SPHERE: Confronting in-lab performance with system analysis predictions
Kjetil Dohlen, François P. Wildi, Jean-Luc Beuzit, Pascal Puget, David Mouillet and teh SPHERE consortium
Laboratoire d’Astrophysique de Marseille; Observatory of Geneva; Institut de Planétologie et d’Astrophysique de Grenoble
SPHERE is an extra-solar planet imager instrument for ESO’s VLT telescope. Scheduled for first light in 2012, aims to detect giant extra-solar planet in the vicinity of bright stars and to characterise the objects found through spectroscopic and polarimetric observations. The observations will be done both within the Y, J, H and Ks atmospheric windows ( 0.95 – 2.32μm) by the aid of a dual imaging camera (IRDIS) and an integral field spectrograph (IFS), and in the visible using a fast-modulating polarizing camera (ZIMPOL). The instrument employs an extreme-AO turbulence compensation system, focal plane tip-tilt correction, and interferential coronagraphs.
The aim of this paper is to analyse the approach taken for system analysis and implementation in the light of forthcoming instruments of this type to be design and built for ELT-class telescopes. In particular, we review the performance analysis concept used for SPHERE, with, as far as results are available, comparison with actually obtained in-lab performance. We also consider the implementation of practical aspects related to alignment, integration, and testing activities, again comparing plans with reality. In the light of this experience, we tempt an extrapolation of our approach to next generation systems.