Research Focus: Thirteen partners, seven work packages, one research project

The aim of the project was to develop a new laser system, combined with the necessary process technology, to enable incredibly fast machining speeds. Mittweida University of Applied Sciences, with its specialised polygon scanner technology, was called upon to effectively apply such laser power to the workpiece surface. However, it was not only the necessary technology but also the expertise in laser technologies available at LHM and its well-equipped laboratories that enabled the university to participate successfully in the project.

The planned laser system was to have an average power of 2.5 kW and ultra-short laser pulses lasting from a few picoseconds up to the femtosecond range. Using the polygon scanner developed at the LHM, the laser spot was to be guided across the workpiece surface at speeds of up to one kilometre per second. In conjunction with the laser and the corresponding system technology, this takes industrial applications to the next level. The LHM was not only involved in the technical aspects of the scanner technology but also supported the partners with the equipment available on site as part of the EU Horizon 2020 programme.

Mittweida University of Applied Sciences’ involvement in the project

The project leader at Mittweida University of Applied Sciences was Professor André Streek; the university was involved in the following specialist areas:

Scanner
technology: Here, the polygon scanner developed in Mittweida was further refined and tested to its load limits to ensure it could be used non-destructively within the planned overall system.

Laser Technology and systems engineering
The Laser Technology available at Mittweida was utilised for several of the consortium’s tasks. For example, thanks to its wide range of laser systems, the LHM was able to support the partners in characterising and testing a novel single-mode transport fibre, as well as carrying out coupling and stress tests.

Integration
The scanner system developed in Mittweida was to be integrated into an industrial plant, and all necessary interfaces for the system’s industrial deployment were to be implemented.

Process development
With its many years of experience in various laser processes, the LHM was also consistently called upon for process development within the framework of the EU project. Cutting, welding and structuring processes were tested and optimised on the laser systems available in Mittweida in conjunction with the polygon scanner.

The Research Department, in collaboration with the European Commission, supported the financial management of the EU project.

What has been achieved? – An overview of the key results

As a direct application of the new process, a method has been developed that enables the production of large-scale injection moulds for the automotive industry using laser engraving. These are subsequently used to manufacture plastic components for vehicle interiors.

Welding tests were carried out using the new laser to manufacture solar thermal absorbers. Among other things, the aim was to reduce thermal stresses and improve the bonding of the materials.

The work carried out as part of the project has opened up new fields of application for the Mittweida polygon scanner. Particularly in the field of engraving, the polygon scanning technology has impressively demonstrated its advantages over the current state of the art.

The polygon scanners built as part of the project can now be used for other experimental set-ups. Both scanners are fitted with innovative galvanometer scanner motors, which significantly improve the precision of the scanning system. The load limits of the polygon scanner have been determined, thus allowing for a better assessment of the risks involved in using smaller raw beam diameters.

Coherent beam coupling was an essential part of the project, as the total power of 2.5 kW had to be combined from several individual amplifiers. This highly challenging task required several adjustments to beam geometry, beam quality and temporal overlap in order to achieve pulse amplification. In short, the individual amplifiers had to be synchronised.

The fibre amplifiers and the laser architecture had to be adapted to the project. This made it necessary to combine new systems, such as the novel conical fibres, in order to enable such high power levels in the first place. These fibre amplifiers amplify the existing low-energy laser pulses from so-called seed lasers. ‘Seed’ refers to a seed and thus forms the seed of the laser pulse. Achieving ultra-short pulse durations is no mean feat either, which necessitates design guidelines for the correct seed lasers.

The results mentioned above, as well as further publications, can be found via the following links: Publications | PULSE Laser Project and News | PULSE Laser Project

An explanatory video is available via the following link: https://www.pulselaser.tech/about

Re-registration from the European Commission

On 12 June 2024, the project’s final review meeting with representatives of the European Commission finally took place in Finland, at which the work carried out during the final project period (January 2023 to March 2024) and the overall results of the project were presented. The assessors expressly congratulated the project consortium on the results.

Text: Marcel Wolf
Images: PULSE (1), Laserinstitut Mittweida University of Applied Sciences (2, 3)