【作者】 张晓龙；

【导师】 孙强；

【作者基本信息】 中国科学院研究生院(长春光学精密机械与物理研究所) ， 光学工程， 2014， 博士

【摘要】 成像光谱技术是一种新兴的光电探测技术，能够同时获得目标的图像和光谱信息。由于长波红外波段独特的光谱特性，长波红外成像光谱仪器在地理遥感、化学气体流检测、军事目标侦查、热流分析等军事和民用领域有广泛的应用。分光元件为成像光谱系统的核心器件之一，基于平面闪耀光栅的成熟性、高效性和在长波红外波段能量及成本优势，本文选择平面反射式闪耀光栅作为系统的分光元件。为了保证系统采集数据的准确性和后续图像处理的可行性，在成像光谱系统中要求具有很小的谱线弯曲和色畸变，但平面光栅本身固有的谱线弯曲和色畸变比较大，难以满足光谱仪器的使用要求，因此解决基于平面闪耀光栅成像光谱仪器的谱线弯曲和色畸变问题，具有重要的理论和应用价值。本文主要研究内容包括：1.详细介绍了共轴三反系统初始结构的计算方法，讨论分析了离轴三反系统中间成像情况与轮廓参数和系统焦距的取值之间的关系，并进行了软件模拟和离轴优化设计，根据应用要求设计了无中间像的离轴三反系统。2.计算了平面光栅产生的谱线弯曲和色畸变，首次提出了离轴透镜消谱线弯曲和色畸变的设计思路，分析了离轴透镜的消谱线弯曲和色畸变特性。根据矢量衍射理论分析平面光栅的衍射特性，再通过分析倾斜成像系统在二维视场的像高公式，计算得到了理想成像系统和倾斜成像系统中平面光栅产生的谱线弯曲和色畸变，最后利用空间光线追迹方法分析了离轴透镜的消谱线弯曲和色畸变特性，这为消谱线弯曲平面光栅成像光谱仪器的设计提供了理论依据。3.设计得到了小畸变的准直物镜和具有100%冷光阑效率的二次成像物镜。对比分析了反射式和折射式光谱成像系统，证明了反射式光谱成像系统存在消除挡光和冷光阑设计困难、结构不合理的缺陷，而折射式结构可通过二次成像实现100%冷光阑效率，无挡光、结构合理。4.完成了整个成像光谱系统的优化设计并进行了像质评价和公差分析，系统具有成像质量接近衍射极限、结构紧凑、公差分配宽松的优点。设计的系统谱线弯曲和色畸变最大值分别为8.17μm和13.64μm，小于探测器像元尺寸(30μm)的一半。系统采用平面闪耀光栅分光，推扫式工作方式，其主要性能指标为：光谱分辨率32nm，空间分辨率0.15mrad，焦距200mm，F数为2。更多还原

【Abstract】 Imaging spectral technique is an emerging photoelectric detecting technique,and can get both spatial and spectral information of the target. Due to the spectralcharacteristics of the long-wave infrared, imaging spectrometer of this waveband iswidely used in military and civilian areas, such as geographical remote sensing,detection of chemical gas, military target detection and thermal fluent analysis.Based on the maturity, efficiency and the advantages of energy and cost inlong-wave infrared of plane blazed reflection grating, we choose plane blazedreflection grating as beam split element, which is one of the core components ofimaging spectral system. In order to ensure the accuracy of data collection and thefeasibility of image processing, smile and keystone should be very small in theimaging spectral system. However, a larger smile and keystone will be produced byplane grating. So it is necessary and meaningful whether theoretically or practicallyto solve the problem of smile and keystone. The specific research contents include:1. The calculation method of the initial structure of the coaxial three-mirrorsystem is detailed. And it is discussed that the relationship between intermediateimage and values of profile parameters and focal length of the system. Depending onthe requirements of application, we simulate and design the off-axis three-mirrorsystem without intermediate image.2. The smile and keystone caused by grating are calculated. It is proposed for the first time that using off-axis lens to correct the smile and keystone. Thecharacteristics of eliminating smile and keystone of off-axis lens are analyzed.According to the vector diffraction theory, we analyze the diffraction characteristicsof plane grating. The formulas of the image height of two-dimensional field in tiltedimaging system are also deduced. Then, the smile and keystone caused by planegrating in Gaussian imaging system and tilted imaging system are calculatedrespectively. Finally, the elimination of smile and keystone of the off-axis lens isstudied by means of spatial ray tracing. It provides theory for the design of imagingspectrometer with smile and keystone eliminated.3. Collimating lens with small distortion and secondary imaging lens with100%efficiency of cold aperture are designed. The spectrophotometric systems withrefraction and reflection structure are compared, and the results show that thereflective structure is difficult to optimize the rational optical system with coldaperture and no obscuration. However, for refractive system, the rationalconstruction with100%efficiency of cold aperture and no obscuration can berealized through secondary imagery method.4. The imaging spectral system is optimized; the image quality and tolerance isanalyzed. The system designed has good image quality, tight structure and loosetolerance distribution. The maximum of smile and keystone of the optical systemdesigned are8.17μm and13.64μm, respectively. Both of them are less than half thepixel size of the detector. Plane blazed grating is used in the system to split the light,and it will work in pushbroom mode. The optical system with main performances ofhigh spectral resolution of32nm, spatial resolution of0.15mrad, focal length of200mm and F number of2is obtained.更多还原