Stabilization of the vapor capillary by additional intensity maxima along the beam axis

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Deep penetration laser beam welding offers the possibility of producing welds with a high aspect ratio (great depth with small width) with comparatively low heat input into the component. The laser radiation can penetrate deep into the material through the vapor capillary (keyhole). By varying the energy input into the vapor capillary, the dynamic process behavior can be significantly influenced. The aim of this research project is to increase the welding depth in deep penetration laser welding while at the same time reducing the formation of pores and spatter through targeted optical design with otherwise constant process and system parameters. The challenge lies in the fact that the keyhole depth for given process parameters in laser deep penetration welding is usually limited by the reduced intensity at the capillary bottom. The project is based on the assumption that an increase of the achievable capillary depth as well as a stabilization of the capillary dynamics can be achieved by a modification of the energy input in the form of a suitable axial beam shaping.