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A method is proposed for high-resolution, three-dimensional reconstruction of internal structure of objects from planar transmission images. The described approach can be used with any form of radiation or matter waves, in principle,…

Optics · Physics 2022-08-24 T. E. Gureyev , H. M. Quiney , L. J. Allen

This report extends our recent progress in tackling a challenging 3D inverse scattering problem governed by the Helmholtz equation. Our target application is to reconstruct dielectric constants, electric conductivities and shapes of front…

Computed tomography is a method for synthesizing volumetric or cross-sectional images of an object from a collection of projections. Popular reconstruction methods for computed tomography are based on idealized models and assumptions that…

Numerical Analysis · Mathematics 2022-03-03 Frederik H. Pedersen , Jakob S. Jørgensen , Martin S. Andersen

We propose a physics-informed neural network as the forward model for tomographic reconstructions of biological samples. We demonstrate that by training this network with the Helmholtz equation as a physical loss, we can predict the…

Optics · Physics 2022-07-29 Amirhossein Saba , Carlo Gigli , Ahmed B. Ayoub , Demetri Psaltis

This paper concerns the frequency domain problem of diffraction of a plane wave incident on an infinite right-angled wedge on which impedance (absorbing) boundary conditions are imposed. It is demonstrated that the exact…

Analysis of PDEs · Mathematics 2015-06-22 David P. Hewett , Aaron Morris

We present a simple method for calculation of diffraction effects in a beam passing an aperture. It follows the well-known approach of Miyamoto and Wolf, but is simpler and does not lead to singularities. It is thus shown that in the…

Optics · Physics 2020-01-29 Eitam Luz , Er'el Granot , Boris Malomed

Inverse scattering is the process of estimating the spatial distribution of the scattering potential of an object by measuring the scattered wavefields around it. In this paper, we consider reflection tomography of high contrast objects…

Signal Processing · Electrical Eng. & Systems 2020-12-17 Ajinkya Kadu , Hassan Mansour , Petros T. Boufounos

X-ray fluorescence holography (XFH) is a method for obtaining diffraction-limited images of the local atomic structure around a given type of emitter. The reconstructed wave-field represents a distorted image of the scatterer electron…

Condensed Matter · Physics 2009-09-29 S. Marchesini , C. S. Fadley , F. J. Garcia de Abajo

Inverse source problems are central to many applications in acoustics, geophysics, non-destructive testing, and more. Traditional imaging methods suffer from the resolution limit, preventing distinction of sources separated by less than the…

Machine Learning · Computer Science 2022-08-11 Adar Kahana , Symeon Papadimitropoulos , Eli Turkel , Dmitry Batenkov

This article presents a method to perform diffraction tomography in a standard microscope that includes an LED array for illumination. After acquiring a sequence of intensity-only images of a thick sample, a ptychography-based…

Optics · Physics 2015-10-30 Roarke Horstmeyer , Changhuei Yang

The Differential Fourier Holography (DFH) gives an exact mathematical solution of the inverse problem of diffraction in the Fraunhofer regime. After the first publication [1] the Differential Fourier Holography was successfully applied in…

Optics · Physics 2016-04-20 Sergey G. Podorov , Eckhart Förster

Traditionally, the diffraction of a scalar wave satisfying Helmholtz equation through an aperture on an otherwise black screen can be solved approximately by Kirchhoff's integral over the aperture. Rubinowicz, on the other hand, was able to…

Classical Physics · Physics 2011-12-16 Yi-Chuan Lu

Photothermal imaging is a powerful noncontact and nondestructive technique for subsurface inspection of composite materials, yet its performance is fundamentally limited by the diffusive and irreversible nature of heat transport, leading to…

Applied Physics · Physics 2026-05-06 Pengfei Zhu , Julien Lecompagnon , Philipp Daniel Hirsch , Mathias Ziegler

We consider the Helmholtz equation defined in unbounded domains, external to 2D bounded ones, endowed with a Dirichlet condition on the boundary and the Sommerfeld radiation condition at infinity. To solve it, we reduce the infinite region,…

Numerical Analysis · Mathematics 2021-07-13 Luca Desiderio , Silvia Falletta , Matteo Ferrari , Letizia Scuderi

The aim of electrical impedance tomography is to reconstruct the admittivity distribution inside a physical body from boundary measurements of current and voltage. Due to the severe ill-posedness of the underlying inverse problem, the…

Analysis of PDEs · Mathematics 2022-07-19 Jérémi Dardé , Nuutti Hyvönen , Aku Seppänen , Stratos Staboulis

Ptychography is a popular technique to achieve diffraction limited resolution images of a two or three dimensional sample using high frame rate detectors. We introduce a relaxation of common projection algorithms to account for…

Ptychographic reconstructions in reflection geometries are commonly interpreted with the same two-dimensional thin-sample model used in transmission, yet the validity of this approximation has not been established. We develop a…

Optics · Physics 2026-04-08 Sander Senhorst , Stefan Witte , Wim Coene

A 3-D inverse medium problem in the frequency domain is considered. Another name for this problem is Coefficient Inverse Problem. The goal is to reconstruct spatially distributed dielectric constants from scattering data. Potential…

Numerical Analysis · Mathematics 2016-05-23 Michael V. Klibanov , Hui Liu , Loc H. Nguyen

The aim of electrical impedance tomography is to form an image of the conductivity distribution inside an unknown body using electric boundary measurements. The computation of the image from measurement data is a non-linear ill-posed…

Numerical Analysis · Mathematics 2011-09-28 Samuli Siltanen , Janne P. Tamminen

Ptychography is a computational imaging technique that aims to reconstruct the object of interest from a set of diffraction patterns. Each of these is obtained by a localized illumination of the object, which is shifted after each…

Image and Video Processing · Electrical Eng. & Systems 2024-02-26 Oleh Melnyk , Patricia Römer