New lenses for X-ray examinations

(a) Refractive X-ray lens with a diameter of 600 micrometers. (b) Diffractive X-ray lens with a diameter of 90 micrometers, that is smaller than the diameter of a human hair. (Image Paul Scherrer Institute)

In the Nano Argovia project ACHROMATIX, an interdisciplinary team of researchers is developing a novel lens system that can be used for scientific investigations using X-rays. Dr. Joan Vila-Comamala of the Paul Scherrer Institute is leading the project in which scientists from the Paul Scherrer Institute, the University of Basel and the company XRnanotech are contributing their expertise.

Nowadays, X-rays play an important role not only in everyday medical practice; the special properties of X-rays are also used in research or in material analyses. In X-ray microscopy, lenses are used to focus the X-ray beam on the sample or to create a magnified image. For this purpose, various lenses have been developed in recent years that reflect, refract or diffract the X-rays. These three different types of lenses have advantages and disadvantages.

Refractive and diffractive lenses focus X-rays of different wavelengths at different distances. Experts refer to this as chromatic aberration. If X-ray tubes are used as the source of X-ray radiation, it is therefore necessary to reduce the comparatively broad wavelength range using a monochromator. However, this greatly reduces the number of light particles (photons), which in turn limits the use of the X-ray tube for X-ray microscopy.

“The heart of every microscope is its optics. With new and better optics, unimagined insights into materials and matter can be achieved and new knowledge gained. The Nano Argovia project offers us the opportunity to decisively improve the optics for X-ray microscopes.”

Dr. Florian Döring, CEO and Founder of XRnanotech GmbH

Combination of lenses
In the Nano Argovia project ACHROMATIX, scientists are now developing a combination of a refractive and a diffractive lens. The aim is to design this lens combination in such a way that the chromatic aberration of the two lenses balances out.

First, the researchers determine the best lens combination based on theoretical calculations, which they will then manufacture using state-of-the-art nanofabrication techniques. The finished achromatic X-ray lens will then be characterized and tested in detail.

The lens will later be used for transmission X-ray microscopy to perform biomedical laboratory studies. The researchers expect this to result in an approximately tenfold improvement in photon flux. Investigations that are currently only possible using a synchrotron light source should become possible using X-ray tubes with the new lens, thereby significantly advancing and broadening the use of X-ray investigation for scientific purposes.

In addition to the project leader Dr. Joan Vila-Comamala (PSI), Dr. Christian David (PSI), Dr. Georg Schulz (Department Biomedical Engineering, University of Basel), Professor Bert Müller (Biomaterial Science Center, University of Basel) and Dr. Florian Döring from XRnanotech (Villingen) are involved as partners in the project.

Additional information

XRnanotech
Paul Scherrer Institute
Biomedical Science Center University of Basel