AO4ELT5 Proceedings

Closed–loop Optical Integrated Modeling

Conan, Rod (GMTO), Angeli, George (GMTO), Bouchez, Antonin (GMTO), Irrarazaval, Ben (GMTO), McLeod, Brian (Harvard Smithsonian Center for Astrophysics,), Quiros-Pacheco, Fernando (GMTO), Schwartz, Dave (GMTO)

Adaptive optics has long been an add-on instrument attached to telescopes. Nowadays, with the development of adaptive secondary mirrors, AO is increasingly becoming a part of the telescope itself. As such, AO must now be included at a very early stage in the design of telescopes as they will dictate some stringent requirements like focal plane residual jitter. This requires new modeling tools able to combine finite element models, an optical propagation model, and complex control systems. For the Giant Magellan Telescope, new tools have been developed which combine, in a control system modeling environment, finite element models with optical propagation models. The modeling framework reproduces the telescope dynamics subject to the effects of wind buffeting, for example. It includes the structural coupling of M1 and M2, the mechanical deformations of the mirror surfaces, the dynamic response of the mirror segment actuators and positionners and the feedback of the wavefront sensors of the active and adaptive optics systems. This modeling environment is called DOS for Dynamic Optical Simulation. It relies on commercial software (Matlab, Simulink, Nastran, and Femap) and on custom software for the optical propagation: CEO. CEO (Cuda--Engined--Optics) is a GPU-based and cloud-based geometric and Fourier propagation software. CEO exchanges data with the other simulation components through Simulink using a custom-made Simulink toolbox SimCEO. The paper describes the processes that convert the finite element model of the telescope, the telescope optical prescription and the control algorithms into a format that allows these components to interact with each other. The paper also shows how DOS allows us to evaluate the dynamic performance of the telescope in its different modes of operations.

DOI: 10.26698/AO4ELT5.0144- Proceeding PDF

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