Measuring Turbulence Height Profiles using Extended Sources and a Wide-Field Hartmann-Shack Wavefront-Sensor

2007 ◽  
Author(s):  
T. A. Waldmann ◽  
T. Berkefeld ◽  
O. von der Lühe
Keyword(s):  
Wavefront Sensor ◽  
Wide Field ◽  
Extended Sources

A very wide field wavefront sensor for a very narrow field interferometer

2010 ◽  
Author(s):  
V. Viotto ◽  
R. Ragazzoni ◽  
C. Arcidiacono ◽  
M. Bergomi ◽  
A. Brunelli ◽  
...  
Keyword(s):  
Wavefront Sensor ◽  
Wide Field

scholarly journals The Science Case for a Southern Wide Field of View Detector

2019 ◽  
Vol 209 ◽  
pp. 01035
Author(s):  
Di Sciascio Giuseppe
Keyword(s):  
Galactic Nuclei ◽  
Field Of View ◽  
Wide Field ◽  
Cherenkov Telescopes ◽  
Wide Field Of View ◽  
Scientific Potential ◽  
Energy Domain ◽  
Survey Instruments ◽  
Extended Sources ◽  
Galactic Sources

EAS arrays are survey instruments able to monitor continuously all the overhead sky. Their sensitivity in the sub-TeV/TeV energy domain cannot compete with that of Cherenkov telescopes, but the wide field of view (about 2 sr) is ideal to complement directional detectors by performing unbiased sky surveys, by monitoring variable or flaring sources such as Active Galactic Nuclei (AGN) and to discover transients or explosive events (GRBs). Arrays are well suited to study extended sources, such as the Galactic diffuse emission, and to measure the spectra of Galactic sources at the highest energies (near or beyond 100 TeV). An EAS array is able to detect at the same time events induced by photons and charged cosmic rays, thus studying the connection between these two messengers of the non-thermal Universe. Therefore, these detectors are, by definition, multi-messenger instruments. All EAS arrays presently in operation or under installation are located in the Northern hemisphere. The scientific potential of a next-generation survey instrument in the Southern Hemisphere will be presented and briefly discussed.

Adaptive optics wide-field microscope corrections using a MEMS DM and Shack-Hartmann wavefront sensor

2011 ◽  
Author(s):  
Oscar Azucena ◽  
Xiaodong Tao ◽  
Justin Crest ◽  
Shaila Kotadia ◽  
William Sullivan ◽  
...  
Keyword(s):  
Adaptive Optics ◽  
Wavefront Sensor ◽  
Wide Field

scholarly journals DO-CRIME: Dynamic On-sky Covariance Random Interaction Matrix Evaluation, a novel method for calibrating adaptive optics systems

2020 ◽  
Author(s):  
Olivier Lai ◽  
Mark Chun ◽  
Ryan Dungee ◽  
Jessica Lu ◽  
Marcel Carbillet
Keyword(s):  
Adaptive Optics ◽  
Calibration Procedure ◽  
Wavefront Sensor ◽  
Interaction Matrix ◽  
Wide Field ◽  
Secondary Mirror ◽  
Novel Method ◽  
Measurement Vector ◽  
Random Patterns ◽  
Interaction Matrices

Abstract Adaptive optics systems require a calibration procedure to operate, whether in closed loop or even more importantly in forward control. This calibration usually takes the form of an interaction matrix and is a measure of the response on the wavefront sensor to wavefront corrector stimulus. If this matrix is sufficiently well conditioned, it can be inverted to produce a control matrix, which allows to compute the optimal commands to apply to the wavefront corrector for a given wavefront sensor measurement vector. Interaction matrices are usually measured by means of an artificial source at the entrance focus of the adaptive optics system; however, adaptive secondary mirrors on Cassegrain telescopes offer no such focus and the measurement of their interaction matrices becomes more challenging and needs to be done on-sky using a natural star. The most common method is to generate a theoretical or simulated interaction matrix and adjust it parametrically (for example, decenter, magnification, rotation) using on-sky measurements. We propose a novel method of measuring on-sky interaction matrices ab initio from the telemetry stream of the AO system using random patterns on the deformable mirror with diagonal commands covariance matrices. The approach, being developed for the adaptive secondary mirror upgrade for the imaka wide-field AO system on the UH2.2m telescope project, is shown to work on-sky using the current imaka testbed.

scholarly journals Wide-field AO correction: the large wavefront sensor detector of ARGOS

2010 ◽  
Author(s):  
Gilles Orban de Xivry ◽  
Sebastian Rabien ◽  
Lothar Barl ◽  
Simone Esposito ◽  
Wolfgang Gaessler ◽  
...  
Keyword(s):  
Wavefront Sensor ◽  
Wide Field

