红外高灵敏度成像光学系统合成孔径技术研究

发布时间：2018-05-11 20:14

本文选题：合成孔径 + 红外　；参考：《中国科学院研究生院(上海技术物理研究所)》2015年硕士论文

【摘要】：光学系统的分辨能力与其口径成正比,而系统口径受到体积、质量及加工成本的限制。合成孔径系统是采用了多个子孔径来获得相当于大口径系统的分辨能力的光学系统,其相对单口径光学系统有质量更轻,加工成本更低等优点。此外,对于空间光学系统,大孔径光学系统的发射成本很高,而使用质量轻且可折叠的合成孔径系统可以有效降低发射成本,因此合成孔径系统在空间成像应用中有广阔的前景。本文调研了国内外合成孔径光学系统的发展现状,研究了迈克尔逊式和菲索式两种合成孔径光学系统的成像原理,论述了这两种合成孔径系统在频域覆盖、保证子孔径间共相、恢复目标像等方面的关键技术,并分析了两者的区别和适合的应用领域。针对对地观测系统的特点,设计了一个推扫成像的菲索式红外合成孔径光学系统。该系统工作波段为8~10μm,通过两个子孔径合成将系统在沿轨方向的分辨能力,在穿轨方向则通过亚像元算法提升成像质量。本系统是基于卡塞格林结构的折反射式光学系统,该系统采用双孔径结构提升了系统的成像质量,通过软件仿真分析了系统的加工和装配容差,并给出了检测装调方案。在红外光学系统中,零件自身的热辐射到达探测器会降低的信噪比,为需要降低工作温度来对其进行抑制,通过软件分析不同温度下系统中各光机部件自身热辐射到达像面的辐照度,得到为保证系统信噪比需要达到的仪器工作温度。计算了在低温下透射材料折射率的改变、各光学零件的面型变化以及元件间间隔的变化,并仿真了变化后系统的成像质量。设计结果及分析表明,该系统光路结构合理,性能满足设计要求,双子孔径结构和亚像元等方法的结合有助于在保证系统分辨能力的同时降低系统的重量和加工难度。通过本课题研究,对提高推扫成像系统的空间分辨率的技术途径进行了有益的探索。
[Abstract]:The resolution of optical system is proportional to its aperture, and the aperture of optical system is limited by volume, quality and processing cost. Synthetic aperture system (SAR) is an optical system which uses multiple sub-apertures to obtain the resolution of large aperture system. Compared with single aperture optical system, synthetic aperture system has the advantages of lighter quality and lower processing cost. In addition, for space optical systems, large aperture optical systems have high emission costs, while the use of lightweight and foldable synthetic aperture systems can effectively reduce launch costs. Therefore, synthetic aperture system has a broad prospect in space imaging applications. In this paper, the development of synthetic aperture optical systems at home and abroad is investigated. The imaging principles of Michelson and Fisso synthetic aperture optical systems are studied, and the coverage of these two synthetic aperture systems in frequency domain is discussed. The key technologies of target image restoration are analyzed, and the difference between them and the suitable application fields are analyzed. According to the characteristics of Earth observation system, a Fresso infrared synthetic aperture optical system for push-scan imaging is designed. The operating band of the system is 8 ~ 10 渭 m. The resolution of the system along the orbit direction is improved by two sub-aperture synthesis, and the imaging quality is improved by the sub-pixel algorithm in the transorbital direction. This system is a refraction optical system based on Cassegrain structure. The system adopts double aperture structure to improve the imaging quality of the system. The machining and assembly tolerance of the system is analyzed by software simulation, and the detection and adjustment scheme is given. In an infrared optical system, the thermal radiation of the parts themselves will reduce the signal-to-noise ratio (SNR) of the detector, so it is necessary to reduce the working temperature to suppress it. By analyzing the irradiance of the components of the optical machinery at different temperature to the image plane, the working temperature of the instrument is obtained to ensure the signal-to-noise ratio of the system. The change of refractive index of transmission material, the surface shape of each optical part and the interval between components are calculated at low temperature, and the imaging quality of the system is simulated. The results of design and analysis show that the optical structure of the system is reasonable and the performance of the system meets the design requirements. The combination of the double sub-aperture structure and sub-pixel is helpful to reduce the system weight and processing difficulty while ensuring the system resolution. Through the research of this subject, a useful exploration is made to improve the spatial resolution of the push-scan imaging system.
【学位授予单位】：中国科学院研究生院(上海技术物理研究所)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN219

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