Beam shaper increases femtosecond laser material processing speed and quality
Beam shaper increases femtosecond laser material processing speed and quality lead image
As circuits, sensors and medical devices continue to get smaller and more precise, femtosecond laser material processing (FLMP) is becoming the tool of choice for micromachining at the micro- and nanoscale levels for cutting, drilling and laser ablation.
Researchers have been improving beam shaping using refractive beam shaper techniques to make FLMP faster and more flexible. Refractive beam shapers, which convert a Gaussian laser beam into a collimated top-hat beam, are characterized by their simple structure, high conversion efficiency and adaptability to wavelength changes.
Möhl et al. developed a compact refractive aspheric beam-shaping device to further study the refractive beam shaper method, specifically for generating laser-induced periodic surface structures (LIPSS) for functional ripple-like surfaces on stainless steel.
The formation and properties of LIPSS on stainless steel have been the subject of numerous studies. This latest research builds and improves on past work by investigating whether the new beam-shaping device is suitable for materials processing with a scanner and F-Theta lens.
The authors tested their device to see if it can withstand the high repetition rates of modern laser systems while keeping its high processing efficiency. In combination with a focusing lens, the device transforms a collimated Gaussian beam into different focal intensity distributions, including top-hat and donut profiles, at different working distances.
The researchers found that their beam-shaping approach not only works well within the existing laser system, but also distributed the intensity more evenly while remarkably increasing the processing speed.
Source: “Tailored focal beam shaping and its application in laser material processing,” by Anna Möhl, Sebastian Kaldun, Clemens Kunz, Frank A. Müller, Ulrike Fuchs, and Stephan Gräf, Journal of Laser Applications (2019). The article can be accessed at https://doi.org/10.2351/1.5123051 .
