The objective of this proposal is to validate the high-level design of the Multi-Conjugate Adaptive Optics (MCAO) of the European Solar Telescope (EST) in order to prepare the corresponding Preliminary Design Review (PDR). 

With a 4.2 m primary mirror, EST will be the largest solar telescope in Europe and it will provide the scientific community with a unique tool to observe and understand the Sun and how it establishes the weather conditions in the space around planet Earth. The design and construction of EST constitute a major challenge in terms of instrumentation and other specific technologies, especially those related to adaptive optics and thermal control. For this reason, the construction of EST is a unique opportunity to boost the development of these technologies and also a potential opportunity for European industry to develop EST, whose construction budget exceeds 200 million euros. 

EST will provide Single Conjugate Adaptive Optics (SCAO) and Multi-Conjugate Adaptive Optics systems to correct perturbations produced by the Earth's atmosphere. The telescope's MCAO will correct a 60 arcsecond Field of View (FoV) in a spectral range from 380 to 2500 nm and will simultaneously feed all the telescope's instruments. This adaptive optics system presents significant challenges and represents a major advance in current technology. To date, there is no regularly operating solar MCAO system on a telescope. Therefore, the preliminary design phase is especially important in this project to demonstrate the feasibility and consistency of the EST solar MCAO design and to achieve confidence that the design will fulfil the functional and non-functional requirements of the project. 

EST is currently in the preliminary design phase. The design has been divided in different systems which will be reviewed in separate partial PDRs. A first partial PDR covering the telescope's optical design and the SCAO has already been held in October 2024, and EST has successfully passed this review. During this meeting, an international committee of experts in solar AO and MCAO also evaluated the conceptual design of the EST MCAO, highlighting the importance of the validation tools. Regarding this point, the telescope has developed two powerful tools for the validation of the AO system: a test bench with solar MCAO capabilities and numerical simulation software adapted to the characteristics of EST. These validation tools received positive reviews from the panel of experts at the October 2024 PDR and the team was recommended to continue with the activities of the bench and to increase the simulation activities. In addition, the critical points of MCAO design were identified highlighting the study of the performance of the designed system and its scientific requirements. The EST was recommended to work on these points for the future PDR of the multi-conjugate adaptive optics system. The activities described in this proposal are a consequence of this context and their main objective is to further study the critical characteristics of the design, using the tools already developed and updating these tools as required. 29/