Tolerance analysis of a self-coherent camera for wavefront sensing and dark hole maintenance

Kevin Z. Derby; Sebastiaan Haffert; Jaren Ashcraft; Kian Milani; Heejoo Choi; Young-Sik Kim; Laird Close; Christopher Mendillo; Supriya Chakrabarti; Gregory Allan; Leonid Pogorelyuk; Kerri Cahoy; Mamadou N'Diaye; Daewook Kim; Jared Males; Ewan Douglas

doi:10.1117/12.2629578

27 August 2022 Tolerance analysis of a self-coherent camera for wavefront sensing and dark hole maintenance

Kevin Z. Derby, Sebastiaan Haffert, Jaren Ashcraft, Kian Milani, Heejoo Choi, Young-Sik Kim, Laird Close, Christopher Mendillo, Supriya Chakrabarti, Gregory Allan, Leonid Pogorelyuk, Kerri Cahoy, Mamadou N'Diaye, Daewook Kim, Jared Males, Ewan Douglas

Author Affiliations +

Proceedings Volume 12180, Space Telescopes and Instrumentation 2022: Optical, Infrared, and Millimeter Wave; 1218069 (2022) https://doi.org/10.1117/12.2629578
Event: SPIE Astronomical Telescopes + Instrumentation, 2022, Montréal, Québec, Canada

Conference Poster

Abstract

Exceptional wavefront correction is required for coronagraphs on future space observatories to reach 10^-10 contrasts for direct imaging of rocky exoplanets around Sun-like stars. This picometer level wavefront correction must be stable over long periods of time and should be limited only by photon noise and wavefront sensing architecture. Thus, wavefront errors that arise from optical surface errors, thermal gradients, pointing induced beamwalk, and polarization aberration must be tightly controlled. A self-coherent camera (SCC) allows for image plane correction of mid-spatial frequency errors and a continuous means of dark-hole maintenance. By introducing a reference pinhole at the Lyot stop of a coronagraph, coherent starlight can be interfered with image plane speckles while leaving incoherent planet light untouched. A coronagraph model was created using High Contrast Imaging in Python (HCIPy) to simulate the SCC. Using these tools, realistic input disturbances can be introduced to analyze wavefront sensor performance. Using our model, we first demonstrate the necessity of a complimentary low-order wavefront sensor (LOWFS) to be paired with the SCC. Next, we discuss considerations when creating the modified Lyot stop of an SCC. Finally, a tolerance analysis of the SCC in the presence of optical surface errors, beamwalk due to pointing errors, photon noise, and detector read noise is presented.

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Kevin Z. Derby, Sebastiaan Haffert, Jaren Ashcraft, Kian Milani, Heejoo Choi, Young-Sik Kim, Laird Close, Christopher Mendillo, Supriya Chakrabarti, Gregory Allan, Leonid Pogorelyuk, Kerri Cahoy, Mamadou N'Diaye, Daewook Kim, Jared Males, and Ewan Douglas "Tolerance analysis of a self-coherent camera for wavefront sensing and dark hole maintenance", Proc. SPIE 12180, Space Telescopes and Instrumentation 2022: Optical, Infrared, and Millimeter Wave, 1218069 (27 August 2022); https://doi.org/10.1117/12.2629578

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