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arXiv · 0912.2938

Design of a telescope-occulter system for THEIA

Eric Cady·Ruslan Belikov·Philip Dumont·Robert Egerman·N. Jeremy Kasdin·Roger Linfield·Doug Lisman·Dmitry Savransky·Sara Seager·Stuart Shaklan·David Spergel·Domenick Tenerelli·Robert Vanderbei
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Abstract

The Telescope for Habitable Exoplanets and Interstellar/Intergalactic Astronomy (THEIA) is a mission concept study for a flagship-class telescope-occulter system to search for terrestrial planets and perform general astrophysics with a space-based 4m telescope. A number of design options were considered for the occulter and telescope optical systems; in this paper we discuss the design of occulters and coronagraphs for THEIA and examine their merits. We present two optimized occulters: a 25.6m-radius occulter with 19m petals that achieves 10^-12 suppression from 250-1000nm with a 75mas inner working angle, and a 20.0m-radius occulter with 10m petals that achieves 10^-12 suppression from 250-700nm with a 75mas inner working angle. For more widely separated planets (IWA > 108mas), this second occulter is designed to operate at a second closer distance where it provides 10^-12 suppression from 700-1000nm. We have also explored occulter/coronagraph hybrid systems, and found that an AIC coronagraph that exploits the symmetry of the PSF at the occulter can improve performance; however, it requires very accurate tolerances on the occulter manufacturing of the telescope/occulter system as the AIC does not cancel asymmetric terms. Other coronagraphs proved infeasible, primarily due to the fact that the residual starlight from the occulter is not a plane wave, and so is poorly suppressed by the coronagraph.

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Eric Cady, Ruslan Belikov, Philip Dumont, Robert Egerman, N. Jeremy Kasdin, Roger Linfield, Doug Lisman, Dmitry Savransky, Sara Seager, Stuart Shaklan, David Spergel, Domenick Tenerelli, Robert Vanderbei. 2009-12-15. Design of a telescope-occulter system for THEIA. https://arxiv.org/abs/0912.2938

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