基于Mie散射的可吸入颗粒检测仪的设计

可吸入颗粒物浓度是大气环境监测中的一项重要指标。在Mie散射消光原理的基础上，采用三波长方法并结合了分布式函数算法设计了可精确测量大气中可吸入颗粒物浓度的检测仪器，计算了Mie散射效应中消光因子的光谱依赖关系，在数据处理中对光谱时域信号进行积分从而消除了光谱多峰效应所产生的误差。此检测仪气路部分可实现可吸入颗粒物(PM2.5和PM10)的双通道采集。利用激光光纤将三种不同波长的激光通过耦合器(3合1)耦合进一个光纤后通过样品池，衰减光进行分离后进入光电探测器，由电路模块对探测到的光信号进行转换、数据处理、显示和存储, 并通过3G无线网络实现数据的远程传输和共享。该仪器可以实现可吸入颗粒平均粒径和浓度测量。通过实验验证了检测仪的各项性能指标，数据表明该检测仪的灵敏度为0.01 μg·m-3，响应时间约为90 s，适用于大气中可吸入颗粒物浓度的实时检测。

Design of Inhalable Particulate Matters Measurement Based on the Mie Scattering Extinction

The concentration of inhalable particle is an important indicator in atmospheric environment monitor. Based on Mie scattering extinction, a precise testing instrument which can measure the concentration of inhalable particles at the atmospheric was designed by three-wavelength method in combination with the algorithm of distributed function. The dependence of extinction index on the spectrum was calculated based on Mie scattering theory in this article. Furthermore, the signal of time domain is integrated in the data processing to reduce the effect of error caused by multi-peak of spectra. The PM2.5 and PM10 were collected simultaneously in particle selection. Three different wave-lengths of lasers were coupled into an optical fiber by coupler (3in1) and passed through the sample cell. The attenuated light was detected by a PIN. Output of the detector was converted, amplified, displayed and stored by electronic system. Finally, the data were transmitted and shared in network through the 3G wireless module. The average particle size and concentration of inhalable particles were measured by this device at the same time. The technical specifications of the detector were verified by experiment, the experimental results indicate that the detection sensitivity of the system is 0.01 μg·m-3, the responsive time of system is approximately 90 s and it is suitable for measuring particulate matter concentrations of atmosphere.