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We present a new approach to constrain the spectral energy distribution of the intergalactic UV background observationally by studying metal absorption systems. We study single-component metal line systems exhibiting various well-measured…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-28 Cora Fechner

Large-scale spectroscopic surveys have collectively observed millions of stars across the Milky Way, but each derives stellar labels using independent pipelines with distinct modelling assumptions, introducing systematic offsets that…

Astrophysics of Galaxies · Physics 2026-04-29 Jeff Shen , Joshua S. Speagle , Shirley Ho

Existing learning-based hyperspectral reconstruction methods show limitations in fully exploiting the information among the hyperspectral bands. As such, we propose to investigate the chromatic inter-dependencies in their respective…

Computer Vision and Pattern Recognition · Computer Science 2023-12-19 Xingxing Yang , Jie Chen , Zaifeng Yang

We propose a universal approach for modeling complex integrated photonic resonators based on the scattering matrix method. By dividing devices into basic elements including directional cou-plers and connecting waveguides, our approach can…

Optics · Physics 2025-02-04 David J. Moss

A method to obtain three-dimensional data of real-world objects by integrating their material properties is presented. The material properties are defined by capturing the Reflectance Fields of the real-world objects. It is shown, unlike…

Computer Vision and Pattern Recognition · Computer Science 2012-03-15 Maria-Luisa Sosas , Miguel-Octavio Arias

We discuss a time-harmonic inverse scattering problem for a nonlinear Helmholtz equation with compactly supported inhomogeneous scattering objects that are described by a nonlinear refractive index in unbounded free space. Assuming the…

Analysis of PDEs · Mathematics 2022-02-14 Roland Griesmaier , Marvin Knöller , Rainer Mandel

The complex refractive index m=n+ik of a particle is an intrinsic property which cannot be directly measured, it must be inferred from its extrinsic properties such as the scattering and absorption cross-sections. Bohren and Huffman called…

Diffraction tomography is a noninvasive technique that estimates the refractive indices of unknown objects and involves an inverse-scattering problem governed by the wave equation. Recent works have shown the benefit of nonlinear models of…

Image and Video Processing · Electrical Eng. & Systems 2021-07-09 Tao Hong , Thanh-an Pham , Eran Treister , Michael Unser

Recovering the 3D shape of transparent objects using a small number of unconstrained natural images is an ill-posed problem. Complex light paths induced by refraction and reflection have prevented both traditional and deep multiview stereo…

Computer Vision and Pattern Recognition · Computer Science 2020-07-24 Zhengqin Li , Yu-Ying Yeh , Manmohan Chandraker

In this work we consider the inverse problem of reconstructing the optical properties of a layered medium from an elastography measurement where optical coherence tomography is used as the imaging method. We hereby model the sample as a…

Numerical Analysis · Mathematics 2024-02-23 Peter Elbau , Leonidas Mindrinos , Leopold Veselka

This paper develops a novel framework for phase retrieval, a problem which arises in X-ray crystallography, diffraction imaging, astronomical imaging and many other applications. Our approach combines multiple structured illuminations…

Information Theory · Computer Science 2011-09-21 Emmanuel J. Candes , Yonina Eldar , Thomas Strohmer , Vlad Voroninski

We derive spectral sum rules for inverse powers of the eigenvalues of the Helmholtz equation on a $d$-sphere in the presence of an arbitrary density. By adopting a rigorous renormalization scheme, we remove the divergent contributions of…

Mathematical Physics · Physics 2026-04-02 Paolo Amore

The atmospheres of planets (including Earth) and the outer layers of stars have often been treated in radiative transfer as plane-parallel media, instead of spherical shells, which can lead to inaccuracy, e.g. limb darkening. We give an…

Statistical Mechanics · Physics 2009-11-11 Michael J. Caola

Imaging structures at the molecular level is a fast developing interdisciplinary research field that spans across the boundaries of physics and chemistry. High spatial resolution images of molecules can be obtained with photons or ultrafast…

Atomic Physics · Physics 2016-09-01 R. Puthumpally-Joseph , J. Viau-Trudel , M. Peters , T. T. Nguyen-Dang , O. Atabek , E. Charron

We study the scattering of infrared light by small dielectric core-shell particles taking a sapphire sphere with a CaO core as an example. The extinction efficiency of such a particle shows two intense series of resonances attached,…

Mesoscale and Nanoscale Physics · Physics 2015-05-20 E. Thiessen , F. X. Bronold , R. L. Heinisch , H. Fehske

Dust plays a critical role in the study of the interstellar medium (ISM). Extinction maps derived from optical surveys often fail to capture regions with high column density due to the limited photometric depth in optical wavelengths. To…

Astrophysics of Galaxies · Physics 2025-10-17 Miaomiao Zhang , Jouni Kainulainen , He Zhao , Yang Su , Min Fang , Yuehui Ma , Zhiwei Chen , Zhibo Jiang

We present a multi-scale, multi-wavelength source extraction algorithm called getsources. Although it has been designed primarily for use in the far-infrared surveys of Galactic star-forming regions with Herschel, the method can be applied…

Instrumentation and Methods for Astrophysics · Physics 2015-06-04 A. Men'shchikov , Ph. André , P. Didelon , F. Motte , M. Hennemann , N. Schneider

We present a retrieval method based on Bayesian analysis to infer the atmospheric compositions and surface or cloud-top pressures from transmission spectra of exoplanets with general compositions. In this study, we identify what can…

Earth and Planetary Astrophysics · Physics 2012-06-28 Bjoern Benneke , Sara Seager

A method for measuring the spectrum of a density field by a discrete wavelet space-scale decomposition (SSD) has been studied. We show how the power spectrum can effectively be described by the father function coefficients (FFC) of the…

Astrophysics · Physics 2007-05-23 Jesus Pando , Li-Zhi Fang

Past work has considered the analytic properties of the reflection coefficient for a metal-backed slab. The primary result established a fundamental relationship for the minimal layer thickness to bandwidth ratio achievable for an absorber.…

Optics · Physics 2023-12-18 Willie J. Padilla , Yang Deng , Omar Khatib , Vahid Tarokh