NO2双通道光谱成像定量监测技术研究

Research on quantitative monitoring technology of NO2 dual-channel spectral imaging

二氧化氮(NO)是危害环境和人类健康的主要污染气体之一,需要对其排放进行监测以实现更好的治理。现有成像监测方法具有大范围实时的优点,但存在重建背景准确性和适用性不足的问题。本文提出了一种利用双通道光谱图像对气体浓度进行定量监测的方法,通过405和470 nm双通道光谱图像反演NO浓度,开展了以下理论与实验研究:进行了理论推导,得到气体柱浓度与双通道光强比之间的关系式;分析了双通道曝光时间对标定公式的影响,比较了采集的双通道光强比值与理论值,两者相差0.26%;采集了北纬26.08°不同气象条件的太阳散射辐射光谱,给出了不同太阳天顶角下的双通道光强比经验值;对探测相机系统性能进行了分析,探测限为19.6×10m^(-6);浓度标定与反演实验给出了标定函数,反演了扩散中的气体浓度二维分布图,验证了双通道光谱成像方法定量检测气体浓度的可靠性。

As a main pollution gas, the emission of NOis endangering to the environment and human health, which should be monitored to achieve better governance. The existing imaging detection methods possess the advantages of a wide application range and good real-time performance, while accuracy and applicability are concerned in the reconstruction background. A method for quantitatively monitoring gas concentration using images of dual-channel target gas is proposed in this study. The NOconcentration is retrieved from the ratio of 405 and 470 nm dual-channel light intensity, and the following theoretical and experimental research is carried out. Specifically, the relationship between gas column concentration and dual-channel light intensity ratio is obtained according to theoretical derivation. The effect of the dual-channel exposure time on the calibration equation is analyzed. The collected dual-channel light intensity ratio is compared with the theoretical value, and the difference between them is 0.26%. The optimal value of dual-channel light intensity ratio under different solar zenith angles is measured by collecting the solar scattered radiation spectra at 26.08° north latitude under various meteorological conditions. The performance of the detection camera is analyzed, and the detection range is 19.6 ppm m. Concentration calibration and retrieval experiments give a calibration function, retrieve the two-dimensional distribution of gas concentration in diffusion, and validate the reliability of the dual-channel spectral imaging method for quantitative detection of gas concentration.