Combining spatially filtered Shack-Hartmann wavefront sensing and coronography in closed loop AO simulations

2004 ◽  
Author(s):  
Visa Korkiakoski ◽  
Miska Le Louarn ◽  
Christophe Verinaud
Keyword(s):  
Closed Loop ◽  
Wavefront Sensing

Wavefront sensing and closed-loop control for the Fizeau interferometry testbed

2007 ◽  
Author(s):  
Richard G. Lyon ◽  
Kenneth G. Carpenter ◽  
Alice Liu ◽  
Peter Petrone ◽  
Peter Dogoda ◽  
...  
Keyword(s):  
Closed Loop ◽  
Wavefront Sensing ◽  
Closed Loop Control ◽  
Loop Control

Closed-loop wavefront sensing for a sparse-aperture multitelescope array using broadband phase diversity

2000 ◽  
Author(s):  
John H. Seldin ◽  
Richard G. Paxman ◽  
Vassilis G. Zarifis ◽  
Larry Benson ◽  
Richard E. Stone
Keyword(s):  
Closed Loop ◽  
Wavefront Sensing ◽  
Phase Diversity ◽  
Sparse Aperture

Design and Development of a Closed Loop Adaptive Optics System for Wavefront Sensing and Control

2005 ◽  
Vol 34 (2) ◽  
pp. 67-81 ◽  
Author(s):  
A. R. Ganesan ◽  
P. Arulmozhivarman ◽  
D. Mohan ◽  
Ashok Kumar ◽  
A. K. Gupta
Keyword(s):  
Adaptive Optics ◽  
Closed Loop ◽  
Wavefront Sensing ◽  
Design And Development ◽  
And Control ◽  
Adaptive Optics System

scholarly journals Closed-loop adaptive optics with a single element for wavefront sensing and correction

2011 ◽  
Vol 36 (18) ◽  
pp. 3702 ◽  
Author(s):  
Raúl Martínez-Cuenca ◽  
Vicente Durán ◽  
Justo Arines ◽  
Jorge Ares ◽  
Zbigniew Jaroszewicz ◽  
...  
Keyword(s):  
Adaptive Optics ◽  
Closed Loop ◽  
Single Element ◽  
Wavefront Sensing

scholarly journals Focal-plane wavefront sensing with the vector-Apodizing Phase Plate

2019 ◽  
Vol 632 ◽  
pp. A48 ◽  
Author(s):  
S. P. Bos ◽  
D. S. Doelman ◽  
J. Lozi ◽  
O. Guyon ◽  
C. U. Keller ◽  
...  
Keyword(s):  
Focal Plane ◽  
Closed Loop ◽  
Phase Plate ◽  
Wavefront Sensing ◽  
Internal Source ◽  
Maximum Throughput ◽  
Loop Correction ◽  
Common Path ◽  
Plane Wavefront ◽  
Zernike Modes

Context. One of the key limitations of the direct imaging of exoplanets at small angular separations are quasi-static speckles that originate from evolving non-common path aberrations (NCPA) in the optical train downstream of the instrument’s main wavefront sensor split-off. Aims. In this article we show that the vector-Apodizing Phase Plate (vAPP) coronagraph can be designed such that the coronagraphic point spread functions (PSFs) can act as wavefront sensors to measure and correct the (quasi-)static aberrations without dedicated wavefront sensing holograms or modulation by the deformable mirror. The absolute wavefront retrieval is performed with a non-linear algorithm. Methods. The focal-plane wavefront sensing (FPWFS) performance of the vAPP and the algorithm are evaluated via numerical simulations to test various photon and read noise levels, the sensitivity to the 100 lowest Zernike modes, and the maximum wavefront error (WFE) that can be accurately estimated in one iteration. We apply these methods to the vAPP within SCExAO, first with the internal source and subsequently on-sky. Results. In idealized simulations we show that for 107 photons the root mean square (rms) WFE can be reduced to ∼λ/1000, which is 1 nm rms in the context of the SCExAO system. We find that the maximum WFE that can be corrected in one iteration is ∼λ/8 rms or ∼200 nm rms (SCExAO). Furthermore, we demonstrate the SCExAO vAPP capabilities by measuring and controlling the 30 lowest Zernike modes with the internal source and on-sky. On-sky, we report a raw contrast improvement of a factor ∼2 between 2 and 4 λ/D after five iterations of closed-loop correction. When artificially introducing 150 nm rms WFE, the algorithm corrects it within five iterations of closed-loop operation. Conclusions. FPWFS with the vAPP coronagraphic PSFs is a powerful technique since it integrates coronagraphy and wavefront sensing, eliminating the need for additional probes and thus resulting in a 100% science duty cycle and maximum throughput for the target.

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.

Intestinal Bacteriology of Closed Loop, Strangulated Obstruction in Dogs.

1961 ◽  
Vol 41 (3) ◽  
pp. 245-250 ◽  
Author(s):  
George H. Bornside ◽  
Isidore Cohn
Keyword(s):  
Closed Loop
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