A possibility of improving tribological properties by femtosecond laser irradiation on an example of a steel surface by creating regularly arranged micro-grooved textures that contain self-organized microstructures and nano laser-induced periodic surface structures (LIPSS) was determined. The friction coefficient of the treated surface of a sample of cold-rolled 1.4301 stainless steel was evaluated using a CSM Instruments SA tribometer according to a Pin-on-disk test scheme at a specific pressure of 1 MPa. It was found that the coefficient of friction was reduced by 35% compared to the initial grinded surface. Such laser treatment can find application for using parts in conditions of dry or boundary friction, mainly in units, in which the use of lubricant is unacceptable or extremely undesirable.

Femtosecond laser processing significantly alters the surface structure and chemical composition, impacting its wetting properties. Post-treatments such as immersion in a hydrocarbon liquid (petrol) or storage in a vacuum can significantly reduce ice adhesion, making the surfaces interesting for anti-ice applications. This study investigates their durability against acetone, ethylene glycol, and UV radiation. The laser-structured surfaces were immersed in the respective liquids for up to 48 h. The results indicate limited durability of the superhydrophobic and icephobic layers when submerged in acetone and ethylene glycol, with more favorable results for petrol treatment than vacuum treatment. Similar results were obtained after 100 h of UV exposure, showing a decrease in superhydrophobic properties and an increase in ice adhesion. However, repeated vacuum treatments conducted after the chemical durability tests revealed the potential for partial recovery of the hydrophobic and icephobic properties. XPS analysis was performed throughout the experiments to evaluate changes in surface chemistry resulting from the post-laser treatments and the durability tests.

Ice accumulation on lift-generating surfaces, such as rotor blades or wings, degrades aerodynamic performance and increases various risks. Active measures to counteract surface icing are energy-consuming and should be replaced by passive anti-icing surfaces. Two major categories of surface treatments—coating and structuring—already show promising results in the laboratory, but none fulfill the current industry requirements for performance and durability. In this paper, we show how femtosecond laser structuring of stainless steel (1.4301) combined with a hydrocarbon surface treatment or a vacuum treatment leads to superhydrophobic properties. The anti-ice performance was investigated in an icing wind tunnel under glaze ice conditions. Therefore, flexible steel foils were laser-structured, wettability treated and attached to NACA 0012 air foil sections. In the icing wind tunnel, hydrocarbon treated surfaces showed a 50 s ice build-up delay on the leading edge as well as a smoother ice surface compared to the reference. To demonstrate the erosion resistance of these surfaces, long-term field tests on a small-scale wind turbine were performed under alpine operating conditions. The results showed only minor erosion wear of micro- and nano-structures after a period of six winter months.

Ultrafast laser processing is constrained by an inherent throughput–resolution trade-off, typically addressed either by high-speed single-beam scanning or by parallel processing approaches. Here, a scanning-based dynamic mask projection concept is presented, combining both strategies by integrating a digital micromirror device (DMD) for dynamic binary amplitude mask generation with galvanometric scanning for high-speed lateral repositioning of the projected pattern. A high-numerical-aperture microscope objective is used to project the mask for thin film laser ablation with sub-micrometer feature sizes, while scanning extends the processing area beyond a single projected pattern, ultimately limited by the objective’s field of view. The concept is demonstrated by selective single-pulse pattern ablation of 10 nm thick tantalum nitride (TaN) thin films on glass substrates using 230 fs pulses at a center wavelength of 515 nm. The optical system enables a 770 nm minimum feature size across a scan field with an area-equivalent circular diameter of 550 µm. Dynamic mask projection combined with fast scanning offers a scalable route to high-throughput laser nanoprocessing and is relevant to fabrication and processing of nanomaterials, digital mask lithography, and micro- and nanomachining.

Four-beam Direct Laser Interference Patterning (DLIP) enables the fabrication of periodic surface micro- or nanostructures with various geometrical features. In practice, even a small deviation in beam alignment can alter the resulting morphology, leading to isotropic circular dot patterns, anisotropic structures, rotated patterns, and secondary periodic modulation superimposed on the primary structure. In this work, five representative four-beam DLIP cases were experimentally fabricated, resulting in clearly distinguishable surface morphologies. To identify the incident beam parameters from the fabricated patterns, a Two-Beam Decomposition Method (TBDM) was used. The complex four-beam DLIP structures were decomposed into their six pairwise two-beam configurations, and the angles of incidence (AoIs) and azimuthal angles were reconstructed from the measured spatial periods and relative fringe orientations. Based on the reconstructed beam parameters, an analytical wavevector framework was used to explain the formation of primary structure periods and the secondary period. The obtained results establish a direct correlation between the beam geometry and fabricated surface morphology in four-beam DLIP. The proposed TBDM approach provides a systematic framework for analyzing multi-beam interference patterns and for intentionally designing the complex DLIP-based surface structures with controlled primary and secondary periods.