SAXO+, a second-stage adaptive optics for SPHERE on VLT: optical and mechanical design concept

SPHERE+ is a proposed upgrade of the SPHERE instrument at VLT, which will boost the current performances of detection and characterization of exoplanets and disks, and will serve as a demonstrator for the future planet finder (PCS) of the European ELT. The performance gain will be delivered by a second-stage AO module (SAXO+), including a dedicated wavefront sensor and deformable mirror to remove the residual wavefront errors left by the primary AO loop. This paper is focused on the optical and mechanical implementation of SAXO+ and describes the baseline design concept, selected from trade-off analysis of different options.