LEDs-DOAS系统的标定及反演方法研究

针对氙弧灯作为主动差分吸收谱(DOAS)宽带热光源带来严重的能源浪费和一些不必要的干扰,提出采用新型冷光源—发光二极管(LEDs)作为光学遥感DOAS系统的光源。研究了LEDs-DOAS系统的标定及反演方法,首先介绍了LEDs-DOAS光学遥感系统的结构,分析了其获取痕量气体大气浓度的原理;然后通过把具有线状吸收谱特性的汞灯光引入到LEDs-DOAS仪器,得到仪器函数,对系统进行标定;再把标准库待测气体的吸收截面和仪器函数卷积,得到该痕量气体的在LEDs-DOAS仪器吸收强度,并基于最小二乘原理反演痕量气体的大气浓度;最后利用NO2样品标定LEDs-DOAS系统的测量精度,实验结果表明,测量误差小于5%。

Study on calibrating and inversing method of light emitting diodes-differential optical absorption spectroscopy

In order to avoid the serious energy w astage and unnecessary interference using xenon arc lamps as the broadband hot l ight source in active differential optical absorption spectroscope (DOAS) system s,the light emitting diode (LED) is developed as a new type of cold light source for optical remote sensing DOAS systems in this paper.A study on calibrating an d inversing method of light emitting diodes differential optical absorption spec troscopy (LEDs-DOAS) system is introduced.Firstly,the structure of LEDs-DOAS s ystem is described,and the inversing principle of atmospheric trace gases concen trations is analyzed based on the differential absorption of trace gases.The lin e-shaped absorption spectrum of Hg lamp is introduced into LEDs-DOAS instrumen t to get the instrument function.The standard absorption section of trace gas is convoluted with the instrument function.Then the absorption strength of the tra ce gas is gained by the LEDs-DOAS system.Concentrations of trace gases are retr ieved based on the least-squares fitting method.At last,the NO_2cells are al so used to test the accuracy of the LEDs-DOAS system.Experimental results show that the measuring relative error is less than 5%,which demonstrates that the li ght-emitting diode as a light source of LEDs-DOAS system is feasible and relia ble to measure the atmospheric trace gases.