29 July 2016 In-focus phase retrieval using JWST-NIRISS's non-redundant mask
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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.
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Alexandra Z. Greenbaum, Alexandra Z. Greenbaum, Noah Gamper, Noah Gamper, Anand Sivaramakrishnan, Anand Sivaramakrishnan, } "In-focus phase retrieval using JWST-NIRISS's non-redundant mask", Proc. SPIE 9904, Space Telescopes and Instrumentation 2016: Optical, Infrared, and Millimeter Wave, 990448 (29 July 2016); doi: 10.1117/12.2233314; https://doi.org/10.1117/12.2233314
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