Building an ELT simulator in the lab for subsystem testing of METIS/SCAO

The SCAO subsystem is crucial to enable METIS to achieve its scientific goals, delivering a Strehl ratio of 0.93 in the N band at the ELT. The ELT itself will only be available after integration of METIS at the facility, clearly too late in the development life cycle for subsystem testing. Therefore, we are building a hardware ELT simulator for use in the laboratory, capable of applying atmospheric distortions and receiving and applying real-time corrections from SCAO, closing the loop in the laboratory. In this contribution we present the design of the telescope simulator, MITESI, highlighting which functionality of the ELT it can and cannot replicate. We also detail what aspects of SCAO MITESI will allow us to validate. Finally, we present tests of components of MITESI and a timeline for developing it further.