The Optical Transmission Model Building And Emulation Through Plane-Window In Aero-Dynamic Thermal Environment

When optical imaging guidance air vehicle flies in atmosphere at a high speed, the intensive interaction between the optical plane window and the atmosphere will cause intensive aero-optical effects. In aero-dynamic environment, the shape and optical property of optical window will change because of thermal transmission and thermal stress effects, and then the window whose original optical property is homogeneous distorts, which results in gradient distribution of the refractive index inside the window. When the plane-wave transmits in the distorted window, the aplanatic emergent wave after the window will deviate from the ideal wave front because of the distorted optical window and gradient distribution of refractive index of it. Thus the object ray from the window will distort and cause bore-sight error.The main task of this paper is researching the influences of distorted shape of the optical window and gradient refraction index on the imaging of object lights. In this paper, we have coded the ray-tracing program cross the distorted and non-uniform index window, drew the distorted wave front chart, and calculated the optical evaluation function(include PSF, MTF, Strehl ration).The theory of pixel-matching is applied to image-evaluation for the first time.First of all, from the point view of ray tracing, by the computer 3D processor and optical design, the OPD was calculated from the reference wave to the reconverted wave front, and then a corresponding ray-tracing program was compiled in Visual C++ 6.0 environment, and the program provides reference for disclosure aero-optics effect and the method of validating the aero-optics.Besides, PSF, MTF, Encircled energy, wavefront variance and Strehl ration were calculated for evaluating the image quality. Two methods of solving pixel-matching problems were offered. After comparing them, algorithm 2 was selected as the preferential method.After the analysis of simulation results, some influence factors of image distortion were summarized for the first time. Then, a verification program was compiled. The result of the verification program indicated that the ray-tracing program of optical window and the following image-evaluating program were feasible and the research was useful for practical engineering.