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Numerous vector angular spectrum methods have been presented to model the vectorial nature of diffractive electromagnetic field, facilitating optical field engineering in polarization-related and high numerical aperture systems. However,…

Optics · Physics 2025-09-29 Chengda Song , Jing He , Guanghui Yuan

We investigate the inverse source problem for the wave equation, arising in photo- and thermoacoustic tomography. There exist quite a few theoretically exact inversion formulas explicitly expressing solution of this problem in terms of the…

Analysis of PDEs · Mathematics 2018-08-01 Ngoc Do , Leonid Kunyansky

A method for the determination of the projection geometry of highly magnifying cone beam micro computed tomography systems based on few rotating fiducial markers of unknown position within the field of view is derived. By employing the…

Image and Video Processing · Electrical Eng. & Systems 2021-06-07 Jonas Graetz

An approach to diffraction tomography is investigated for two-dimensional image reconstruction of objects surrounded by an arbitrarily-shaped curve of sources and receivers. Based on the integral theorem of Helmholtz and Kirchhoff, the…

Mathematical Physics · Physics 2014-11-20 G. T. Clement

The image subtraction method is a powerful tool to analyze the light variations in crowded fields. This method is able to achieve a nearly optimal differential photometry, even in very dense regions. However, image subtraction is not…

Astrophysics · Physics 2007-05-23 C. Alard

We study inversion of the spherical Radon transform with centers on a sphere (the data acquisition set). Such inversions are essential in various image reconstruction problems arising in medical, radar and sonar imaging. In the case of…

Classical Analysis and ODEs · Mathematics 2017-09-25 Gaik Ambartsoumian , Rim Gouia-Zarrad , Venkateswaran P. Krishnan , Souvik Roy

Coherent vector beams with involved states of polarization (SOP) are widespread in the literature, having applications in laser processing, super-resolution imaging and particle trapping. We report novel vector beams obtained by…

In this paper we derive a variational formulation for a linear curved beam which is natively expressed in global Cartesian coordinates. During derivation the beam midline is assumed to be implicitly described by a vector distance function…

Numerical Analysis · Mathematics 2014-04-09 Peter Hansbo , Mats G. Larson , Karl Larsson

We introduce the concept of bi-conformal transformation, as a generalization of conformal ones, by allowing two orthogonal parts of a manifold with metric $\G$ to be scaled by different conformal factors. In particular, we study their…

Mathematical Physics · Physics 2016-08-16 Alfonso García-Parrado , José M. M. Senovilla

A novel approach based on the two-channel moir\'e deflectometry has been used to measure both wave-front and transverse component of the Poynting vector of an optical vortex beam. Generated vortex beam by the q-plate, an inhomogeneous…

Convolution is an efficient technique to obtain abstract feature representations using hierarchical layers in deep networks. Although performing convolution in Euclidean geometries is fairly straightforward, its extension to other…

Machine Learning · Computer Science 2019-01-04 Sameera Ramasinghe , Salman Khan , Nick Barnes

In this article, we study various aspects of the mixed ray transform of $(k + \ell)$-tensor fields that are symmetric in its first $k$ and last $\ell$ indices. As a first result, we derive an inversion algorithm to recover the solenoidal…

Analysis of PDEs · Mathematics 2024-04-17 Rohit Kumar Mishra , Suman Kumar Sahoo , Chandni Thakkar

The second-order tangent set is an important concept in describing the curvature of the set involved. Due to the existence of the complementarity condition, the second-order cone (SOC) complementarity set is a nonconvex set. Moreover,…

Optimization and Control · Mathematics 2019-06-25 Jein-Shan Chen , Jane J. Ye , Jin Zhang , Jinchuan Zhou

The aim of this research is to reconstruct the 3D X-ray refractive index gradient maps by the proposed vector Radon transform and its inverse, assuming that the small-angle deviation condition is met. Theoretical analyses show that the…

Medical Physics · Physics 2023-09-20 Keliang Liao , Qili He , Panyun Li , Liang Luo , Peiping Zhu

The problem of image reconstruction in thermoacoustic tomography requires inversion of a generalized Radon transform, which integrates the unknown function over circles in 2D or spheres in 3D. The paper investigates implementation of the…

Numerical Analysis · Mathematics 2007-05-23 Gaik Ambartsoumian , Sarah K. Patch

3D point clouds deep learning is a promising field of research that allows a neural network to learn features of point clouds directly, making it a robust tool for solving 3D scene understanding tasks. While recent works show that point…

Computer Vision and Pattern Recognition · Computer Science 2022-03-22 Zhiyuan Zhang , Binh-Son Hua , Sai-Kit Yeung

While 360{\deg} cameras offer tremendous new possibilities in vision, graphics, and augmented reality, the spherical images they produce make core feature extraction non-trivial. Convolutional neural networks (CNNs) trained on images from…

Computer Vision and Pattern Recognition · Computer Science 2018-12-10 Yu-Chuan Su , Kristen Grauman

Fourier transform is applied to annular beams of simplified flat two-level geometry: bright outer ring with a darker core. The pattern of focal beam profile (i.e. far field) is calculated and characterized with respect of its intensity…

Optics · Physics 2009-04-14 D. N. Astadjov

Focused ion beam (FIB) tomography provides high resolution volumetric images on a micro scale. However, due to the physical acquisition process the resulting images are often corrupted by a so-called curtaining or waterfall effect. In this…

Numerical Analysis · Mathematics 2016-04-06 Jan Henrik Fitschen , Jianwei Ma , Sebastian Schuff

We present an algorithm for solving inverse problems on graphs analogous to those arising in diffuse optical tomography for continuous media. In particular, we formulate and analyze a discrete version of the inverse Born series, proving…

Combinatorics · Mathematics 2017-04-26 Francis J. Chung , Anna C. Gilbert , Jeremy G. Hoskins , John C. Schotland
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