The European Solar Telescope (EST) will be part of the next generation of ground-based solar telescopes. With a primary mirror of 4.2 meters, it will be the largest solar telescope ever built in Europe offering a large collecting area and extremely sharp images, due to the Adaptive Optics (AO) system integrated within the optical path to compensate for atmospheric turbulence. The current status of the optical design includes a 4.2m active primary mirror and a 0.8m Adaptive Secondary Mirror, arranged in an on-axis Gregorian configuration, 4 deformable mirrors that make up the upgrade to Multi-Conjugated Adaptive Optics (MCAO) system and a dioptric system to transfer the aplanatic F2 focus to the science focus. The system has been optimised to include the minimum number of optical elements that maximize throughput without any loss of performance, in addition to be compensated for instrumental polarization which will be induced by each of the individual mirrors that compose the system. EST ultimately results in a telecentric and diffraction- limited focus, in a spectral range from 380 nm to 2300 nm, which will be delivered to the instruments in the Coudé Rooms.

This poster outlines the optical and opto-mechanical design of EST at the Preliminary Design phase, from the primary mirror to the science instrumentation, as well as the expected performance delivered by the telescope.