High-Contrast Imaging from Space: Speckle Nulling in a Low-Aberration Regime

By P. Bordé, Wesley A. Traub. 2005

241 citations recorded by the source corpus.

High-contrast imaging from space must overcome two major noise sources to successfully detect a terrestrial planet angularly close to its parent star: photon noise from diffracted starlight and speckle noise from starlight scattered by instrumentally generated wave front perturbation. Coronagraphs tackle only the photon noise contribution by reducing diffracted starlight at the location of a planet. Speckle noise should be addressed with adaptive optics systems. Following the tracks of Malbet, Yu, and Shao, we develop in this paper two analytical methods for wave front sensing and control that aims at creating "dark holes," i.e., areas of the image plane cleared of speckles, assuming an ideal coronagraph and small aberrations. The first method, "speckle field nulling," is a fast FFT-based algorithm that requires the deformable-mirror influence functions to have identical shapes. The second method, "speckle energy minimization," is more general and provides the optimal deformable mirror shape via matrix inversion. With an N × N deformable mirror, the size of the matrix to be inverted is either N2 × N2 in the general case or only N × N if the influence functions can be written as the tensor product of two one-dimensional functions. Moreover, speckle energy minimization makes it possible to trade off some of the dark hole area against an improved contrast. For both methods, complex wave front aberrations (amplitude and phase) are measured using just three images taken with the science camera (no dedicated wave front sensing channel is used); therefore, there are no noncommon path errors. We assess the theoretical performance of both methods with numerical simulations including realistic speckle noise and experimental influence functions. We find that these speckle-nulling techniques should be able to improve the contrast by several orders of magnitude.

Subfields: Astronomy and Astrophysics, Atomic and Molecular Physics, and Optics, Statistical and Nonlinear Physics

View Paper: https://www.semanticscholar.org/paper/09cd2d3c0f0abff4eaadc3dcac6fcaa77133819a

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

In Atomic and Molecular Physics, and Optics

In Statistical and Nonlinear Physics

Citations in the corpus

Theoretical Limits on Extrasolar Terrestrial Planet Detection with Coronagraphs (2006, methodology): “Several authors have recently explored promising wavefront control schemes free of aliasing and non-common path aberrations (Codona & Angel 2004; Labeyrie 2004; Guyon 2005; Bordé & Traub 2006), and contrast levels obtained in laboratory (Trauger et al. 2003) are approaching the desired performance.”
Broadband wavefront correction algorithm for high-contrast imaging systems (2007, unknown): “ā = ⎡ ⎣ {G} · · · {G} ⎤ ⎦ −1 ⎡ ⎣ {iEab} · · · {iEab} ⎤ ⎦ (5)”
Spectral Evolution of an Earth-like Planet (2006, background): “…(TPF-C), are designed to detect terrestrial exoplanets, and to measure the color and spectra of terrestrial planets, giant planets, and zodiacal dust disks around nearby stars (see, e.g., Beichman et al. 1999; 2006; Fridlund 2000; Kaltenegger 2004; Kaltenegger & Fridlund 2005; Borde & Traub 2006).”
PALM-3000: EXOPLANET ADAPTIVE OPTICS FOR THE 5 m HALE TELESCOPE (2013, methodology): “We have implemented both speckle nulling (Bordé and Traub 2006) and Electric Field Conjugation (Give’on et al. 2007) algorithms for laboratory testing, but on-sky demonstration of these techniques with PALM-3000 remains a topic for future publication.”
FUNDAMENTAL LIMITATIONS OF HIGH CONTRAST IMAGING SET BY SMALL SAMPLE STATISTICS (2014, background): “…field of view (FoV) is accessible, as with, e.g., the APP (Quanz et al. 2010; Kenworthy et al. 2010, 2013) or half dark holes (Malbet et al. 1995; Bordé & Traub 2006; Give’on et al. 2007), reducing the number of DOF by another factor of two, penalizing contrast thresholds and FPF/CLs even more…”