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Spatial coherence plays an important role in several real-world applications ranging from imaging to communication. As a result, its accurate characterization and measurement are extremely crucial for its optimal application. However,…

Optics · Physics 2024-03-04 Pranay Mohta , Abhinandan Bhattacharjee , Anand K. Jha

Opaque scintillators are designed to have a short scattering length such that scintillation photons are probabilistically confined to a small region of space about their origin. The benefit of this feature is that information on the…

Instrumentation and Detectors · Physics 2023-02-10 Andrew Wilhelm , Garrett Wendel , Brandon Collins , Doug Cowen , Igor Jovanovic

In this paper we present and analyse a high accuracy method for computing wave directions defined in the geometrical optics ansatz of Helmholtz equation with variable wave number. Then we define an "adaptive" plane wave space with small…

Numerical Analysis · Mathematics 2021-07-22 Qiya Hu , Zezhong Wang

Unit norm finite frames are generalizations of orthonormal bases with many applications in signal processing. An important property of a frame is its coherence, a measure of how close any two vectors of the frame are to each other. Low…

Signal Processing · Electrical Eng. & Systems 2018-06-21 Cristian Rusu , Nuria Gonzalez-Prelcic , Robert W. Heath

The modern definition of optical coherence highlights a frequency dependent function based on a matrix of spectra and cross-spectra. Due to general properties of matrices, such a function is invariant in changes of basis. In this article,…

Optics · Physics 2016-03-09 Bernard Lacaze

We report what is believed to be the first example of fully continuous, 24-hour vertical monitoring of atmospheric optical turbulence. This is achieved using a novel instrument, the 24-hour Shack-Hartmann Image Motion Monitor (24hSHIMM).…

Instrumentation and Methods for Astrophysics · Physics 2023-04-18 Ryan Griffiths , James Osborn , Ollie Farley , Tim Butterley , Matthew J. Townson , Richard Wilson

The accuracy of wavefront reconstruction from discrete slope measurements depends on the sampling geometry, coherence length of the incoming wavefronts, wavefront sensor specifications and the accuracy of the reconstruction algorithm. Monte…

Instrumentation and Methods for Astrophysics · Physics 2009-11-08 M B Roopashree , Akondi Vyas , B Raghavendra Prasad

It is known that a spatially partially coherent light field produces better imaging contrast compared to a spatially coherent field and that the contrast increases as the spatial coherence length of the field becomes smaller. The transverse…

Coherence refers to correlations between field vibrations at two separate points in degrees of freedom such as space, time, and polarisation. In the context of space, coherence theory has been formulated between two transverse positions…

A comprehensive study of the spatial resolution and detection efficiency of sensor prototypes developed for the LHCb VELO upgrade is presented. Data samples were collected at the CERN SPS H8 beam line using a hadron mixture of protons and…

In this work we define a spatial concordance coefficient for second-order stationary processes. This problem has been widely addressed in a non-spatial context, but here we consider a coefficient that for a fixed spatial lag allows one to…

Methodology · Statistics 2019-05-14 Ronny Vallejos , Javier Pérez , Aaron M. Ellison , Andrew D. Richardson

We study theoretically the spatial correlations between the intensities measured at the input and output planes of a disordered scattering medium. We show that at large optical thicknesses, a long-range spatial correlation persists and…

Optics · Physics 2015-09-23 N. Fayard , A. Cazé , R. Pierrat , R. Carminati

An important factor which affects performance of solar adaptive optics (AO) systems is the accuracy of tracking an extended object in the wavefront sensor. The accuracy of a centre-ofmass approach to image shift measurement depends on the…

Instrumentation and Methods for Astrophysics · Physics 2015-08-21 M. J. Townson , A. Kellerer , C. D. Saunter

As we look to the next generation of adaptive optics systems, now is the time to develop and explore the technologies that will allow us to image rocky Earth-like planets; wavefront control algorithms are not only a crucial component of…

Earth and Planetary Astrophysics · Physics 2023-09-06 J. Fowler , Rico Landman

The Earth's atmosphere is comprised of turbulent layers that result in speckled and blurry images from ground-based visible and infrared observations. Adaptive Optics (AO) systems are employed to measure the perturbed wavefront with a…

Instrumentation and Methods for Astrophysics · Physics 2024-10-03 Zhenxi Du , Saavidra Perera , Daniel Levinstein , Quinn Konopacky , Alex Madurowicz , Bruce Macintosh , Lisa Poyneer , Richard Wilson , Ollie Farley

Locality-sensitive hashing (LSH) is a fundamental technique for similarity search and similarity estimation in high-dimensional spaces. The basic idea is that similar objects should produce hash collisions with probability significantly…

Computational Geometry · Computer Science 2017-09-25 Joachim Gudmundsson , Rasmus Pagh

Quantum imaging with spatially entangled photons offers advantages such as enhanced spatial resolution, robustness against noise, and counter-intuitive phenomena, while a biphoton spatial aberration generally degrades its performance.…

Quantum Physics · Physics 2025-09-10 Yi Zheng , Zhao-Di Liu , Jian-Shun Tang , Jin-Shi Xu , Chuan-Feng Li , Guang-Can Guo

Measuring the positions of optical vortices is an essential part in the researches of speckles and adaptive optics. The measurement accuracy is restricted by the performance of optical devices and the properties of optical vortices, such as…

Optics · Physics 2022-05-25 Hantao Wang , Huajun Zhang , Mingyuan Ren , Wenkai Yao , Yu Zhang

The performance metrics of different centroiding algorithms at low light level conditions were optimized in the case of a Shack Hartmann Sensor (SHS) for efficient performance of the adaptive optics system. For short exposures and low…

Instrumentation and Methods for Astrophysics · Physics 2010-01-18 Akondi Vyas , M. B. Roopashree , B. Raghavendra Prasad

We show a monotonic relationship between performances of various computer vision tasks versus degrees of coherence of illumination. We simulate partially coherent illumination using computational methods, propagate the lightwave to form…

Computer Vision and Pattern Recognition · Computer Science 2024-01-08 Zichen Xie , Ken Xingze Wang