idw – Informationsdienst Wissenschaft
Nachrichten, Termine, Experten
Nachrichten, Termine, Experten
Ultrashort pulse lasers have been a hot topic in precision material processing for years. To discuss the later developments, the UKP workshop in Aachen has become the meeting place for the constantly growing community. This year, the major topics were beam sources, system technology, beam shaping and, of course, applications. Many of the innovations presented had a common goal: scaling down to smaller structure sizes and scaling up productivity.
On April 8 and 9, 120 experts from 22 countries met in Aachen for the 8th UKP Workshop Ultrafast Laser Technology – UKP stands for the German “Ultrakurzpuls“. The name says it all: This workshop is dedicated to the generation and application of laser pulses in the picosecond (ps) and femtosecond (fs) range. These laser pulses can process practically any material. In recent years, research and development has once again made great progress in the generation and application of laser pulses, so that this year's technical discussions mostly revolved around the scaling of processes in addition to new applications.
Scaling with higher power and more wavelengths
Industrial-grade laser beam sources with up to 1000 watts are currently available, for example from the system provider TRUMPF. Its laser – which has pulse energies of up to 10 mJ at pulse lengths of less than 1 ps – is available for testing in the Fraunhofer Cluster of Excellence Advanced Photon Sources CAPS application laboratory at Fraunhofer ILT or at TRUMPF itself in Schramberg, Germany.
There is a trend towards ultraviolet (UV) and deep UV (DUV) wavelengths of laser systems, with the discussion revolving around the advantages of the smaller focus spot and the ablation of transparent materials. Applications in the consumer electronics market, especially display production, are driving further development. Excimer lasers still dominate there, but solid-state UKP lasers are gaining ground, as Coherent explained.
At the workshop, Light Conversion presented interesting data on the performance and service life of various lasers. The overview ranged from more than 10,000 hours for the 30 W UV system to just under 30 minutes for tests to generate a wavelength of 172 nanometers, which corresponds to the 6th harmonic.
A new system from EKSPLA, which delivers ns and fs pulses from a laser, held the visitors in awe. The pulses are synchronized with a source and users have the option of freely setting the duration and spacing the pulses. "It's like roughing and finishing on one machine," commented one participant. The EKSPLA system also allows users to program MHz and GHz bursts flexibly. A few years ago, these were still the subject of basic lectures – now they are standard in modern UKP beam sources.
Modulators and scanner systems for more throughput
As the experts have gained a better understanding of how these processes function in material, the workshop focused more on system technology. This year, particular attention was paid to the topic of beam shaping. Hamamatsu offers a new LCoS modulator (liquid crystal on silicon) for this purpose, which can withstand outputs of up to 700 watts or 3 kW/cm² thanks to the use of sapphire. Users can shape beams to almost any shape: Ring and top hat profiles are just two examples. They can also generate multi-beam profiles or correct aberrations.
Silicon Light Machines presented similar modulators based on micro-electromechanical systems (MEMS). They are faster (100-500 kHz refresh rate) than LCoS modulators, can handle up to 10 kW/cm², but have a lower resolution. Those who do not need the flexibility of modulators can use diffractive optical elements (DOE), which combine high resolution with a high damage threshold. HOLO/OR presented their advantages and disadvantages when used with scanner systems.
Such scanner systems have also made considerable progress. The polygon scanner from MOEWE can deflect the laser beam at a speed of up to 1000 m/s. The developers had to solve a central problem: handling the enormous data volumes of up to 38 GB per square meter of processing area, data that are generated during fast engraving, for example. For print rollers with a surface area of over 100 square meter, they therefore opted for segmented surfaces. For such applications, experts expect a considerable increase in productivity by using more powerful beam sources.
Companies such as SCANLAB and AEROTECH combine scanners, acousto-optical modulators and axis systems selectively to utilize the strengths of the respective systems for higher throughput. By cascading the components, they expect a higher duty cycle of the process, which leads to higher productivity.
UKP lasers in industrial use
Martin Reininghaus presented another way of scaling productivity with the multi-beam machines from Pulsar Photonics. In addition to the multi-beam head, Pulsar has developed a multi-scanner and multi-scanner head concept. Multi-beam heads are suitable for the highly productive production of periodic structures, while multi-scanner setups allow each scanner to operate independently. However, it is a challenge to distribute the large amounts of data and laser pulses to the various scanners at the right time.
