Advanced laser sources enable manufacturers to produce weld seams of high quality at high process velocities. These processes require high degrees of precision and furthermore, process parameters have to be kept in close limits. The welding speed is one of the most important parameters among laser power which has to be held constantly in order to achieve a stable quality of the manufactured products. Only a constant energy input per unit length may ensure steady qualities of welded or brazed seams.
Even by highly sophisticated handling systems, the influence of mass inertia cannot be fully suppressed when moving with high accelerations. Small deflection angles at the processing head cause large displacements at the Tool Center Point (TCP).
In this paper new approaches to measure the real velocity at the TCP seamlessly are being published. A new image processing technique provides the ability, to measure welding velocities at high precision and high sampling rates directly on the work piece. By combining the values of the measured laser power at the processing head with the actual velocity, this technology enables the direct measurement of the energy input per unit length at real time. This new measurement method offers a high degree of quality gain and may even empower the end user to keep welding depths in small boundaries. Especially laser welding at long focal distances and setups with handling systems of mere precision (i.e. remote welding) will benefit from this measuring method.