Dresden 2011 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 6: Quantum Effects: Light Scattering and Propagation

Q 6.6: Vortrag

Montag, 14. März 2011, 12:00–12:15, SCH A01

Wavefield Back-Propagation in High-Resolution X-ray Holography with a Movable Field of View — •Erik Guehrs¹, Christian Günther², Bastian Pfau¹, Torbjörn Rander¹, Stefan Schaffert¹, William Schlotter³, and Stefan Eisebitt¹ — ¹TU-Berlin — ²Helmholtz-Zentrum Berlin — ³Centre for Free-Electron Laser Science, Universität Hamburg

Mask-based Fourier transform holography (FTH) is used to record images of biological objects with 2.2 nm X-ray wavelength. The holography mask and the object are separated from each other allowing us to move the field of view of the sample. Due to the separation of the holography mask and the sample on different X-ray support membranes, a gap between both windows of several 10s of microns typically exists which can be due to misalignment or dust or is desired to protect the sample from direct contact. The depth of field, thus limits the gap size for which sharp images of the sample can be reconstructed using a 2D Fourier Transform of the hologram. In this contribution, we systematically investigate the imaging and reconstruction conditions for mask-sample separations up to 400 μm. We demonstrate the feasibility to combine FTH and wavefield backpropagation to obtain a focused image even for large separations and discuss the limitations of our approach which are mainly associated with Fresnel illumination. In particular for high-resolution imaging with soft X-rays and the associated small fields of view below 2 μm, our approach is crucial in order to obtain diffraction limited resolution combined with experimental ease regarding the scanning setup.