Ensuring metrological traceability in the field of radiation thermometryMlačnik, Vid (Avtor) Pušnik, Igor (Mentor) traceabilityradiation thermometrymodel of radiation thermometrymeasurement uncertaintyemissivity evaluationreal conditionsThis dissertation establishes a comprehensive framework for ensuring metrological traceability in radiation thermometry, extending from ideal black-body calibrations to real-world measurements of non-ideal emitters. Current calibration practices rely on black-body radiation thermometry (BBRT), where traceability is well defined however, this method is not traceable in practical conditions with nonideal emissivity. In practice, grey body radiation thermometry (GBRT) model is used, which is not totally compliant with the use in real conditions, as it is not clear, how the theoretical model of radiation thermometry of grey bodies could account for specrtral properties of measured surface, environmental and atmospheric influences. Traceable measurements using this model are therefore only possible under simplification to scalar emissivity, with increased emissivity uncertainty, corresponding to spectral variability of spectral emissivity in operating spectral range of the measurement instrument. In established Established practices therefore prefer experimental evaluations of instrumental emissivity evaluation. To address this problem, a physical and inverse model of radiation thermometry were developed, allowing traceable temperature measurements for both black and real bodies. The influence of atmospheric transmissivity, previously often assessed from uncertainty budgets or rarely empirically measured for specific devices, was quantified through a spectral model derived from HITRAN data base and validated against experiments, demonstrating that atmospheric effects can significantly contribute to measurement uncertainty. A Monte Carlo simulation was then applied to propagate spectral and emissivity-related uncertainties, enabling robust evaluation of nonlinear system behavior. Building on this, traceable methods for emissivity evaluation were derived and tested. A spectral approach enables conversion of emissivity spectra into effective instrumental parameters, while an experimental method combines radiation and contact thermometers to directly evaluate effective emissivity and its uncertainty. Comparative analysis demonstrated convergence of both methods for stable samples, while highlighting sample instability and inhomogeneity as dominant contributions to uncertainty. The contributions of this research extend traceability beyond laboratory calibration to practical radiation thermometry, which is already widely spread, ensuring reliable uncertainty evaluation under realistic measurement conditions. By addressing atmospheric effects, defining a traceable model of real-body emissivity compensation, and developing validated emissivity evaluation methods, this work significantly advances the reliability and applicability of radiation thermometry in science and industry.20252025-11-21 14:20:03Doktorsko delo/naloga176113VisID: 61155COBISS_ID: 258236163sl