Exoplanets & Exomoons

Wavefront Error Tolerancing For Direct Imaging Of Exo-Earths With A Large Segmented Telescope In Space

By Keith Cowing
Press Release
September 23, 2019
Filed under
Wavefront Error Tolerancing For Direct Imaging Of Exo-Earths With A Large Segmented Telescope In Space
Piston pair aberrations on a segmented pupil (top) and the resulting image plane intensity distributions in the dark-hole (bottom), using the baseline APLC for LUVOIR (see Sec. 4). The left three panels show different interference pairs with corresponding Young-like interference fringes, while the right panel shows a random distribution of local piston on all segments of the pupil and the resulting image plane intensities. All plots appear on the same scale.

Direct imaging of exo-Earths and search for life is one of the most exciting and challenging objectives for future space observatories.

Segmented apertures in space will be required to reach the needed large diameters beyond the capabilities of current or planned launch vehicles. These apertures present additional challenges for high-contrast coronagraphy, not only in terms of static phasing but also in terms of their stability. The Pair-based Analytical model for Segmented Telescope Imaging from Space (PASTIS) was developed to model the effects of segment-level optical aberrations on the final image contrast.

In this paper, we extend the original PASTIS propagation model from a purely analytical to a semi-analytical method, in which we substitute the use of analytical images with numerically simulated images. The inversion of this model yields a set of orthonormal modes that can be used to determine segment-level wavefront tolerances. We present results in the case of segment-level piston error applied to the baseline coronagraph design of LUVOIR A, with minimum and maximum wavefront error constraint between 56 pm and 290 pm per segment. The analysis is readily generalizable to other segment-level aberrations modes, and can also be expanded to establish stability tolerances for these missions.

Iva Laginja, Lucie Leboulleux, Laurent Pueyo, Rémi Soummer, Jean-François Sauvage, Laurent Mugnier, Laura E. Coyle, J. Scott Knight, Kathryn St. Laurent, Emiel H. Por, James Noss
(Submitted on 20 Sep 2019)
Comments: 15 pages, 10 figures; published
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)
Journal reference: Proc. SPIE 11117, Optical Engineering + Applications: Techniques and Instrumentation for Detection of Exoplanets IX; 1111717 (2019)
DOI: 10.1117/12.2530300
Cite as: arXiv:1909.09683 [astro-ph.IM] (or arXiv:1909.09683v1 [astro-ph.IM] for this version)
Submission history
From: Iva Laginja
[v1] Fri, 20 Sep 2019 19:15:14 UTC (10,746 KB)

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