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。

Light-emitting diode (LED) is a promising new type of light source for differential optical absorption spectroscopy (DOAS). Fabry-Perot etalon structures in the emission spectrum of some LED, however, influence DOAS retrievals. The cause of emergence of these structures in a blue LED (Luxeon, LXHL-LR3C) and the relation between them and the angle of incidence are analyzed. The emission spectrum of LED may become smooth by tilting the LED in the fiber coupling so as to remove the etalon structures. Long-path DOAS measurements on atmospheric NO2 are carried out with the LED with four different angles of incidence and the measurement results are compared with these of conventional long-path DOAS with an arc lamp. The results show that NO2 concentrations are in very good agreement with one another when tilting angle is 30°. The detection limit of long-path DOAS measurements with the LED is only about 13% of that without tilting LED. These prove that if selected angle of incidence is so appropriate that the spectrum of LED becomes smooth, the influence of etalon structures of LED on DOAS retrievals can be effectively removed.