Development of an L-band vector vortex coronagraph for NACO


O. Absil, C. Delacroix, C. Hanot, D. Mawet, S. Habraken, J. Surdej, M. Karlsson




Recent observational results have demonstrated the potential of the L band for the detection of extrasolar planets by direct imaging on large ground-based telescopes. The achievable inner working angle is however currently limited by the lack of optimized coronagraphic devices for this specific wavelength, which in combination with the relatively poor angular resolution in L band leads to a limited discovery space. In this talk, we present the science case for the implementation of an L-band vector vortex coronagraph inside CONICA, the infrared camera behind NAOS, the current adaptive optics system at the VLT. We present the design of an L-band Annular Groove Phase Mask Coronagraph made out of subwavelength gratings in diamond for that purpose. This coronagraphic mask provides a clear 360° discovery space down to lambda/D. We discuss the expected performance of such a combination, which will provide unique benefits (next generation ExAO systems won’t provide L-band capabilities) and pave the way towards equivalent instruments on the ELT (e.g., METIS).

Attached documents

Lyot2010proc s8 poster AbsilO.pdf
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