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Proceedings Paper

Nulling interferometers: the importance of systematic errors and the X-array configuration
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Paper Abstract

The nulling interferometers proposed for planet detection are arrays of collector telescopes whose amplitudes and phases are carefully controlled to generate a null response at the star. Perturbations in the amplitude and phase response of the instrument lead to time-dependent fluctuations in the stellar leakage that can mimic a planet signal. Understanding these non-linear systematic errors is important, since they drive most of the instrument requirements for missions such as the Terrestrial Planet Finder and Darwin. We show that 'amplitude-phase' errors are the dominant source of instrument noise. They are unaffected by the technique of phase chopping, increase rapidly at short wavelengths, are largely independent of the size and transmission efficiency of the collector optics, and depend only weakly on the nulling configuration and distance to the target system. Detection of an Earth around a G-type star like the sun requires ~1.5 nm of path control and ~0.1% control of the amplitude, integrated over all frequencies, including DC. This paper also introduces the X-Array - a new nulling configuration with 4 collectors and a central combiner arranged in an X pattern. This has a number of advantages over the standard dual Bracewell layout, and over other configurations that have been proposed.

Paper Details

Date Published: 20 October 2004
PDF: 12 pages
Proc. SPIE 5491, New Frontiers in Stellar Interferometry, (20 October 2004); doi: 10.1117/12.552109
Show Author Affiliations
Oliver P. Lay, Jet Propulsion Lab. (United States)
Serge Dubovitsky, Jet Propulsion Lab. (United States)


Published in SPIE Proceedings Vol. 5491:
New Frontiers in Stellar Interferometry
Wesley A. Traub, Editor(s)

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