Analysis and experiment of small target detection in high speed flow field of near space

With the deepening of space security and application exploration, the target-detectability of space vehicle in near space has become a core issue of research. For some multi-dimensional information of target, such as shape, spectrum and motion characteristics, can be directly captured by optical imaging detection device, optical detection has become an important means of space imaging and target detection. Under the conditions of atmospheric density, pressure and atmospheric convection in near space, imaging quality and detection range of optical detection device installed in high-speed aircraft could be affected seriously. By using target detection model with three analysis elements (imaging system, atmospheric transmission system and target-background system) and the theory of aero-optical effect, evaluation equation of aero-optical effect for high speed flow field has been established, to analyze imaging performance of typical scenes such as earth and space background. A ground verification test of target detection in high speed flow field has also been designed. The experimental results show that it’s an effective way for detecting plume flow of high-speed space targets by using short wave infrared detector (SWIR: 900-1 700 nm) with quartz window (with thickness of more than 10 mm). Meanwhile, by reducing exposure time of camera, optimizing exposure control strategy and selecting optical filter, stray light in background and aero-optical effect can be effectively suppressed.