When infrared imaging guided aircraft is flying at high speed, the aerodynamic heated dome generates strong infrared radiation, which reduces the detection performance of system. In order to research the influence of high-temperature dome on imaging quality and improve simulation efficiency, firstly, a fluid thermal solid coupling calculation model of dome under trajectory is established to obtain the non-uniform temperature field with time, secondly, the inverse ray tracing method is proposed according to reversibility of optical path, trace light emitted from detector pixel to the inner surface of dome, then irradiance of the pixel is obtained through radiation emission and transmission characteristics of the dome, finally, traverse all pixels to obtain the thermal noise image. The results show that when working time is 7s and the aircraft speed and height gradually decrease, the dome temperature reaches maximum value of 417.6K at the end, irradiance reaches maximum value of 0.1297W/m2, image signal-to-noise ratio(SNR) decreases by 32.73% and contrast decreases by 80.59%. The calculation method of ray transmission based on inverse ray tracing and the evaluation method for degraded image quality are proposed in this paper, which lays a foundation for optimization of infrared detection system band and suppression of aerodynamic heat in the follow-up work.
When infrared imaging-guided aircraft is flying at high speed, the optical dome is heated strongly aerodynamically and generates infrared radiation, which forms background noise on detector, which reduces target detection performance.In order to research the influence of the continuous high dynamic change of temperature of the dome on infrared imaging, the fluid thermal solid coupling calculation model of the dome under the trajectory is established, and the time-varying non-uniform temperature field of the dome is obtained. The aerodynamic thermal radiation distribution on the detector is obtained by ray tracing, and a simple method of solid angle discretization is proposed for reference.The results show that the temperature of the dome reaches the maximum value of 417.6 K at the end of flight, and the irradiance of the image plane reaches the maximum value of 0.8791W/m2. The signal-to-noise ratio(SNR) and contrast gradually decrease with the flight time. When the target is located in the background gray-scale slope area, the SNR drops the most that drops by 66.77% compared with the reference image without aerodynamic heating at the end of flight. Contrast decline is basically independent of the location of the target, and the end time drops by 93.42%. The simulation method of aerodynamic thermal radiation and the evaluation method of degraded image quality proposed in this paper have a certain reference significance, which lays a foundation for the optimization of response wave band of infrared detection system and the suppression of aerodynamic thermal.
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