In laser material processing, a variety of parameters like pulse fluence, total dose, step size, and pulse‐to‐pulse overlap are used to define and compare laser processes. Of these parameters, the pulse‐to‐pulse overlap can be the hardest to access as it is not implemented directly but instead depends on the spot diameter, its shape, and the respective scanning path that is used to cover the surface. This article shows that existing calculation routes overestimate the actual overlap by up to 21%. A novel calculation route is developed that greatly facilitates the determination of the pulse overlap and thereby the average number of laser pulses that interact with a given point on the surface. This approach makes it possible to achieve more reliable and comparable laser processes, which in return leads to better control of the procedure as the effect of individual parameters on a given output can be determined with greater precision.

State of the art approaches to produce photocatalytic surfaces generally require multiple processing steps to achieve highly active surfaces. Following recent trends to facilitate the production of active surfaces, this work presents a single‐step method to create porous photocatalytic surfaces via direct laser interference patterning (DLIP) of a titanium substrate with pulses in the picosecond range. The resulting surfaces contain a variety of titanium oxides while both their composition and morphology can be controlled through the laser process parameters. This makes it possible to tailor these surfaces for specific applications such as antimicrobial surfaces, implant materials or water treatment. Surface characterization was executed by applying scanning electron microscopy complemented by focused ion beam cross‐sectioning and energy dispersive X‐ray spectroscopy as well as gracing incidence X‐ray diffractometry. The photocatalytic activity achieved by different laser parameters is assessed by methylene blue degradation under UV‐A light. As DLIP is already established in industrial applications, this approach could greatly facilitate the use of photocatalytic surfaces for water treatment or medical applications, as it does not require nanoparticle synthesis or additional coating steps.

Natural micro- and nano-patterned surfaces demonstrate unique biological interactions and inspire surface functionalization strategies for medical devices. In particular, groove-like microstructures have been demonstrated to guide cell behavior, while nanoscale features stimulate platelet activation - both of which are critical for cardiovascular implants. Direct laser interference patterning (DLIP) with a femtosecond (fs) laser was employed to generate hierarchical groove structures with defined nano-substructures on biomedical CoCr. The initial examinations on the laser-material interactions revealed the materials ablation dynamics accompanied by the formation of laser induced periodic surface structures (LIPSS). Next, fully structured surfaces were topographically analyzed, revealing detailed insights in the pattern geometry and morphological surface characteristics. Further spectroscopic analysis demonstrated the chemical modification of the surfaces as a consequence of ultra-short pulse laser processing. To assess biological relevance, the biocompatibility was evaluated using human cardiac myocytes (HCM). The structured CoCr surfaces had a notable effect on cell morphology, alignment, and contact guidance along the groove direction. The findings demonstrate that DLIP enables precise and reproducible fabrication of micro-nano hierarchical surfaces with strong potential to improve cell response, biocompatibility, and integration of cardiovascular implants.

Direct laser interference patterning (DLIP) has in previous work shown to be an effective tool for producing photocatalytic surfaces in a single relatively simple processing step. These surfaces can be interesting candidates for antifouling or self‐cleaning surfaces, as well as substrates for photocatalytic water treatment. In this contribution, various heat treatments are performed both during and after the laser processing to create surfaces with even higher photocatalytic activities and to better understand the formation of various process oxides and their effect on the resulting activity. The photocatalytic activity of the samples is measured by methylene blue degradation and correlated to their chemical composition and morphology. Furthermore, a small prototype is built using low‐cost materials to prove the scalability of the approach.

Fingerprints, a butterfly’s wings, or a lotus leaf: when it comes to surfaces, there is no such thing as coincidence in animated nature. Based on their surfaces, animals and plants control their wettability, their swimming resistance, their appearance, and much more. Evolution has optimized these surfaces and developed a microstructure that fits every need. It is all the more astonishing that, with regard to technical surfaces, man confines himself to random roughnesses or “smooth” surfaces. It is surely not a problem of a lack of incentives: structured surfaces have already provided evidence of optimizing friction and wear [1, 2, 3, 4], improving electrical contacts [5, 6], making implants biocompatible [7, 8], keeping away harmful bacteria [9], and much more. How come we continue counting on grinding, polishing, sandblasting, or etching? As so often, the problem can be found in economic cost effectiveness. It is possible to produce interesting structures such as those of the feather in Fig. 1. However, generating fine structures in the micro and nanometer range usually requires precise processing techniques. This is complex, time-consuming, and cannot readily be integrated into a manufacturing process. Things are different with Direct Laser Interference Patterning, DLIP) [10, 11]. This method makes use of the strong interference pattern of overlapped laser beams as a “stamp” to provide an entire surface area with dots, lines, or other patterns – in one shot. It thus saves time, allows for patterning speeds of up to 1 m ² /min and does it without an elaborate pre- or post-treatment [10, 12]. The following article intends to outline how the method works, which structures can be generated, and how the complex multi-scale structures that nature developed over millions of years can be replicated in only one step.