Development of a General Model for Direct Laser Interference Patterning of Polymers

Results of the work in the Laser4Fun project has been published as:

S. Alamri, A.F. Lasagni (2017): Development of a General Model for Direct Laser Interference Patterning of Polymers, Optics Express, 25, 9, 287359

Abstract

This study investigates the general mechanism of Direct Laser Interference Patterning (DLIP) involved in the structuring process of polymer materials. An empirical model is developed taking into account experimental observations of DLIP-treated pigmented and transparent polycarbonate substrates with UV (263 nm) and IR (1053 nm) laser radiation. Depending on the used laser processing conditions, the type of material as well as the spatial period of the interference pattern, four different structuring mechanisms can be identified. The treated surfaces are investigated using confocal microscopy, scanning electron microscopy and focus ion beam and as a result from the experimental data analysis, the developed model predicts the material surface topography after the patterning process, by means of a set of material-dependent coefficients.

Links

Ultrashort pulse laser-induced texturing of stainless steel at 1 MHz and high average power: impact of process parameters

Results of the work in the Laser4Fun project has been published as:

Fotis Fraggelakis, Girolamo Mincuzzi, John Lopez, Inka Manek-Hönninger, and Rainer Kling. Texturing metal surface with MHz ultra-short laser pulses. Optics Express 25(15), pp. 18131-18139, 2017

Abstract

Exploitation of surface texturing by ultra-short pulse laser (UPL) technology for commercial purposes requires the undertaking of several issues including a reliable and robust set-up compatible with large area and high throughput production. A technological strategy to rise to this challenge could be the use of polygon scanner which can deflect a laser beam with unprecedented speed (up to some hundreds of m/s) over an optical field of some tens of cm, jointly with high average power UPL delivering pulse energies of few tens of micro joule and repetition rates in the range of MHz. Nevertheless, unwanted thermal effects are expected to arise, when utilising average power as high as several tens of Watts, compromising the surface texturing morphology. Here a study is reported on the surface texturing of stainless steel carried out utilising an industrial UPL emitting both in the near infrared (λ = 1030 nm) and visible (λ = 515 nm) with high average power (up to 20 W) and operating at high repetition rate (1 MHz). The impact of the fundamental process parameters like single pulse fluence, beam scan speed, number of successive scans and energy dose has been studied. The evolution of the surface morphology has been investigated using scanning electron microscopy (SEM) analysis. We believe our results will contribute to an in deep understanding of the UPL laser texturing with high power, as preliminary step to increase in the next future surface texturing by UPL technological readiness.

Link(s)

Direct laser interference patterning of transparent and colored polymer substrates: ablation, swelling, and the development of a simulation model

Results of the work in the Laser4Fun project has been published as:

Sabri Alamri and Andrés F. Lasagni (2017) Direct laser interference patterning of transparent and colored polymer substrates: ablation, swelling, and the development of a simulation model. Proc. SPIE 10092, Laser-based Micro- and Nanoprocessing XI, 1009219 (February 17, 2017)

Abstract

It is well known that micro and sub-micrometer periodical structures play a significant role on the properties of a surface. Ranging from friction reduction to the bacterial adhesion control, the modification of the material surface is the key for improving the performance of a device or even creating a completely new function. Among different laser processing techniques, Direct Laser Interference Patterning (DLIP) relies on the local surface modification process induced when two or more beams interfere and produce periodic surface structures. Although the produced features have controllable pitch and geometry, identical experimental conditions applied to different polymers can result on totally different topologies. In this frame, observations from pigmented and transparent polycarbonate treated with ultraviolet (263 nm) and infrared (1053 nm) laser radiation permitted to identify different phenomena related with the optical and chemical properties of the polymers. As a result from the experimental data analysis, a set of material-dependent constants can be obtained and both profile and surface simulations can be retrieved, reproducing the material surface topography after the surface patterning process.

Links