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

Abstract

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.

arXiv comment27 pages, 9 figures

References in corpus (6)

• Angular Differential Imaging: a Powerful High-Contrast Imaging Technique
• Detection and Characterization of Exoplanets and Disks using Projections on Karhunen-Loeve Eigenimages
• High-contrast Imaging from Space: Speckle Nulling in a Low Aberration Regime
• Optimal Dark Hole Generation via Two Deformable Mirrors with Stroke Minimization
• Kalman filtering techniques for focal plane electric field estimation
• A dim candidate companion to εCephei

Cited by in corpus (6)

• Imaging exoplanets with coronagraphic instruments
• Analytical tolerancing of segmented telescope co-phasing for exo-Earth high-contrast imaging
• High-Contrast Coronagraphy
• Information-theoretical Limits of Recursive Estimation and Closed-loop Control in High-contrast Imaging
• High-Contrast Integral Field Spectrograph (HCIFS): multi-spectral wavefront control and reduced-dimensional system identification
• Reduced Order Estimation of the Speckle Electric Field History for Space-Based Coronagraphs