基于CCD后向散射激光信号的PM2.5测量研究

Measurement of PM 2.5 Concentration Based on the Charge-Coupled Device Backward Scattering Lidar

根据米散射理论和激光传播方程,建立PM 2.5颗粒物浓度与后向散射光强的关系模型,并提出了基于电荷耦合器件(CCD)后向散射激光雷达的实时PM 2.5颗粒物浓度的监测方法。设计了以532 nm波长的激光器为光源、CCD为接收器的后向散射激光雷达实验装置。根据获得的实时大气颗粒物后向散射图像,提取灰度值矩阵并分析了散射图像的光强分布;对比赛默飞世尔科技公司的PM 2.5监测仪(SHARP)的实验结果,拟合了PM 2.5颗粒物浓度与散射光强的5个关系式,拟合度均在0.95以上。这种成本较低、操作便利的实时PM 2.5颗粒物浓度监测装置的推广,有助于建立PM 2.5污染物的分布和运动模型并绘制污染地图,具有重要意义。

A theoretical measurement model of atmospheric particulate concentration is built, considering Mie scattering theory and laser propagation equation. An experimental device is designed to monitor the real-time PM 2.5 concentration is introduced by using a charge-coupled device （CCD） backward scattering lidar. The experimental system consists of a 532 nm wavelength laser as the light source and a CCD as detector of back scattering light. According to the real time image captured by the CCD, the gray level value matrix is extracted, while the intensity distribution of the scattering image is analyzed. Compared with the results of a PM 2.5 monitor for Thermo Fisher Scientific Company, five formulas about PM 2.5 concentration and scattering lighting are concluded with a fitting degree better than 0.95. A further popularization of this atmospheric particulate concentration monitoring device which is low in cost and convenient in use, will play a significant role in investigating the movement of PM 2.5 and depicting pollutant distribution.