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The main objective of the present project is to explore the viability of an adaptive optics control system based exclusively on Field Programmable Gate Arrays (FPGAs), making strong use of their parallel processing capability. In an…

天体物理仪器与方法 · 物理学 2018-07-03 Avinash Surendran , Mahesh P. Burse , A. N. Ramaprakash , Padmakar Parihar

Recently, linear computed tomography (LCT) systems have actively attracted attention. To weaken projection truncation and image the region of interest (ROI) for LCT, the backprojection filtration (BPF) algorithm is an effective solution.…

计算机视觉与模式识别 · 计算机科学 2023-09-26 Zhisheng Wang , Zihan Deng , Fenglin Liu , Yixing Huang , Haijun Yu , Junning Cui

Here we present a laboratory analysis of the use of a 19-core photonic lantern (PL) in combination with neural network (NN) algorithms as an efficient focal plane wavefront sensor (FP-WFS) for adaptive optics (AO), measuring wavefront…

光学 · 物理学 2023-11-06 Jin Wei , Barnaby Norris , Christopher Betters , Sergio Leon-Saval

The orbital angular momentum (OAM) of photons is a promising degree of freedom for high-dimensional quantum key distribution (QKD). However, effectively mitigating the adverse effects of atmospheric turbulence is a persistent challenge in…

信号处理 · 电气工程与系统科学 2020-06-24 Jiapeng Zhao , Yiyu Zhou , Boris Braverman , Cong Liu , Kai Pang , Nicholas K. Steinhoff , Glenn A. Tyler , Alan E. Willner , Robert W. Boyd

Observational tests of ground layer wavefront recovery have been made in open loop using a constellation of four natural guide stars at the 1.55 m Kuiper telescope in Arizona. Such tests explore the effectiveness of wide-field seeing…

天体物理学 · 物理学 2011-02-11 Christoph Baranec , Michael Lloyd-Hart , N. Mark Milton

We performed a series of three-dimensional numerical simulations of supersonic homogeneous Euler turbulence with adaptive mesh refinement (AMR) and effective grid resolution up to 1024^3 zones. Our experiments describe non-magnetized driven…

天体物理学 · 物理学 2016-08-30 Alexei G. Kritsuk , Michael L. Norman , Paolo Padoan

Orthogonal time frequency space (OTFS) modulation has recently emerged as a potential 6G candidate waveform which provides improved performance in high-mobility scenarios. In this paper we investigate the combination of OTFS with…

信号处理 · 电气工程与系统科学 2023-04-27 Stephen McWade , Arman Farhang , Mark F. Flanagan

Disturbances such as atmospheric turbulence and aero-optic effects lead to wavefront aberrations, which degrade performance in imaging and laser propagation applications. Adaptive optics (AO) provide a method to mitigate these effects by…

信号处理 · 电气工程与系统科学 2024-10-17 Jeffrey Utley , Gregery Buzzard , Charles Bouman , Matthew Kemnetz

Long-range imaging inevitably suffers from atmospheric turbulence with severe geometric distortions due to random refraction of light. The further the distance, the more severe the disturbance. Despite existing research has achieved great…

计算机视觉与模式识别 · 计算机科学 2024-07-18 Shengqi Xu , Run Sun , Yi Chang , Shuning Cao , Xueyao Xiao , Luxin Yan

Channel estimation at millimeter wave (mmWave) is challenging when large antenna arrays are used. Prior work has leveraged the sparse nature of mmWave channels via compressed sensing based algorithms for channel estimation. Most of these…

信息论 · 计算机科学 2018-06-19 Nitin Jonathan Myers , Robert W. Heath

In time series analysis, when fitting an autoregressive model, one must solve a Toeplitz ordinary least squares problem numerous times to find an appropriate model, which can severely affect computational times with large data sets. Two…

机器学习 · 统计学 2021-12-28 Ali Eshragh , Oliver Di Pietro , Michael A. Saunders

We present two reduced-rank channel estimators for large-scale multiple-input, multiple-output (MIMO) systems and analyze their mean square error (MSE) performance. Taking advantage of the channel's transform domain sparseness, the…

信息论 · 计算机科学 2016-09-09 Ko-Feng Chen , Yen-Cheng Liu , Yu T. Su

In this paper, we study low-complexity algorithms for beam and channel tracking for millimeter-wave (mmWave) communications. In particular, the least mean squares (LMS) and bidirectional LMS (BiLMS) algorithms are derived for a mobile…

信息论 · 计算机科学 2018-12-21 Yavuz Yapici , Ismail Guvenc

Closed-loop adaptive optics systems which use minimum mean square error wavefront reconstruction require the computation of pseudo open loop wavefront slopes. These techniques incorporate a knowledge of atmospheric statistics which must…

天体物理仪器与方法 · 物理学 2019-04-10 Alastair Basden , David Jenkins , Tim Morris , James Osborn , Matthew Townson

Realizing high-throughput aberration-corrected Scanning Transmission Electron Microscopy (STEM) exploration of atomic structures requires rapid tuning of multipole probe correctors while compensating for the inevitable drift of the optical…

机器学习 · 计算机科学 2026-01-28 Utkarsh Pratiush , Austin Houston , Richard Liu , Gerd Duscher , Sergei Kalinin

The translation of imaging Mueller polarimetry to clinical practice is often hindered by large footprint and relatively slow acquisition speed of the existing instruments. Using polarization-sensitive camera as a detector may reduce…

Machine learning (ML) starts to be widely used to enhance the performance of multi-user multiple-input multiple-output (MU-MIMO) receivers. However, it is still unclear if such methods are truly competitive with respect to conventional…

信息论 · 计算机科学 2021-07-01 Mathieu Goutay , Fayçal Ait Aoudia , Jakob Hoydis , Jean-Marie Gorce

Magnetic resonance (MR)-$T_2^*$ mapping is widely used to study hemorrhage, calcification and iron deposition in various clinical applications, it provides a direct and precise mapping of desired contrast in the tissue. However, the long…

图像与视频处理 · 电气工程与系统科学 2020-08-06 Shuai Huang , James J. Lah , Jason W. Allen , Deqiang Qiu

The Adaptive Optics Facility (AOF) project envisages transforming one of the VLT units into an adaptive telescope and providing its ESO (European Southern Observatory) second generation instruments with turbulence corrected wavefronts. For…

天体物理仪器与方法 · 物理学 2015-06-23 A. Garcia-Rissmann , A. Guesalaga , J. Kolb , M. Le Louarn , P. -Y. Madec , B. Neichel

Latency in the control loop of adaptive optics (AO) systems can severely limit performance. Under the frozen flow hypothesis linear predictive control techniques can overcome this, however identification and tracking of relevant turbulent…

天体物理仪器与方法 · 物理学 2020-06-10 Xuewen Liu , Tim Morris , Chris Saunter , Francisco Javier de Cos Juez , Carlos González-Gutiérrez , Lisa Bardou