Pulsed laser beam welding is an established process when it comes to welding of gas and liquid tight components. This thermal joining process is used in different branches, e.g., medical technology, for aluminum alloys of the 6xxx group due to their low density combined with high strength. However, the formation of hot cracks during solidification in the pulsed welding process is challenging with these alloys. The alloying elements result in phases with different solidification temperatures. A dendritic network is formed during the cooling from the molten phase (approx. duration: 1.1 ms) but remaining low melting phases are hindered to fill the dendrite spaces due to the short times which is a major issue for the occurrence of hot-cracks. In order to facilitate the flow of the highly viscous remaining melt by shattering the dendritic network the application of vibrations during solidification is a suitable solution. The use of vibrating systems applied to the metal sheet has been studied several times [1, 2, 3]. However, inducing vibration via oscillating laser beam power is a novel approach showing a high potential due to the absence of moving mechanical parts. A power control of the pulsed welding process was realized via real-time computer providing an analog signal to the laser beam source to adjust the laser power over time at high frequencies up to 750 Hz. To visualize the melt pool behavior during solidification, high-speed X-ray synchrotron imaging was utilized (up to 120 kHz) and analyzed via image processing. Figure 1a shows the set laser power (analog power control) in orange and the measured laser power in black proving the system works correctly even at high frequencies. The melt pool width is shown as a function of time on the second axis. This parameter allows the calculation of solidification rates over time based on the high-speed X-ray images. To determine the influence on dendrite propagation or hot cracking behavior, micro tomographic images of the welded specimens were studied. Figure 1b shows the hot crack network of the solidified specimen from an isometric perspective. The network is shown upside down and is based on the specimen surface. A change in the crack behavior can be seen depending different frequencies and resulting solidification rates.