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Proceedings Paper

In-focus phase retrieval using JWST-NIRISS's non-redundant mask
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Paper Abstract

The James Webb Space Telescope’s Near InfraRed Imager and Slitless Spectrograph (NIRISS) contains a 7-hole non-redundant mask (NRM) in its pupil. NIRISS’s Aperture Masking Interferometry (AMI) mode is useful both for science as well as wavefront sensing. In-focus science detector NRM and full pupil images of unresolved stars can be used to measure the wavefront without any dedicated wavefront sensing hardware or any moving mirrors. Using routine science operational sequences, these images can be taken before or after any science visit. NRM fringe phases constrain Gerchberg-Saxton phase retrieval to disambiguate the algorithm’s two-fold degeneracy. We summarize how consecutive masked and unmasked exposures provide enough information to reconstruct a wavefront with up to ∼1-2 rms radians of error. We present our latest progress on using this approach on laboratory experiments, and discuss those results in the context of contingency for JWST segment phasing. We discuss extending our method to ground-based AO systems and future space telescopes.

Paper Details

Date Published: 29 July 2016
PDF: 8 pages
Proc. SPIE 9904, Space Telescopes and Instrumentation 2016: Optical, Infrared, and Millimeter Wave, 990448 (29 July 2016); doi: 10.1117/12.2233314
Show Author Affiliations
Alexandra Z. Greenbaum, Johns Hopkins Univ. (United States)
Noah Gamper, Univ. of Maryland, College Park (United States)
Anand Sivaramakrishnan, Space Telescope Science Institute (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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