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Proceedings Paper

Accuracy analysis of a new method to estimate chromatic wavefront error
Author(s): Dan Sirbu; Eugene Pluzhnik; Ruslan Belikov
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Paper Abstract

An internal coronagraph with an adaptive optical system for wavefront correction for direct imaging of exoplanets is currently being considered for many mission concepts: a dedicated instrument undergoing development on the upcoming WFIRST mission, and prime instruments on the large-scale HabEx and LUVOIR mission studies, as well as smaller-scale missions such as ACESAT. To enable direct imaging of exoplanets with an internal coronagraph both diffraction and scattered light from the stellar point spread function must be directly suppressed using the coronagraph instrument or corrected in post-processing. Both of these tasks require estimation of the chromatically-dependent complex electric field in the focal plane either using the main science camera or the integral field spectrograph (IFS) camera. To date, the most common method to estimate the chromaticity of the complex electric field is using a heterodyne term generated by DM probes and requiring sequence of narrowband filters to increase coherence. We extend this concept to enable estimation using direct broadband images using a well-calibrated broadband response matrix of the DM probes. Our broadband focal plane estimation method can be used with a single broadband filter providing an alternative to more complicated methods that require several monochromatic channels or a dedicated integral field spectrograph. This capability can also enable low- cost, low-complexity coronagraph missions. We demonstrate the broadband estimation method using fully 30% bandwidth broadband input light with an optical simulator featuring a PIAA coronagraph.

Paper Details

Date Published: 29 July 2016
PDF: 14 pages
Proc. SPIE 9904, Space Telescopes and Instrumentation 2016: Optical, Infrared, and Millimeter Wave, 99045N (29 July 2016); doi: 10.1117/12.2232351
Show Author Affiliations
Dan Sirbu, NASA Ames Research Ctr. (United States)
Eugene Pluzhnik, NASA Ames Research Ctr. (United States)
Ruslan Belikov, NASA Ames Research Ctr. (United States)

Published in SPIE Proceedings Vol. 9904:
Space Telescopes and Instrumentation 2016: Optical, Infrared, and Millimeter Wave
Howard A. MacEwen; Giovanni G. Fazio; Makenzie Lystrup; Natalie Batalha; Nicholas Siegler; Edward C. Tong, Editor(s)

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