Binary wavefront control in the focal plane for improved fiber coupling in air-to-air laser communication

2007 ◽  
Author(s):  
Peter Crabtree ◽  
Charles Woods ◽  
Jed Khoury ◽  
Matthew Goda ◽  
Michael Temple ◽  
...  
Keyword(s):  
Focal Plane ◽  
Laser Communication ◽  
Wavefront Control ◽  
Fiber Coupling

scholarly journals Calibration of the island effect: Experimental validation of closed-loop focal plane wavefront control on Subaru/SCExAO

2018 ◽  
Vol 610 ◽  
pp. A18 ◽  
Author(s):  
M. N’Diaye ◽  
F. Martinache ◽  
N. Jovanovic ◽  
J. Lozi ◽  
O. Guyon ◽  
...  
Keyword(s):  
Image Quality ◽  
Focal Plane ◽  
Closed Loop ◽  
Near Infrared ◽  
Experimental Tests ◽  
Relative Increase ◽  
Visible Range ◽  
Wavefront Control ◽  
Island Effect ◽  
Plane Wavefront

Context. Island effect (IE) aberrations are induced by differential pistons, tips, and tilts between neighboring pupil segments on ground-based telescopes, which severely limit the observations of circumstellar environments on the recently deployed exoplanet imagers (e.g., VLT/SPHERE, Gemini/GPI, Subaru/SCExAO) during the best observing conditions. Caused by air temperature gradients at the level of the telescope spiders, these aberrations were recently diagnosed with success on VLT/SPHERE, but so far no complete calibration has been performed to overcome this issue. Aims. We propose closed-loop focal plane wavefront control based on the asymmetric Fourier pupil wavefront sensor (APF-WFS) to calibrate these aberrations and improve the image quality of exoplanet high-contrast instruments in the presence of the IE. Methods. Assuming the archetypal four-quadrant aperture geometry in 8 m class telescopes, we describe these aberrations as a sum of the independent modes of piston, tip, and tilt that are distributed in each quadrant of the telescope pupil. We calibrate these modes with the APF-WFS before introducing our wavefront control for closed-loop operation. We perform numerical simulations and then experimental tests on a real system using Subaru/SCExAO to validate our control loop in the laboratory and on-sky. Results. Closed-loop operation with the APF-WFS enables the compensation for the IE in simulations and in the laboratory for the small aberration regime. Based on a calibration in the near infrared, we observe an improvement of the image quality in the visible range on the SCExAO/VAMPIRES module with a relative increase in the image Strehl ratio of 37%. Conclusions. Our first IE calibration paves the way for maximizing the science operations of the current exoplanet imagers. Such an approach and its results prove also very promising in light of the Extremely Large Telescopes (ELTs) and the presence of similar artifacts with their complex aperture geometry.

scholarly journals The Subaru coronagraphic extreme AO (SCExAO) system: wavefront control and detection of exoplanets with coherent light modulation in the focal plane

2010 ◽  
Author(s):  
Olivier Guyon ◽  
Frantz Martinache ◽  
Vincent Garrel ◽  
Frederic Vogt ◽  
Kaito Yokochi ◽  
...  
Keyword(s):  
Focal Plane ◽  
Light Modulation ◽  
Coherent Light ◽  
Wavefront Control

scholarly journals SCExAO: First Results and On-Sky Performance

2013 ◽  
Vol 8 (S299) ◽  
pp. 34-35 ◽  
Author(s):  
Thayne Currie ◽  
Olivier Guyon ◽  
Frantz Martinache ◽  
Christophe Clergeon ◽  
Michael McElwain ◽  
...  
Keyword(s):  
Adaptive Optics ◽  
Focal Plane ◽  
Closed Loop ◽  
Giant Planets ◽  
Wavefront Sensor ◽  
Strehl Ratio ◽  
Wavefront Control ◽  
Contrast Gain ◽  
First Results ◽  
Plane Wavefront

AbstractWe present new on-sky results for the Subaru Coronagraphic Extreme Adaptive Optics imager (SCExAO) verifying and quantifying the contrast gain enabled by key components: the closed-loop coronagraphic low-order wavefront sensor (CLOWFS) and focal plane wavefront control (“speckle nulling”). SCExAO will soon be coupled with a high-order, Pyramid wavefront sensor which will yield > 90% Strehl ratio and enable 106–107 contrast at small angular separations allowing us to image gas giant planets at solar system scales. Upcoming instruments like VAMPIRES, FIRST, and CHARIS will expand SCExAO's science capabilities.

