*2.5. Surface Analysis*

Surface analysis was done by micrographs of the surface using a stereo microscope M205 C by Leica Microsystems. An objective with a numerical aperture of 0.35 and a maximum optical resolution of up to 1050 LP/mm (line pairs per millimeter) was used.

Since stylus roughness measurements are often not meaningful to determine the effect of LμP on surface roughness [27], systematic white light interferometry (WLI) measurements of laser-polished areas were conducted. Surface analysis was done by an analysis of the spectral composition of surface roughness, which is typically presented as a roughness spectrum (Sa spectrum) [18,27,50,51]. The WLI measurements for these Sa spectra were conducted with a "Newview 7300" (Ametek-Zygo, Berwyn, PA, USA). The maximum vertical resolution was approximately 0.1 nm, while the spatial resolution ranged between 0.36 and 9.50 μm. The control and analysis software Zygo MetroPro (V10.3) was used for all measurements.
