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Proceedings Paper

Diffraction modeling of finite subband EFC probing on dark hole contrast with WFIRST-CGI shaped pupil coronagraph
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Paper Abstract

Current coronagraph instrument design (CGI), as a part of a proposed NASA WFIRST (Wide-Field InfraRed Survey Telescope) mission, allocates two subband filters per full science band in order to contain system complexity and cost. We present our detailed investigation results on the adequacy of such limited number of finite subband filters in achieving full band dark hole contrast with shaped pupil coronagraph. The study is based on diffraction propagation modeling with realistic WFIRST optics, where each subband’s complex field estimation is obtained, using Electric Field Conjugation (EFC) wavefront sensing / control algorithm, from pairwise pupil plane deformable mirror (DM) probing and image plane intensity averaging of the resulting fields of multiple (subband) wavelengths. Multiple subband choices and probing and control strategies are explored, including standard subband probing; mixed wavelength and/or weighted Jacobian matrix; subband probing with intensity subtraction; and extended subband probing with intensity subtraction. Overall, the investigation shows that the achievable contrast with limited number of finite subband EFC probing is about 2~2.5x worse than the designed post-EFC contrast for current SPC design. The result suggests that for future shaped pupil design, slightly larger over intended full bandwidth should be considered if it will be used with limited subbands for probing.

Paper Details

Date Published: 9 August 2016
PDF: 11 pages
Proc. SPIE 9911, Modeling, Systems Engineering, and Project Management for Astronomy VII, 99111S (9 August 2016); doi: 10.1117/12.2232129
Show Author Affiliations
Hanying Zhou, Jet Propulsion Lab. (United States)
John Krist, Jet Propulsion Lab. (United States)
Bijan Nemati, Jet Propulsion Lab. (United States)

Published in SPIE Proceedings Vol. 9911:
Modeling, Systems Engineering, and Project Management for Astronomy VII
George Z. Angeli; Philippe Dierickx, Editor(s)

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