical cavity module 30, a signal processing module 40 and a display module 50, wherein: The receiver module 20 performs photoelectric conversion to receive the return optical signal on the detection path; The integrated transceiver optical cavity module 30 is used for amplifying the transmitting optical path and detecting the receiving optical path; The signal processing module 40 is used to generate synchronization signals and control signals, and perform joint calculations of online wavelength laser and offline wavelength laser on the collected signals; The display module 50 is used to display the water vapor content results along the detection path.

[0034] In a preferred embodiment, the transceiver integrated optical cavity module 30 includes a collimating lens, a plano-convex cylindrical lens, a 45° reflector, a beam expander, a window, and an integrated casting, wherein: Collimating lens, used to convert the light beam emitted by the laser emission module into a parallel light beam; Plano-convex cylindrical lens, which can be adjusted to focus a parallel beam of light to a single point; 45° reflector, used to change the optical path of the returning laser beam; Beam expander, used to amplify the transmitted and received beams; A window is used to protect the internal optical path of the transceiver integrated optical cavity module 30; One-piece casting for fixed mounting of lenses, beam expanders and windows.

[0035] The integrated casting also includes a fine-tuning structural part for adjusting the position of the collimating lens, the plano-convex cylindrical lens, and the 45° reflector.

[0036] The differential absorption micro-pulse lidar water vapor profile detection system of this application obtains the vertical distribution characteristics of water vapor content by detecting the scattered signal intensity of the pulsed laser by the atmosphere at different altitudes. It has higher time and spatial resolution, better environmental adaptability and daytime detection performance.

[0037] In this embodiment, a differential absorption lidar water vapor profile detection system is provided with an integrated detection process of transmitting and receiving. Figure 5 As shown, the process includes the following steps: Step S301, by establishing an optical model of the lens to calculate the curvature and thickness of the lens, so as to adapt to the integrated transceiver optical cavity module 30 and form the effect of light path collimation. The collimating lens includes an incident surface, a front-stage reflection surface, a rear-stage reflection surface and an exit surface. The light generated by the laser emission module passes through three parts. The first part of the light is emitted from the exit surface at the top of the lens without passing through any optical medium; the second part of the light is refracted by the incident surface and then incident on the rear-stage reflection surface after total reflection from the exit surface, and then emitted from the exit surface after reflection from the rear-stage reflection surface; the third part of the light is refracted by the incident surface and enters the front-stage emission surface, and is emitted from the exit surface through total reflection from the front-stage emission surface.

[0038] Step S302: A plano-convex cylindrical lens is used to focus the parallel light beam to a point through adjustment, which is mainly used to adjust the emission light path; Step S303 , a 45° reflector, the 45° reflector of the transceiver integrated optical cavity module 30 is used to change the optical path of the returning laser beam and irradiate the laser beam to the receiving module after angle calculation.

[0039] Step S304: a beam expander is used to expand the parallel input beam to produce a parallel output beam with a larger diameter, which is mainly used to amplify and enhance the transmitted and received beams; In step S305, the window, primarily a lens, effectively protects the laser emitting module from external interference and damage, such as the adhesion of dust, moisture, and impurities. It also prevents external laser beams or system-generated lasers from bouncing back into the laser emitting module 10, potentially damaging optical components and causing system failure. The window's transmittance reaches 98%.

[0040] Step S306: The integrated casting is used to securely mount the lens, beam expander, and window, and provides a fine-tuning mechanism for adjusting the position of the lenses. The fine-tuning mechanism rotates a threaded rod to adjust the distance between the plano-convex cylindrical lens, 45° reflector, and mounting plate, thereby achieving angle adjustment.

[0041] In this embodiment, the laser emission process of the differential absorption lidar water vapor profile detection system is as follows: Figure 6 As shown, the process includes the following steps: In step S401 , the power supply circuit unit converts the AC 220V mains input into 24V and 5V DC outputs to supply power to the driving circuit unit.

[0042] Step S402, the driving circuit unit includes an analog voltage conversion circuit and a current stabilization circuit; the input end of the analog voltage conversion circuit is respectively connected to the power supply circuit, and is used to convert the DC voltage provided by the power supply circuit unit into an analog voltage; the input end of the current stabilization circuit is connected to the output end of the analog voltage conversion circuit and the PID current unit, and the output end of the current stabilization circuit is connected to the laser diode of the tunable laser unit, and is used to provide a stable current for the tunable laser unit.

