Correcting the Influence of the Angle-Dependent Emissivity on Pyrometric Temperature Measurements for Laser Processes

Abstract Pyrometric temperature measurements, commonly used for quality assurance in laser processes, face a significant challenge due to the angle-dependence of the emissivity, as the local geometry can vary significantly during laser processing. If the emissivity changes during the measurement due to a change in the local inclination angle, this can lead to incorrect temperature measurements for a measurement in single-color mode. Therefore, this paper presents an approach to correct the influence of the angle-dependent emissivity on the pyrometric temperature measurements by simultaneously measuring the surface temperature and the geometry. The approach is demonstrated on test samples made of copper with a defined geometry. The corrected temperatures are in good agreement with a reference measurement for all samples tested, showing that the correction was successful and that the influence of the angle-dependent emissivity can be compensated.