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ENCIT 2020
18th Brazilian Congress of Thermal Sciences and Engineering
Methodology to Evaluate the Accuracy of Thermal Camera's Non-uniformity Correction Using Raw Data and a Blackbody Radiator.
Submission Author:
Vitor Furtado Paes , MG , Brazil
Co-Authors:
Vitor Furtado Paes, Rafael Augusto Magalhães Ferreira, Matheus Porto
Presenter: Vitor Furtado Paes
doi://10.26678/ABCM.ENCIT2020.CIT20-0740
Abstract
Herein we introduce a novel methodology to estimate the measurement uncertainty of thermal imagers due to the non-uniformity correction (NUC) procedure. NUC technique is largely discussed in the literature, on the other hand, its metrological accuracy is not so often debated. NUC is the most important step during the calibration of thermal imagers, and it corrects the precision of each pixel in the matrix. Despite being an efficient method to mitigate spatial noise (spatial precision), the NUC method does not provide a temperature correction, thus it must be made in a similar fashion as for the calibration of thermocouples. The scientific community fails not providing a gold standard method to relate non-uniformity correction procedures with temperature uncertainty. In this study, we introduce a novel method to mitigate the aforementioned issues, proposing to evaluate the uncertainties of the traditional two-point NUC using raw data and a blackbody radiator as the reference source. Three thermal imagers were tested under controlled conditions and the results for the performance evaluation of the NUC model show that the two-point NUC technique is an efficient method to reduce spatial noise in a narrow range of operation. The uncertainty propagation showed that the components related to the blackbody radiator were dominant in the proposed model, followed by the standard deviation and correction model uncertainties. To fully categorize the uncertainties in the correction model, a further examination of the thermal imager components must be made, considering the spectral response, intrinsic errors and detector's self emission.
Keywords
Infrared Termography, calibration, Spatial non-uniformity
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