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Volume 4, 2015

Fred Bijkerk and his entire research group recently moved from FOM institute DIFFER to MESA+. All about in-car meetings and compiling a tool kit for extreme ultraviolet light.

Why didn’t you move to Eindhoven with the rest of the FOM institute DIFFER?
“The institute wanted to focus mainly on research into energy. So I needed to decide whether to shift my research into that new direction or to continue delving deeper into the subject of thin films. I chose the thin films and their applications in mirrors, spectroscopy, chips, lithography. This led to a second question: where to conduct my research? Thin films are investigated in Eindhoven, true, but Twente both literally and figuratively added a new dimension to my research.”

Literally and figuratively added a new dimension? It sounds like marketing lingo.
“It’s not. I’m concentrating on thin films. In essence, these are two-dimensional structures. But here at Twente, we are able to add functionalities to this two-dimensional structure. A grille pattern, for instance. This turns it three-dimensional. So, literally, a new dimension. And the figurative dimension is about being able to push the research envelope here at Twente. It is a seed-bed of research into thin films and associated scientific fields. And that keeps encouraging us to continue our work.”

No regrets about the move?
“Not at all. We’ve improved all-round. Coming to Twente was a great move. I’m thoroughly happy having made this decision.”

So, there is nothing you miss from your days at DIFFER?
“Oh, but there is. DIFFER was of a smaller scale and therefore more efficient. When having to make a sizeable investment or suchlike, I only needed to get one or two people to sign for approval. Here at Twente, I’m part of a larger organization with all the associated layers. I now need to gather some seven or eight signatures if I want to get something done.”

Did you move private residence as well?
“No. Our children have left home already, and my wife and I had just bought a new house close to Zeist when I decided to go to Twente. We had just renovated it. So I want to enjoy that house for a while yet.”

Do you commute from Utrecht to Twente every day?
“No. With some other colleagues who haven’t moved yet, I set up a carpool system. Every Monday morning, we drive to Twente. We stay in a small boardinghouse close to the university during the week. We expect to keep this system up for some six months yet. Carpooling turns out to be very useful, by the way. Our trip has more or less become an extra work meeting.”

That’s quite enough on moving house and private affairs. Back to the thin films. What are your plans for the next few years?
“Our research is developing in a logical fashion. We were comfortable with working in two dimensions and the associated strict quality requirements already. We’re now expanding our field of research. Thanks to the advanced lithographic equipment available in the NanoLab, we were able to move from Bragg-based physics (reflection) to Bragg-Fresnel (reflection and diffraction). We are now able to create mirrors featuring multiple nanolayers and to insert grille patterns such as variants of zone plates, expanding the field of optics. The techniques we developed can be used for eliminating undesired spectral bands, for instance.”

Ah! Industry. Do businesses actually want to wait for long-term research to produce results?
“They’re far from disinterested. In fact, it’s industry patronage that allows me to conduct my research in the first place. ASML started thinking about microchip machines using short-wave light some years ago. Such a machine could not use lenses. It would need mirrors. So they came to us, and by now we are able to produce mirrors that reflect a full seventy percent of light. The lithographers at ASML and Zeiss are physicists themselves. Some of them even obtained their PhDs under my tutelage! They are fully aware of the fact that research can take a long time. By the by, so as to be perfectly clear: I am conducting my research because it touches upon so much interesting physics aspects. Interest is a sine qua non for me to start up new research. There is so much to research on extreme ultraviolet light still. By now, the optics community compiled a complete tool kit to work with visible light, but this is far from the case where XUV is concerned. My aim is to have my group explore all that can be done with XUV. And MESA+ is the best place to do this.”

Name: Fred Bijkerk (1954)

Position: Industrial Focus Group XUV Optics programme leader at MESA +

Previously: Bijkerk obtained his PhD at the VU University and FOM Rijnhuizen in Amsterdam in 1993. He had conducted research into X-radiation and plasma sources. In 1986 he started working at the FOM institute DIFFER (then still called FOM institute for Plasmaphysics in Rijnhuizen). In 2005, he became a professor in extreme ultraviolet light sources and optics at the University of Twente. In 2014, he and his entire research group moved from Rijnhuizen to Enschede. Bijkerk was the recipient of the 2010 FOM Valorization Prize. Together with ASML and Zeiss, Bijkerk developed various methods of guiding extreme UV light so as to allow it to be used in microchip fabrication and to unravel processes at the atomic/molecular level.

AT MESA +... “I feel at home with our research activities.”