The IFS of SPHERE: integration and laboratory performances

Abstract

SPHERE is an exo-solar planet imager, which goal is to detect giant exo-solar planets in the vicinity of bright stars and to characterize them through spectroscopic and polarimetric observations. It is a complete system with a core made of an extreme-Adaptive Optics (AO) turbulence correction, pupil tracker and NIR and Visible coronagraph devices. At its back end, a differential dual imaging camera and an integral field spectrograph (IFS) work in the Near Infrared (NIR) Y, J, H and Ks bands (0.95≤λ≤2.32 μm) and a high resolution polarization camera covers the visible (0.6≤λ≤0.9 μm). The IFS is a low resolution spectrograph (R~50) which works in the near IR (0.95≤λ≤1.6 μm), an ideal wavelength range for the detection of planetary features. The IFS is based on a new conception microlens array (BIGRE) of 145X145 lenslets designed to reduce as low as possible the contrast. The IFU will cover a field of view of about 1.7 x 1.7 square arcsecs reaching a contrast of 10^-7, giving an high contrast and high spatial resolution "imager" able to search for planet well inside the star PSF. In the last year it has been integrated onto the huge optical bench of SPHERE and fully tested.