scholarly journals Processing of Hierarchical Structures on Stainless Steel by Direct Laser Interference Patterning

2021 ◽  
Keyword(s):  
Stainless Steel ◽  
Hierarchical Structures ◽  
Laser Interference ◽  
Direct Laser ◽  
Direct Laser Interference Patterning

scholarly journals Direct laser interference patterning of stainless steel by ultrashort pulses for antibacterial surfaces

2020 ◽  
Vol 123 ◽  
pp. 105954 ◽  
Author(s):  
Alexander Peter ◽  
Adrian H.A. Lutey ◽  
Sebastian Faas ◽  
Luca Romoli ◽  
Volkher Onuseit ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Ultrashort Pulses ◽  
Laser Interference ◽  
Direct Laser ◽  
Direct Laser Interference Patterning ◽  
Antibacterial Surfaces

scholarly journals An Incompressible Smoothed Particle Hydrodynamics (ISPH) Model of Direct Laser Interference Patterning

Computation ◽  
2020 ◽  
Vol 8 (1) ◽  
pp. 9
Author(s):  
Cornelius Demuth ◽  
Andrés Fabián Lasagni
Keyword(s):  
Stainless Steel ◽  
Smoothed Particle Hydrodynamics ◽  
Shear Stresses ◽  
Laser Interference ◽  
Melt Pool ◽  
Direct Laser ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Periodic Microstructures ◽  
Direct Laser Interference Patterning

Functional surfaces characterised by periodic microstructures are sought in numerous technological applications. Direct laser interference patterning (DLIP) is a technique that allows the fabrication of microscopic periodic features on different materials, e.g., metals. The mechanisms effective during nanosecond pulsed DLIP of metal surfaces are not yet fully understood. In the present investigation, the heat transfer and fluid flow occurring in the metal substrate during the DLIP process are simulated using a smoothed particle hydrodynamics (SPH) methodology. The melt pool convection, driven by surface tension gradients constituting shear stresses according to the Marangoni boundary condition, is solved by an incompressible SPH (ISPH) method. The DLIP simulations reveal a distinct behaviour of the considered substrate materials stainless steel and high-purity aluminium. In particular, the aluminium substrate exhibits a considerably deeper melt pool and remarkable velocity magnitudes of the thermocapillary flow during the patterning process. On the other hand, convection is less pronounced in the processing of stainless steel, whereas the surface temperature is consistently higher. Marangoni convection is therefore a conceivable effective mechanism in the structuring of aluminium at moderate fluences. The different character of the melt pool flow during DLIP of stainless steel and aluminium is confirmed by experimental observations.

scholarly journals Scanner‐based Direct Laser Interference Patterning on Stainless Steel

2021 ◽  
Author(s):  
Aleksander Madelung ◽  
Sabri Alamri ◽  
Tobias Steege ◽  
Benjamin Krupop ◽  
Andrés Fabián Lasagni ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Laser Interference ◽  
Direct Laser ◽  
Direct Laser Interference Patterning

In-Depth Investigation of Copper Surface Chemistry Modification by Ultrashort Pulsed Direct Laser Interference Patterning

Langmuir ◽  
2020 ◽  
Vol 36 (45) ◽  
pp. 13415-13425 ◽  
Author(s):  
Daniel W. Müller ◽  
Anne Holtsch ◽  
Sarah Lößlein ◽  
Christoph Pauly ◽  
Christian Spengler ◽  
...  
Keyword(s):  
Surface Chemistry ◽  
Copper Surface ◽  
Laser Interference ◽  
Direct Laser ◽  
Surface Chemistry Modification ◽  
Direct Laser Interference Patterning

scholarly journals Direct Laser Interference Patterning of Diffraction Gratings in Safrofilcon-A Hydrogel: Fabrication and Hydration Assessment

Polymers ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 679
Author(s):  
Daniel Sola ◽  
Stephan Milles ◽  
Andrés F. Lasagni
Keyword(s):  
Laser Fluence ◽  
Contact Lenses ◽  
Laser Source ◽  
Spatial Period ◽  
Laser Interference ◽  
Periodic Patterns ◽  
Hydration Properties ◽  
Water Contact ◽  
Direct Laser ◽  
Direct Laser Interference Patterning

Refractive index modification by laser micro-structuration of diffractive optical devices in ophthalmic polymers has recently been applied for refractive correction in the fields of optics and ophthalmology. In this work, Safrofilcon-A hydrogel, used as soft contact lenses, was processed by direct laser interference patterning (DLIP) to fabricate linear periodic patterns on the surface of the samples. Periodic modulation of the surface was attained under two-beam interference by using a Q-switched laser source with emission at 263 nm and 4 ns pulse duration. Features of processed areas were studied as a function of both the interference spatial period and the laser fluence. Optical confocal microscopy used to evaluate the topography of the processed samples showed that both structured height and surface roughness increased with laser fluence. Static water contact angle (WCA) measurements were carried out with deionized water droplets on the structured areas to evaluate the hydration properties of DLIP structures. It was observed that the laser structured areas induced a delay in the hydration process. Finally, microstructural changes induced in the structured areas were assessed by confocal micro-Raman spectroscopy showing that at low laser fluences the polymer structure remained almost unaltered. In addition, Raman spectra of hydrated samples recovered the original shape of areas structured at low laser fluence.

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