To further reduce the secondary source size, to increase coherence, and to achieve a smooth wavefront for holographic illumination, an x-ray waveguide formed by 1 mm long lithographic channels in silicon with a cross-section of about 100 nm was positioned in the focal plane of the KB-mirrors, resulting in an exit flux of 1–4⋅109 photon/s (depending on alignment and storage ring), as measured with the single photon counting detector (Pilatus, Dectris).