Enabling super-nyquist wavefront control on WFIRST  (Conference Presentation)

Eduardo A. Bendek; Dan Sirbu; Ruslan Belikov; Stuart Shaklan; A J Eldorado Riggs

doi:10.1117/12.2313478

10 July 2018 Enabling super-nyquist wavefront control on WFIRST (Conference Presentation)

Eduardo A. Bendek, Dan Sirbu, Ruslan Belikov, Stuart Shaklan, A J Eldorado Riggs

Proceedings Volume 10698, Space Telescopes and Instrumentation 2018: Optical, Infrared, and Millimeter Wave; 106982N (2018) https://doi.org/10.1117/12.2313478
Event: SPIE Astronomical Telescopes + Instrumentation, 2018, Austin, Texas, United States

Abstract

A large fraction of Sun-like stars is contained in binary systems. Within 10pc there are 70 FGK stars, out of which 43 belong to a multi-star system, and 28 have companion leak that is greater than 1e-9 contrast, assuming typical Hubble-quality space optics. Currently, those binary stars are not included in the WFIRST-CGI target list, but they could be observed if high-contrast imaging around binary star systems using WFIRST is possible, potentially significantly increasing the number of possible FGK targets. The Multi-Star Wavefront Control (MSWC) algorithm can be used to suppress the companion star leakage. If the targets have angular separations larger than the Nyquist controllable region of the Deformable Mirror, MSWC must operate in its Super-Nyquist (SN) mode. This mode requires a target star replica within the SN region in order to provide the ability to null speckles at SN angular separations. For the case of WFIRST, more than half of the targets that can be observed using MSWC, including Alpha Centauri, have angular separations larger than the Nyquist controllable region of the 48x48 actuator Deformable Mirror (DM) to be used. Here, we discuss multiple alternatives to generate those PSF replicas with minimal or no impact to the WFIRST Coronagraph instrument, such as: 1) the addition of a movable diffractive pupil mounted on the Shaped Pupil wheel; 2) design of a modified Shape Pupil capable of creating a dark zone and at the same time diffracting a small fraction of the starlight on the SN region; 3) predicting the minimum residual quilting on the WFIRST DM that would allow observing a given target.

Conference Presentation

Citation Download Citation

Eduardo A. Bendek, Dan Sirbu, Ruslan Belikov, Stuart Shaklan, and A J Eldorado Riggs "Enabling super-nyquist wavefront control on WFIRST (Conference Presentation)", Proc. SPIE 10698, Space Telescopes and Instrumentation 2018: Optical, Infrared, and Millimeter Wave, 106982N (10 July 2018); https://doi.org/10.1117/12.2313478

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KEYWORDS

Stars

Wavefronts

Deformable mirrors

Imaging systems

Actuators

Astronomical imaging

Coronagraphy

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