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二氧化硫是大气中最常见、最重要的污染物之一。差分吸收激光雷达探测二氧化硫具有高时空分辨率、高探测精度等优点。用两台Nd:YAG激光器泵浦两台染料激光器后,通过倍频晶体得到测量大气二氧化硫所需的两个波长,它们分别是λon=300.05 nm和λoff=301.5 nm。将两束光束用几组反射镜合为一束光束,经扩束镜6倍扩束后垂直发射进入到大气中。接收望远镜收集两个激光波长的大气后向散射信号,信号采集单元记录两个波长的后向散射回波信号的垂直高度分布。通过数据反演获得二氧化硫的高度分布。初步实验结果表明,实验期间合肥西郊董铺岛垂直高度0.3~1.6 km的二氧化硫在0~14 ppb范围内波动。最后分析并估算了该二氧化硫差分吸收激光雷达的四个主要误差来源。
Sulfur dioxide is one of the most common and important pollutants in the atmosphere. Differential absorption lidar detection of sulfur dioxide with high spatio-temporal resolution, high detection accuracy and so on. After two dye lasers were pumped with two Nd: YAG lasers, the two wavelengths needed to measure atmospheric sulfur dioxide were obtained by doubling the crystals at λon = 300.05 nm and λoff = 301.5 nm, respectively. The two beams with several sets of mirrors into a beam, the beam expander 6 times after the vertical beam expansion into the atmosphere. The receiving telescope collects the atmospheric backscatter signal at two laser wavelengths and the signal acquisition unit records the vertical height distribution of the two-wavelength backscattered echo signal. The height distribution of sulfur dioxide is obtained by data inversion. The preliminary experimental results show that during the experiment, sulfur dioxide with a vertical height of 0.3-1.6 km at Dongpu Island in the west of Hefei fluctuated from 0 to 14 ppb. Finally, the four main sources of error for the sulfur dioxide differential absorption lidar are analyzed and estimated.