MAPS: a turbulence simulator for MCAO

The Multi-Atmospheric Phase screens and Stars (MAPS) instrument is a powerful tool that has been developed in the framework of the ESO Multi-conjugate Adaptive optics Demonstrator project (MAD). It allows emulating a 3D evolving Paranal-like atmosphere as well as up to 12 sources in a 2 arc minutes field of view, as seen at a Nasmyth focus of one of the VLT. It will be used to perform advanced laboratory tests on MAD before its shipment to Chile. In this paper we present the opto-mechanical design of MAPS. This one simulates the characteristics of the VLT focus and achieves a high Strehl Ratio over the whole Field of View in the visible as well as in the infrared. A curved entrance plate crowded with fibers emulates various stars configurations including real sky asterisms. In order to simulate the atmosphere, three rotating Phase Screens are placed in the beam and conjugated with different altitudes. Those are glass plates dig in their surface in a way that the beam passing through is distorted as it would be by an atmospheric turbulent layer. In this poster we also present the process of research that lead to the choice of a reliable technique to imprint the aberrations into the screens, their properties and expected performance.