Dresden 2017 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 39: X-Ray Imaging, Holography, Ptychography and Tomography

MA 39.3: Vortrag

Mittwoch, 22. März 2017, 10:15–10:30, MER 02

The Fluence-Resolution Relationship in Holographic and Coherent Diffractive Imaging — •Johannes Hagemann and Tim Salditt — Institut für Röntgenphysik, Friedrich-Hund-Platz 1, University Göttingen, 37077 Göttingen

The simple question "Which resolution do I get for the invested photon fluence?" is extremely important for x-ray imaging of radiation sensitive specimen, such as biological cells and tissues. This work [1] presents a numerical study of the fluence-resolution behavior for two coherent lens-less x-ray imaging techniques. To this end we compare in numerical experiments the fluence-resolution relationship of inline near-field holography (NFH) and far-field coherent diffractive imaging (CDI). To achieve this, we carry out the phase reconstruction using iterative phase retrieval algorithms on simulated noisy data. Using the incident photon fluence on the specimen as control parameter we study the achievable resolution for two exemplary phantoms (cell and bitmap). A survey based on maximum likelihood estimation [2] of CDI and NFH showed in principle no difference in the encoded information of the measured data for a given fluence. In the current approach we assess the actual reconstructability of the CDI/NFH data via direct phase retrieval. We use then the Fourier Ring Correlation as measure of reconstruction quality i.e. the achievable resolution. Our results indicate a superior performance of holography compared to CDI, for the same fluence and phase reconstruction procedure.
[1] J. Hagemann and T. Salditt, Acta Crystallogr. A, (in review) [2] T. Jahn et al., Acta Crystallogr. A, (2017), 73, 1-11