High-Dynamic-Range Imaging Using a Deformable Mirror for Space Coronography

Malbet, Fabien; Yu, Jeffrey W.; Shao, Michael

doi:10.1086/133563

Cited by 194 publications

(154 citation statements)

References 9 publications

(14 reference statements)

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“…For a given diameter D L of the Lyot pupil, the highest frequency attainable for a N ×N actuators DM (N actuators across the pupil diameter) is Nλ/(2D L ) in one of the principal directions of the mirror and √ 2Nλ/(2D L ) in the diagonal. The largest correction zone, called dark hole (DH) in Malbet et al (1995) is the zone…”

Section: Dark Holesmentioning

confidence: 99%

“…Theses methods can use either the spectral signature and polarization state of the planet or differential rotation in the image (Marois et al 2004(Marois et al , 2006. Second, even before applying these post-processing techniques, an active suppression of speckles (Malbet et al 1995) has to be implemented to reach very high contrasts. It uses a deformable mirror (DM) controlled by a specific wavefront sensor that is immune against NCPA.…”

Section: Introductionmentioning

confidence: 99%

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Estimation and correction of wavefront aberrations using the self-coherent camera: laboratory results

Mazoyer

Baudoz

Galicher

et al. 2013

A&A

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Context. Direct imaging of exoplanets requires very high contrast levels, which are obtained using coronagraphs. But residual quasistatic aberrations create speckles in the focal plane downstream of the coronagraph which mask the planet. This problem appears in ground-based instruments as well as in space-based telescopes.Aims. An active correction of these wavefront errors using a deformable mirror upstream of the coronagraph is mandatory, but conventional adaptive optics are limited by differential path aberrations. Dedicated techniques have to be implemented to measure phase and amplitude errors directly in the science focal plane. Methods. First, we propose a method for estimating phase and amplitude aberrations upstream of a coronagraph from the speckle complex field in the downstream focal plane. Then, we present the self-coherent camera, which uses the coherence of light to spatially encode the focal plane speckles and retrieve the associated complex field. This enabled us to estimate and compensate in a closed loop for the aberrations upstream of the coronagraph. We conducted numerical simulations as well as laboratory tests using a four-quadrant phase mask and a 32 × 32 actuator deformable mirror. Results. We demonstrated in the laboratory our capability to achieve a stable closed loop and compensated for phase and amplitude quasi-static aberrations. We determined the best-suited parameter values to implement our technique. Contrasts better than 10 −6 between 2 and 12 λ/D and even 3 × 10 −7 (rms) between 7 and 11 λ/D were reached in the focal plane. It seems that the contrast level is mainly limited by amplitude defects created by the surface of the deformable mirror and by the dynamic of the detector. Conclusions. These results are promising for a future application to a dedicated space mission for exoplanet characterization. A number of possible improvements have been identified.

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Section: Dark Holesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Estimation and correction of wavefront aberrations using the self-coherent camera: laboratory results

Mazoyer

Baudoz

Galicher

et al. 2013

A&A

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show abstract

“…A number of recently proposed coronagraphs can potentially be used to reduce the bright starlight (e.g., Guyon et al 2006a), but scattering by nonideal telescope optics and atmospheric seeing fluctuations severely limits the off-axis detection capabilities of all types of coronagraphs, with performance ultimately set by the quality of the corrected stellar wavefront (Malbet et al 1995). Indeed, classical ''Lyot'' coronagraphs employing opaque focal plane starlight blockers should yield significant contrast gains only for stellar Strehl ratios exceeding %90% (Sivaramakrishnan et al 2001).…”

Section: Introductionmentioning

confidence: 99%

Extreme Adaptive Optics Imaging with a Clear and Well‐Corrected Off‐Axis Telescope Subaperture

Serabyn¹,

Wallace²,

Troy³

et al. 2007

ApJ

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Rather than using an adaptive optics (AO) system to correct a telescope's entire pupil, it can instead be used to more finely correct a smaller subaperture. Indeed, existing AO systems can be used to correct a subaperture 1 3 to 1 2 the size of a 5Y10 m telescope to extreme adaptive optics (ExAO) levels. We discuss the potential performance of a clear off-axis well-corrected subaperture (WCS), and describe our initial imaging results with a 1.5 m diameter WCS on the Palomar Observatory's Hale Telescope. These include measured Strehl ratios of 0.92Y0.94 in the infrared (2.17 m) and %0.12 in the B band, the latter allowing a binary of separation 0.34 00 to be easily resolved in the blue. Such performance levels enable a variety of novel observational modes, such as infrared ExAO, visible-wavelength AO, and high-contrast coronagraphy. One specific application suggested by the high Strehl ratio stability obtained (1%) is the measurement of planetary transits and eclipses. Also described is a simple ''dark hole'' experiment carried out on a binary star, in which a comatic phase term was applied directly to the deformable mirror, in order to shift the diffraction rings to one side of the point-spread function.

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“…5 Deformable Mirror (DM)s are a critical technology for planned internal space coronagraphs to directly image extrasolar planets. 6 A single DM can correct phase and amplitude errors across half of a coronagraphic image 7 and two in series allow simultaneous correction of both phase and amplitude terms across a "dark hole" symmetrically around the stellar Point Spread Function (PSF). Neglecting amplitude errors, a simple derivation of dark hole contrast (C) as a function of controlled root mean squared (RMS) wavefront error (h RM S ) and the number of DM actuators across the pupil (N ), or the number of spatial modes corrected, is given by Traub and Oppenheimer [9, equation 124]:…”

Section: Introductionmentioning

confidence: 99%

Design of the deformable mirror demonstration CubeSat (DeMi)

Douglas

Cahoy

Merck

et al. 2017

Techniques and Instrumentation for Detection of Exoplanets VIII

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The Deformable Mirror Demonstration Mission (DeMi) was recently selected by DARPA to demonstrate in-space operation of a wavefront sensor and Microelectromechanical system (MEMS) deformable mirror (DM) payload on a 6U CubeSat. Space telescopes designed to make high-contrast observations using internal coronagraphs for direct characterization of exoplanets require the use of high-actuator density deformable mirrors. These DMs can correct image plane aberrations and speckles caused by imperfections, thermal distortions, and diffraction in the telescope and optics that would otherwise corrupt the wavefront and allow leaking starlight to contaminate coronagraphic images. DeMi is provide on-orbit demonstration and performance characterization of a MEMS deformable mirror and closed loop wavefront sensing.The DeMi payload has two operational modes, one mode that images an internal light source and another mode which uses an external aperture to images stars. Both the internal and external modes include image plane and pupil plane wavefront sensing. The objectives of the internal measurement of the 140-actuator MEMS DM actuator displacement are characterization of the mirror performance and demonstration of closed-loop correction of aberrations in the optical path. Using the external aperture to observe stars of magnitude 2 or brighter, assuming 3-axis stability with less than 0.1 degree of attitude knowledge and jitter below 10 arcsec RMSE, per observation, DeMi will also demonstrate closed loop wavefront control on an astrophysical target. We present an updated payload design, results from simulations and laboratory optical prototyping, as well as present our design for accommodating high-voltage multichannel drive electronics for the DM on a CubeSat.

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High-Dynamic-Range Imaging Using a Deformable Mirror for Space Coronography

Cited by 194 publications

References 9 publications

Estimation and correction of wavefront aberrations using the self-coherent camera: laboratory results

Estimation and correction of wavefront aberrations using the self-coherent camera: laboratory results

Extreme Adaptive Optics Imaging with a Clear and Well‐Corrected Off‐Axis Telescope Subaperture

Design of the deformable mirror demonstration CubeSat (DeMi)

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