Applications of Radiometric Measurements in Non-Contact Thermometry and Mesopic Photometry: Dissertation

Radiometry deals with the measurement of electromagnetic radiation, its power and spectral and spatial distributions. Radiometric measurement techniques find use in many practical applications, including the measurement of visible light and its colour in photometry, measurement of temperature in pyrometry, chemical composition and physical properties in spectroscopy. The two main focus areas in this thesis are the non-contact measurement of temperature of a microscopic object and the practical application of mesopic photometry. The subject in the study of the non-contact temperature measurement was a silicon microbridge emitter. The temperature of the microbridge was determined from its radiance spectrum in the visible and near-infrared regions. In contrast to previous studies, a grey body assumption was not used, and the determination of temperature was done by modelling spectral emissivity of the multi-layered structure of the microbridge. To accurately model the emissivity, the optical properties of the silicon at high temperatures were studied, which was not previously done for silicon with high doping concentrations. The extinction coefficient was determined from the radiance of a test sample placed in a furnace. Mesopic photometry is a relatively new technique for measuring light, which takes into account the change of visual response in the overlapping region between the so-called day and night visions in the human eye. In this thesis, a novel dual channel photometer developed and characterised for the measurements in the mesopic luminance range is presented. The recommended system for mesopic photometry was published by the International Commission on Illumination (CIE) in 2010, and it provides mathematical tools for calculating mesopic quantities. The CIE mesopic system was studied in detail for this thesis and its applicability was analysed for all possible conditions in the mesopic range. Two problem areas were discovered at the edges of the mesopic range, where the mathematical model either did not converge or exhibited discontinuity. As a practical solution, a set of parameterised equations is presented that provides closed-form solutions and continuous transitions, with minimal deviation from the CIE system.