Speaker
Description
Ptychography is a type of coherent diffraction imaging which uses a strongly coherent X-ray source from a synchrotron to reconstruct high resolution images. By shifting the illumination source, it exploits redundancy of multiple diffraction patterns to robustly solve the related phase retrieval problem. The shift parameters are often subject to uncertainty and introduce additional ill-posedness in the reconstruction task. Motivated by applications in single particle imaging, we consider the extreme task of entirely unknown shifts, which have to be recovered jointly with the image. The resulting blind inverse problem requires careful regularization. We explore the ability of learned priors, encoded by a score-based diffusion model, to jointly solve the reconstruction problem and recover the scan positions. In particular, we discuss a Bayesian approach, solving the above task within a variational inference framework.
