Three possible types of coronagraphs for the E-ELT PCS instrument

Abstract

The spectral characterization in the near infrared of Neptune-like planets and super-Earths is one of the main science objectives of the E-ELT. The planetary camera and spectrograph (PCS) will be in charge of making it possible. We have designed three different instruments: pure apodizers, apodized Lyot coronagraphs, and apodized vortex coronagraphs. In each cases the central obscuration and the secondary supports are taken into account in the design of the apodizer. We present a trade study of the imaging performance of these coronagraphs, and we describe how sensitive these coronagraphs are to various aberrations. This is used to assess the potential complementarity between these three types of instruments. Finally, we also consider the feasibility of an active control of aperture discontinuities and/or a phase induced amplitude apodization using the two deformable mirrors of an extreme adaptive optics system associated with the coronagraphs.

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