Focal Plane and non-linear Curvature Wavefront Sensing for High Contrast Adaptive Optics

2007 ◽  
Author(s):  
Olivier Guyon
Keyword(s):  
Adaptive Optics ◽  
Focal Plane ◽  
Wavefront Sensing ◽  
High Contrast ◽  
Non Linear

scholarly journals Extremely fast focal-plane wavefront sensing for extreme adaptive optics

2012 ◽  
Author(s):  
Christoph U. Keller ◽  
Visa Korkiakoski ◽  
Niek Doelman ◽  
Rufus Fraanje ◽  
Raluca Andrei ◽  
...  
Keyword(s):  
Adaptive Optics ◽  
Focal Plane ◽  
Wavefront Sensing ◽  
Plane Wavefront

scholarly journals Focal-plane wavefront sensing with high-order adaptive optics systems

2014 ◽  
Author(s):  
Visa Korkiakoski ◽  
Christoph U. Keller ◽  
Niek Doelman ◽  
Matthew Kenworthy ◽  
Gilles Otten ◽  
...  
Keyword(s):  
Adaptive Optics ◽  
Focal Plane ◽  
High Order ◽  
Wavefront Sensing ◽  
Plane Wavefront

scholarly journals FOCAL PLANE WAVEFRONT SENSING USING RESIDUAL ADAPTIVE OPTICS SPECKLES

2013 ◽  
Vol 767 (2) ◽  
pp. 100 ◽  
Author(s):  
Johanan L. Codona ◽  
Matthew Kenworthy
Keyword(s):  
Adaptive Optics ◽  
Focal Plane ◽  
Wavefront Sensing ◽  
Plane Wavefront

scholarly journals SPHERE/ZIMPOL high resolution polarimetric imager

2018 ◽  
Vol 619 ◽  
pp. A9 ◽  
Author(s):  
H. M. Schmid ◽  
A. Bazzon ◽  
R. Roelfsema ◽  
D. Mouillet ◽  
J. Milli ◽  
...  
Keyword(s):  
High Resolution ◽  
Adaptive Optics ◽  
Spatial Resolution ◽  
Focal Plane ◽  
Surface Brightness ◽  
Absolute Calibration ◽  
Wind Effect ◽  
High Contrast ◽  
Atmospheric Conditions ◽  
Very High

Context. The SPHERE “planet finder” is an extreme adaptive optics (AO) instrument for high resolution and high contrast observations at the Very Large Telescope (VLT). We describe the Zurich Imaging Polarimeter (ZIMPOL), the visual focal plane subsystem of SPHERE, which pushes the limits of current AO systems to shorter wavelengths, higher spatial resolution, and much improved polarimetric performance. Aims. We present a detailed characterization of SPHERE/ZIMPOL which should be useful for an optimal planning of observations and for improving the data reduction and calibration. We aim to provide new benchmarks for the performance of high contrast instruments, in particular for polarimetric differential imaging. Methods. We have analyzed SPHERE/ZIMPOL point spread functions (PSFs) and measure the normalized peak surface brightness, the encircled energy, and the full width half maximum (FWHM) for different wavelengths, atmospheric conditions, star brightness, and instrument modes. Coronagraphic images are described and the peak flux attenuation and the off-axis flux transmission are determined. Simultaneous images of the coronagraphic focal plane and the pupil plane are analyzed and the suppression of the diffraction rings by the pupil stop is investigated. We compared the performance at small separation for different coronagraphs with tests for the binary α Hyi with a separation of 92 mas and a contrast of Δm ≈ 6m. For the polarimetric mode we made the instrument calibrations using zero polarization and high polarization standard stars and here we give a recipe for the absolute calibration of polarimetric data. The data show small (< 1 mas) but disturbing differential polarimetric beam shifts, which can be explained as Goos-Hähnchen shifts from the inclined mirrors, and we discuss how to correct this effect. The polarimetric sensitivity is investigated with non-coronagraphic and deep, coronagraphic observations of the dust scattering around the symbiotic Mira variable R Aqr. Results. SPHERE/ZIMPOL reaches routinely an angular resolution (FWHM) of 22−28 mas, and a normalized peak surface brightness of SB0 − mstar ≈ −6.5m arcsec−2 for the V-, R- and I-band. The AO performance is worse for mediocre ≳1.0″ seeing conditions, faint stars mR ≳ 9m, or in the presence of the “low wind” effect (telescope seeing). The coronagraphs are effective in attenuating the PSF peak by factors of > 100, and the suppression of the diffracted light improves the contrast performance by a factor of approximately two in the separation range 0.06″−0.20″. The polarimetric sensitivity is Δp < 0.01% and the polarization zero point can be calibrated to better than Δp ≈ 0.1%. The contrast limits for differential polarimetric imaging for the 400 s I-band data of R Aqr at a separation of ρ = 0.86″ are for the surface brightness contrast SBpol( ρ)−mstar ≈ 8m arcsec−2 and for the point source contrast mpol( ρ)−mstar ≈ 15m and much lower limits are achievable with deeper observations. Conclusions. SPHERE/ZIMPOL achieves imaging performances in the visual range with unprecedented characteristics, in particular very high spatial resolution and very high polarimetric contrast. This instrument opens up many new research opportunities for the detailed investigation of circumstellar dust, in scattered and therefore polarized light, for the investigation of faint companions, and for the mapping of circumstellar Hα emission.