Florian Lendner from GFH demonstrated how important inline process control is. By consistently monitoring the process and environmental parameters, his team identified a long-term drift that could be compensated for by an automated correction routine. This improved the dimensional accuracy of the components to ± 1 µm, which further increased the accuracy of micromachining.
Dr. Jens Ulrich Thomas from Schott AG shared his experience in glass microwelding. Schott has implemented the process at wafer level and can generate joints with a shear strength of over 50 MPa. The company uses the technology in medical technology. Adhesive-free joining processes reduce the time for certification there.
With its special application of laser pulses through a liquid layer, Lidrotec is targeting the semiconductor market to reduce material losses when separating chips. Accordingly, Lidrotec is preparing the technology for large-scale applications.
Hands-on laser technology: "the Marketplace" on campus
The tour through the laboratories of Fraunhofer ILT, the RWTH Aachen Digital Photonic Production Research Campus and the RWTH Aachen Chair for Laser Technology LLT and the RWTH Aachen Chair for Technology of Optical Systems TOS offered the opportunity to see many of the technologies presented in the workshop live at nine stations. This included, for example, selective laser-induced etching (SLE). In this process, the focused laser beam writes the contour of the desired component into a glass blank, which is then exposed via an etching process.
Astrid Saßmannshausen (Fraunhofer ILT) used the same process in the laboratory and later in the workshop to demonstrate how she produces micro- and macro-optical components such as lenses. The advantage of this process lies in the freedom of design ("complexity for free") and the customizability. Once the shape has been created, the surface is laser polished. The UKP laser can also ablate the surface of glass directly, whereby a compromise must always be found between process speed and surface quality.
Many of the activities relating to beam shaping using liquid crystal modulators were also on display. Martin Kratz and Martin Osbild (both Fraunhofer ILT) provided examples of the SLE process and surface structuring.
Beam shaping can be used to reduce spherical aberrations, generate multi-beam profiles or form optical stamps with which larger surfaces can be structured in one piece. In his presentation, Paul Buske from RWTH Aachen Chair for Technology of Optical Systems demonstrated how these beam shapes can be generated as perfectly as possible using neural networks.
Open, highly specialized, future-oriented – the UKP Workshop 2025
"It is always impressive how openly the UKP community talks about technical details here," said Dr. Dennis Haasler, group leader at Fraunhofer ILT and chair of the workshop, at the end of the 8th UKP Workshop Ultrafast Laser Technology. "Once again, the workshop has proven to be an excellent platform for exchange between research and development and industry," added Dr. Christian Vedder, head of the Surface Technology and Ablation Department at Fraunhofer ILT.
This year's focus was on the further scaling of manufacturing processes, for which numerous innovations were discussed, particularly in the field of process technology. The next UKP Workshop Ultrafast Laser Technology is planned for April 28 and 29, 2027.
Dr.-Ing. Dennis Haasler
Group Leader Micro and Nano Structuring
Telephone +49 241 8906-8321
dennis.haasler@ilt.fraunhofer.de
Dr. Christian Vedder
Head of Department Surface Technology
Telephone +49 241 8906-378
christian.vedder@ilt.fraunhofer.de
Fraunhofer Institute for Laser Technology ILT
Steinbachstraße 15
52074 Aachen, Germany
www.ilt.fraunhofer.de
http://www.ilt.fraunhofer.de/en
Dr. Dennis Haasler opened the 8th UKP Workshop of the Fraunhofer ILT at DAS LIEBIG in Aachen.
© Fraunhofer ILT, Aachen, Germany.
Twelve companies presented their innovations at the two-day exhibition and encouraged the participan ...
© Fraunhofer ILT, Aachen, Germany.
Lab tour with live demonstration at Fraunhofer ILT. The Fraunhofer researchers presented the capabilities of USP processing to the participants.
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Elektrotechnik, Energie, Informationstechnik, Maschinenbau, Werkstoffwissenschaften
überregional
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Dr. Dennis Haasler opened the 8th UKP Workshop of the Fraunhofer ILT at DAS LIEBIG in Aachen.
© Fraunhofer ILT, Aachen, Germany.
Twelve companies presented their innovations at the two-day exhibition and encouraged the participan ...
© Fraunhofer ILT, Aachen, Germany.
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