论文部分内容阅读
发光二极管(LED)作为一种新型光源,应用于差分吸收光谱技术(DOAS)中具有较大潜力。但一些LED灯谱中的法布里-珀罗标准具结构影响DOAS的反演。分析了一种蓝光LED(Luxeon,LXHL-LR3C)灯谱中出现标准具结构的原因,研究了这些结构与入射角度之间的关系。通过改变LED的入射角度,可以使LED灯谱变得平滑,达到去除LED标准具结构的目的。在长光程DOAS上进行了四种不同入射角度下测量大气NO2的实验,并与传统的氙弧灯长光程DOAS测量结果进行了比较。结果显示,当LED倾斜30°入射时,两者的测量结果有很好的一致性,系统的探测极限也只有正入射时的13%左右。说明只要选择合适的入射角度,使LED谱平滑,就可以有效去除LED标准具结构对DOAS反演的影响。
As a new light source, light-emitting diodes (LEDs) have great potential for application in differential absorption spectroscopy (DOAS). However, the Fabry-Perot etalon structure in some LED spectrometers affects the DOAS inversion. The reason for the appearance of etalon in the spectrum of a blue LED (Luxeon, LXHL-LR3C) is analyzed, and the relationship between these structures and the incident angle is studied. By changing the angle of incidence of LED, LED light spectrum can be smoothed, to achieve the purpose of removing the LED etalon structure. The experiment of measuring atmospheric NO2 under different incident angles was carried out on the long-path DOAS and compared with the traditional long-path DOAS measurement of xenon arc. The results show that when the LED is tilted 30 ° incidence, both measurements are in good agreement, the detection limit of the system is only about 13% of normal incidence. As long as the appropriate angle of incidence is selected and the spectrum of LED is smooth, the influence of LED etalon structure on DOAS inversion can be effectively removed.