双散射角光学粒子计数器测量气溶胶折射率的新方法研究

根据米氏(Mie)散射理论,通过数值模拟分析了气溶胶折射率虚部n_i在不同散射角度上对双散射角激光光学粒子计数器(L-OPC)响应曲线的影响,定义了敏感函数。根据分析,散射角应该在小于20°和40°～60°之间选取。以散射角系统ψ=9°,β=5°,λ=0．65μm和ψ=50°,β=20°,λ=0．65μm为例,其中一个散射角受折射率虚部n_i的影响较小,另一个较大。在测量粒子谱分布的同时,利用n_i对不同散射角度响应曲线的影响差异,来确定n_i值,并提出确定n_i的方法。还给出了双散射角激光光学粒子计数器的模拟测量结果。

New Method to Deduce Imaginary Part of Refractive Index of Aerosol with Double-Scattering Angles Laser Optical Particle Counter

The sensitivity of a laser optical particle counter (L-OPC) measuring to the refractive index of particles is analysed, and the dependence of response on ni, the imaginary part of the refractive index is discused. Sensitivity function fi is defined. A scattering angle less than 20° is chosen and another is between 40° and 60° according to analysis of theory. For example, scattering angles system ψ=9°, β=5°, λ=0.65 μm and ψ=50°, β=20°,λ=0.65 μm, the one is slightly not effacted by ni, the other is greatly. By useing different sensitivity of different scattering angles to ni, the value of ni can be deduced from the measurement by a laser optical particle counter of double scattering system. The simulation method will be used to deduce ni.