Multispot fiber laser welding

This dissertation presents work and results achieved in the field of multi beam fiber laser welding. The project has had a practical approach, in which simulations and modelling have been kept at a minimum.
Different methods to produce spot patterns with high power single mode fiber lasers have been examined and evaluated. It is found that both diamond turned DOE’s in zinc sulphide and multilevel etched DOE’s (Diffractive Optical Elements) in fused silica have a good performance.
Welding with multiple beams in a butt joint configuration has been tested. Results are presented, showing it has been possible to control the welding width in incremental steps by adding more beams in a row. The laser power was used to independently control the keyhole and consequently the depth of fusion.
An example of inline repair of a laser weld in butt joint configuration was examined. Zinc powder was placed in the weld causing expulsion of the melt pool. Trailing beams were applied to melt additional material and ensure a melt pool. The method showed good results for increasing tolerances to impurities and reduction of scrapped parts from blowouts during laser welding.