Design of the performance verification unit for the MAORY system

The ESO ELT is expected to come into operation in 2025 and it will be the largest optical telescope in the world. Its performance relies heavily on Adaptive Optics (AO) systems including the integrated adaptive M4 mirror in the ELT and post focus MAORY system featuring an additional two adaptive mirrors. A performance verification unit (aka ’Test Unit’ (TU) is conceived to test the MAORY functionality prior its installation on the telescope. The TU requirements and the solution to emulate natural and laser guide stars, atmospheric turbulence and partial correction by the telescope M4 are described.