Industrial application of ultra short pulsed lasers in system and process technology

The use of ultra short pulsed (USP) lasers in industrial applications has been a major focus of research for several years. The focus seminar “Basics and New Developments in Ultra Short Pulse Laser Technology”, which was held recently in Aachen as part of the 9th International Laser Technology Congress AKL’12, showed that there is considerable user interest in this field. The high expectations for the half-day seminar were once again exceeded, with almost 200 people attending.

Beam sources are no longer a limiting factor

For many years, beam sources were considered to be the limiting factor in industrial applications of USP technology. One of the results of the seminar led by Dr. Arnold Gillner from the Fraunhofer Institute for Laser Technology ILT was that this situation has now changed radically. There are two reasons for this. Firstly, it appears that there is an optimum pulse energy for maximum material ablation using USP systems: Two presentations demonstrated that for small spot sizes the pulse energy should be in the microjoule range, a level that can easily be achieved by available systems. To increase ablation performance, the pulse repetition rate must then be increased accordingly.
Secondly, the last few years have seen significant progress in regard to beam sources, and the seminar participants were shown examples of robust laser systems with pulse energies in the µJ range and repetition rates as high as the multi megahertz range. Systems with an average output power of 500 watts are commercially available, and kilowatt systems are already under development. The majority of the USP systems that are currently in use operate in the picosecond range, while femtosecond systems are still mostly at the test phase.

Major advances required in scanner technology

Developers are now primarily focusing their work on mechanical engineering. The seminar included discussions on different approaches towards achieving the huge advances that are required in scanner technology. In purely mathematical terms, the need to maximize repetition rates gives rise to speeds in excess of 100 meters a second for the movement of the laser spot on the workpiece – at a resolution of just a few micrometers. Special polygon scanners that can achieve these parameters were presented at the seminar. Alternatively, it is also possible to use acousto-optic deflectors, though these only cover a relatively small scanning field.

USP systems at work – results of the BMBF-funded PIKOFLAT project
During the second half of the seminar, various project partners presented the results of the PIKOFLAT project, which was funded by the German federal ministry of education and research (BMBF) as part of the MABRILAS funding initiative. Under the heading “System and process technology for structuring large surfaces with high-performance picosecond lasers”, the partners presented a range of innovations which led to the development of a new rotogravure system for machining printing and embossing cylinders. These included solutions in the fields of systems and mechanical engineering as well as research into the corresponding processes.
At a special evening event, the partners in the project, which was led by Dr. Stephan Büning (Schepers GmbH & Co. KG, Vreden), received the prestigious Innovation Award Laser Technology for their outstanding achievements.

Outlook

The goal of the PIKOFLAT project was to develop the machine and process technology for an industrial system capable of structuring large surfaces with high-performance picosecond lasers. This goal has been successfully achieved and the technology is now being further developed within the scope of new projects. A key part of the funding for these projects is being provided by the BMBF as part of its recently launched funding initiative “Ultra short pulsed lasers for precision micromachining”. In the light of the results of the PIKOFLAT project, there was a broad consensus among the seminar participants that this kind of technology funding in thematic alliances offers the best opportunity to rapidly transition the new, basic USP technologies into industrial use.

The focus seminar “Basics and New Developments in Ultra Short Pulse Laser Technology” will continue to be held as part of the International Laser Technology Congress in the future. Fraunhofer ILT will be organizing a two-day USP workshop every odd-numbered year. The second ultra short pulsed laser workshop will take place from April 17 – 18, 2013. Registration for the event is already open on the website www.ultrakurzpulslaser.de.

Your contacts at Fraunhofer ILT
If you have any questions regarding this topic, please feel free to contact our expert:

Dr. Arnold Gillner
Phone +49 241 8906-148
arnold.gillner@ilt.fraunhofer.de
Fraunhofer Institute for Laser Technology ILT
Steinbachstrasse 15
52074 Aachen
Phone +49 241 8906-0
Fax +49 241 8906-121

PIKOFLAT project partners
Edgeware GmbH
Fraunhofer Institute for Laser Technology ILT
Lumera Laser GmbH
Sauer Lasertech GmbH
Saueressig GmbH & Co. KG
Schepers GmbH & Co. KG