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Published November 9, 2020 | Published + Accepted Version
Journal Article Open

Wavefront sensing and control in space-based coronagraph instruments using Zernike's phase-contrast method


Future space telescopes with coronagraph instruments will use a wavefront sensor (WFS) to measure and correct for phase errors and stabilize the stellar intensity in high-contrast images. The HabEx and LUVOIR mission concepts baseline a Zernike wavefront sensor (ZWFS), which uses Zernike's phase contrast method to convert phase in the pupil into intensity at the WFS detector. In preparation for these potential future missions, we experimentally demonstrate a ZWFS in a coronagraph instrument on the Decadal Survey Testbed in the High Contrast Imaging Testbed facility at NASA's Jet Propulsion Laboratory. We validate that the ZWFS can measure low- and mid-spatial frequency aberrations up to the control limit of the deformable mirror (DM), with surface height sensitivity as small as 1 pm, using a configuration similar to the HabEx and LUVOIR concepts. Furthermore, we demonstrate closed-loop control, resolving an individual DM actuator, with residuals consistent with theoretical models. In addition, we predict the expected performance of a ZWFS on future space telescopes using natural starlight from a variety of spectral types. The most challenging scenarios require ∼1  h of integration time to achieve picometer sensitivity. This timescale may be drastically reduced by using internal or external laser sources for sensing purposes. The experimental results and theoretical predictions presented here advance the WFS technology in the context of the next generation of space telescopes with coronagraph instruments.

Additional Information

© 2020 Society of Photo-Optical Instrumentation Engineers (SPIE). Paper 20098 received Jul. 9, 2020; accepted for publication Oct. 19, 2020; published online Nov. 9, 2020. We thank Stuart Shaklan and Stefan Martin for useful discussions. Keith Patterson led the design and commissioning of the DST. This work was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.

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Published - 045005_1.pdf

Accepted Version - 2010.10541.pdf


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September 15, 2023
October 23, 2023