Radiative properties of opaque materials, examination of experimental methods, measurements of emissivity of metallic compounds, analysis of oxidised layers and modelling

This research thesis addresses the interaction between electromagnetic waves and matter while taking polarization into account. After having reported a bibliographical study, the author reports the study of electromagnetic flow sensors, of their theoretical and technological limits which define the minimum detectable flow. An experimental installation is then presented. Then, after a review of reflectometers with specular reflecting surfaces, the author shows that a uniform and isotropic flow, necessary for the determination of the directional hemispherical reflectivity, can be obtained by using a specific surface, named Fokon. A study performed by using Monte Carlo methods and ray tracing methods allows the quality of radiation uniformity and isotropy to be assessed. Diffuse reflection reflectometers are then studied. A technical adaptation is proposed to improve their performance. Analytical calculations and calculations based on a Monte Carlo method are performed. The apparatus sizing, its operation domain, and corrective terms to be applied to measurements are also indicated. After a theoretical recall, monochromatic, directional and polarised emissivities are computed for iron, nickel, chromium and more or less oxidised steels. Bibliographic data and sample analysis by optic spectroscopy lead to the proposition of structures for surface layers. Measured and computed values of emissivities are compared and discussed