Hard x-ray waveguides can be strongly curved
Waveguide channels x-rays via grazing-incidence reflection.
|In the new waveguide, most of the x-ray radiation follows the curved path (dark red), but a small amount leaks into the surrounding material, as shown in this computer simulation. (Image: American Physical Society's Physics Focus)|
Hard x-rays are used for imaging at the nanometer scale -- for example, imaging cells. However, optically routing hard x-rays traditionally requires very large (up to meter-length) bulk optics operating at grazing-incidence angles. Now, as noted by the American Physical Society's Physics Focus, an international team led by researchers at the University of Göttingen (Göttingen, Germany) have created 100-nm-wide waveguides that can bend a hard x-ray beam by up to 30° over a 5 mm distance.1
The waveguide is a narrow, open channel cut into a solid piece of tantalum, with the beam propagating via grazing incidence along the channel, with a critical angle of total reflection of 1°.
To maximize x-ray throughput, the team used intense beams generated at the DESY synchrotron facility in Hamburg, Germany, and, in a second test, the European Synchrotron Radiation Facility in France. They focused the beams to a width of a few hundred nanometers at the entrances of the waveguides.
This new work "changes x-ray optics from fairly [large-scale] devices to miniature devices, with all the attendant advantages," says Sunil Sinha of the University of California, San Diego.
1. T. Salditt et al., Physical Review Letters (2015); http://dx.doi.org/10.1103/PhysRevLett.115.203902