Implementation of an Interferometric Sensor for Measuring the Depth of a Capillary Laser Welding

The welding laboratory located at the Commissariat a l’Energie Atomique et Aux Energies Alternatives (CEA) Valduc center in France uses pulsed and continuous wave (CW) laser sources to assemble metallic parts of low thicknesses. This article discusses the results obtained by the recent implementation of the In-process Depth Meter (IDM) of PRECITEC keyhole depth measurement sensor in our laboratory. This distance measurement technology uses a Michelson interferometer adapted to the very special conditions of the laser beam welding. Micrographs of pulsed welding tests on 316L stainless steel, TA6V plane sheets butt joints are analyzed and compared to the inline collected signals. The system’s ability to follow dynamically the formation of the keyhole into the molten metal is evaluated and compared to numerical models performed in the lab using the nite element COMSOL Multiphysics software.