Optimized beam shaping for high power laser welding applications

Laser welding by means of multi-kW solid state lasers can be considerably improved if the focused welding spot is embedded in pre-heating spot. This intensity distribution generated by means of two different laser sources decreases the spatter formation, and thus improves the quality and yield of the welding processes. To improve the compactness of the optical system, performed same functionality can be effectively achieved by means of diffractive diffusers. These DOEs may not only generate the required focus distribution but may also include the focusing function to avoid the used of extra lenses. Because such a diffractive optical solution may suffer from the presence of speckles if the light source is too coherent, a comprehensive characterization of the laser source, and its evolution depending on the optical power must be performed. In the presentation we will demonstrate the development of the DOEs performing the desired intensity distributions. This includes the design, the compensation of the difference in the intensity levels, the fabrication and the optical performances of the fabricated DOEs. We furthermore present the functionality of the DOEs in the welding process