Mathematical analysis of dynamic high power laser beam shaping using Galvanometer Scanners or Deformable Mirrors

In high power laser material processing technologies, such as laser welding, laser cladding or laser surface treatment, tailoring the spatial intensity profile of the laser beam, popularly known as beam shaping, is used to optimize the processing results in terms of processing quality and/or production rate. To allow for dynamic beam shaping — i.e. tailoring the intensity profile during processing — dynamic optics in the optical setup are required. Current dynamic optical devices suitable to shape a single high power laser beam are Galvanometer Scanners and Deformable Mirrors. However, an objective comparison of the beam shaping capabilities, such as resolution and shaping performance, of these beam shaping devices is lacking. This work proposes a novel mathematical framework to analyze and compare the two beam shaping concepts. This framework is used to quantify beam shaping capabilities as function of relevant laser setup parameters. Next, using the mathematical framework, the performance of the Galvanometer Scanner and Deformable Mirror is simulated when targeting a splitted laser beam, creating a horseshoe shaped intensity profile and creating a square uniform profile. Results show that, in practice, both devices will be able to create these three desired laser intensity profiles in the focal plane, with similar small average errors when compared to the desired beam shape. However, the error distributions show differences which are characteristic for the physical limitations of each individual beam shaping device. • A novel mathematical framework to analyze beam shaping methods is presented. • Performance of Galvanometer Scanners and Deformable Mirrors is analyzed. • Mathematical framework helps in determining dynamic beam shaping setup parameters. • Splitted, horseshoe shaped and square uniform intensity profiles are targeted. • Beam shaping methods can target desired beam shapes, however error fields differ.