Monolithic focused reference beam X-ray holography.

Geilhufe, J; Pfau, B; Schneider, M; Büttner, F; Günther, C M; Werner, S; Schaffert, S; Guehrs, E et al. · Nat Commun · 2014

basic_science · Level V

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Abstract

Fourier transform holography is a highly efficient and robust imaging method, suitable for single-shot imaging at coherent X-ray sources. In its common implementation, the image contrast is limited by the reference signal generated by a small pinhole aperture. Increased pinhole diameters improve the signal, whereas the resolution is diminished. Here we report a new concept to decouple the spatial resolution from the image contrast by employing a Fresnel zone plate to provide the reference beam. Superimposed on-axis images of distinct foci are separated with a novel algorithm. Our method is insensitive to mechanical drift or vibrations and allows for long integration times common at low-flux facilities like high harmonic generation sources. The application of monolithic focused reference beams improves the efficiency of high-resolution X-ray Fourier transform holography beyond all present approaches and paves the path towards sub-10 nm single-shot X-ray imaging.