Influence of Laser Process Factors on Laser-Induced X-Ray Emission in High-Repetition Laser Processes

Lasers have established themselves as a versatile tool that generates innovations in a wide range of fields, from automotive to surface engineering, medical applications, etc. A current research field for lasers is surface texturing in biomimetic, which aims to mimic nature-inspired functionalities and mechanisms, for example, to tailor and control wetting, adhesion/friction, or optical properties of technical surfaces. Therefore, ultrashort pulse lasers are often the right choice to alter surface structures at microscopic scale. Moreover, the ongoing trend toward high-average power lasers reaching "kilowatt class" levels even for ultrashort pulse lasers seems to be beneficial to increase throughput of this powerful laser technology for industrial production. However, several recent studies are reported on harmful X-ray emissions arising from high-intense ultrashort laser pulses which must be considered as a secondary laser beam hazard in risk assessment. Shining light on this topic, this article reports on a set of experiments investigating X-rays emission induced by ultrashort pulse laser processing of different laser-pretreated stainless steel sheets. The X-ray measurements show the effect of roughness and scan number on the laser-induced X-ray emission dose. In addition, the dependency of X-ray emission on the scan direction relatively to the laser beam polarization state is discussed. Ultrashort pulse lasers are established in multiple applications, like surface texturing in biomimetic. However, undesirable effects can occur during processing, such as laser-induced X-ray emission. Various process parameters are considered here to assess the potential hazards during the processes. For this purpose, the influence of surface roughness and polarization state during stainless steel processing on the X-ray doses is determined.image (c) 2024 WILEY-VCH GmbH