Prof. DeRoo recently reported the results of testing a prototype X-ray reflection grating at the PANTER X-ray Test Facility in Garching, Germany (just outside of Munich). This grating was tested in an echelle-like mounting, in which the grating grooves are angled relative to the incident light allowing access to extremely high orders (24th - 30th orders @ 1.5 keV, see photo). The mosaic is a stitched image of approximately 20,000 individual X-rays, many of which have been deflected by almost a full meter away from the focus position by the grating!
An spectrometer instrument increases its spectral resolution by working at higher order, improving its ability to sample finely spaced features or to detect faint absorption signals on top of continuum. For comparison, the Chandra X-ray Transmission Grating Spectrometers work in +/-1st order at these energies, meaning that an instrument designed around these gratings could be much more sensitive.
These gratings and the test data taken are stepping-stones towards realizing the high resolution, blazed reflection gratings that would enable next-generation X-ray spectrometers. Congrats to all the authors!
A link to the full-text of the paper is here.