The overall objective of this proposal is to support the continuation of the Multi Conjugated Adaptive Optics (MCAO) demonstrator for the European Solar Telescope (EST). EST will be the largest solar telescope in Europe. It will include a 4-meter diameter primary mirror and the most advanced technologies, providing astronomers with a unique tool to observe and understand the Sun and how it establishes the weather conditions in the space around planet Earth.
EST design and construction is an important challenge in adaptive optics, instrumentation or thermal control. For this reason, EST construction is a unique opportunity to push forward the development of these technologies and also a potential opportunity for the European industry to develop EST, whose construction budget is over 200M.
EST is currently in its preliminary design phase, whose objective is to be prepared for a later phase when the design is detailed and EST is built. One of the main scientific requirements is that EST must observe the Sun surface with a spatial resolution in the diffraction limit imposed by its aperture diameter (4 meters), in a Field of View (FoV) with a diameter of 60 arcsec, despite the disturbances of the earths
atmosphere that blurs the images from the Sun. In order to achieve it, EST includes a complex Adaptive Optics system. MCAO which is the technique in which Deformable Mirrors (DM) are integrated in the optical path, adapting their reflective surface shape continuously to compensate the disturbance of the atmosphere based on WaveFront Sensors (WFS) that measure the WaveFront Error (WFE). Before the EST detailed design is carried out, the feasibility of some technological challenges, that may become a risk for the telescope, must be demonstrated.
To overcome the challenging requirements imposed by the AO, two powerful tools have been developed at IAC: a test bench with AO capabilities and a numerical simulation software.
The test bench comprises an illumination system coupled with a configurable turbulence simulator; a wavefront corrector composed by three DMs conjugated to altitude layers; three correlation WFS with different resolutions; a science camera to evaluate the performance of the whole system; a control system including a high performance computer and a real time software controller (DARC) developed by the
University of Durham and adapted to EST. Numerous control and calibration strategies have been already proven with point-like SCAO thus enabling to settle some technical issues before MCAO integration. The test bench is currently fully operative for SCAO and ready to be upgraded to MCAO.
Numerical simulation provides a complementary tool to those scenarios that cannot be tested on the bench. At the present moment, DASP(The Durham Adaptive Optics Simulation Platform) is the oficial software simulator selected in the project to simulate a realistic solar MCAO case corresponding to a 4m telescope. DASP has already been successfully tested in IAC for 1.5m solar MCAO and, in the next steps of the project, it shall be extended and optimized for regular and intensive tests of 4m solar MCAO.
Accordingly, both hardware simulators (MCAO optical bench) and software simulators are complementary tools so that using them in parallel, adapting each tests to the most suitable simulator, allows to have the best of each approach.