[0043] Step S403: The tunable laser unit is composed of a laser diode and a grating. The laser diode continuously outputs narrow-linewidth, tunable laser light, and the grating performs wavelength fine-tuning and scanning.

[0044] The signal receiving and processing flow of the differential absorption lidar water vapor profile detection system is to perform photoelectric conversion through the high-sensitivity receiver module 20 to realize the reception of the received optical signal, such as Figure 7 As shown, the process includes the following steps: Step S501: a photoelectric detector is used to receive a high-frequency laser echo signal and generate an electrical signal accordingly; Step S502: a limiting amplifier circuit amplifies the electrical signal output by the photodetector and suppresses noise mixed in the electrical signal; Step S503: The secondary amplifier circuit performs secondary amplification on the signal output by the limiting amplifier circuit; Step S504: The shaping circuit performs shaping processing on the signal after the secondary amplification and finally outputs a level signal.

[0045] The signal processing flow of the differential absorption lidar water vapor profile detection system is as follows: Figure 8 As shown, the process includes the following steps: In step S601, the synchronization circuit generates a synchronization signal with a differential output signal level in the form of a negative pulse, triggered by the falling edge of a negative pulse, and sent to the laser transmitter module and receiver module 20, respectively. The reference signal frequency is 80 MHz. After power-on initialization, the synchronization circuit operates in a default state, generating corresponding synchronization signals and issuing control words. The synchronization circuit receives the communication control word sent by the main controller via optical fiber and determines whether the data is valid. If valid, the control word is updated, parsed, and issued, while generating the corresponding synchronization signal. Otherwise, if invalid, the previous control state is maintained.

[0046] Step S602, the main controller is responsible for the main control function of the entire differential absorption lidar water vapor profile detection system including the signal processing module 40, the input is the main display control software module data and synchronization circuit pulses, and the main controller outputs the electrical network signal.

[0047] Step S603: The data board is used to obtain the level signal of the receiver module 20, convert it into data information, and perform relevant calculation processing.

[0048] Step S604: The bus interface circuit is used to transmit status information of the main controller and each control unit, and to transmit information between the main controller and the transceiver chip on the data board to complete information interaction.

[0049] In this embodiment, the software display process of the differential absorption lidar water vapor profile detection system, including a software installation package for platform interaction, is deployed on a Windows platform to perform real-time status monitoring and data display of the differential absorption lidar water vapor profile detection system.

[0050] Although the embodiments of the present application have been described with reference to the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present application, and such modifications and variations shall fall within the scope defined by the appended claims.

Claims

1. A differential absorption micro-pulse laser emitting unit, characterized in that: It includes laser emission module, temperature and current control module, and pulse control module, among which: A laser emission module, used for generating online wavelength laser and offline wavelength laser; A temperature and current control module, used to control the temperature and current of the laser emission module to generate online wavelength laser and offline wavelength laser; The pulse control module is used to control the laser emission module to generate micro-pulse laser output at a certain pulse repetition frequency.

2. The differential absorption micropulse laser emitting unit according to claim 1, characterized in that: The laser emission module includes a power supply circuit unit, a drive circuit unit and a tunable laser unit, wherein: a power supply circuit unit, used for supplying power to the driving circuit unit; A tunable laser unit includes a laser diode and a grating. The laser diode continuously outputs narrow-linewidth, tunable laser light, and the grating performs wavelength fine-tuning and scanning. The driving circuit unit includes an analog voltage conversion circuit and a current stabilization circuit; the input end of the analog voltage conversion circuit is respectively connected to the power supply circuit, and is used to convert the DC voltage provided by the power supply circuit unit into an analog voltage; the input end of the current stabilization circuit is connected to the output end of the analog voltage conversion circuit and the temperature and current control module, and the output end of the current stabilization circuit is connected to the laser diode of the tunable laser unit, and is used to provide a stable current for the tunable laser unit.

