scholarly journals Utilizing a Diffractive Focus Beam Shaper to Enhance Pattern Uniformity and Process Throughput during Direct Laser Interference Patterning

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 591
Author(s):  
Mikhael El-Khoury ◽  
Bogdan Voisiat ◽  
Tim Kunze ◽  
Andrés Fabián Lasagni
Keyword(s):  
Intensity Distribution ◽  
Laser Interference ◽  
Gaussian Laser Beam ◽  
Laser Beam Intensity ◽  
Direct Laser ◽  
Standard Configuration ◽  
Laser Sources ◽  
Direct Laser Interference Patterning ◽  
The Impact ◽  
Beam Mode

Uniform periodic microstructure formation over large areas is generally challenging in Direct Laser Interference Patterning (DLIP) due to the Gaussian laser beam intensity distribution inherent to most commercial laser sources. In this work, a diffractive fundamental beam-mode shaper (FBS) element is implemented in a four-beam DLIP optical setup to generate a square-shaped top-hat intensity distribution in the interference volume. The interference patterns produced by a standard configuration and the developed setup are measured and compared. In particular, the impact of both laser intensity distributions on process throughput as well as fill-factor is investigated by measuring the resulting microstructure height with height error over the structured surface. It is demonstrated that by utilizing top-hat-shaped interference patterns, it is possible to produce on average 44.8% deeper structures with up to 60% higher homogeneity at the same throughput. Moreover, the presented approach allows the production of microstructures with comparable height and homogeneity compared to the Gaussian intensity distribution with increased throughput of 53%.

scholarly journals Improving Throughput and Microstructure Uniformity in Direct Laser Interference Patterning Utilizing Top-Hat Shaped Beams

2021 ◽  
Author(s):  
Mikhael El-Khoury ◽  
Bogdan Voisiat ◽  
Tim Kunze ◽  
Andrés Fabián Lasagni
Keyword(s):  
Intensity Distribution ◽  
Laser Interference ◽  
Gaussian Laser Beam ◽  
Laser Beam Intensity ◽  
Direct Laser ◽  
Standard Configuration ◽  
Laser Sources ◽  
Periodic Microstructures ◽  
Direct Laser Interference Patterning ◽  
The Impact

Abstract Uniform periodic microstructures formation over large areas is generally challenging in Direct Laser Interference Patterning (DLIP) due to the Gaussian laser beam intensity distribution inherent to most commercial laser sources. In this work, a diffractive fundamental beam-mode shaper (FBS) element is implemented in a four-beam DLIP optical setup to generate a square-shaped top-hat intensity distribution in the interference volume. The interference patterns produced by a standard configuration and the developed setup are measured and compared. In particular, the impact of both laser intensity distributions on process throughput as well as fill-factor is investigated by measuring the resulting microstructure height with height error over the structured surface. It is demonstrated that by utilizing top-hat-shaped interference patterns, it is possible to produce on average 44.8 % deeper structures with up to 60 % higher homogeneity at the same throughput. Moreover, the presented approach allows the production of microstructures with comparable height and homogeneity compared to the Gaussian intensity distribution with increased throughput of 53%.

scholarly journals High Throughput Direct Laser Interference Patterning of Aluminum for Fabrication of Super Hydrophobic Surfaces

Materials ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1484 ◽  
Author(s):  
Valentin Lang ◽  
Bogdan Voisiat ◽  
Andrés Fabián Lasagni
Keyword(s):  
High Throughput ◽  
Hydrophobic Surface ◽  
Surface Structures ◽  
Laser Interference ◽  
Heat Accumulation ◽  
Water Contact ◽  
Laser Beam Intensity ◽  
Aspect Ratios ◽  
Direct Laser ◽  
Direct Laser Interference Patterning

This work addresses the fabrication of hydrophobic surface structures by means of direct laser interference patterning using an optical setup optimized for high throughput processing. The developed optical assembly is used to shape the laser beam intensity as well as to obtain the two sub beams required for creating the interference pattern. The resulting beam profile consists of an elongated rectangular laser spot with 5.0 mm × 0.1 mm size, which enables the optimized utilization of the laser fluence available from an ns-pulsed laser with a wavelength of 1064 nm. Depending on the pulse repetition rate applied, heating of the substrate volume generated by heat accumulation encouraged exceptionally high aspect ratios of the trench structures due to melt flow dynamic material deformation. Finally, water contact angle measurements of the produced structures permitted the demonstration of the capability of controlling the wetting angle, in which this effect does not only depend on the height of the generated surface structures but also on their morphology.

scholarly journals Prediction of Optimum Process Parameters Fabricated by Direct Laser Interference Patterning Based on Central Composite Design

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4101
Author(s):  
Mikhael El-Khoury ◽  
Bogdan Voisiat ◽  
Tim Kunze ◽  
Andrés Fabián Lasagni
Keyword(s):  
Central Composite Design ◽  
Process Parameters ◽  
Performance Criteria ◽  
Laser Interference ◽  
Holistic View ◽  
Direct Laser ◽  
Structure Height ◽  
Direct Laser Interference Patterning ◽  
The Impact ◽  
Central Composite

In this study, we report on the optimization of the direct laser interference patterning process by applying the design of experiments approach. The periodic line-like microstructures of a 8.50 µm spatial period were fabricated by a two-beam interference setup with nanosecond laser pulses, varying laser fluence, pulse overlap, and hatch distance. Central composite design with three factors and five levels was implemented to optimize the required number of experiments. The experimental and numerical results show the impact of various structuring process parameters on surface uniformity. The responses measured are the structure height, height error, and waviness of the pattern. An analysis of the microstructures on the patterned surface was conducted by confocal microscopy and scanning electron microscopy. A 3D-characterization method based on morphological filtering, which allows a holistic view of the surface properties, was applied, and a new qualification scheme for surface microstructures was introduced. Empirical models were also developed and validated for establishing relationships between process parameters and performance criteria. Multi-objective optimization was performed to achieve a minimal value of structure height errors and waviness.

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.

Sign in / Sign up

Export Citation Format

Share Document