Authors

B. Macintosh (1), J.-L. Beuzit (2)

Affiliations

(1) Lawrence Livermore National Laboratory, (2) IPAG

Abstract

The first true extreme adaptive optics (ExAO) instruments for 8-m telescopes are nearing completion - SPHERE for the Very Large Telescope, and the Gemini Planet Imager for Gemini South. With N=40 to 44 subapertures across the telescope, these high-performance systems represent an important step towards the N=60+ systems that will be needed for general-purpose AO on ELTs. GPI and SPHERE each incorporate many key technologies - high-density deformable mirrors, computationally efficient advanced wavefront control algorithms, zero-noise CCDs, multi-stage wavefront correction, new calibration algorithms, etc. - that will have to be incoprorated into the ELT facilities. We will review these features and the status of the two instruments, and the lessons learned for the design of ELT AO, both normal and extreme