The design and implementation of a pair of 100 mm-long grazing-incidence total-reflection mirrors for the hard
X-ray beamline Nanoscopium at Synchrotron Soleil is presented. A vertically and horizontally nanofocusing
mirror pair, oriented in Kirkpatrick-Baez geometry, has been designed and fabricated with the aim of creating a
diffraction-limited high-intensity 5 − 20 keV beam with a focal spot size as small as 50 nm. We describe the design
considerations, including wave-optical calculations of figures-of-merit that are relevant for spectromicroscopy,
such as the focal spot size, depth of field and integrated intensity. The mechanical positioning tolerance in the
pitch angle that is required to avoid introducing high-intensity features in the neighborhood of the focal spot
is demonstrated with simulations to be of the order of microradians, becoming tighter for shorter focal lengths
and therefore directly affecting all nanoprobe mirror systems. Metrology results for the completed mirrors are
presented, showing that better than 1.5 °A-rms figure error has been achieved over the full mirror lengths with
respect to the designed elliptical surfaces, with less than 60 nrad-rms slope errors.
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