3. The differential absorption micro-pulse lidar water vapor profile detection system according to claim 2, characterized in that: The temperature and current control module includes a temperature monitoring unit, a temperature control unit, a PID temperature unit, a current monitoring unit, a current control unit and a PID current unit, wherein: A temperature monitoring unit, used to monitor the temperature of the laser emission module in real time; A PID temperature unit is used to determine the target opening of the cooling plate or heating plate inside the PID temperature unit according to the monitoring value of the temperature monitoring unit and the initial temperature distance value, so as to achieve temperature control accuracy; A temperature control unit, comprising a cooling plate or a heating plate, for adjusting the current temperature parameters of the laser emission module and performing cooling and heating control on the laser emission module in real time according to the PID temperature unit; A current monitoring unit, used to monitor the power supply current of the laser emission module driving circuit board in real time; A PID current unit is used to determine a PWM module duty cycle of the PID current unit based on the monitoring value of the current monitoring unit and the initial current distance value, and at the same time, based on the temperature interpolation value returned by the PID temperature unit, so as to achieve current control accuracy; The current control unit is used to adjust the current parameters of the laser emission module and control the power supply current of the laser emission module driving circuit board in real time according to the PID current unit.

4. The differential absorption micro-pulse lidar water vapor profile detection system according to claim 3, characterized in that: The pulse control module includes a timing control unit, a parallel / serial conversion module, a high-speed serial differential output module, and an output interface plug-in, wherein: A timing control unit, used to control the pulse width, duty cycle and pulse repetition frequency of the transmitted pulse; A parallel / serial conversion module, used to convert parallel control signals into serial signals; A high-speed serial differential output module, configured to output the high-speed serial differential signal output by the parallel / serial conversion module; The output interface plug-in is used for signal connection of the laser emission module driving circuit unit.

5. A temperature and current control method for a differential absorption micropulse laser emitting unit, using the differential absorption micropulse laser emitting unit according to any one of claims 1 to 4, characterized in that: Control methods include: Step S101, real-time monitoring of the temperature of the laser emission module; Step S102, cooling and heating control of the laser emission module; Step S103, determining the target opening of the cooling plate or heating plate inside the PID temperature unit according to the monitoring value of the temperature monitoring unit and the initial temperature distance value, so as to achieve temperature control accuracy; Step S104, real-time monitoring of the power supply current of the driving circuit board of the laser emission module; Step S105, controlling the power supply current of the driving circuit of the laser emission module in real time according to the PID current unit; Step S106 , based on the monitoring value of the current monitoring unit and the initial current distance value, and at the same time, based on the temperature difference value returned by the PID temperature unit.

6. The temperature and current control method of the differential absorption micropulse laser emitting unit according to claim 5, characterized in that: The temperature difference control range is between -55℃ and 125℃.

7. A pulse control method for a differential absorption micropulse laser emitting unit, using the differential absorption micropulse laser emitting unit according to any one of claims 1 to 4, characterized in that: Step S201, controlling the pulse width, duty cycle and pulse repetition frequency of the transmit pulse; Step S202, converting the parallel control signal into a serial signal; Step S203, outputting a high-speed serial differential signal; Step S204: connecting the laser emission module drive circuit.

8. A differential absorption micro-pulse lidar water vapor profile detection system, characterized in that: The differential absorption micropulse laser emitting unit according to any one of claims 1 to 4 further comprises a receiver module, a transceiver integrated optical cavity module, a signal processing module and a display module, wherein: The receiver module performs photoelectric conversion to receive the return optical signal on the detection path; The integrated transceiver optical cavity module is used for amplifying the transmitting optical path and detecting the receiving optical path; The signal processing module is used to generate synchronization signals and control signals, and perform joint calculations of online wavelength laser and offline wavelength laser on the collected signals; The display module is used to display the water vapor content results on the detection path.

9. The differential absorption micro-pulse lidar water vapor profile detection system according to claim 8, characterized in that: The transceiver integrated optical cavity module includes a collimating lens, a plano-convex cylindrical lens, a 45° reflector, a beam expander, a window, and an integrated casting, wherein: A collimating lens, used to convert the light beam emitted by the laser emission module into a parallel light beam; Plano-convex cylindrical lens, which can be adjusted to focus a parallel beam of light to a single point; 45° reflector, used to change the optical path of the returning laser beam; Beam expander, used to amplify the transmitted and received beams; A window, used to protect the internal optical path of the transceiver integrated optical cavity module; An integrated casting is used for fixing and mounting the lens, the beam expander and the window.

10. The differential absorption micro-pulse lidar water vapor profile detection system according to claim 9, characterized in that: The integrated casting includes a fine-tuning structure for adjusting the positions of the collimating lens, the plano-convex cylindrical lens, and the 45° reflector.

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