Conferences - Seminars

  Tuesday 18 September 2018 17:15 - 18:15 CM 1 4

The Geometry of the Phase Retrieval Problem

By Prof. Charles L. Epstein (University of Pennsylvania)

One of the most powerful approaches to imaging at the nanometer or subnanometer length scale is coherent diffraction imaging using X-ray sources. For amorphous (non-crystalline) samples, the raw data can be interpreted as the modulus of the continuous Fourier transform of the unknown object. Making use of prior information about the sample (such as its support), a natural goal is to recover the phase through computational means, after which the unknown object can be visualized at high resolution. While many algorithms have been proposed for this phase retrieval problem, careful analysis of its well-posedness has received relatively little attention. In fact the problem is, in general, not well-posed and describe some of the underlying geometric issues that are responsible for the ill-posedness. We then show how this analysis can be used to develop experimental protocols that lead to better conditioned inverse problems.

Organization Prof. Hongler

Contact Marie Munoz

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