  Wavefront estimation using in-focus image data is critical to many
applications. This data is invariant to a sign flip with complex conjugation of
the complex amplitude in the pupil, making for a non-unique solution.
Information from an in-focus image taken through a non-redundant pupil mask
(NRM) can break this ambiguity, enabling the true aberration to be determined.
We demonstrate this by priming a full pupil Gerchberg-Saxton phase retrieval
with NRM fringe phase information. We apply our method to measure simulated
aberrations on the segmented James Webb Space Telescope (JWST) mirror using
full pupil and NRM data from its Near Infrared Imager and Slitless Spectrograph
(NIRISS).
