| Laser system is the core component unit of atmospheric lidar.The development of lidar function and performance highly depends on the laser system,which makes its structure complex,and the requirements for its index accuracy,working stability and intelligent degree are also higher and higher.Especially for the complex lidar system,intelligent and automatic operation is the key to promote the application and popularization of lidar for atmospheric detection.The main research work and innovation of this paper are as follows:(1)a simple and practical multi-channel laser energy monitoring method is proposed,and the simultaneous monitoring of multi-channel,multi wavelength pulse and continuous laser energy is experimentally realized;(2)on this basis,an intelligent frequency stabilization technology scheme based on primary sub frequency discrimination pulse laser energy monitoring is proposed,and the experimental research and research are carried out The results effectively improve the stability and index accuracy of the laser system,and provide an important guarantee for the operation of lidar in complex field environment.The specific research work is as follows:In order to improve the detection performance of lidar and realize the simultaneous detection of multiple parameters,frequency doubling,frequency stabilization,Q-switching,pulse amplification and other technologies are usually used.The use of these technologies makes the laser transmission link more,and any change of laser parameters will affect the detection results of lidar.Therefore,in the operation of lidar,multiple links need to be monitored at the same time.The monitoring data can provide important information for lidar data inversion and real-time diagnosis of lidar operation status.However,the atmospheric lidar uses pulse laser as the transmitting laser,the pulse time is about 10ns,and the repetition rate is low.This makes it very difficult to monitor the laser state parameters of atmospheric lidar.In this paper,based on the atmospheric lidar,the monitoring technology of pulse laser energy change is studied,and the multi-channel single pulse laser energy change monitoring method is proposed.A multi-channel single pulse laser energy change monitoring device for lidar single pulse laser energy change monitoring is developed In this paper,the simultaneous monitoring of multiple parameters of laser output from all elevation lidar is carried out all day.On this basis,using one channel of multi-channel single pulse laser energy change monitoring,a pulse fuel laser frequency stabilization device based on atomic frequency discrimination is built to realize the frequency stabilization of pulse fuel laser.Thus,the monitoring system of pulsed laser is preliminarily formed.Finally,the application of multi-channel single pulse laser energy change monitoring device is prospected.(1)In this paper,the detection theory of pulse optical signal is analyzed,and various single pulse optical signal detectors and their acquisition circuits are introduced.It is analyzed that the random error is large when using point detector to measure a single laser pulse;when using area array detection to monitor,using multiple point detectors on the surface detector can effectively reduce the measurement error.The working principle of photodiode,photocell,pyroelectric detector,photomultiplier tube,solid-state photomultiplier tube,CCD and CMOS are introduced.It is proposed that CMOS is used to detect the single pulse laser signal,which can make the signal-to-noise ratio high and the measurement error small.(2)In order to realize the simultaneous monitoring of multi parameters in the laser transmitting unit of lidar,a multi-channel single pulse laser energy change monitoring method is proposed and a multi-channel single pulse laser energy change monitoring device is developed.The device uses customized multi in one fiber bundle for distributed sampling of the laser to be measured.The output end of the multi in one fiber bundle is not fused,but placed side by side to form the output end face of the fiber bundle,so that it can be distinguished from space.The sampled light of each optical fiber is imaged on the CMOS sensitive surface through achromatic lens.According to the position of the light spot,the photosensitive unit on the CMOS photosensitive surface is detected Each block corresponds to a monitoring channel.A data acquisition software based on Lab VIEW is designed to realize fast data acquisition of multiple channels.Finally,the device is applied to the full elevation all-time atmospheric lidar,and the real-time monitoring of the energy changes of 1064nm,532nm,589nm and ASE light in the full elevation all-time lidar is realized.The frequency doubling efficiency of SHG2 crystal and the conversion efficiency of pulse dye laser are obtained by calculation.(3)This paper introduces the method of atomic mechanism frequency stabilization and pulse dye laser.Based on the above experiments,a pulse fuel laser frequency stabilization device based on atomic frequency discrimination is built by using one channel of multi-channel single pulse laser energy change monitoring.The frequency stabilization control software of pulse dye laser is designed,and the frequency stabilization of pulse fuel laser is realized.Thus,the monitoring system of pulsed laser is preliminarily formed.Finally,the,application of multi-channel single pulse laser energy change monitoring device is prospected. |
