Deepak A, Box M A
Appl Opt. 1978 Oct 1;17(19):3169-76. doi: 10.1364/AO.17.003169.
This paper, second of two parts, presents a parametric study of the forwardscattering corrections for experimentally measured optical extinction coefficients in polydisperse particulate media, since some forward scattered light invariably enters, along with the direct beam, into the finite aperture of the detector. Forwardscattering corrections are computed by two methods: (1) using the exact Mie theory, and (2) the approximate Rayleigh diffraction formula for spherical particles. A parametric study of the dependence of the corrections on mode radii, real and imaginary parts of the complex refractive index, and half-angle of the detector's view cone has been carried out for three different size distribution functions of the modified Gamma type. In addition, a study has been carried out to investigate the range of these parameters in which the approximate formulation is valid. The agreement is especially good for small-view cone angles and large particles, which improves significantly for slightly absorbing aerosol particles. Also discussed is the dependence of these corrections on the experimental design of the transmissometer systems.
本文是两篇系列文章中的第二篇，针对多分散颗粒介质中通过实验测量的光学消光系数的前向散射校正进行了参数研究，因为总会有一些前向散射光与直射光束一起进入探测器的有限孔径。前向散射校正通过两种方法计算：（1）使用精确的米氏理论，（2）针对球形颗粒的近似瑞利衍射公式。针对三种不同的修正伽马型尺寸分布函数，对校正量与模式半径、复折射率的实部和虚部以及探测器视锥半角之间的依赖关系进行了参数研究。此外，还进行了一项研究，以探究近似公式有效的这些参数范围。对于小视锥角和大颗粒，两者的一致性特别好，对于略微吸收的气溶胶颗粒，一致性显著提高。还讨论了这些校正量对透射仪系统实验设计的依赖性。
