End-to-end simulation of the image stability for the airborne telescope SOFIA

To provide astronomers access to infrared wavelength unavailable from the ground the airborne telescope SOFIA is in development. This paper focuses on the image stability of the telescope, its modelling and simulation. The operation of the telescope under the harsh environmental conditions in the aircraft makes the prediction of the image stability during the design process necessary. For this purpose an integrated mathematical simulation model, which includes the optics, the structural dynamics and the control loops has been constructed. Because of the high relevance of the structural dynamics for image stability and control design, special attention is paid to the import and reduction of the finite element model of the telescopes mechanical structure. Different control approaches are considered for the attitude control and the compensation of the impact of the structural flexibility on the image motion. Additionally the secondary mirror servo-mechanism is utilized to optimize the image stability. Simulation results are shown.