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Ground-based adaptive optics coronagraphic performance under closed-loop predictive control

Year: 2018
Type: article
Abstract: The discovery of the exoplanet Proxima b highlights the potential for the coming generation of giant segmented mirror telescopes (GSMTs) to characterize terrestrial—potentially habitable—planets orbiting nearby stars with direct imaging. This will require continued development and implementation of optimized adaptive optics systems feeding coronagraphs on the GSMTs. Such development should proceed with an understanding of the fundamental limits imposed by atmospheric turbulence. Here, we seek to address this question with a semianalytic framework for calculating the postcoronagraph contrast in a closed-loop adaptive optics system. We do this starting with the temporal power spectra of the Fourier basis calculated assuming frozen flow turbulence, and then apply closed-loop transfer functions. We include the benefits of a simple predictive controller, which we show could provide over a factor of 1400 gain in raw point spread function contrast at 1 λ/D on bright stars, and more than a factor of 30 gain on an I=7.5 mag star such as Proxima. More sophisticated predictive control can be expected to improve this even further. Assuming a photon-noise limited observing technique such as high-dispersion coronagraphy, these gains in raw contrast will decrease integration times by the same large factors. Predictive control of atmospheric turbulence should therefore be seen as one of the key technologies that will enable ground-based telescopes to characterize terrestrial planets.
DOI: 10.1117/1.jatis.4.1.019001
Language: English
Open Access status: hybrid
Funders: National Science Foundation, National Aeronautics and Space Administration, California Institute of Technology, NASA Exoplanet Science Institute, Jet Propulsion Laboratory, Japan Society for the Promotion of Science
OpenAlex ID: W2776309731
FWCI: 6.368
Cites: 51
Cited by: 69
Related to: 20