The nanoworld revealed thanks to an innovative X-ray lens

Scientists at the Paul Scherrer Institute have developed an innovative achromatic lens for X-rays. This allows X-ray beams to be accurately focused on a single point even if they have different wavelengths. The new lens will make it much easier to study nanostructures using X-rays, according to a paper just published by researchers in the scientific journal Nature Communications. Achromatic lenses are essential for producing sharp images in photography and optical microscopes. They ensure that different colors, that is light of different wavelengths, have a common focal point. To date, however, achromatic lenses have not been available for X-rays, so high-resolution X-ray microscopy has only been possible with monochromatic X-rays. In practice, this means that all other wavelengths must be filtered out of the spectrum of the X-ray beam and therefore only a small part of the light can be used effectively, resulting in a relatively inefficient image acquisition process.

A team of scientists from PSI has now solved this problem by successfully developing an achromatic X-ray lens for X-rays. Since X-rays can reveal much smaller structures than visible light, the innovative lens will go particularly to the benefit of research and development work in areas such as microchips, batteries and materials science, among others.

The fact that it has taken a long time until now to develop an achromatic lens for X-rays may at first seem surprising: for visible light, achromatic lenses have been around for over 200 years. These are usually made up of two different materials. Light penetrates the first material and splits into its spectral colors, just like when it passes through a conventional glass prism. Then go through a second material to reverse this effect. In physics, the process of separating different wavelengths is called "scattering".




Credits: Paul Scherrer Institute / Umut Sanli So instead of looking for the answer in the combination of two materials , scientists linked two different optical principles together. “The trick was to realize that we could place a second refractive lens in front of our diffractive lens,” said Adam Kubec, lead author of the new study. Until recently, Kubec was a researcher in Christian David's group and now works for XRnanotech, a spin-off that emerged from PSI's research in X-ray optics.


“Our achromatic X-ray lens will help enormously with this: it will enable compact X-ray microscopes that industrial companies can operate on their premises, ”said Kubec. Together with XRnanotech, PSI plans to commercialize the new lens. Kubec says they already have adequate contacts with companies that specialize in building laboratory-scale X-ray microscopy facilities.

They also tested the new lens using a method where the sample is moved through focus of the X-ray beam in small raster steps. When the wavelength of the X-ray beam is changed, the images produced with a conventional X-ray lens become very blurry. This, however, does not happen when using the new achromatic lens.

“When we finally got a clear image of the test sample over a wide range of wavelengths, we knew our lens it was working, ”said Zdora. David added: “The fact that we were able to develop this achromatic X-ray lens at PSI and will soon bring it to market with XRnanotech shows that the kind of research we do here can lead to practical applications over a very long period of time. short ".