The SPHERE XAO system SAXO: integration, test, and laboratory performance

Abstract

Direct detection and spectral characterization of extra-solar planets is one of the most exciting and challenging areas in modern astronomy due to the very large contrast between the host star and the planet at very small angular separations. SPHERE (Spectro-Polarimetric High-contrast Exoplanet Research in Europe) is a second-generation instrument for the ESO VLT dedicated to this scientific objective. It combines an extreme adaptive optics system, various coronagraphic devices and a suite of focal instruments providing imaging, integral field spectroscopy and polarimetry capabilities in the visible and near-infrared spectral ranges. The extreme Adaptive Optics (AO) system, SAXO, is the heart of the SPHERE system, providing to the scientific instruments a flat wavefront corrected from all the atmospheric turbulence and internal defects. We present an updated analysis of SAXO assembly, integration and performance. This integration has been defined in a two step process. While first step is now over and second one is ongoing, we propose a global overview of integration results. The main requirements and system characteristics are briefly recalled, then each sub system is presented and characterized. Finally the full AO loop first performance is assessed. First results demonstrate that SAXO shall meet its challenging requirements.