The increasing trend towards electrification creates new challenges for electrical contacts, which can generate a high electrical and thermal conductivity. With the usage of high brightness fiber laser sources small laser spots can be realized which allows a stable keyhole-based deep penetration welding process even in copper and aluminum. Unfortunately, these small laser spots lead to a small connection area between the two joining partners, which reduces the mechanical resistance and the electrical conductivity. To avoid these small connection areas, spatial power modulation — a linear feed with superposed circular motion — has been introduced. The additional parameters of oscillation frequency and amplitude enable new strategies to control and optimize the efficiency of the laser welding process leading to an increased molten volume of the seam. The raise of the efficiency can be caused by a higher energy input in relation to a conventional laser welding process.
This paper presents recent results on the energy input of a laser micro welding process by using spatial modulation for different regimes of molten pool movement. The welding process is realized inside an integrating sphere which detects the reflected radiation by using photodiodes. Furthermore, we discuss effects of the spatial power modulation - in particular the different path speed – on the incoupling energy.