New lenses for 3D imaging In the Nano-Argovia project Nano Diffractive Optics, an interdiscipli- nary team is developing optical elements on a nanometer scale that can be used for three-dimensional imaging in an optical coherence tomography (OCT) system. Concentric ring lenses The researchers are focusing on the production of so-called fraxicon lenses. Unlike a normal lens, these lenses are not smooth or spherical but rather consist of numerous thin, concentric rings. These rings have jagged or stepped structures that deflect light — in this case, laser light — into a narrow beam (a Bessel beam) that remains the same over a long distance. In this two-year project, led by project manager Professor Bojan Resan (University of Applied Sciences and Arts Northwestern Switzerland FHNW, School of Engineering and Environment), the researchers plan to produce fraxicon lenses with a sharp tip in the sub-micrometer range using direct laser writing techniques. Determine the potential of mass production To this end, the team is analyzing and optimizing each process step so that the lenses can subsequently be produced in large quantities. The researchers will then test the lenses in a recently developed ul- tra-high-resolution OCT imaging system. The team from FHNW, the Paul Scherrer Institute and the industrial partner XRnanotech is also inves- tigating how various optical gratings can be produced using different lithography techniques. These grat- ings need to have numerous lines per millimeter and deflect either infrared or UV rays depending on their structure. Gratings of this kind are already well estab- lished, but the production methods used today are difficult, costly and inflexible. In the Nano Diffractive Optics project, the researchers want to explore the potential for mass production through direct writing or nanoimprinting. Collaboration between: FHNW School of Engi- neering and Environ- ment Paul Scherrer Institute XRnanotech GmbH (Villigen) Further information: Nano-Argovia program PSI FHNW XRnanotech “We’re proud to be participating in the Nano-Argovia program, which will signifi- cantly accelerate our R&D and product prototyping efforts, putting XRnanotech in a position to access new markets within the next year.” Dr. Gérard Perren, XRnanotech AG Nano-Argovia Project 8 SNI INSight June 2025