scholarly journals Comparing focal plane wavefront control techniques: Numerical simulations and laboratory experiments

2020 ◽  
Vol 635 ◽  
pp. A192 ◽  
Author(s):  
A. Potier ◽  
P. Baudoz ◽  
R. Galicher ◽  
G. Singh ◽  
A. Boccaletti
Keyword(s):  
Numerical Simulations ◽  
Focal Plane ◽  
Spectral Band ◽  
Wavefront Sensing ◽  
High Contrast ◽  
Contrast Imaging ◽  
Wavefront Control ◽  
Control Techniques ◽  
High Contrast Imaging ◽  
Plane Wavefront

Context. Fewer than 1% of all exoplanets detected to date have been characterized on the basis of spectroscopic observations of their atmosphere. Unlike indirect methods, high-contrast imaging offers access to atmospheric signatures by separating the light of a faint off-axis source from that of its parent star. Forthcoming space facilities, such as WFIRST/LUVOIR/HabEX, are expected to use coronagraphic instruments capable of imaging and spectroscopy in order to understand the physical properties of remote worlds. The primary technological challenge that drives the design of these instruments involves the precision control of wavefront phase and amplitude errors. To suppress the stellar intensity to acceptable levels, it is necessary to reduce phase aberrations to less than several picometers across the pupil of the telescope. Aims. Several focal plane wavefront sensing and control techniques have been proposed and demonstrated in laboratory to achieve the required accuracy. However, these techniques have never been tested and compared under the same laboratory conditions. This paper compares two of these techniques in a closed loop in visible light: the pair-wise (PW) associated with electric field conjugation (EFC) and self-coherent camera (SCC). Methods. We first ran numerical simulations to optimize PW wavefront sensing and to predict the performance of a coronagraphic instrument with PW associated to EFC wavefront control, assuming modeling errors for both PW and EFC. Then we implemented the techniques on a laboratory testbed. We introduced known aberrations into the system and compared the wavefront sensing using both PW and SCC. The speckle intensity in the coronagraphic image was then minimized using PW+EFC and SCC independently. Results. We demonstrate that both techniques – SCC, based on spatial modulation of the speckle intensity using an empirical model of the instrument, and PW, based on temporal modulation using a synthetic model – can estimate the wavefront errors with the same precision. We also demonstrate that both SCC and PW+EFC can generate a dark hole in space-like conditions in a few iterations. Both techniques reach the current limitation of our laboratory bench and provide coronagraphic contrast levels of ∼5 × 10−9 in a narrow spectral band (< 0.25% bandwidth). Conclusions. Our results indicate that both techniques are mature enough to be implemented in future space telescopes equipped with deformable mirrors for high-contrast imaging of exoplanets.

scholarly journals Broadband focal plane wavefront control of amplitude and phase aberrations

2012 ◽  
Author(s):  
Tyler D. Groff ◽  
N. Jeremy Kasdin ◽  
Alexis Carlotti ◽  
A. J. Eldorado Riggs
Keyword(s):  
Focal Plane ◽  
Wavefront Control ◽  
Plane Wavefront ◽  
Phase Aberrations

scholarly journals Measurements of Speckle Lifetimes in Near-infrared Extreme Adaptive Optics Images for Optimizing Focal Plane Wavefront Control

2018 ◽  
Vol 130 (992) ◽  
pp. 104502 ◽  
Author(s):  
Sean B. Goebel ◽  
Olivier Guyon ◽  
Donald N. B. Hall ◽  
Nemanja Jovanovic ◽  
Julien Lozi ◽  
...  
Keyword(s):  
Adaptive Optics ◽  
Focal Plane ◽  
Near Infrared ◽  
Wavefront Control ◽  
Plane Wavefront

scholarly journals Closed-loop focal plane wavefront control with the SCExAO instrument

2016 ◽  
Vol 593 ◽  
pp. A33 ◽  
Author(s):  
Frantz Martinache ◽  
Nemanja Jovanovic ◽  
Olivier Guyon
Keyword(s):  
Focal Plane ◽  
Closed Loop ◽  
Wavefront Control ◽  
Plane Wavefront
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