4273-29

Nulling Interferometry for Spectroscopic Investigation of Exoplanets -
A Statistical Analysis of Imperfections

by

Oswald Wallner, Klaus Kudielka and Walter R. Leeb

Copyright, Paul Shuch

Abstract

In ESA's InfraRed Space Interferometry mission, a multi-aperture interferometer fed by telescopes will serve to analyze exoplanets orbiting bright stars.  For a Sun/Earth-like constellation, a rejection ratio - the factor by which the star light is suppressed, when comparing the interferometer with a standard, wide-field-of-view telescope - of some 80 dB is required.

We investigate the nulling capability of space-based interferometers, realized either in fiber or bulk optics, in the presence of imperfections of the structure and of optical components.  Mismatch of amplitude, optical path length, and polarization among the interferometer arms is taken into account, as well as multiple reflections and telescope imperfections.  Parameters influenced by environmental disturbances are modeled stochastically.

We analyze Sun/Earth-like constellations by numerical simulation for a wavelength range of 6 to 18 microns.  The expected value of the star light rejection ratio is calculated for several interferometer configurations.

The exemplary numerical results confirm the extreme requirements for interferometer uniformity and give a quantitative insight into the dependence of the attainable rejection ratio on individual and/or combined interferometer imperfections.

Keywords

Nulling interferometry, rejection ratio, imperfections, statistical analysis.

• The paper (author Web site)

Principal Author Biography

Oswald Wallner was born in Scheibbs, Austria in January 1975.  He received the Dipl.-Ing. degree in electrical engineering from the Vienna University of Technology, Austria, in March 2000.  Since then, he is doing Ph.D. studies on nulling interferometry.  His special field of interest are telescope array systems for astronomical interferometry.

Principal Author Affiliation

Institute of Communications and Radio-Frequency Engineering,
Vienna University of Technology,
Gusshausstrasse 25/389,
A - 1040 Wien/Vienna,
Austria.
Tel: +43-1-58801-38996
Fax: +43-1-58801-38999
Email: owallner@nt.tuwien.ac.at

Secondary Author Affiliations

Klaus Kudielka,
Contraves Space AG
Schaffhauserstrasse 580
CH-8052, Zurich,
Switzerland.
Tel: +41-1-306-2093
Fax: +41-1-306-3823
Email: klaus.kudielka@ieee.org

Walter R. Leeb,
Institute of Communications and Radio-Frequency Engineering,
Vienna University of Technology,
Gusshausstrasse 25/389,
A - 1040 Wien /Vienna,
Austria.
Tel: +43-1-58801-38953
Fax: +43-1-58801-38999
Email: walter.leeb@tuwien.ac.at