scholarly journals Experimental validation of coronagraphic focal-plane wavefront sensing for future segmented space telescopes

2020 ◽  
Vol 639 ◽  
pp. A70
Author(s):  
Lucie Leboulleux ◽  
Jean-François Sauvage ◽  
Rémi Soummer ◽  
Thierry Fusco ◽  
Laurent Pueyo ◽  
...  
Keyword(s):  
Focal Plane ◽  
Wavefront Sensing ◽  
High Contrast ◽  
Space Telescopes ◽  
Contrast Imaging ◽  
Primary Mirror ◽  
Hardware System ◽  
High Contrast Imaging ◽  
Earth Like Planets ◽  
Plane Wavefront

Context. Direct imaging of Earth-like planets from space requires dedicated observatories, combining large segmented apertures with instruments and techniques such as coronagraphs, wavefront sensors, and wavefront control in order to reach the high contrast of 1010 that is required. The complexity of these systems would be increased by the segmentation of the primary mirror, which allows for the larger diameters necessary to image Earth-like planets but also introduces specific patterns in the image due to the pupil shape and segmentation and making high-contrast imaging more challenging. Among these defects, the phasing errors of the primary mirror are a strong limitation to the performance. Aims. In this paper, we focus on the wavefront sensing of segment phasing errors for a high-contrast system, using the COronagraphic Focal plane wave-Front Estimation for Exoplanet detection (COFFEE) technique. Methods. We implemented and tested COFFEE on the High-contrast imaging for Complex Aperture Telescopes (HiCAT) testbed, in a configuration without any coronagraph and with a classical Lyot coronagraph, to reconstruct errors applied on a 37 segment mirror. We analysed the quality and limitations of the reconstructions. Results. We demonstrate that COFFEE is able to estimate correctly the phasing errors of a segmented telescope for piston, tip, and tilt aberrations of typically 100 nm RMS. We also identified the limitations of COFFEE for the reconstruction of low-order wavefront modes, which are highly filtered by the coronagraph. This is illustrated using two focal plane mask sizes on HiCAT. We discuss possible solutions, both in the hardware system and in the COFFEE optimizer, to mitigate these issues.

Fast focal plane wavefront sensing as a second stage adaptive optics wavefront sensor

2020 ◽  
Author(s):  
Benjamin L. Gerard ◽  
Jean-Pierre Véran ◽  
Garima Singh ◽  
Glen Herriot ◽  
Olivier Lardière ◽  
...  
Keyword(s):  
Adaptive Optics ◽  
Focal Plane ◽  
Wavefront Sensor ◽  
Wavefront Sensing ◽  
Second Stage ◽  
Plane Wavefront

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 Focal plane wavefront sensing and control strategies for high-contrast imaging on the MagAO-X instrument

2018 ◽  
Author(s):  
Kelsey L. Miller ◽  
Jared R. Males ◽  
Olivier Guyon ◽  
Laird M. Close ◽  
David S. Doelman ◽  
...  
Keyword(s):  
Focal Plane ◽  
Control Strategies ◽  
Wavefront Sensing ◽  
High Contrast ◽  
Contrast Imaging ◽  
High Contrast Imaging ◽  
Plane Wavefront ◽  
And Control

High contrast imaging with focal plane wavefront sensing for ground based telescopes

2006 ◽  
Author(s):  
Olivier Guyon ◽  
Basile Gallet ◽  
Eugene A. Pluzhnik ◽  
Hideki Takami ◽  
Motohide Tamura
Keyword(s):  
Focal Plane ◽  
Wavefront Sensing ◽  
High Contrast ◽  
Contrast Imaging ◽  
High Contrast Imaging ◽  
Plane Wavefront
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