The performance achievable in laser material processing depends not only on the optical power of the source but also on the quality (for example in terms of the beam-parameter-product) of the beam incident on the workpiece. Therefore, to optimize the production yield, flexible laser machines must have the possibility to change the beam quality depending on the specific process in which they are used. A typical example is sheet metal cutting with fiber lasers, as thin and thick sheets require two different beam quality values. The paper reports on a new device that allows continuously and dynamically changing the beam quality of laser beams in the kilowatt range to optimize the performance of laser cutting of sheet metals of different thicknesses. When the device is used with 100 μm input and output fibers, the beam parameter product can be tuned from about 4 mm⋅mrad to 7.5 mm⋅mrad with coupling efficiency always larger than 95%. An even broader beam parameter product range up to 9 mm⋅mrad can be achieved when using 50 μm input and 100 μm output fibers, respectively.

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M. Bassignana, M. Riva, A. Braglia, and G. Perrone, "Dynamic high power laser beam shaping device," Proc. SPIE 10911, High-Power Laser Materials Processing: Applications, Diagnostics, and Systems VIII, 109110Q (Presented at SPIE LASE: February 07, 2019; Published: 27 February 2019); https://doi.org/10.1117/12.2510655.