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Closed formulas are derived for the field in the focal region of a diffraction limited lens, such that the electric field component in a given direction at the focal point is larger than that of all other focused fields with the same power…

Optics · Physics 2008-12-26 H. P. Urbach S. F. Pereira

This paper is concerned with the inverse medium problem of determining the location and shape of penetrable scattering objects from measurements of the scattered field. We study a sampling indicator function for recovering the scattering…

Numerical Analysis · Mathematics 2023-03-13 Dinh-Liem Nguyen , Trung Truong

This paper presents an uncalibrated deep neural network framework for the photometric stereo problem. For training models to solve the problem, existing neural network-based methods either require exact light directions or ground-truth…

Computer Vision and Pattern Recognition · Computer Science 2021-04-20 Berk Kaya , Suryansh Kumar , Carlos Oliveira , Vittorio Ferrari , Luc Van Gool

We present an optical system based on two toroidal mirrors in a Wolter configuration to focus broadband XUV radiation. Optimization of the focusing optics alignment is carried out with the aid of an XUV wavefront sensor. Back-propagation of…

We introduce a new type of lens that focuses a plane wave into a spherical one, where light comes from all directions. Our method also suggests the design of ideal optical tweezers or, in the reverse direction, photo-detection of nearly all…

Optics · Physics 2025-04-01 Shay Rabani , Kirill Shvalb , Boris Malomed , Tal Carmon

A scalar field method to obtain transverse solutions of the vector Laplace and Helmholtz equations in spherical coordinates for boundary-value problems with azimuthal symmetry is described. Neither scalar nor vector potentials are used.…

Classical Physics · Physics 2007-05-23 Ernesto A. Matute

We propose a free-space, inverse design of nanostructure's effective mode-matching fields via a backward propagation of tightly focused vector beams to the pupil plane of an aplanatic system of high numerical aperture. First, we study the…

Optics · Physics 2022-10-25 Xiaorun Zang , Ari T. Friberg , Tero Setälä , Jari Turunen

Consider the inverse problem of scattering of time-harmonic acoustic waves by an inhomogeneous medium with complex refractive index. We show that an approximate factorization method can be applied to reconstruct the support of the complex…

Numerical Analysis · Mathematics 2019-03-27 Fenglong Qu , Haiwen Zhang

Most problems in gravitational lensing require numerical solutions. The most frequent types of problems are (1) finding multiple images of a single source and classifying the images according to their properties like magnification or…

Astrophysics · Physics 2007-05-23 Matthias Bartelmann

Optical stellar interferometers have demonstrated milli-arcsecond resolution with few apertures spaced hundreds of meters apart. To obtain rich direct images, many apertures will be needed, for a better sampling of the incoming wavefront.…

Instrumentation and Methods for Astrophysics · Physics 2014-09-17 Arun Surya , Swapan K. Saha , Antoine Labeyrie

Multipole expansion of an incident radiation field - that is, representation of the fields as sums of vector spherical wavefunctions - is essential for theoretical light scattering methods such as the T-matrix method and generalised…

Optics · Physics 2007-05-23 T. A. Nieminen , H. Rubinsztein-Dunlop , N. R. Heckenberg

The inverse reflector problem aims to design a freeform reflecting surface that can direct the light from a specified source to produce the desired illumination in the target area, which is significant in the field of geometrical…

Numerical Analysis · Mathematics 2025-03-28 Gang Bao , Yixuan Zhang

We consider the interpolation problem with the inverse multiquadric radial basis function. The problem usually produces a large dense linear system that has to be solved by iterative methods. The efficiency of such methods is strictly…

Numerical Analysis · Mathematics 2022-05-10 Stefano De Marchi , Nadaniela Egidi , Josephin Giacomini , Pierluigi Maponi , Alessia Perticarini

We present Neural Microfacet Fields, a method for recovering materials, geometry, and environment illumination from images of a scene. Our method uses a microfacet reflectance model within a volumetric setting by treating each sample along…

Computer Vision and Pattern Recognition · Computer Science 2023-10-18 Alexander Mai , Dor Verbin , Falko Kuester , Sara Fridovich-Keil

Inverse scattering involving microwave and ultrasound waves require numerical solution of nonlinear optimization problem. To alleviate the computational burden of a full three-dimensional (3-D) inverse problem, it is a common practice to…

Numerical Analysis · Mathematics 2022-07-14 Mert Hidayetoglu , Michael Oelze , Erhan Kudeki , Weng Cho Chew

Efficient optical excitation of hybridized plasmon modes in nanoantennas is vital to achieve many promising functionalities, but it can be challenging due to a field-profile mismatch between the incident light and the hybrid mode. We…

We present an inverse method for transforming a given parallel light emittance to two light distributions at different parallel target planes using two freeform reflectors. The reflectors control both the spatial and directional target…

An analytical description of arbitrary strongly aberrated axially symmetric focusing is developed. This is done by matching the solution of geometrical optics with a wave pattern which is universal for the underlying ray structure. The…

Optics · Physics 2007-05-23 Johannes Kofler , Nikita Arnold

In this work, we are interested in the determination of the shape of the scatterer for the two dimensional time harmonic inverse medium scattering problems in acoustics. The scatterer is assumed to be a piecewise constant function with a…

Numerical Analysis · Mathematics 2021-01-12 J. Huang , Z. Deng , L. Xu

A rigorous mathematical model and an efficient computational method are proposed to solving the inverse elastic surface scattering problem which arises from the near-field imaging of periodic structures. We demonstrate how an enhanced…

Analysis of PDEs · Mathematics 2017-12-08 Huaian Diao , Peijun Li , Xiaokai Yuan