* Astronomy

Title: First results from a next-generation off-plane X-ray diffraction grating
Authors: Randall McEntaffer, Casey DeRoo, Ted Schultz, Brennan Gantner, James Tutt, Andrew Holland, Stephen O'Dell, Jessica Gaskin, Jeffrey Kolodziejczak, William W. Zhang, Kai-Wing Chan, Michael Biskach, Ryan McClelland, Dmitri Iazikov, Xinpeng Wang, Larry Koecher

Future NASA X-ray spectroscopy missions will require high throughput, high resolution grating spectrometers. Off-plane reflection gratings are capable of meeting the performance requirements needed to realise the scientific goals of these missions. We have identified a novel grating fabrication method that utilises common lithographic and microfabrication techniques to produce the high fidelity groove profile necessary to achieve this performance. Application of this process has produced an initial pre-master that exhibits a radial (variable line spacing along the groove dimension), high density (>6000 grooves/mm), laminar profile. This pre-master has been tested for diffraction efficiency at the BESSY II synchrotron light facility and diffracts up to 55% of incident light into usable spectral orders. Furthermore, tests of spectral resolving power show that these gratings are capable of obtaining resolutions well above 1300 (\lambda/\Delta\lambda) with limitations due to the test apparatus, not the gratings. Obtaining these results has provided confidence that this fabrication process is capable of producing off-plane reflection gratings for the next generation of X-ray observatories.

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