The world's sharpest X-ray beam shines at DESY

Sep 30, 2013
This is an electron micrograph of the micro lens on the tip of a needle. The lens has a diameter of just two microns (thousandths of a millimeter). Credit: University of Göttingen

The world's sharpest X-ray beam shines at DESY. At the X-ray light source PETRA III, scientists from Göttingen generated a beam with a diameter of barely 5 nanometres – this is ten thousand times thinner than a human hair. This fine beam of X-ray light allows focusing on smallest details. The research groups of Professor Tim Salditt from the Institute of X-ray Physics and of Professor Hans-Ulrich Krebs from the Institute of Materials Physics of the University of Göttingen published their work in the research journal Optics Express.

High-energy (hard) X-ray light cannot be focused as easily as visible light by using a burning glass. "Instead of a common lens, we use a so-called Fresnel lens which consists of several layers," explains co-author Dr. Markus Osterhoff. The central support is a fine tungsten wire with the thickness of only a thousandth of a millimetre. Around the wire, nanometre-thin silicon and tungsten layers are applied in an alternating way. The physicists then cut a thin slice from the coated wire. "This slice has 50 to 60 silicon and tungsten layers, comparable to growth rings of a tree," explains team member Florian Döring. "And the layer thicknesses have to be extremely precise," adds Christian Eberl. The two PhD students have optimized the different fabrication steps.

The wire slice with a size of only about two thousandths of a millimetre is used as a lens. However, it does not diffract light like a glass lens but scatters it like an optical grid generating a pattern of bright and dark patches. In this case, the thickness of the layers is selected in such a way that the bright areas of the diffraction pattern coincide at the same spot. The more precise the lens is fabricated, the sharper becomes the X-ray focus. With this method, the physicists obtained an X-ray of 4.3 nanometres (millionth of a millimetre) diameter in horizontal direction and 4.7 nanometres diameter in vertical direction. Until recently it was even debated whether fundamental limits of X-ray optics would stand against such small focal widths. The outstanding brilliance of DESY's X-ray source PETRA III helped to make a usable nano focus possible.

This is the reconstruction of the two-dimensional focus field. The intensity is color coded. Credit: University of Göttingen

The fine X-ray beam opens up new possibilities for materials science, e.g. the investigation of nano wires to be used in solar cells. "Usually, when investigating the chemical composition of a sample, the beam size limits the sharpness of the image. Before this experiment, this limit was at about 20 nanometers", said DESY researcher Dr. Michael Sprung, responsible scientist for the PETRA measuring station P10, where the experiments are carried out.

As a next step, the scientists want to improve the performance by depositing the layers on ultrathin and extremely uniform glass fibres. Moreover, they plan to scan first nanoscopic structures with their novel ultra-sharp beam. In the future, such a should help to create foci of ultimate flux density with free-electron laser (FEL) radiation.

Explore further: Optical nanoantennas set the stage for a NEMS lab-on-a-chip revolution

More information: "Sub-5 nm hard x-ray point focusing by a combined Kirkpatrick-Baez mirror and multilayer zone plate"; F. Döring, A.L. Robisch, C. Eberl, M. Osterhoff, A. Ruhlandt, T. Liese, F. Schlenkrich, S. Hoffmann, M. Bartels, T. Salditt and H.U. Krebs; Optics Express, Vol. 21, No. 16, (2013); DOI: 10.1364/OE.21.019311

Related Stories

Sharper images for extreme LCLS experiments

Apr 17, 2013

(Phys.org) —An imaging technique conceived 50 years ago has been successfully demonstrated at SLAC's Linac Coherent Light Source, where it is expected to improve results in a range of experiments, including ...

Bubbles are the new lenses for nanoscale light beams

Aug 09, 2013

Bending light beams to your whim sounds like a job for a wizard or an a complex array of bulky mirrors, lenses and prisms, but a few tiny liquid bubbles may be all that is necessary to open the doors for ...

Recommended for you

New filter could advance terahertz data transmission

14 hours ago

University of Utah engineers have discovered a new approach for designing filters capable of separating different frequencies in the terahertz spectrum, the next generation of communications bandwidth that ...

The super-resolution revolution

15 hours ago

Cambridge scientists are part of a resolution revolution. Building powerful instruments that shatter the physical limits of optical microscopy, they are beginning to watch molecular processes as they happen, ...

Precision gas sensor could fit on a chip

16 hours ago

Using their expertise in silicon optics, Cornell engineers have miniaturized a light source in the elusive mid-infrared (mid-IR) spectrum, effectively squeezing the capabilities of a large, tabletop laser onto a 1-millimeter ...

A new X-ray microscope for nanoscale imaging

17 hours ago

Delivering the capability to image nanostructures and chemical reactions down to nanometer resolution requires a new class of x-ray microscope that can perform precision microscopy experiments using ultra-bright ...

New research signals big future for quantum radar

Feb 26, 2015

A prototype quantum radar that has the potential to detect objects which are invisible to conventional systems has been developed by an international research team led by a quantum information scientist at the University ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.