BRIGUGLIO PELLEGRINO, RUNA ANTONIORUNA ANTONIOBRIGUGLIO PELLEGRINO0000-0002-0495-0543PARIANI, GiorgioGiorgioPARIANI0000-0003-3724-7667XOMPERO, MARCOMARCOXOMPERO0000-0002-5565-084XRICCARDI, ArmandoArmandoRICCARDI0000-0001-5460-2929Tintori, MatteoMatteoTintoriLazzarini, PaoloPaoloLazzariniSpanò, PaoloPaoloSpanò2020-07-222020-07-22201697815106019870277-786Xhttp://hdl.handle.net/20.500.12386/265778s stands for Optical Test TOwer Simulator (with 8 read as in italian 'otto'): it is a simulation tool for the optical calibration of the E-ELT deformable mirror M4 on its test facility. It has been developed to identify possible criticalities in the procedure, evaluate the solutions and estimate the sensitivity to environmental noise. The simulation system is composed by the finite elements model of the tower, the analytic influence functions of the actuators, the ray tracing propagation of the laser beam through the optical surfaces. The tool delivers simulated phasemaps of M4, associated with the current system status: actuator commands, optics alignment and position, beam vignetting, bench temperature and vibrations. It is possible to simulate a single step of the optical test of M4 by changing the system parameters according to a calibration procedure and collect the associated phasemap for performance evaluation. In this paper we will describe the simulation package and outline the proposed calibration procedure of M4.ELETTRONICOenConference paper10.1117/12.22316342-s2.0-85001968749000387429700211https://www.spiedigitallibrary.org/conference-proceedings-of-spie/9909/1/8s-a-numerical-simulator-of-the-challenging-optical-calibration-of/10.1117/12.2231634.full2016SPIE.9909E..7ABFIS/05 - ASTRONOMIA E ASTROFISICA