Phase retrieval

Monday, August 14, 2017 - 2:00pm - 2:45pm
Stefano Marchesini (Lawrence Berkeley National Laboratory)
An overview of phase retrieval algorithms and experimental schemes developed for high through-put imaging applications using state of the art x-ray sources, detectors and computing facilities.
Friday, August 18, 2017 - 10:30am - 11:00am
Sami Merhi (Michigan State University)
A novel phase retrieval method, motivated by ptychographic imaging, is proposed for the approximate recovery of a compactly supported, complex-valued specimen function from its continuous short time Fourier transform (STFT) spectrogram measurements. The method, partially inspired by the well known PhaseLift algorithm, is based on a lifted formulation of the infinite dimensional problem which is then later truncated for the sake of computation. Numerical experiments demonstrate the promise of the proposed approach.
Wednesday, August 16, 2017 - 2:00pm - 2:45pm
Guoan Zheng (University of Connecticut)
Fourier ptychography (FP) is a recently developed phase retrieval technique for wide-field, high-resolution imaging. This technique stitches together many variably illuminated, low-resolution measurements in the Fourier space to expand the frequency passband and recover the high-resolution complex sample image. Without involving any mechanical scanning, it facilitates gigapixel imaging in a simple and robust manner.
Thursday, August 17, 2017 - 10:30am - 11:00am
Brian Preskitt (University of California, San Diego)
The phase retrieval problem has appeared in a multitude of applications for decades. While ad hoc solutions have existed since the early 1970s, recent developments have provided algorithms that offer promising theoretical guarantees under increasingly realistic assumptions. Motivated by ptychographic imaging, we generalize a recent result on phase retrieval of a one dimensional signal to recover a two dimensional image from phaseless measurements, using a tensor product formulation to extend the previous work.
Monday, August 14, 2017 - 10:00am - 10:45am
Andreas Menzel (Paul Scherrer Institute)
Ptychography comprises sampling and analyzing the object’s spatial spectrogram by windowed (or “short-space”) Fourier transforms. Its capability to reconstruct both image and illumination, as well as other experimental conditions including instabilities has proven promising for high-resolution X-ray microscopy.
Tuesday, August 15, 2017 - 2:00pm - 2:45pm
James Fienup (University of Rochester)
Phase retrieval has grown in popularity in recent years on account of its success in x-ray coherent diffractive imaging, including ptychography. Our development of phase retrieval for image reconstruction will be reviewed, including both passive and active imaging, in both optics and x-rays, enabling imaging from the nano-scale to the astronomical scale. Iterative transform and nonlinear optimization algorithms will be compared.
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