Results 81 to 90 of about 6,501 (284)

Turbulence characterisation for Astronomical Observatories [PDF]

, 2012
Atmospheric turbulence has two effects in astronomy; (i) the broadening of the point spread function due to phase fluctuations limiting the resolution of imaging and (ii) producing intensity fluctuations known as scintillation.
SHEPHERD, HARRY,WILLIAM, Shepherd, Harry William   +1 more
core  

Ultra high precision wavefront sensing for Extreme-AO on ELTs

, 2010
High precision wavefront sensing is the key to detect low mass (potentially rocky) planets with ELTs. Ideally, a wavefront sensor for an Extreme-AO system should be both very sensitive (to allow high speed wavefront correction) and very accurate (to ...
O. Guyon
core   +1 more source

Optical Windows for Transcranial Brain Imaging in Living Mice: Skull Thinning, Clearing, and Beyond

Advanced Science, EarlyView.
Longitudinal, noninvasive in vivo imaging is crucial for studying brain physiology. Advances in transcranial optical windows and multiphoton microscopy have improved imaging depth, but their performance often deteriorates over time. This work investigated various transcranial window approaches and found that skull regrowth limits image quality.
Yiming Fu, Gewei Yan, Zhentao She, Yingzhu He, Kangqi Liu, Jianan Qu   +5 more
wiley   +1 more source

Non‐Uniform Space‐Time‐Coding Modulation for Low‐Complexity Diagnostics of Reconfigurable Intelligent Surfaces

Advanced Electronic Materials, EarlyView.
A diagnostic method for reconfigurable intelligent surfaces (RIS) based on non‐uniform space‐time‐coding modulation is presented. Fault localization is achieved via amplitude‐only spectral measurements, eliminating the need for complex signal processing. A one‐to‐one mapping between harmonic components and RIS elements enables accurate detection.
Xiao Qing Chen, Lei Zhang, Yi Ning Zheng, Bing Bing Zhu, Marco Rossi, Giuseppe Castaldi, Shuo Liu, Vincenzo Galdi, Tie Jun Cui   +8 more
wiley   +1 more source

Higher-resolution wavefront sensing based on sub-wavefront information extraction

Frontiers in Physics
The limited spatial sampling rates of conventional Shack–Hartmann wavefront sensors (SHWFSs) make them unable to sense higher-order wavefront distortion.
Hongli Guan, Hongli Guan, Hongli Guan, Hongli Guan, Wang Zhao, Wang Zhao, Wang Zhao, Shuai Wang, Shuai Wang, Shuai Wang, Kangjian Yang, Kangjian Yang, Kangjian Yang, Mengmeng Zhao, Mengmeng Zhao, Mengmeng Zhao, Shenghu Liu, Shenghu Liu, Shenghu Liu, Shenghu Liu, Han Guo, Han Guo, Han Guo, Ping Yang, Ping Yang, Ping Yang   +25 more
doaj   +1 more source

Conformal Reconfigurable Intelligent Surfaces: A Cylindrical Geometry Perspective

Advanced Electronic Materials, EarlyView.
Cylindrical reconfigurable intelligent surfaces are explored for low‐complexity beam steering using one‐bit meta‐atoms. A multi‐level modeling approach, including optimization‐based synthesis, demonstrates that even minimal hardware can support directive scattering.
Filippo Pepe, Ivan Iudice, Giuseppe Castaldi, Marco Di Renzo, Vincenzo Galdi   +4 more
wiley   +1 more source

Wavefront Sensing via High Speed DSP

, 2004
Future light-weighted and segmented primary mirror systems require active optical control to maintain mirror positioning and figure to within nanometer tolerances.
Dean, Bruce, Smith, J. Scott
core  

Wavefront curvature sensing and control in microscopy [PDF]

, 2022
The purposes are multiples: creation of a wavefront curvature sensor, use of the curvature sensing to control a multi-actuator lens developed at CNR-IFN of Padua (18 piezoelectric actuators) and use of the multi-actuator lens to generate an astigmatic ...
Dalle Rive, Gianluca
core  

Terahertz Channel Modeling, Estimation and Localization in RIS‐Assisted Systems

Advanced Electronic Materials, EarlyView.
Reconfigurable intelligent surfaces have become a recent intensive research focus. Based on practical applications, channel strategies for RIS‐assisted terahertz wireless communication systems are categorized into three different types: channel modeling, channel estimation, and channel localization.
Hongjing Wang, Weipeng Wang, Xuan Cong, Shiyu Wang, Gao Li, Sen Gong, Lin Huang, Hongxin Zeng, Yaxin Zhang, Ziqiang Yang   +9 more
wiley   +1 more source

Wavefront Curvature Sensing from Image Projections

, 2006
This research outlines the development and simulation of a signal processing approach to real time wavefront curvature sensing in adaptive optics. The signal processing approach combines vectorized Charge Coupled Device (CCD) read out with a wavefront ...
Buffington, Jonathan C.
core