  The dark-field signal uncovers details beyond conventional X-ray attenuation
contrast, which is especially valuable for material sciences. In particular,
dark-field techniques are able to reveal structures beyond the spatial
resolution of a setup. However, its implementation is yet limited to the
micrometer regime. Therefore, we propose a technique to extend full-field
transmission X-ray microscopy by the dark-field signal. The proposed method is
based on a well-defined illumination of a beam-shaping condenser, which allows
to block the bright-field by motorized apertures in the back focal plane of the
objective's lens. This method offers a simple implementation and enables rapid
modality changes while maintaining short scan times, making dark-field imaging
widely available at the nanometer scale.
