Laser technology has now penetrated almost every field in our society, including medicine, communication, the environment, trade and mobility. Lasers developed through the wide range of cooperative projects at the Fraunhofer ILT are unlocking new applications and potential for further development.
“The sign of a really good idea is that its realisation seems impossible from the outset.” When he said this, the German physicist and Nobel Prize winner Albert Einstein could not know the inestimable benefits his theoretical findings about how light and atoms interact would bring. It was not until the 1960s that Theodore Maiman of the Hughes Research Laboratories succeeded in using stimulated emission to incorporate the findings on radiation amplification into the first LASER (Light Amplification by Stimulated Emission of Radiation). Since then, the term “laser” has stood not only for the amplification technique, but instead for the haptic beam source. While the laser was considered “a device looking for an application” in its early phases, the situation today is very different.
Barely a problem is considered without investigating to see whether lasers could contribute to significant improvement. Some applications have only been made possible at all thanks to lasers. For example, it was only the laser-supported process that made eye operations for treating poor vision possible. Laser technology has now penetrated almost every field in our society, including medicine, communication, the environment, trade and mobility. In Germany, the success of laser technology is based on the traditionally close links between industry, science and research ministries. For example, the science organisations have succeeded in systematically training excellent young talents for industry. For many years now, industry has taken advantage of the focused and strategically orientated research programmes of the Federal Ministry of Education and Research (BMBF) and the state ministries to develop innovative laser beam sources and laser processes, in close cooperation with the research centres.
In North Rhine-Westphalia, this symbiosis has been implemented excellently around the Fraunhofer Institute for Laser Technology ILT. Both laser beam source manufacturers and laser users have been among the R&D partners since the institute’s inception in 1985. New lasers developed at the Fraunhofer ILT paved the way for new applications, while new requirements from production technicians led to the development of new laser beam sources: a perfect circle that drove the technology forward consistently and triggered fast growth at the centre in Aachen. Three years after the institute’s inception, the first companies relocated directly into the Fraunhofer ILT building, in order to act as “spin-ins” – driving forward particularly risky developments in mixed project teams on site. Not only users from the steel industry, microtechnology and measuring technology, but also laser beam source manufacturers made good use of the infrastructure – the only one of its kind in Europe. This environment produced numerous innovations, such as laser-supported surface cleaning, the generation of dental prostheses using laser-supported rapid manufacturing processes, and automated laser surface polishing. With over 350 employees and approx. 150 further staff at the associated chairs at RWTH Aachen University, the Fraunhofer ILT is among the sector’s leading contract research and development centres. Over 380 patents have been registered and around 30 spin-off companies founded from the association during its 25-year history. These spin-offs produce laser beam sources themselves or use them as users or system manufacturers. All initiatives are guided by the principle of the Institute’s management: “Every project should be led by a vision, accompanied by professional management and followed by a benefit for society.”
What is so special about laser light? Its extraordinary properties, such as high performance, directed radiation, good focusing abilities and short pulses. Laser radiation can be tailored – for any application. This provides high levels of flexibility, productivity and quality. The application spectrum of lasers is very diverse, ranging from joining and cutting to generating and ablating to texturing and polishing. The laser is a multifunctional tool that can be used flexibly for material processing. Because the laser processes can also be constantly monitored or even controlled, they are perfect for automated production processes with online quality control.
Where are we now and what can we expect in the future? The applications in the field of laser cutting, which forms the largest share of the market and is without a doubt among the most sophisticated processes, are very diverse. Be it steel sheets, paper or plywood, lasers are used to cut almost any material. Examples in micro-processing include laser finish blanking for stents (used to support blood vessels in cardiac and vascular surgery) and precision components in the watch industry.
Be it welding, soldering or bonding, laser joining is used in both the macro and micro fields. Examples include welding continuous pipes in the metalworking industry and gearbox parts in the automotive industry. In the next few years, interest will be focused on new material combinations. For example, the automotive sector will see an increase in the use of fibre-reinforced plastics in future. Development of laser joining and cutting processes in this field is still in its infancy.
Worldwide competition is increasingly demanding tailored series products. Generating processes, such as Selective Laser Melting (SLM), which was developed at the Fraunhofer ILT in Aachen, play a central role here. The process allows three-dimensional metallic components to be literally printed out, based on CAD data (computer-supported designs). A laser beam hardens the powdery material layer by layer, thus gradually building up the component. The process also allows specified cavities to be implemented with ease. The aircraft industry, tool making and medical technology have recognised the benefits of the SLM process and now use it in the production of innovative turbines, internallycooled moulded inserts and tailored titanium implants. Another new prospect can also be seen in this field: the production of “resorbable” implants – artificial replacement bones made from polylactide. Enclosed in the material are tricalcium phosphate (TCP) particles, which provide hardness and stimulate the bones’ natural healing process. The adjoining bone can grow into the material’s porous internal structure. What makes the technology really special is the fact that the implant can be decomposed inside the body to the same extent as the healthy bone grows back. In future, tailored, resorbable implants could be used particularly in facial, jaw and cranial surgery.
Development has not stood still in laser beam sources, either. While gas, solid-state and diode lasers are already in widespread use, ultrashort pulse lasers are only at the very start of their development. These are specialised solid-state lasers that emit extremely short pulses (< 10-10 s) with a very high peak intensity (> 1010 W/cm²). The pulses are so short that, in contrast to previous lasers, the material only heats up slightly after the end of the pulse. In the case of drilling for example, this means that the material is carried away almost exclusively via evaporation, with almost no residual melted material. This significantly increases the quality of the drilled holes and allows even very hard materials made from ceramic and diamond to be processed with a high degree of precision.
These are just a few examples of the many developments coming up over the next few years. Sectors such as medical technology, energy technology and biophotonics are leading the way and unlocking many more unforeseen prospects for laser technology. NRW’s research-intensive and well-connected regions in particular make a key contribution to adding value here. Together with their industrial partners, R&D centres like the Fraunhofer Institute for Laser Technology will continue to open up new horizons for optical technologies, in line with the credo of Antoine de Saint-Exupéry: “As for the future, your task is not to foresee it, but to enable it.”
Prof. Dr. Reinhart Poprawe
The author was born in 1954 and graduated in Physics from California State University, Fresno. After obtaining his undergraduate degree and, in 1984, his doctorate in Darmstadt, he joined the staff of the Fraunhofer Institute for Laser Technology in Aachen. Prof Dr Reinhart Poprawe was managing director of Thyssen Laser-Technik GmbH from 1989 to 1996, before returning to the Fraunhofer Institute as its director.
Dipl.-Phys. Axel Bauer
The author began his career as a research fellow at the Fraunhofer Institute for Laser Technology in Aachen in 1989, after gaining his undergraduate degree in Physics from RWTH Aachen University. Since 1994, he has been responsible for the Institute’s marketing and communication. Axel Bauer has been a founding member of the Fraunhofer-Gesellschaft’s marketing network since 1995, and of its PR network since 2001. Since 2002, he has also been the executive director of the Arbeitskreis Lasertechnik e.V. in Aachen.