Temperature measurement in laser–metal processing using optical sensing: Radiometric calibration and validation of a multispectral camera

This work establishes a radiometric calibration and validation methodology for a multispectral camera used in laser–metal processing. Capturing multiple spectral bands enables the simultaneous determination of absolute temperature and surface emissivity. The calibrated system reaches around 2% error for solid-state temperature measurement and accurately resolves liquid-phase temperatures during phase transition, providing a quantitative foundation for melt pool thermography in laser-based additive manufacturing.