"Polychromatic Ptychographic Imaging (Phase Retrieval from Spectrogram Measurements)"Filbir, FrankPtychography is a computational imaging techinque. A detector (CCD camera) mea- sures the intensity of many diffraction patterns each obtained by illuminating a small part of the object at a time. The measurements are produced by using light (X- rays) of one specific very short wavelength ? and the detector placed in the far-field distance (Fraunhofer diffraction). Mathematically this experimental set-up leads to a phase retrieval problem from spectrogram measurements, i.e. we are given samples of ???? ???? I?(x, ?) = ???????? R2 f(y) g?(y ? x)e ?2?i?·y/? ????2dy???????? for a known window function g and we have to reconstruct f. However, there are experimental set-ups which do not allow to work with one specific wavelength ? but we have to deal with polychromatic measurements, i.e. we are given I?(x, ?) for ? ? {?1, . . . , ?L}. Moreover, in many cases even the g?’s are unknown. This then leads to what is called Blind Polychromatic Ptychographic Imaging (BPPI). In this talk we will provide an overview of BPPI and we present some reconstruction methods and results. The talk is based on joint work with Oleh Melnyk (Helmholtz Munich), Felix Krahmer (Technische Universita ?t Mu ?nchen) and our project partners Jan Rothardt (GSI Jena) and Nico Hoffmann (HZDR, Dresden ) within the Helmholtz Imaging Platform project AsoftXm. |
| http://univie.ac.at/projektservice-mathematik/e/talks/Filbir_2022-02_Abstract_Strobl22(Filbir).pdf |
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