Diffraction‐Based Strategy for Monitoring Topographical Features Fabricated by Direct Laser Interference Patterning

Abstract

The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adem.202201889.

Diffraction-based approach for real-time monitoring of nanosecond direct laser interference patterning structure formation on stainless steel

“…5c. Furthermore, these changes are in agreement with the findings reported in 48 , where the average depth of dot-like geometries produced by ns-DLIP treatment could be estimated based on the variation of the relative intensities of the zero and first diffraction orders.…”

“…As described in the experimental section, the specular reflectivity of the area irradiated by the probe laser (CW, He:Ne at 635 nm wavelength), which is undergoing the structuring process with the two-beam DLIP setup, is directed and captured by the photodetector. Because during the DLIP process a periodic grating is formed, the cw laser beam is diffracted into different diffractions orders 48 . In this work, the photodetector was located at the position of the zero diffraction order, which means that the changes observed in the captured signal can be produced by local changes of the reflectivity due to its dependency with temperature, and/or due to the formation of the periodic structure.…”

The development of direct laser interference patterning: past, present, and new challenges

“…Diffractive approach: to monitor and evaluate the surface topography of periodic structures, different approaches can be used, for instance scatterometry [35,36]. This technique consists of illuminating the structure surface with a low power laser beam and later capturing the diffracted beams with a camera system.…”

“…In addition, by measuring the distance by the different diffractions orders, also the spatial periods can be determined. Further information has been already published in [35,36]. Monitoring DLIP using thermal cameras: For investigating the thermal effects occurring during DLIP in steel, areas of 5 × 40 mm² were processed.…”

“…The measured areas corresponding to the different diffraction orders are shown in Figure 3c,d. As can be seen, once the curves are fitted, the structure depth can be estimated with accuracies between 3 and 15% [36]. In addition, by measuring the distance by the different diffractions orders, also the spatial periods can be determined.…”