Development of a hyperspectral imaging technique for monitoring laser-based material processing

In this paper, a new observation technique for monitoring laser-based material processing on the basis of hyperspectral imaging (HSI) is presented. HSI techniques integrate both spatial and spectral information upon the object/process to be investigated. Essentially, the spectral information can be used to derive the absolute temperature of the object/process. The presented observation tool employing HSI-techniques comprises a high-speed camera and a self-developed HSI-lens system. It offers a time resolution in the microsecond-range and a spectral resolution of ∼4 nm. A proof-of-concept of temperature determination based upon HSI-derived spectra is given, and the initial observation results of the laser welding process are presented. These observations include the temperature evolution of the melting process of two different metal alloys over time. Moreover, we can show that the maximal temperature in the process zone does not exceed the evaporation temperature when processing construction steel and aluminum.