The use of femtosecond laser ablation as a novel tool for rapid micro-mechanical sample preparation

Publication date: 5 May 2017
Source:Materials & Design, Volume 121
Author(s): Manuel J. Pfeifenberger, Melanie Mangang, Stefan Wurster, Jens Reiser, Anton Hohenwarter, Wilhelm Pfleging, Daniel Kiener, Reinhard Pippan
The focused ion beam technique has become a standard tool for micro-mechanical sample preparation in the last decade due to its high precision and general applicability in material removal. Besides disadvantages such as possible ion damage and high operation costs especially the characteristically small removal rates represent a bottleneck for this application. In contrast, femtosecond lasers provide material removal rates orders of magnitude higher, with small or ideally without thermal impact on the surrounding material. Hence, a combination of these two methods offers an ideal tool for time-efficient, micrometer-sized sample preparation. A prototype implementing this idea is presented here in combination with a case study. Cantilevers with a length of several hundred micrometers were machined into 25 μm, 50 μm and 100 μm thick, cold rolled tungsten foils. Scanning electron microscopy analyses reveal the influence of laser parameters and different scanning routines on the resulting sample quality and the effect of the laser pulse length (femtoseconds versus nanoseconds) on the ultra-fine grained microstructure. Finally, the performance for unprecedented rapid sample preparation is demonstrated with a sample array consisting of 100 cantilevers with a dimension of 420×60×25 μm³ processed in only half an hour, opening completely new testing possibilities.

Graphical abstract

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