UKP Lasers Conquer Macro Processing

In the meantime, ultrashort pulse (UKP) lasers have become firmly established in science and micromachining. At this year's "UKP Workshop: Ultrafast Laser Technology" in Aachen, a new trend emerged: with the availability of multi-100-watt UKP lasers up to kW, they are also becoming interesting for large-area applications. For this purpose, the complete process chain right through to fully digitized processes is being developed.

The UKP workshop has grown again: More than 170 participants from 14 countries came to Aachen this year to discuss the latest trends in the development of UKP laser technology for industrial applications

"The UKP laser has arrived in the industry," Dr. Arnold Gillner, Head of Abrasion and Joining Competence at the Fraunhofer Institute for Laser Technology ILT and initiator of the UKP workshop, already at the beginning of the event. The next goal is to provide lasers with capabilities such as CO₂ and fiber lasers, which are now used for material processing of macroscopic components. "The challenge is how to bring the photons to the workpiece," Gillner described the core topic of the workshop.

Many innovative technologies for this were presented in the UKP workshop: the latest examples are enough, from new laser beam sources to fast scanner systems and new beam shaping concepts to fully automated and digitized processes.

Technology development in a network
There was a consensus on beam sources: UKP lasers up to 100 W have now arrived in the market, systems with several 100 W are available and are already being integrated into the first machines. In addition, UKP lasers in the multi-kW range, such as those developed by the Fraunhofer Institutes for Applied Optics and Precision Mechanics IOF in Jena and Laser Technology ILT in Aachen in the Fraunhofer Cluster of Excellence "Advanced Photon Sources", will be added soon. Both institutes have set new world records in recent months: The Jena group showed 3.5 kW average output power from a fiber laser system and the Aachen 500 W at only 30 fs pulse duration with a Yb: Innoslab laser.

Altogether, 12 institutes are working in the Fraunhofer Cluster "Advanced Photon Sources". Together, they want to provide newly developed beam sources together with corresponding system technology for a wide variety of applications in two application labs in Jena and Aachen.

Also laser developer Eric Mottay, Amplitude Systèmes, emphasized that the system technology for the new lasers can only be developed in close cooperation of the different technology carriers. This became apparent in the following lectures on fast scanners, multi-beam systems and special optics: Together, laser manufacturers, scanner experts and users work on a multi-beam concept in which an energy-rich laser pulse is split into many individual laser pulses and guided parallel over the surface to larger areas to work efficiently.

In detail, Stephan Brüning, Schepers GmbH, tested the multi-jet concept for the structuring of printing rolls. Previously, four lasers were used in parallel, now a 500 W UKP laser beam with a diffractive optical element is distributed over 16 partial beams. By means of acousto-optic modulators, the partial beams are independently controllable and achieve a significantly higher productivity.

The design of optics with up to 196 similar partial beams was explained by Oskar Hofmann from RWTH Aachen University. The challenge with these optical concepts lies in the compensation and correction of the different aberrations.

The fact that efficiency gains can also be achieved with individual beams was demonstrated by Benedikt Nohn, Volkswagen AG. His example was the structuring of tools for embossing interior design elements. Optimized scanner technology more than doubled throughput.

Efficient simulation for digital process chains
"The laser enables a continuous process chain for digital photonic production" - this is the vision of the outgoing director of the Fraunhofer ILT, Prof. Reinhart Poprawe. The prerequisite for this is not only a close integration of the various processes, but also a deep process understanding and a fast and efficient simulation of the laser-material interactions. Markus Niessen from the Fraunhofer ILT discussed the usual approaches and how to reduce the computational time dramatically with a reduced model. Microscopic interaction processes and material effects are considered separately from macroscopic effects. In the long term, Niessen has a clear strategy: "Our goal is first-time-right production."

Production of standard parts is running
The progress of the UKP laser technology can now be read off the quality of the applications. This is also the case with Claus Dold, EWAG AG, an expert in the manufacture of tools made of ultra-hard materials. In the workshop, he explained how well the UKP laser can process polycrystalline diamonds or carbide materials. Especially for the production of carbide drills he presented a complete manufacturing system, where the operator enters only the geometrical data and inserts blanks. The laser machine itself selects the necessary settings and produces the drills with micrometer precision. The machines can be fully automated and operated in a global network. In a digital marketplace, production capacities can be controlled globally and adapted to demand.

More power and more applications
The UKP laser technology is increasingly accepted in the industry. After glass cutting and applications in measuring and medical technology, the large-surface processing of surfaces is on the rise.

With the availability of laser sources in the multi-kW range, the main advantage of the UKP technology, ie an extremely high precision in the processing, will lead to a more widespread use. Efficient process technology and a very good understanding of the process are prerequisites for industrial application. New applications from generation of EUV radiation to quantum technology are on the rise. A new challenge must be the protection against X-rays.

The »UKP Workshop: Ultrafast Laser Technology« reached its capacity limits in 2019 in its exclusive venue - the lounge of the Aachen football stadium. On 21 and 22 April 2021, the 6th UKP Workshop will take place, then probably in a new location with larger premises.

The Fraunhofer ILT at the LASER World of PHOTONICS

More UKP technology will be available from 24 to 26 June 2019 at the Fraunhofer joint booth A2.431 at the LASER World of PHOTONICS in Munich.