Measurement of the complex refractive index of particles based on Mie theory and transmission method

The optical constant of particles is not equal to that of the material which makes of them. In both theory and wide practical use, it is significant that the radiation properties of a particle and assemble particles are researched with its spectral complex refractive index. The complex refractive index of a particle cannot be directly measured experimentally, since there is not direct measurement instrument. It has to be inversed through other quantity from experimental measurement and associative theoretical model. The solving process belongs to inverse problem. According to the simplified Mie scattering theory and Kramers-Kronig relation expression, the transmissivity of Al2O3 particles and coal ash particles were measured experimentally with a FTIR spectrometer, and combining associative theoretical model, their complex refractive indexes were inversely solved. The influence of the transmissivity measurement error on the inversed results was analyzed.