Contact-less temperature measurement and control with applications to laser cladding

In material processing, heat input into parts is a major issue. To reduce heat impact, temperatures can be evaluated to optimize processes, i.e., for low distortion, low dilution, or small heat-affected zones. A new sensor, which combines ratio pyrometry with 2D-resolved measurement, is presented and compared to existing temperature sensors in the context of laser processing. The advantages of independence of emissivity and attenuation of the thermal radiation together with 2D temperature information are demonstrated on laser cladding. The temperature distribution at the parts' surfaces becomes available quantitatively and with high precision. This information was successfully applied to determine melt pool diameters, latent heat, as well as to validate FEM-based temperature field simulations.