Berlin 2015 – wissenschaftliches Programm

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MI: Fachverband Mikrosonden

MI 10: Poster: Microanalysis and Microscopy

MI 10.5: Poster

Mittwoch, 18. März 2015, 15:00–17:30, Poster B

Sparsity Constraint for Phase Retrieval in X-Ray Imaging — •Anne Pein and Tim Salditt — University of Göttingen, Institute for X-Ray Physics, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany

A powerful approach for phase retrieval in x-ray propagation imaging is to exploit prior information of the signal as for example a rough knowledge about the support of the object. Iterative algorithms then alternately project onto constraint sets based on this prior information and the measurement in order to approximate the wave-field directly behind the object.

Recently, Loock and Plonka have proposed to use a priori knowledge that the exit wave-field is sparse in a certain representation system, i.e. that only a few representation coefficients are nonzero, and they have presented promising results with this method by numerical simulations [1]. This approach is implemented based on a shearlet frame system [2]. In this work we present an extensive numerical evaluation of this approach, including a quantitative comparison with other common constraints.

[1] S. Loock, G. Plonka, 'Phase retrieval for Fresnel measurements using a shearlet sparsity constraint', Inverse Problems 30 (2014).

[2] ShearLab 3D Toolbox from http://www.shearlab.org