Conference Agenda

Overview and details of the sessions of this conference. Please select a date or location to show only sessions at that day or location. Please select a single session for detailed view (with abstracts and downloads if available).

Please note that all times are shown in the time zone of the conference. The current conference time is: 27th Jan 2022, 10:34:48pm CET

Program for LiM 2021
Micro: Ablation 2
Tuesday, 22/June/2021:
11:15am - 12:30pm

Session Chair: Stefanie Kohl, Institute of Photonic Technologies (LPT), Germany
Location: Room 3
ICM Ground Floor 125

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11:15am - 11:30am

Laser ablation of thermoplastic composite for aerospace application

Hagen Dittmar, Simon Hirt, Verena Wippo, Peter Jaeschke, Stefan Kaierle, Ludger Overmeyer

Laser Zentrum Hannover e.V., Germany

Carbon fibre reinforced plastic (CFRP) is a well-established material in modern aerospace products. While primary structural components contain a thermoset matrix material, secondary components are increasingly made of thermoplastic matrix systems. Due to their superb performance and advantageous production properties, thermoplastics matrices are now also pushing into primary structural applications like fuselage, cowlings, and wings.

These structures are subject to an increased risk of damage during operation. Thus, repair strategies that address thermoplastic CFRP come to the fore. The repair by conventional tooling faces challenges that result from the thermoplastics’ abilities to melt, which cause the tools to clog and decrease process efficiency. Laser ablation poses an alternative approach allowing precise material removal without material related wear and thus a constant process quality.

This study demonstrates process efficiency of a laser ablation process on a CFRP with polyphenylene sulphide (PPS) matrix and the used processing parameters on the repair quality.

11:30am - 11:45am

Magnetic field assisted laser ablation of silicon by using short and ultrashort laser pulses

Yiyun Kang1, Garik Torosyan1, Falicienne G. Keabou1, Hicham Derouach1, Mareike Schäfer1, Pavel N. Terekhin2, Bärbel Rethfeld2, Johannes A. L'huillier1

1Photonik-Zentrum Kaiserslautern e.V. and Research Center OPTIMAS, Technische Universität Kaiserslautern, 67663 Kaiserslautern, Germany; 2Department of Physics and Research Center OPTIMAS, Technische Universität Kaiserslautern, 67663 Kaiserslautern, Germany

A controlled machining process with optimum energy-matter coupling in micro-scale by short and ultrashort laser pulses brings great benefits in industrial applications. The influence of external magnetic field on the ablation process of silicon irradiated by laser pulses in the infrared range was investigated. The external field is applied parallel to the laser beam to prevent escaping of the charge carriers in the laser-induced plasma plume from the ablation area. We performed single- and multi-pulse ablation in three different duration ranges: femtosecond, picosecond and nanosecond. We observed that the effect of external magnetic field depends strongly on pulse duration. An essential improvement in the quality and efficiency of material removal was achieved for pulses with longer durations. Additionally, by femtosecond excitation in multi-pulse mode a change of the surface texture around the ablation point was observed, which could be suppressed by means of the magnetic field.

11:45am - 12:00pm

Modeling of selective laser ablation of lithium-ion battery electrodes

Max-Jonathan Kleefoot1, Simon Ruck1, Jiří Martan2, Jens Sandherr1, Marius Bolsinger1, Volker Knoblauch1, Harald Riegel1

1Aalen University, Germany; 2University of West Bohemia, Czech Republic

Lithium-ion batteries are an important component of the current energy and mobility transition. Various approaches are being pursued in current research regarding the production of fast chargable electrodes. These electrode layers consist of various components that can be divided into two groups. One is the active material phase and the other is the binder material phase. In addition to laser perforation, selective laser ablation to remove inactive electrode components is also being investigated in research. Within this study, a model was developed that predicts the temperatures during the laser process inside the electrode at different depths. Experimental investigations were also able to show that the active material is permanently damaged by an excessively high energy input. A comparison with the model shows good agreement here. Thus, with the help of the model, a parameter optimisation can be carried out in which the active material particles are exposed but not damaged.

12:00pm - 12:15pm

Theoretical analysis of the incubation effect on the ablation behavior using spatial shaped ultra-short pulse laser

Marco Smarra1, Evgeny Gurevich2, Cemal Esen1, Andreas Ostendorf1

1Ruhr-Universität Bochum, Germany; 2Fachhochschule Münster, Germany

Ultra-short laser pulses are well known for their low thermal effect on the ablation process and therefore are used in numerous applications like surface texturing and functionalization. However, high peak fluence leads to a reduction in ablation efficiency. Beam shaping can be used to solve this issue. Beam errors, like defocus or astigmatism, lead to larger beam diameter and to decreasing peak fluence on the surface of the workpiece. This paper is focused on the theoretical study of the incubation effect and its influences on the ablated volume per pulse by analyzing the effects of the waist position of the laser beam and the ablation threshold of the sample material. This work is fundamental for handling the ablation process using high pulse energies.

12:15pm - 12:30pm

Expanding perspectives for processing with agile high power femtosecond lasers

Eric Audouard, Guillaume Bonamis, Martin Delaigue, Benoît Tropheme, Julien Pouysegur, Florent Basin, Jorge Sanabria, Eric Mottay, Clemens Honniger


300 W industrial laser is already available, and the mean power will reach soon the kW level. We are at a turning point in femtosecond technologies, which will enable new fields of use and new methods of production: The "agility" of the lasers and associated beam engineering make them relevant tools for flexible, reconfigurable production. We report on a versatile industrial high power femtosecond laser platform responding to the most demanding application requirements and opening the way to “macro” applications to femtosecond lasers. The platform generates femtosecond pulses at more than 300 W average power, the capability for efficient frequency conversion to 343 nm, free triggering of the laser output pulses, and burst generation and shaping over a wide range of parameters including GHz bursts.

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