Work

Ptychographic reconstruction with object initialization

Year: 2022

Type: article

Abstract: X-ray ptychography is a cutting edge imaging technique providing ultra-high spatial resolutions. In ptychography, phase retrieval, i.e., the recovery of a complex valued signal from intensity-only measurements, is enabled by exploiting a redundancy of information contained in diffraction patterns measured with overlapping illuminations. For samples that are considerably larger than the probe we show that during the iteration the bulk information has to propagate from the sample edges to the center. This constitutes an inherent limitation of reconstruction speed for algorithms that use a flat initialization. Here, we experimentally demonstrate that a considerable improvement of computational speed can be achieved by utilizing a low resolution sample wavefront retrieved from measured diffraction patterns as object initialization. In addition, we show that this approach avoids phase artifacts associated with large phase gradients and may alleviate the requirements on phase structure within the probe. Object initialization is computationally fast, potentially beneficial for bulky sample and compatible with flat samples. Therefore, the presented approach is readily adaptable with established ptychographic reconstruction algorithms implying a wide spread use.

Source: Optics Express

DOI: 10.1364/oe.465397

Authors: Felix Wittwer, Dennis Brückner, Peter Modregger

Institutions: Lawrence Berkeley National Laboratory, University of Siegen, Deutsches Elektronen-Synchrotron DESY, National Energy Research Scientific Computing Center

Language: English

Topic: Advanced X-ray Imaging Techniques

Subfield: Radiation

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $2,270

Funder: Deutsches Elektronen-Synchrotron