May 31, 2017

The faster way to microstructuring

					Ultrashort pulse lasers

Ultrashort pulse lasers deliver maximum precision in micro material processing. New concepts should enable faster and more productive processes.

The eight research partners in the eVerest project have ambitious plans. By 2018, with almost 2.5 million euros in funding from the Federal German Ministry of Research, they want to implement a laser system that will raise micro material processing to a new level of productivity. This system will alternate between hot nanosecond pulses for rapid material removal and cold picosecond pulses to introduce fine micrometer-scale structures. Despite its flexibility, it should be possible to operate this system “without any substantial knowledge of laser ablation procedures.”

This would solve several problems in micro material processing. Whereas previously used etching processes lack reproducibility, and operating them required a high level of specialist expertise, existing laser processes are either resching precision limits or lack productivity. Nanopulses allow too much material to melt, which stands in the way of precision. By contrast, picosecond and femtosecond lasers create clean microstructures—but need more time to do so.

Combined expertise

The combination of short and ultrashort pulse technology promises to solve this dilemma. To ensure that’s achieved, the eVerest project combines the expertise of four highly specialized medium-sized companies, three research institutes and one global conglomerate. Amphos, a specialist for high-power ultrashort pulse lasers, is developing the flexible picosecond/nanosecond laser system. SCANLAB will use its knowledge of scanning systems to develop a system for the highly dynamic positioning of the laser focus on free-form surfaces. And Precitec Optronik will contribute appropriate sensor technology to control and measure the laser structuring process in situ. Sauer Ultrasonic is an integrator from the mechanical engineering sector. In addition to the machine hardware, the DMG-Mori subsidiary will also develop the process control. The aim is to put the new system into trial operation at Volkswagen by 2018.

Alongside the industrial partners, two university institutes at RWTH Aachen and FH Münster, and the Fraunhofer Institute for Laser Technology (ILT) in Aachen will also assume central tasks in the project. The Laboratory for Photonics in Münster will implement a z-shifter on the basis of piezo-driven mirrors, which will adjust the laser beam’s constantly changing focus within milliseconds. Meanwhile, the ILT researchers will use their process expertise to optimize ablation and polishing processes in the interplay of nanosecond and picosecond pulses. Their colleagues at RWTH will take on the algorithms for surface parametrization, structural synthesis and visualization, as well as the load paths for the processes.

Target markets in automotive and mechanical engineering

The eVerest partners’ goal is more efficient production of large-format 3D molds with micro-structured design or functional surfaces, whether it’s to produce elegant surfaces in the interiors of cars, aircraft or trains, or bionic surfaces with optimized flow or friction properties for bearings, engines, aircraft or hydraulic systems, or high-resolution printing and embossing dies.

Given that the performance, frequencies and reliability of ultrashort pulse lasers have been increasing for years, the next logical step is to combine nanosecond and picosecond pulses in one system. Scanning systems that direct laser beams across surfaces at speeds of up to one kilometer per second, and multibeam systems that split laser beams into hundreds of subbeams using diffractive optics, have already markedly speeded up cold microprocessing processes. Combining this with effective nanosecond technology is a further step toward broad industrial use of ultrashort pulse lasers.