Use of Mie theory to analyze experimental data to identify infrared properties of fused quartz containing bubbles

Abstract

An improved method for determining the absorption and scattering characteristics of a weakly absorbing substance containing bubbles is suggested. The identification procedure is based on a combination of directional-hemispherical measurements and predictions of the Mie scattering theory including approximate relations for a medium with polydisperse bubbles. A modified two-flux approximation is suggested for calculating directional-hemispherical transmittance and reflectance of refracting and scattering medium. The complete identification procedure gives not only the spectral radiative properties but also the volume fraction of bubbles and the characteristics of possible impurity of the medium.This procedure is used to obtain new data on near infrared properties of fused quartz samples containing bubbles.

Infrared radiative properties of polymer coatings containing hollow microspheres

“…Not only the total reflectance and transmittance were measured but also their diffuse components, which do not include the specularly reflected radiation and the radiation transmitted in the direction of the incident collimated beam. In contrast to similar measurements for fused quartz containing gas bubbles [8] the spectra of directional-hemispherical reflectance and transmittance are not very noisy. The standard absolute deviation is less than 5% for both transmittance and reflectance in the entire spectral range.…”

“…(1), one can find the average wall thickness d Nomenclature a particle radius A, B, C, D, D 1 , E coefficients in analytical solutions (4), (8) and ( We have no data for the dependence of d(a). For this reason, the further analysis will be based on the results for the following two assumptions:…”

“…The modified two-flux approach suggested in papers [8,11] for the normally incident collimated radiation is applied to the radiation transfer equation for the model transport scattering function. The use of transport approximation enables us to separate the real diffuse component of the radiation field in the case of collimated incident radiation.…”

Modeling radiation characteristics of semitransparent media containing bubbles or particles

“…31 From image analysis of the total number of bubbles Nt=212, the bubbles size distribution was determined and depicted in Fig. 12.…”

“…The spectral value of κ 0 can be recovered from the normal spectral transmittance data denoted by T(λ) based on the relationship between T(λ) and κ 0 in which multiple internal reflections at the sample boundaries are accounted for: 22,31,36 …”