Laboratory quantification of a plenoptic wavefront sensor with extended objects

2020 ◽  
Vol 497 (4) ◽  
pp. 4580-4586
Author(s):  
Zhentao Zhang ◽  
Nazim Bharmal ◽  
Tim Morris ◽  
Yonghui Liang
Keyword(s):  
Adaptive Optics ◽  
Closed Loop ◽  
Optical Design ◽  
Wavefront Sensor ◽  
Wavefront Sensing ◽  
Wide Field ◽  
Loop Correction ◽  
Wavefront Correction ◽  
Set Up ◽  
Experimental Bench

ABSTRACT Adaptive optics (AO) is widely used in ground-based telescopes to compensate the effects of atmosphere distortion, and the wavefront sensor is a significant component in the AO systems. The plenoptic wavefront sensor has been proposed as an alternative wavefront sensor adequate for extended objects and wide field of views. In this paper, a experimental bench has been set up to investigate the slope measurement accuracy and closed-loop wavefront correction performance for extended objects. From the experimental results, it has been confirmed that plenoptic wavefront sensor is suitable for extended objects wavefront sensing with proper optical design. The slope measurements have a good linearity and accuracy when observing extended objects. The image quality is significantly improved after closed-loop correction. A method of global tip/tilt measurement using only plenoptic wavefront sensor frame is proposed in this paper, it is also a potential advantage of plenoptic wavefront sensor in extended objects wavefront sensing.

scholarly journals Experience with wavefront sensor and deformable mirror interfaces for wide-field adaptive optics systems

2016 ◽  
Vol 459 (2) ◽  
pp. 1350-1359 ◽  
Author(s):  
A. G. Basden ◽  
D. Atkinson ◽  
N. A. Bharmal ◽  
U. Bitenc ◽  
M. Brangier ◽  
...  
Keyword(s):  
Adaptive Optics ◽  
Wavefront Sensor ◽  
Deformable Mirror ◽  
Wide Field

scholarly journals The Galactic Center at 327 MHz

2002 ◽  
Vol 199 ◽  
pp. 268-271
Author(s):  
T.N. LaRosa ◽  
Namir E. Kassim ◽  
T. Joseph W. Lazio ◽  
S.D. Hyman
Keyword(s):  
Large Scale ◽  
Galactic Center ◽  
Galactic Plane ◽  
Dynamic Range ◽  
Small Diameter ◽  
Critical Issue ◽  
Wide Field ◽  
Origin And Evolution ◽  
Extended Sources ◽  
Sgr A

Figure 1 presents a wide-field, high dynamic-range, 327 MHz VLA2 image of the Galactic center (GC). This image was constructed from archival VLA data using new 3-D image restoration techniques which resolve the problem of non-coplanar baselines encountered at long wavelengths. In a recent paper (LaRosa et al. 2000) we presented a catalog of over a hundred sources from this image, 23 extended sources and 78 small-diameter sources. The catalog contains flux densities, positions, sizes, and, where possible, a 20/90 cm spectral index. We also present subimages of all the extended sources. We refer the reader to LaRosa et al. (2000) for the details. In this note we will concentrate on observations of the nonthermal filaments and briefly describe a new model for their formation.The origin and evolution of the nonthermal filaments (NTFs) observed in the GC is an outstanding problem. All of the 7 classified NTFs are visible on Figure 1: Four of these are labeled threads, the other three are the “Snake,” the “Pelican,” and the Sgr C filament. The wide-field imaging at 327 MHz lead to the discovery of the “Pelican” (Lang et al. 1999). This filament has the distinction of being the farthest NTF in projection from Sgr A and the only NTF that is parallel to the Galactic plane. One critical issue for understanding the activity and overall structure of the GC is whether these filamentary sources trace a pervasive, large-scale magnetic field or are local independent structures (e.g., Yusef-Zadeh 1989; Morris 1994, 1996; Uchida & Gusten 1995; Yusef-Zadeh, Wardle & Parastaran 1997; Shore & LaRosa 1999; Lang et al. 1999; Lang, Morris & Echevarria 1999; LaRosa et al. 2000).

Characterizing daytime wind profiles with the wide-field Shack–Hartmann wavefront sensor

2019 ◽  
Vol 483 (4) ◽  
pp. 4910-4921
Author(s):  
Zhiyong Wang ◽  
Lanqiang Zhang ◽  
Changhui Rao
Keyword(s):  
Wavefront Sensor ◽  
Wide Field ◽  
Wind Profiles
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