消谱线弯曲长波红外成像光谱仪器的研究

	消谱线弯曲长波红外成像光谱仪器的研究
	张晓龙
学位类型	博士
导师	孙强
	2014-07
学位授予单位	中国科学院大学
学位专业	光学工程
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。
其他摘要	Imaging spectral technique is an emerging photoelectric detecting technique, and can get both spatial and spectral information of the target. Due to the spectral characteristics of the long-wave infrared, imaging spectrometer of this waveband is widely 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 in long-wave infrared of plane blazed reflection grating, we choose plane blazed reflection grating as beam split element, which is one of the core components of imaging spectral system. In order to ensure the accuracy of data collection and the feasibility of image processing, smile and keystone should be very small in the imaging spectral system. However, a larger smile and keystone will be produced by plane grating. So it is necessary and meaningful whether theoretically or practically to solve the problem of smile and keystone. The specific research contents include: 1. The calculation method of the initial structure of the coaxial three-mirror system is detailed. And it is discussed that the relationship between intermediate image and values of profile parameters and focal length of the system. Depending on the requirements of application, we simulate and design the off-axis three-mirror system 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. The characteristics of eliminating smile and keystone of off-axis lens are analyzed. According to the vector diffraction theory, we analyze the diffraction characteristics of plane grating. The formulas of the image height of two-dimensional field in tilted imaging system are also deduced. Then, the smile and keystone caused by plane grating in Gaussian imaging system and tilted imaging system are calculated respectively. Finally, the elimination of smile and keystone of the off-axis lens is studied by means of spatial ray tracing. It provides theory for the design of imaging spectrometer with smile and keystone eliminated. 3. Collimating lens with small distortion and secondary imaging lens with 100% efficiency of cold aperture are designed. The spectrophotometric systems with refraction and reflection structure are compared, and the results show that the reflective structure is difficult to optimize the rational optical system with cold aperture and no obscuration. However, for refractive system, the rational construction with 100% efficiency of cold aperture and no obscuration can be realized through secondary imagery method. 4. The imaging spectral system is optimized; the image quality and tolerance is analyzed. The system designed has good image quality, tight structure and loose tolerance distribution. The maximum of smile and keystone of the optical system designed are 8.17μm and 13.64μm, respectively. Both of them are less than half the pixel 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 of high spectral resolution of 32nm, spatial resolution of 0.15mrad, focal length of 200mm and F number of 2 is obtained.
语种	中文
文献类型	学位论文
条目标识符	http://ir.ciomp.ac.cn/handle/181722/41503
专题	中科院长春光机所知识产出
推荐引用方式 GB/T 7714	张晓龙. 消谱线弯曲长波红外成像光谱仪器的研究[D]. 中国科学院大学,2014.

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