Fast cadence speckle-free high-contrast imaging: SFADI and SFI
Abstract
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.
- Publication:
-
Adaptive Optics Systems VI
- Pub Date:
- July 2018
- DOI:
- 10.1117/12.2312614
- Bibcode:
- 2018SPIE10703E..2UL