Headway Group Of Research

Volume 7 Issue 1

Power Spectral Density Evaluation of Laser Milled Surfaces

Raoul-Amadeus Lorbeer, Jan Pastow, Michael Sawannia, Peter Klinkenberg, Daniel Johannes Förster and Hans-Albert Eckel

1
German Aerospace Center (DLR), Institute of Technical Physics, Pfaffenwaldring 38-40, 70569 Stuttgart, Germany
2Institut für Strahlwerkzeuge, University of Stuttgart, Pfaffenwaldring 43, 70569 Stuttgart, Germany
*Author to whom correspondence should be addressed.
Abstract
Ablating surfaces with a pulsed laser system in milling processes often leads to surface changes depending on the milling depth. Especially if a constant surface roughness and evenness is essential to the process, structural degradation may advance until the process fails. The process investigated is the generation of precise thrust by laser ablation. Here, it is essential to predict or rather control the evolution of the surfaces roughness. Laser ablative milling with a short pulse laser system in vacuum (≈1 Pa) were performed over depths of several 10 µm documenting the evolution of surface roughness and unevenness with a white light interference microscope. Power spectral density analysis of the generated surface data reveals a strong influence of the crystalline structure of the solid. Furthermore, it was possible to demonstrate that this effect could be suppressed for gold.
Keywords:surface roughness; surface unevenness; laser milling; power spectral density; micro crystalline; Hall-Petch; EBSD
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