Development of a spatial light modulator-based test-bed for sequential simulation of wide field adaptive optics systems: toward the validation of morfeo's reconstruction and control algorithms

Ground-based astronomical observations in the visible and near-infrared are limited by atmospheric turbulence, which can be compensated using Adaptive Optics (AO) systems. The effect of the turbulence on observations increases with the telescope diameter, making compensation crucial for current 8-m and future 40m class telescopes. The European Extremely Large Telescope (ELT) will rely on the Multi-conjugate adaptive Optics Relay For ELT Observations (MORFEO) to address this challenge. However, MORFEO faces new and challenging issues, that need to be tested and prototyped before its integration and troubleshooting on sky. Furthermore, realising a realistic telescope simulator for ELTs is complex due to optical constraints, requiring the development of simplified test-beds to assess the performance and critical aspects of the upcoming AO facilities. In this context, this work was aimed at developing a test-bed that reduces complexity and still allow to assess the performance and critical aspects of MORFEO reconstruction and control algorithms. To do so, we broke down the complex Multi-Conjugate AO (MCAO) process into a simpler, sequentially executed Single-Conjugate AO (SCAO) test-bed. This hybrid approach of using hardware alongside simulation enables a reliable system validation by addressing problems close to those in the real system (like wavefront sensor noise, alignment, and sensor imperfections), compared to pure end-to-end simulations. To reproduce the atmospheric disturbance and compensation on our test-bench, we used a 1920 × 1152 XY Phase Series Spatial Light Modulator (SLM) manufactured by Meadowlark Optics. The high spatial resolution makes the SLM a promising phase modulator for reproducing atmospheric phase screens on ELT’s complex pupil in our laboratory test-bed. However, such devices are known to have limitations that prevents from a full phase modulation. Thus, a careful characterisation of the SLM is required to quantify its impact on the sequentially executed MCAO loop. This project established a solid experimental reference, needed for the testing MORFEO’s control and reconstruction strategies, defining a road map for hardware-in-the-loop simulations.