Light Sci. Appl. 7, 17162 (2018) https://doi.org/10.1038/lsa.2017.162

The ability to focus X-rays to spots on the nanometre scale is attractive for high-resolution analysis of a variety of samples. Now, Saša Bajt and co-workers have developed high numerical aperture (NA) diffractive optical elements called Laue lenses and have shown that they can focus 16.3 keV (0.077 nm wavelength) X-rays to a focal spot of 8.4 × 6.8 nm in size. The lenses operate in a similar manner to a Fresnel zone plate lens and consist of thousands of alternating layers of tungsten carbide and silicon carbide with varying periodicity. The team fabricated a pair of lenses, one for horizontal focusing and one for vertical focusing. The former was 21.8 μm in height and composed of 3,326 bilayers and had a focal length of 1.36 mm and a NA of 0.008. The latter was 29.9 μm high and consisted of 5,100 bilayers and had a focal length of 2.02 mm and a NA of 0.0074. The lenses were tested with X-ray beamlines at the PETRA III synchrotron facility at DESY in Germany and the National Synchrotron Light Source II at Brookhaven National Laboratory in the US. The researchers say that the approach offers a path to X-ray imaging with 1 nm resolution.