Keywords: 
• thermal optical analysis /
• aerodynamic effect /
• optical window /
• finite element analysis /
• imaging performance analysis

Abstract: In order to improve the imaging performance of aviation camera optical system in high-altitude and high-speed environment, an analysis of the influence on the optical window surface deformation caused by the aerodynamic pressure and aerodynamic heat loading in different flying altitudes environment was conducted, and the thickness of optical window was well designed. Based on fluid-solid interaction model and fluid-heat interaction model with finite element, how aerodynamic pressure and aerodynamic heat loadings affected optical window was simulated and how different flying environment altitude impacted on the surface deformation of different thickness of optical window was analyzed. A proper optical window thickness was chosen in the consideration of not only strength requirement but also various flying altitude circumstances to meet unique flying environment demands; and then, to judge the influence on the imaging performance of optical system caused by the surface deformation of optical window with that thickness can be accepted or not, Zernike polynomial was used to fit the surface deformation of optical window in that working condition. Putting the Zernike polynomial coefficients into optical software, taking MTF and wavefront error as assessment indexes, the influence of deformation of optical window on the imaging performance of optical system was analyzed. Finally, the appropriate thickness of optical window was gotten. The result shows when an aviate flies at a speed of 3 Ma, in the 5 -30 km altitude ranges and with the 5 angle, designing its optical window thickness to be 15 mm is fitted with the 200 mm diameter. A foundation is also built in the aspect of selecting and optimizing for the thickness of optical window in different flying altitude scopes.