Research On 532nm Doppler Lidar Based On Triple Fabry-Perot Interferometer For Troposphere Wind Field

The wind field is a very important atmospheric parameter.Wind is the main driving force of water vapor,aerosol,carbon cycle and air-sea exchange.For a long time,the atmosphere from the boundary layer to the stratosphere(approximately 2km?15km)lacked specific atmospheric wind field remote sensing equipment,resulting in a lack of continuous atmospheric wind field data,thus limiting scientific research on the atmosphere.Doppler lidar is a new type of atmospheric wind field remote sensing detection device developed in the past 30 years.It has a greater improvement in space resolution,angle azimuth,integration time and maneuverability than traditional sonar and microwave radar.It is the current research hotspot and has broad application prospects.This article focuses on the design and development of the Rayleigh-Mie Doppler lidar system for detecting troposphere atmospheric wind field,including system parameter optimization and hardware design,key technology research on frequency stabilization and frequency locking,wind field inversion method research,and field comparison Experiment and error analysis.The paper firstly introduces the design and development plan of the Rayleigh-Mie Doppler lidar to detect the troposphere atmospheric wind field.The optimized design of the FP etalon for the core frequency discrimination device of the wind measurement lidar is carried out.The results are:FSR=8GHz,F WHM=1GHz,and the peak spacing between the two edge channels is 3.48GHz.Secondly,the system is simulated according to the design indicators.The simulation results show that in the detection of the troposphere wind field,the wavelength of 532nm is the most advantageous.The 800mm telescope and the Nd:YAG laser of single pulse energy of 800mJ are selected.Furthermore,the entire system is optimized for design,including the transmitting subsystem,the receiving subsystem,the transceiver optical subsystem,the rotating system,and the square cabin layout of the entire system.The frequency drift of the emitted laser and the FP spectrum drift will increase the measurement error of the wind field.So the method of combining absolute frequency stabilization technology and relative frequency locking technology are adopted.Firstly,to eliminate the long-term drift of the laser frequency,a temperature control box for the seed laser is designed and developed.To reduce the short-term jitter of laser,the frequency stabilization system with the iodine molecular absorption cell is developed and it finally stabilizes the frequency of laser within±8MHz.Secondly,the scanning calibration of the FP etalon is introduced by with the continuous light and pulsed light,and the scanned transmittance curves with various fitting methods are compared.Finally,in the relative frequency-locking technology,the relative locking scheme of the emitted laser frequency and the FP etalon spectrum is improved.The pulse signal is directly collected through a high-speed acquisition card,and the pulse signal integration method is used instead of taking the pulse peak to obtain the pulse signal more accurately.The intensity improves the frequency locking accuracy,so that the emitted laser frequency is always kept near the cross point of the FP etalon spectrum.The frequency locking accuracy reaches 3.7MHz.In the wind field inversion method,the horizontal wind field is inverted through three steps,including FP etalon transmission curve calibration,radial wind speed inversion and horizontal wind field synthesis.The method of inversion of aerosol scattering signal and molecular scattering signal in the lower atmosphere is introduced.In the measurement of the wind field,the spatial and temporal resolution of the single radial wind speed measurement is 2min and 75m,the system has the wind field detection capability in the height range of about 10km and 17km during the day and night,respectively.The horizontal wind speed and direction data observed by the Doppler lidar and sounding balloon have a good agreement within 2.7km?10km at daytime and 1.5km?10km in evening.The deviation of 70.8%of the horizontal wind speed and wind direction data at night is less than 2m/s and 10°,95%of the horizontal wind speed and wind direction data deviation is less than 5m/s and 15°,which fully verifies the accuracy of the wind speed measurement results by Doppler lidar.