REFLECTOMETRY MODEL OF A SELF-CALIBRATING INTEGRATING SPHERE

Reported measurement methods for determining emissivity, reflectivity and absorptivity of materials have tended to disregard contributions arising from total internal reflections of the primary signal. In this book, a self-calibrating mathematical model has been developed that takes care of contributions from internally reflected radiation. The model considers both specimen and standard samples in the form of a flat strip placed simultaneously in their respective sphere apertures as incident laser radiation tuned at 900nm is alternately targeted at them. Emissivity is found to depend on reflectivity. Spectral directional-hemispherical reflectivity of the specimen is determined in relation to known reflectivity of BaSO4 reference sample using integrating sphere reflectometry. This model can be used in simulated experiments to assess the magnitude of specific phenomena due to temperature transients in a specimen in relation to sphere geometry and to specific thermophysical properties of the material. The book can be used by students and researchers interested in modeling thermal processes while workers in metal industry would find it useful in metal casting simulations.