差分吸收激光雷达是高精度测量大范围二氧化氮浓度的有效途径。介绍了差分吸收激光雷达原理及系统结构, 基于可调谐固体激光吸收技术, 以0.01 nm为步长, 测量了二氧化氮在3.410~3.435 μm吸收光谱, 实验结果表明, 在1.0 atm(1 atm=1.013×105 Pa)、25 ℃情况下, 所测吸收光谱与模拟计算吸收光谱相关系数为92.01%, 基于实测吸收光谱分析确定了二氧化氮测量激光波长对为on-line 3.424 μm、off-line 3.414 μm。并研究了差分吸收激光雷达二氧化氮测量信号预处理方法和去噪算法, 仿真计算结果表明, 采用信号预处理结合多重自相关检测法, 可有效将1 km内模拟探测所得二氧化氮浓度反演结果误差降为±0.1 mg/m3。

Differential absorption lidar(DIAL) is an effective way to measure the concentration of nitrogen dioxide in extensive air with high precision. Based on the tunable solid-state laser absorption technique, the principle and systematic structure of differential absorption lidar were introduced. The absorption spectra of nitrogen dioxide in the range from 3.410 μm to 3.435 μm were measured with a step of 0.01 nm. The experimental results show that the correlation coefficient between the measured and the simulated absorption spectrum reaches to 92.01% at the standard condition (i.e., 1.0 atm, 25 ℃). Based on the analysis of measured absorption spectrum,the laser wavelength pair which includes the on-line 3.424 μm and the off-line 3.414 μm is determined. In addition, the signal pre-processing and denoising methods were studied. The simulation results show that the concentration errors of nitrogen dioxide can be less than ±0.1 mg/m3 within 1 km by combining the signal pre-processing and the multiple autocorrelation.