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题名	小型化可见/近红外宽波段实时成像光谱技术研究
作者	刘兵
学位类别	博士
答辩日期	2015-05
授予单位	中国科学院大学
导师	孙强
关键词	实时成像光谱仪 可见/近红外 棱镜分光 线色散 谱线弯曲
其他题名	Research on Miniature Visible/Near-infrared Wide Range Real-time Imaging Spectrum Technology
学位专业	光学工程
中文摘要	高光谱成像光谱仪由于能够获得目标的图像信息和光谱信息，已广泛应用于航空、航天等观测系统。一般情况下，地面植被的反射谱段主要集中在可见/近红外波段(400nm-1000nm)，在此波段上成像光谱仪接收到的太阳辐射能量强，图像信噪比高。因此，伴随着小卫星、无人机等航空航天设备的发展，基于可见/近红外波段的成像光谱仪广泛应用于植物生长监控、植物类型鉴别、军事伪装鉴别等领域，尤其是小型化实时成像光谱仪的需求尤为突出。国外小型化实时成像光谱技术比较成熟，形成一系列性能优异的产品，国内还处于起步状态，其原因是研制的关键技术比较多，且不易突破。本文在考虑现有技术状况的基础上，主要针对前置望远物镜和光谱成像系统展开研究。 前置望远物镜是整个系统的眼睛，用于对外界目标的能量信息和空间信息的收集，其性能的好坏直接影响着目标的彩色图像质量和系统的光谱分辨率，因此，前置望远物镜的优化设计是整个系统光学设计的关键技术之一。本文详细介绍了对称结构双高斯物镜的初始结构计算方法，在此基础上对其进行失对称变形和复杂化优化设计，并对其进行远心控制，最终实现光学系统宽谱段上小F、小畸变以及高成像质量的要求。 光谱成像系统由准直系统、分光系统以及收集系统组成，为减少杂散光影响，采用透射式光路设计。分光系统是成像光谱系统最为核心的器件，鉴于棱镜具有高能量利用率、成像宽谱段、杂散光干扰少等优点，本文选择胶合棱镜组作为分光系统，为保证系统全谱段的带宽配准、采集光谱数据的准确性和后期图像的视觉效果，要求胶合棱镜组分光系统的色散线性、谱线弯曲小和色畸变小。基于此解决胶合棱镜组式成像光谱仪的色散非线性、谱线弯曲和色畸变问题，具有重要的实际价值。本文理论计算了三胶合棱镜组中心波长光束共轴条件，为光学系统共轴设计以及参数指标计算提供了理论依据。提出了三胶合棱镜组和对称结构五胶合棱镜组初始结构的计算方法和胶合棱镜组实现色散线性化方法，利用光线追迹法计算得到胶合棱镜组产生的谱线弯曲和色畸变，进而对以上两种弯曲量进行消除，为可见/近红外宽谱段实时成像光谱仪的设计提供理论依据。为保证最终光谱成像质量，收集系统采用物方远心设计，准直系统为收集系统的倒置设计，设计中还要考虑到与前置望远物镜和灰度相机的匹配。 整机装调决定着系统的最终性能，对整机进行合理装调。设计波长定标的实验平台，分析定标关键位置，完成全视场内的波长定标工作，最后对不同种类、不同生长状态的果蔬以及真假植株进行测试，得到十分理想的效果，为果蔬、农作物产品在线快速检测、军事伪装鉴别提供行之有效的新方法。 完成小型化可见/近红外宽谱段实时成像光谱仪的设计，系统最终实现空间分辨率0.15mrad，平均光谱分辨率优于12nm，基本实现线色散设计，谱线弯曲和色畸变的数值小于探测器像元尺寸的一半，满足光谱仪的使用要求。整机具有有尺寸小，加工与装调简易，工作时稳定性好等优点。
英文摘要	Hyperspectral imaging spectrometer is widely used in aviation, aerospace and other observation systems because it could acquire both of the spectral and image information. Normally, reflectance spectrum of ground vegetation mainly concentrates in the visible/near-infrared wave band (400 nm to 1000 nm), and on this band imaging spectrometer performs with high signal-to-noise ratio of image under strong solar radiation energy. Therefore, along with the development of aerospace equipments such as small satellites and unmanned aerial vehicles, visible/near-infrared imaging spectrometer especially real-time imaging spectrometer is widely used to monitor plant growth, identify plant type, and distinguish military camouflage. The technology of real-time imaging spectrometer is relatively mature abroad, and there are so many excellent products. However, domestic products are still in its infancy. This is because some key technologies are hard to break. Considering the basis of the existing technical conditions, this paper mainly deals with the front telescope objective system and the spectral imaging system. Front telescopic objective is the eye of the whole system which is used to collect the energy and spatial information of the target. The performance of front telescopic objective affects color image quality of the target and spectral resolution of the system, and so its optimization design is the key of the whole optical system design. In this paper we introduce the calculation method of the symmetrical double gauss lens firstly, and then make the symmetrical structure asymmetric and deformation, and object telecentric control in order to achieve small F number, small distortion and high image quality. Spectral imaging system, including collimation system, beam splitting system and collection system, is of transmission light path design to reduce stray light. We choose prisms as beam splitting system because of its high energy utilization ratio and little stray light on the wide wave band. In order to realize bandwidth match, and collect correct spectral data and image, beam splitting system should be with linear dispersion, little smile and little keystone. It possesses important actual value to solve the problems of nonlinear dispersion, smile and keystone in prismatic imaging spectrometer. By theoretical calculation，the central wavelength coaxial condition of triplet prisms is given, which provides important theoretical basis in the design of coaxial optical system and the calculation of parameters. Method to calculate initial structure of triplet prisms and five-element symmetric prisms is proposed, and method to realize linear dispersion is given. Smile and keystone produced by prisms are calculated by ray tracing, and then they are eliminated by prisms structure design. In order to ensure the final spectral imaging quality, collection system is object telecentric and collimation system is of inverse of the collection system. It should be also considered to match them with front telescope objective system and grayscale camera. The system’s performance depends strongly on alignment of the whole instrument. The wavelength calibration platform is designed, the key position is analyzed and the wavelength calibration of whole field is completed. Finally, some imaging experiments of different types of fruits, different growth of vegetables, and true or false plants are completed. The results show that the instrument could be used in the detection of fruits and vegetables on-line, and in the discrimination of military camouflage. The characteristics of the instrument are are as follows. The spatial resolution is 0.15mrad, the average spectral resolution is better than 12nm, the dispersion linearity design is achieved, and the smile and keystone are less than half of the pixel size. The system has the advantages such as small in instrument size, easy for processing and alignment, good in working stability.
公开日期	2015-12-24
内容类型	学位论文
源URL	[http://ir.ciomp.ac.cn/handle/181722/48871]
专题	长春光学精密机械与物理研究所_中科院长春光机所知识产出
推荐引用方式 GB/T 7714	刘兵. 小型化可见/近红外宽波段实时成像光谱技术研究[D]. 中国科学院大学. 2015.

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