Hybrid Lyot coronagraph for WFIRST: high-contrast broadband testbed demonstration

Seo, Byoung-Joon; Cady, Eric; Gordon, Brian; Kern, Brian; Lam, Raymond; Marx, David; Moody, Dwight; Muller, Richard E.; Patterson, Keith; Poberezhskiy, Ilya; Prada, Camilo Mejia; Sidick, Erkin; Trauger, John T.; Wilson, Daniel W.

doi:10.1117/12.2274687

Cited by 24 publications

(24 citation statements)

References 5 publications

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“…The Roman mission technology effort has demonstrated contrast approaching 10 −9 in testbeds. 34 It is reasonable to expect that a future telescope, customized for a specific coronagraph, could achieve another order of magnitude better performance in contrast. Therefore, we assume a range of initial contrast values in the 10 −10 vicinity and compute a sensitivity curve for each wavefront error mode.…”

Section: Wavefront Error Approximationmentioning

confidence: 99%

Method for deriving optical telescope performance specifications for Earth-detecting coronagraphs

Nemati

Stahl

et al. 2020

J. Astron. Telesc. Instrum. Syst.

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Direct detection and characterization of extrasolar planets has become possible with powerful new coronagraphs on ground-based telescopes. Space telescopes with active optics and coronagraphs will expand the frontier to imaging Earth-sized planets in the habitable zones of nearby Sun-like stars. Currently, NASA is studying potential space missions to detect and characterize such planets, which are dimmer than their host stars by a factor of 10 10. One approach is to use a star-shade occulter. Another is to use an internal coronagraph. The advantages of a coronagraph are its greater targeting versatility and higher technology readiness, but one disadvantage is its need for an ultrastable wavefront when operated open-loop. Achieving this requires a system-engineering approach, which specifies and designs the telescope and coronagraph as an integrated system. We describe a systems engineering process for deriving a wavefront stability error budget for any potential telescope/coronagraph combination. The first step is to calculate a given coronagraph's basic performance metrics, such as contrast. The second step is to calculate the sensitivity of that coronagraph's performance to its telescope's wavefront stability. The utility of the method is demonstrated by intercomparing the ability of several monolithic and segmented telescope and coronagraph combinations to detect an exo-Earth at 10 pc. © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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Section: Wavefront Error Approximationmentioning

confidence: 99%

Method for deriving optical telescope performance specifications for Earth-detecting coronagraphs

Nemati

Stahl

et al. 2020

J. Astron. Telesc. Instrum. Syst.

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“…Equations (25), (26) and (28) allow for a standard formulation of an Extended Kalman Filter (EKF) with non-additive noise (see Appendix A). The approximation in Eq.…”

Section: High-intensity Regime Recursive Estimationmentioning

confidence: 99%

“…The estimator of the speckle field is an extended Kalman filter (see, for example [33]) corresponding to the state equations (25), (26), the measurement equation (28) and the process noise statistics given by Eqs. (13), (14).…”

Section: A Dark Hole Maintenance Algorithmmentioning

confidence: 99%

Dark Hole Maintenance and A Posteriori Intensity Estimation in the Presence of Speckle Drift in a High-contrast Space Coronagraph

Pogorelyuk

Kasdin²

2019

ApJ

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Direct exoplanet imaging via coronagraphy requires maintenance of high contrast in a dark hole for lengthy integration periods. Wavefront errors that change slowly over that time accumulate and cause systematic errors in the star's Point Spread Function (PSF) which limit the achievable signal-to-noise ratio of the planet. In this paper we show that estimating the speckle drift can be achieved via intensity measurements in the dark hole together with dithering of the deformable mirrors to increase phase diversity. A scheme based on an Extended Kalman Filter and Electric Field Conjugation is proposed for maintaining the dark hole during the integration phase. For the post-processing phase, an a posteriori approach is proposed to estimate the realization of the PSF drift process and the intensity of the planet light incoherent with the speckles.

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“…4 The optical prescription is similar to earlier HLC coronagraph testbeds in HCIT. 6,7 One distinguishing feature of DST is that it only uses 6 OAPs with no flat fold mirrors to reduce the number of optics in the system, thus, making DST have a very simple optical layout and superior thermal and mechanical stability. angle between 3 λ/D and 8 λ/D.…”

Section: Testbed Designmentioning

confidence: 99%

Testbed demonstration of high-contrast coronagraph imaging in search for Earth-like exoplanets

Seo

Patterson

Balasubramanian

et al. 2019

Techniques and Instrumentation for Detection of Exoplanets IX

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Direct imaging of an Earth-like exoplanet requires starlight suppression with a contrast ratio on the order of 1 × 10 −10 at small angular separations of 100 milliarcseconds or less in visible light with more than 50 nm bandwidth. To our knowledge, the technology needed to achieve the contrast and stability has not been demonstrated as of January 2019. The science requirements for near future National Aeronautics and Space Administration (NASA) missions such as James Webb Space Telescope (JWST)'s Near Infrared Camera (NIRCam) coronagraph and Wide-Field InfraRed Survey Telescope (WFIRST) Coronagraph Instrument (CGI) are at least 10 times short. To investigate and guide the technology to reach this capability, we built a high contrast coronagraph testbed at NASA's Jet Propulsion Laboratory (JPL). Titled the Decadal Survey Testbed (DST), this state-of-art testbed is based on the accumulated experience of JPL's High Constrast Imaging Testbed (HCIT) team. Currently, the DST hosts a Hybrid Lyot Coronagraph (HLC) with an unobscured, circular pupil. The DST also has two deformable mirrors and is equipped with the Low Order Wavefront Sensing and Control (LOWFS/C) subsystem to sense and correct the dynamic wavefront disturbances. In this paper, we present up-to-date progress of the testbed demonstration. As of January 2019, we repeatedly obtain convergence below 4 × 10 −10 mean contrast with 10% broadband light centered at 550 nm in a 360 degrees dark hole with a working angle between 3 λ/D and 8 λ/D. We show the key elements used in the testbed and the performance results with associated analysis.

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Hybrid Lyot coronagraph for WFIRST: high-contrast broadband testbed demonstration

Cited by 24 publications

References 5 publications

Method for deriving optical telescope performance specifications for Earth-detecting coronagraphs

Method for deriving optical telescope performance specifications for Earth-detecting coronagraphs

Dark Hole Maintenance and A Posteriori Intensity Estimation in the Presence of Speckle Drift in a High-contrast Space Coronagraph

Testbed demonstration of high-contrast coronagraph imaging in search for Earth-like exoplanets

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