为了对重化工污染区甲醛气体进行探测，开展了差分吸收激光雷达甲醛气体浓度探测研究。基于差分吸收激光雷达原理，针对甲醛气体在中红外波段有较强的吸收波段，并考虑开放光程下大气干扰气体的影响，选择了系统的探测波长 ${\lambda _{\rm on}}$、 ${\lambda _{\rm off}}$；依据差分吸收激光雷达浓度反演方法，结合系统参数，对设计的DIAL系统的探测距离、气体浓度及干扰气体的可能影响进行了仿真研究。结果表明，该系统有望对浓度为0.017~1.5 ppm (1 ppm=10⁻⁶)，距离为0.4~1.1 km范围内的甲醛气体进行探测，相对误差小于5%，可满足对重化工污染区甲醛气体浓度探测需求。文中的研究可为应用于化工重污染区域甲醛气体无组织排放监测的中红外差分吸收激光雷达系统的研制提供理论依据和技术基础。

In order to detect formaldehyde gas in severe chemical pollution area, the research of concentration detection for formaldehyde by differential absorption lidar (DIAL) is carried out in this paper. Based on the principle of differential absorption lidar and the strong absorption of formaldehyde gas in the mid infrared band, the detection wavelengths of ${\lambda _{\rm on}}$ and ${\lambda _{\rm off}}$for the formaldehyde are selected in consideration of the influence of atmospheric interference gas under open optical path. According to the concentration inversion method of differential absorption lidar and combined with the system parameters, the effects of the detection distance, gas concentration and interfering gas on the system perform are studied. The results show that the system can detect formaldehyde concentration in the range of 0.017-1.5 ppm (1 ppm=10^-6) and within the distance of 0.4-1.1 km, and the relative error is less than 5%, which can meet its demand for formaldehyde detection in severe chemical pollution area. This paper can provide a theoretical and technical basis for the development of mid infrared differential absorption lidar system for monitoring the unorganized emission of formaldehyde in severe chemical pollution area.