Phase-retrieval-based wavefront metrology for high contrast coronagraphy

Brady, Gregory R.; Moriarty, Christopher; Petrone, Peter; Laginja, Iva; Brooks, Keira; Comeau, Thomas; Leboulleux, Lucie; Soummer, Rémi

doi:10.1117/12.2314368

Cited by 8 publications

(8 citation statements)

References 18 publications

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“…To shape the wavefront, HiCAT uses two continuous Boston kilo-DMs: DM1 in a pupil plane and DM2 out of a pupil plane to allow both phase and amplitude control. A prior calibration of HiCAT was performed to experimentally produce DM flat commands (or 'flat maps') that minimize the number of static aberrations on the testbed (Brady et al 2018). HiCAT also uses both of these DMs to further reject starlight and enhance the contrast in a given region of the coronagraphic image using DH optimization algorithms.…”

Section: Experimental Setup On Hicatmentioning

confidence: 99%

Low-order wavefront control using a Zernike sensor through Lyot coronagraphs for exoplanet imaging

Pourcelot

N’Diaye

Por

et al. 2022

A&A

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Context. The combination of large segmented space telescopes, coronagraphy, and wavefront control methods is a promising solution for producing a dark hole (DH) region in the coronagraphic image of an observed star in order to study planetary companions. The thermal and mechanical evolution of such a high-contrast instrumental setup leads to wavefront drifts that degrade the DH contrast during the observing time, thus limiting the ability to retrieve planetary signals. Aims. Lyot-style coronagraphs are starlight-suppression systems that remove the central part of the image for an unresolved observed star, that is, the point spread function, with an opaque focal plane mask (FPM). When implemented with a flat mirror containing an etched pinhole, the mask rejects part of the starlight through the pinhole which can be used to retrieve information about low-order aberrations. Methods. We propose an active control scheme using a Zernike wavefront sensor (ZWFS) to analyze the light rejected by the FPM, control low-order aberrations, and stabilize the DH contrast. We first present the concept formalism and then describe how we characterized the sensor behavior in simulations and in the laboratory. We performed experimental tests to validate a wavefront control loop using a ZWFS on the HiCAT testbed. Results. By controlling the first 11 Zernike modes, we show a decrease in the standard deviation of the wavefront error by a factor of up to 9 between open- and closed-loop operations using the ZWFS. In the presence of wavefront perturbations, we show the ability of this control loop to stabilize a DH contrast around 7 × 10−8 with a standard deviation of 7 × 10−9. Conclusions. Active control with a ZWFS proves to be a promising solution in Lyot coronagraphs with an FPM-filtered beam for controlling and stabilizing low-order wavefront aberrations and DH contrast for exoplanet imaging with future space missions.

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Section: Experimental Setup On Hicatmentioning

confidence: 99%

Low-order wavefront control using a Zernike sensor through Lyot coronagraphs for exoplanet imaging

Pourcelot

N’Diaye

Por

et al. 2022

A&A

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“…The testbed is calibrated to a final wavefront error of the order of 1 nm rms using the phase retrieval camera, which is used to measure the wavefront at a focal-plane mask (FPM) proxy location by introducing a high-quality flat mirror into the beam. 12 We have since then also implemented a dOTF calibration (differential Optical Transfer Function), 13 which is simpler operationally (E. Por, in prep). The dOTF calibration combines an image with a flat wavefront with an image where one of the Boston DM actuators is poked near the edge of the projected pupil to retrieve the complex amplitude of the pupil plane.…”

Section: Testbed Descriptionmentioning

confidence: 99%

High-contrast imager for complex aperture telescopes (HiCAT): 8. Dark zone demonstration with simultaneous closed loop low-order wavefront sensing and control

Soummer

Por

Pourcelot

et al. 2022

Space Telescopes and Instrumentation 2022: Optical, Infrared, and Millimeter Wave

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HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

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“…The phase retrieval camera can be used to measure the wavefront at a focal plane mask (FPM) proxy location by introducing a high-quality flat mirror into the beam. 27,28 A Zernike wavefront sensor has been assembled as part of the low-order wavefront sensor, using the light rejected by the FPM. 29…”

Section: The Hicat Projectmentioning

confidence: 99%

Predicting contrast sensitivity to segmented aperture misalignment modes for the HiCAT testbed

Laginja,

Soummer,

Mugnier

et al. 2020

Preprint

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This paper presents the setup for empirical validations of the Pair-based Analytical model for Segmented Telescope Imaging from Space (PASTIS) tolerancing model for segmented coronagraphy. We show the hardware configuration of the High-contrast imager for Complex Aperture Telescopes (HiCAT) testbed on which these experiments will be conducted at an intermediate contrast regime between 10 −6 and 10 −8 . We describe the optical performance of the testbed with a classical Lyot coronagraph and describe the recent hardware upgrade to a segmented mode, using an IrisAO segmented deformable mirror. Implementing experiments on HiCAT is made easy through its top-level control infrastructure that uses the same code base to run on the real testbed, or to invoke the optical simulator. The experiments presented in this paper are run on the HiCAT testbed emulator, which makes them ready to be performed on actual hardware. We show results of three experiments with results from the emulator, with the goal to demonstrate PASTIS on hardware next. We measure the testbed PASTIS matrix, and validate the PASTIS analytical propagation model by comparing its contrast predictions to simulator results. We perform the tolerancing analysis on the optical eigenmodes (PASTIS modes) and on independent segments, then validate these results in respective experiments. This work prepares and enables the experimental validation of the analytical segment-based tolerancing model for segmented aperture coronagraphy with the specific application to the HiCAT testbed.

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Phase-retrieval-based wavefront metrology for high contrast coronagraphy

Cited by 8 publications

References 18 publications

Low-order wavefront control using a Zernike sensor through Lyot coronagraphs for exoplanet imaging

Low-order wavefront control using a Zernike sensor through Lyot coronagraphs for exoplanet imaging

High-contrast imager for complex aperture telescopes (HiCAT): 8. Dark zone demonstration with simultaneous closed loop low-order wavefront sensing and control

Predicting contrast sensitivity to segmented aperture misalignment modes for the HiCAT testbed

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