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The optical properties of nanoparticles can be substantially affected by their assembly in compact aggregates. This is a common situation notably for nanoparticles synthesised and self-assembled into rigid clusters in colloidal form, where…

Optics · Physics 2022-04-27 Atefeh Fazel-Najafabadi , Baptiste Auguié

The familiar tools of Fourier analysis and Fisher matrices are applied to derive the uncertainties on photometric, astrometric, and weak-lensing measurements of stars and galaxies in real astronomical images. Many effects or functions that…

Astrophysics · Physics 2007-05-23 Gary Bernstein

We present our investigation into the impact of wavefront errors on high accuracy astrometry using Fourier Optics. MICADO, the upcoming near-IR imaging instrument for the Extremely Large Telescope, will offer capabilities for relative…

Instrumentation and Methods for Astrophysics · Physics 2020-12-15 J. A. van den Born , W. Jellema , R. Navarro , E. Tolstoy , B. Jayawardhana , A. W. Janssen

Pupil mapping is a promising and unconventional new method for high contrast imaging being considered for terrestrial exoplanet searches. It employs two (or more) specially designed aspheric mirrors to create a high-contrast amplitude…

Astrophysics · Physics 2007-05-23 Ruslan Belikov , N. Jeremy Kasdin , Robert J. Vanderbei

Lenses are typically based on refractive index profiles derived from the geometric approximation of high-frequency waves, yet the critical issue of impedance mismatch is often neglected. Mismatched devices suffer from unwanted reflections…

Optics · Physics 2025-06-18 Sebastiano Cominelli

The advantages of convergent beam electron diffraction for symmetry determination at the scale of a few nm are well known. In practice, the approach is often limited due to the restriction on the angular range of the electron beam imposed…

Materials Science · Physics 2013-07-09 Richard Beanland , Paul J. Thomas , David I. Woodward , Pamela A. Thomas , Rudolf A. Roemer

This paper studies the theoretical construction and analytic error estimation of complex Bessel function-based conformal mappings in regions with randomly perturbed boundaries. First, we construct a conformal mapping applicable to such…

Complex Variables · Mathematics 2024-11-13 Qiang Kang

Consistent in-focus input imagery is an essential precondition for machine vision systems to perceive the dynamic environment. A defocus blur severely degrades the performance of vision systems. To tackle this problem, we propose a…

Image and Video Processing · Electrical Eng. & Systems 2021-03-11 Jisheng Li , Qi Dai , Jiangtao Wen

We derive two forms of conditional a posteriori error estimates for a finite volume scheme approximating the parabolic-elliptic Keller-Segel system. The estimates control the error in the $L^\infty(0,T, L^2(\Omega))$- and…

Numerical Analysis · Mathematics 2025-09-23 Marc Hoffmann , Jan Giesselmann

With recent advancements in observing supermassive black holes with the Event Horizon Telescope, there has been persistent exploration into what the images can reveal about fundamental physics, including space-time geometries and…

General Relativity and Quantum Cosmology · Physics 2024-03-15 Qing-Hua Zhu

A new formalism of beam-optics and polarization has been recently presented, based on an exact matrix representation of the Maxwell equations. This is described in Part-I and Part-II. In this Part, we present the application of the above…

Optics · Physics 2007-05-23 Sameen Ahmed Khan

Weak lensing studies typically require excellent seeing conditions for the purpose of maximizing the number density of well-resolved galaxy images. It is interesting to ask to what extent the seeing size limits the usefulness of the…

Cosmology and Nongalactic Astrophysics · Physics 2022-09-14 Jun Zhang , Cong Liu , Pedro Alonso Vaquero , Hekun Li , Haoran Wang , Zhi Shen , Fuyu Dong

In coherent X-ray diffraction microscopy the diffraction pattern generated by a sample illuminated with coherent x-rays is recorded, and a computer algorithm recovers the unmeasured phases to synthesize an image. By avoiding the use of a…

Establishing a precise connection between imaged intensity and the incident wavefront is essential for emerging applications in adaptive optics, holography, computational microscopy, and non-line-of-sight imaging. While prior work has shown…

Image and Video Processing · Electrical Eng. & Systems 2026-04-02 Ali Almuallem , Nicholas Chimitt , Bole Ma , Qi Guo , Stanley H. Chan

The axis tilt of light beam in optical system would introduce the dispersion of orbital angular momentum (OAM) spectrum. To deal with it, a two-step method is proposed and demonstrated. First, the tilt angle of optical axis is identified…

Optics · Physics 2020-04-27 Peng Zhao , Shikang Li , Yu Wang , Xue Feng , Kaiyu Cui , Fang Liu , Wei Zhang , Yidong Huang

The keyhole phenomenon has been widely observed in laser materials processing, including laser welding, remelting, cladding, drilling, and additive manufacturing. Keyhole-induced defects, primarily pores, dramatically affect the performance…

The efficiency of the beam extraction and collimation systems in circular accelerators with the use of the channeling effect in a bent crystal is determined. The dependences of the extraction efficiency on the geometrical parameters of the…

Accelerator Physics · Physics 2022-03-02 I. A. Yazynin , V. A. Maisheev , Yu. A. Chesnokov

Weak-lensing peak counts provide a straightforward way to constrain cosmology by linking local maxima of the lensing signal to the mass function. Recent applications to data have already been numerous and fruitful. However, the importance…

Cosmology and Nongalactic Astrophysics · Physics 2018-06-13 Chieh-An Lin , Martin Kilbinger

In this paper, the performance of signaling strategies with high peak-to-average power ratio is analyzed in both coherent and noncoherent fading channels. Two recently proposed modulation schemes, namely on-off binary phase-shift keying and…

Information Theory · Computer Science 2007-07-13 Mustafa Cenk Gursoy

We derive a computable a posteriori error estimator for the $\alpha$-harmonic extension problem, which localizes the fractional powers of elliptic operators supplemented with Dirichlet boundary conditions. Our a posteriori error estimator…

Numerical Analysis · Mathematics 2015-05-20 Long Chen , Ricardo H. Nochetto , Enrique Otárola , Abner J. Salgado