The formation of a melt pool, during an additive manufacturing process, is a complex multi-physical process. Apparent factors, contributing to its complexity, are among others: the high temperatures, the existence of the material in multiple physical states and the involved high dynamics. However, it is a challenge to have full real-time control over all these factors. In this contribution, we will present our results and shed light, on the basis of measurements with a scanning laser doppler vibrometer, on how the vibrational behavior of the melt pool relates to its penetration depth into the substrate.