The performance of the calibration module for SPHERE

One of the main challenges to obtain the contrast of >15mag targeted by the extra-solar planet imager SPHERE lies in the calibration of all the different elements participating in the final performance. The Adaptive Optics (AO) system and its three embedded loops, the coronagraphs, the Near Infrared (NIR) dual band imager, the NIR integral field spectrograph, the NIR spectrograph, the visible high accuracy polarimeter and the visible imager all require sophisticated calibration. The calibration process relies on a specific complex calibration module that provides the different sources across the spectrum (500-2320nm) with the stabilities and precisions required and positions them when the need to be. This calibration module has just passed all verification tests and its performance is now well characterized. Its design and performance is the object of this article.