Determination of the optical constants of high temperature monodisperse particles

Based on the concept of equivalent spectral transmittance ratio (ESTR), an inverse model has been developed to determine the optical constants of the high temperature particles. Combined with the Mie theory and Kramers-Kronig (K-K) relations, the complex refractive indices of the high temperature particles are retrieved with forward simulation of the complete radiative transfer equation (RTE). In order to validate the present model, the optical constants of the fly-ash particles available in the references are selected as the 'true values', and the direct simulation values of ESTR in one-dimensional (1D) slab by Monte Carlo method are regarded as the 'experimental values'. Good agreement was obtained between the retrieved optical constants and the known 'true value'. The influence of measurement error on the inverse results was also investigated. All the results show that the proposed inverse model could be used to determine the optical constants from the in-situ ESTR measurements of high temperature particles effectively, which is more important for directing the experiment of retrieving optical constants of high temperature particles in the further research.