Pixel-wise in situ calibration method for high accuracy infrared thermography of moving targets
K. H. Schweikert, Axel Sielaff, Peter Stephan
Abstract
We present a calibration method for the measurement of temperature using infrared cameras that enables high-accuracy thermography of moving targets with locally varying emissivity. Correlation-based image matching techniques are applied to calculate position-dependent calibration functions with sub-pixel accuracy. The calibration method is described in detail and demonstrated using an experimental setup consisting of a rotating cube. The measurement uncertainty is analysed in comparison to a conventional pixel-wise in situ method used for non-moving measurements. An analysis is carried out for varying levels of sub-pixel resolution and within different regions of the field of view. The results show that the measurement uncertainty decreases with increasing sub-pixel resolution and is comparable to levels obtained with a pixel-wise in situ calibration applied on a non-moving target. The error introduced by the motion of the sample was reduced by 75% on a high emissivity surface and by 96% within an area of the field of view, which experienced significant emissivity changes due to the motion of the sample.