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

Author(s):  
V. Viotto ◽  
R. Ragazzoni ◽  
C. Arcidiacono ◽  
M. Bergomi ◽  
A. Brunelli ◽  
...  
Keyword(s):  
2011 ◽  
Author(s):  
Oscar Azucena ◽  
Xiaodong Tao ◽  
Justin Crest ◽  
Shaila Kotadia ◽  
William Sullivan ◽  
...  

Author(s):  
Olivier Lai ◽  
Mark Chun ◽  
Ryan Dungee ◽  
Jessica Lu ◽  
Marcel Carbillet

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.


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

2020 ◽  
Vol 497 (4) ◽  
pp. 4580-4586
Author(s):  
Zhentao Zhang ◽  
Nazim Bharmal ◽  
Tim Morris ◽  
Yonghui Liang

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.


2016 ◽  
Vol 459 (2) ◽  
pp. 1350-1359 ◽  
Author(s):  
A. G. Basden ◽  
D. Atkinson ◽  
N. A. Bharmal ◽  
U. Bitenc ◽  
M. Brangier ◽  
...  

2019 ◽  
Vol 483 (4) ◽  
pp. 4910-4921
Author(s):  
Zhiyong Wang ◽  
Lanqiang Zhang ◽  
Changhui Rao

2015 ◽  
Vol 13 (12) ◽  
pp. 120801-120805 ◽  
Author(s):  
Lebao Yang Lebao Yang ◽  
Lifa Hu Lifa Hu ◽  
Dayu Li Dayu Li ◽  
Zhaoliang Cao Zhaoliang Cao ◽  
Quanquan Mu Quanquan Mu ◽  
...  

Author(s):  
M. G. Lagally

It has been recognized since the earliest days of crystal growth that kinetic processes of all Kinds control the nature of the growth. As the technology of crystal growth has become ever more refined, with the advent of such atomistic processes as molecular beam epitaxy, chemical vapor deposition, sputter deposition, and plasma enhanced techniques for the creation of “crystals” as little as one or a few atomic layers thick, multilayer structures, and novel materials combinations, the need to understand the mechanisms controlling the growth process is becoming more critical. Unfortunately, available techniques have not lent themselves well to obtaining a truly microscopic picture of such processes. Because of its atomic resolution on the one hand, and the achievable wide field of view on the other (of the order of micrometers) scanning tunneling microscopy (STM) gives us this opportunity. In this talk, we briefly review the types of growth kinetics measurements that can be made using STM. The use of STM for studies of kinetics is one of the more recent applications of what is itself still a very young field.


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