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10 July 2018 Fast cadence speckle-free high-contrast imaging: SFADI and SFI
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We present the R and D status of the Speckle-Free Angular Differential Imaging method (SFADI), that we developed for the SHARK-VIS high-contrast imager for the LBT telescope. The technique bases on the acquisition of kHz frame-rate image sequences, which we combine in post-processing after speckle identification and suppression in each frame. With respect to the standard angular differential imaging, this method reaches a much smoother residual background and hence higher detection contrast at a given signal-to-noise ratio. Furthermore, it can reveal faint extended sources around bright central stars, and can use de-rotated images as well as quick second-lasting sequences. We reached a contrast of around 10-5 for integration times of the order of tens of minutes at 100 mas for a 5.7th magnitude star, as we demonstrated on both a real-sky acquisition and at the SHARK-VIS laboratory test bench. Such long sequences though produces a large amount of data (around a million frames every 15 minutes) that we manage to processed in a reasonable computation time with the described implementation scheme.
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G. Li Causi, M. Stangalini, S. Antoniucci, F. Pedichini, M. Mattioli, V. Testa, and R. Piazzesi "Fast cadence speckle-free high-contrast imaging: SFADI and SFI", Proc. SPIE 10703, Adaptive Optics Systems VI, 107032U (10 July 2018); doi: 10.1117/12.2312614;

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