Control Software And Experimental Study On Mid-infrared DIAL

Differential absorption lidar has the advantages of high spatial resolution,fast scanning speed and high detection sensitivity.It is widely used in remote sensing of the atmosphere,oceans,and land.In the field of atmospheric detection,the concentration of trace gas can be real-timely distributed in real time.while the mid-infrared band covers the absorption peaks of many inorganic molecules and organic molecules,it has great potential advantages in the detection of atmospheric pollution and makes full use of the typical window absorption characteristics of atmospheric gases in the mid-infrared region.As a new measure of air pollution gas emissions in recent years,the research of mid-infrared differential absorption lidar is critical to the monitoring and management of atmospheric pollution.This article is based on the mid-infrared differential absorption laser radar(MI-DIAL)system research and development,researched data acquisition and experiment.Based on the principle of differential absorption lidar,this paper introduces the theoretical basis,system structure,design parameters and system workflow of mid-infrared differential absorption lidar system.In the Labview compiling environment of the acquisition card,a data acquisition code was developed based on the system algorithm.The pulse accumulation average and five-point sliding combined with multiple correlation detection methods were used to process the echo signals and the measured gas concentration information was displayed in real time.The simulation results show that the error of the inversion result of N02 gas concentration within 1km is ±0.1 mg/m3,which indicates that the combination of the above inversion method can effectively suppress the noise and is beneficial to the extraction of effective signals.Based on the data acquisition and data inversion methods,designs system control software which includes data acquisition,data inversion,data display,simulation module and scan-head control module.The interface design is reasonable and easy to operate.On the basis of this control software,a series of hard target experiments for proving prototype system detection capabilities were conducted and the system’s detection capabilities were effectively evaluated.The results show that the experimental system can detect hard target echo signals within 1 km,atmospheric aerosol echo signals,smoke and water fog echo signals.The signal processing results confirm that the data acquisition procedures and inversion methods can effectively eliminate errors.Programs and inversion methods can effectively eliminate errors.At the same time,the absorption spectrum of multiple absorption baths was compared with that of HITRAN database,and the correlation was 92.01%.Based on this,we select nitrogen dioxide measurement wavelength pair on the measured absorption spectrum.