Search Results for author: Marc Allain

Found 4 papers, 4 papers with code

A matrix-free Levenberg-Marquardt algorithm for efficient ptychographic phase retrieval

1 code implementation27 Feb 2021 Saugat Kandel, S. Maddali, Youssef S G Nashed, Stephan O Hruszkewycz, Chris Jacobsen, Marc Allain

The phase retrieval problem, where one aims to recover a complex-valued image from far-field intensity measurements, is a classic problem encountered in a range of imaging applications.

Retrieval

Detector tilt considerations in high-energy Bragg coherent diffraction imaging: a simulation study

1 code implementation4 Aug 2020 Siddharth Maddali, Marc Allain, Peng Li, Virginie Chamard, Stephan O. Hruszkewycz

This paper addresses three-dimensional signal distortion and image reconstruction issues in x-ray Bragg coherent diffraction imaging (BCDI) in the event of a non-trivial, non-orthogonal orientation of the area detector with respect to the diffracted beam.

Instrumentation and Detectors Image and Video Processing

General approaches for shear-correcting coordinate transformations in Bragg coherent diffraction imaging: Part 2

1 code implementation15 Aug 2019 Peng Li, Siddharth Maddali, Anastasios Pateras, Irene Calvo-Almazan, Stephan O. Hruszkewycz, Virginie Chamard, Marc Allain

To deal with this, the currently favored approach (detailed in Part I) is to perform the entire inversion in conjugate non-orthogonal real and Fourier space frames, and to transform the 3D sample image into an orthogonal frame as a post-processing step for result analysis.

Instrumentation and Detectors Signal Processing

General approaches for shear-correcting coordinate transformations in Bragg coherent diffraction imaging: Part 1

1 code implementation15 Aug 2019 Siddharth Maddali, Peng Li, Anastasios Pateras, Daniel Timbie, Nazar Delegan, Alex Crook, Hope Lee, Irene Calvo-Almazan, Dina Sheyfer, Wonsuk Cha, F. Joseph Heremans, David D. Awschalom, Virginie Chamard, Marc Allain, Stephan O. Hruszkewycz

Part II builds upon the geometric theory developed in Part I with the formalism to correct the shear distortions directly on an orthogonal grid within the phase retrieval algorithm itself, allowing more physically realistic constraints to be applied.

Instrumentation and Detectors

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