ASSIST: the Adaptive Secondary Setup and Instrument Stimulator

In telescopes with a Deformable Secondary Mirror, the testing and calibration of both the DSM itself as well as the instruments using this DSM are expensive and time consuming processes. Especially in telescopes without an intermediate focus before the DSM, a number of calibrations can only be performed on a real star during night time. A full suite of Adaptive Optics systems and AO-assisted instruments is currently under development for the VLT, also know as the VLT Adaptive Telescope. ASSIST was developed to assist in the integration and testing of three elements of the VLT Adaptive Telescope Facility; the DSM; the MUSE AO system 'GALACSI' and the HAWK-I AO system 'GRAAL.' The core of ASSIST is a support infrastructure to integrate the DSM in a compact and stable test setup. A Nasmyth rotator simulator will be provided for attaching the two AO systems, while ASSIST will be fed by a star simulator and turbulence generator for realistic performance measurements of both the DSM as well as the AO system under test. An on-axis high-speed interferometer will be used for additional testing of the functional operation of the DSM. In this paper we present the requirements and design of ASSIST and the projected performance of the test bench for both the testing and calibration of the DSM as well as for the two AO systems under test.