The POD Analysis And Optical Transmission Simulation Of Aero-optical Window

With the rapid development of modern military technology，IR imaging system fortracking，guidance and inspecting have found an increasingly wide application in the researchof high fidelity weapon and high precision guided aircraft. When high-speed aircraft with IRinspecting or tracking imaging system (generally there exist an optical window embedded onit，or an optical hood covered the seeker) is traveling through the atmosphere，complex flowfield such as the shock layer and bounding layer between the optical window and theincoming flow，because of the aero-optical effect，will produce intensive interaction，whichcause aero-thermal effect、thermal radiation effect and optical transmission distortion of the IRinspecting or tracking imaging system inside the aircraft. Images transmitting from the opticalsystem under such condition will produce distortions such as flutter、deviation and blur，andfor the same reason，aero-optical window or hood under such condition will produce uneventemperature gradient distribution and make the surface shape distorted，furthermore comes thethermal stress，which affects the final imaging quality seriously. Consequently，the study ofthe optical transmission in aero-optical window under aero-thermal environment is of greatsignificance.Based on computer simulation，the research in this paper mainly focuses on two parts：first，on the basis of the Proper Orthogonal Decomposition(POD) theory，the coherentrefractive index structure of the aero-optical window under aero-thermal condition wasanalyzed and extracted，the main reason of causing optical distortions of the aero-opticalwindow was studied and a method of using coherent structure to inverse design the windowrefractive index was proposed. According to the POD analysis，the efficiency of loading、saving window reflective index is improved. It is useful for the research of seeking opticaldistortion forecast method. Moreover，the optical transmission of the window was simulatedand the OPD from the reference wave front to the reconverted wave front was calculated.Further optical evaluation function such as PSF、MTF and Strehl Radio was computed then.The actual target was imitated by using a grey-scale bitmap，and the distorted imagetransfered from the aero-optical window was simulated. All the computing task was realizedaccording to the program compiled in VC++6.0environment with Matfor in C Plus Plus。...