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

Mikhael El-Khoury,Tim Kunze,Andrés Fabián Lasagni,Bogdan Voisiat

doi:10.3390/ma15020591

Mikhael El-Khoury, Tim Kunze + Show 2 more

Open Access

https://doi.org/10.3390/ma15020591

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Abstract

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%.

Highlights

In recent years, laser surface texturing (LST) has proven to be a suitable tool for producing various surfaces with controllable topography, leading to improved surface properties, such as wettability [1,2] and self-cleaning [3], tribology [4] and antifouling properties [5]
It has been shown that the number of interfering laser beams, their geometrical arrangement, individual angles, phase and polarization influence the shape of the interference pattern as well as its typical repetitive distance [16,17]
This study presents the usage of fundamental beam-mode shaper (FBS) in combination with a Direct Laser Interference Patterning (DLIP) optical configuration to treat flat metallic surfaces

Summary

Introduction

Laser surface texturing (LST) has proven to be a suitable tool for producing various surfaces with controllable topography, leading to improved surface properties, such as wettability [1,2] and self-cleaning [3], tribology [4] and antifouling properties [5]. Out of the available LST methods, Direct Laser Interference. Patterning (DLIP) has arisen as an innovative and effective tool for high throughput surface micro-structuring [6,7,8,9]. This technique enables a direct fabrication of flexible and perfect periodic surface patterns with a well-defined long-range order based on the interference principle [10,11,12,13,14,15]. Due to the flexibility to achieve highly complex patterns in a one-step process, DLIP is especially interesting for industrial applications. No chemicals, post-treatments or vacuum conditions are required, making it an eco-friendly, fast and cost-optimized process [12]

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