Coherence-matched microfocusing of hard x rays

An efficient, high-resolution microfocusing device for hard x rays is presented. A combination of two linear zone plates mounted with orthogonal orientation is used to provide two-dimensional focusing. Choosing appropriate lens parameters, the device can be matched to the quasielliptical shape of most synchrotron x-ray sources to obtain a symmetric, circular-shaped focal spot. A rectangular device aperture allows the maximization of the light-collecting area and to simultaneously achieve a highly coherent illumination of the device. Such a setup was tested at the European Synchrotron Radiation Facility and test gratings with minimal line widths of 140 nm could be resolved. The gain in flux density was found to be 105 for 12.7 keV photons.