Approach for monitoring the topography of laser-induced periodic surface structures using a diffraction-based measurement method

Recently, monitoring systems have become crucial components in industrial-scale laser machines to increase process reliability and effiency. Particularly, monitoring methods have the potential to optimize and ensure the quality of laser surface patterning by indirectly characterizing the surface topography. Here, a diffraction measurement system, based on scatterometry, is used to determine the mean depth of laser-induced periodic surface structures (LIPSS) on stainless steel by analyzing the characteristics of the resulting diffraction patterns. To this end, LIPSS were produced with a ps-pulsed laser system operating at a wavelength of 1064 nm. The results reveal that the mean depth of LIPSS can extracted from the intensity of the captured diffraction orders down to approximately 14 nm. This compact monitoring tool can be easily adapted to industrial-scale laser systems to improve the quality control and stability of surface microtexturing processes.