前向散射和衍射对气溶胶消光特性测量的影响

摘要

The optical transmissivity is usually used to evaluate the properties of the aerosol. However,forward scattering and diffracting light by particles might reach the detector and would be incorrectly recorded,which would result in that the final optical density and experiment extinction cross section is erroneously low. The beam efficiency and effective extinction cross section are introduced to examine the error. The results indicate that the distance between the aerosol and the detector must be large enough in order to alleviate to error.%气溶胶的消光特性通常利用所测得的透过率来计算得到.然而,在透过率测量中,粒子的前向散射和衍射光将到达探测器,增强了透射光,从而导致计算所得到的消光截面积等参数变小.本文引入束效率因子和有效消光截面来考察上述影响,得出的结果表明,粒子的散射相函数分布决定了误差的大小,为了减小前向散射和衍射带来的误差,气溶胶和探测器之间的距离应尽可能的大.