高变焦比中波红外连续变焦光学系统研究

	高变焦比中波红外连续变焦光学系统研究
	周昊
学位类型	博士
导师	方伟
	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	红外成像技术由于具备很多优点从而在不同领域得到了广泛应用。连续变焦光学系统具备短焦距搜索以及长焦距分辨的功能，并且在变换焦距时还可以保持图像连续。若变焦光学系统具有高变焦比，就意味着系统有更大的视场范围以及更高的分辨率。因此研究高变焦比红外连续变焦光学系统具有一定的意义。为了实现高变焦比，本文提出了一种名为双双组联动机械补偿型的变焦方式，与其它两种机械补偿型变焦方式对比，可知该类机械补偿型变焦方式是实现高变焦比的最佳选择。本文选用双双组联动机械补偿型的变焦方式设计了光学系统的理想结构。根据初级像差理论求解出光学系统的初始结构，经优化设计得到最终的连续变焦光学系统。光学系统的焦距范围为-10mm~-300mm，工作波段为3.7um~4.8um，F数为2。光学系统由8片透镜组成，透镜材料为硅和锗，并引入了4个非球面。光学系统变焦曲线平滑且行程短。在不同焦距位置不同视场处，光学系统成像点列图的均方根半径均小于一个探测器像元的大小，特征频率处的调制传递函数值均高于0.29，光学系统的成像质量符合要求。对光学系统进行公差分析可知本光学系统符合加工要求。光学系统选用的是制冷型探测器，而制冷型红外探测器工作时会看到自身冷像，即有冷反射现象。本文提出了一种定量分析光学系统冷反射效应的方法。据此计算出该系统在不同焦距处的冷反射信号，可知系统在短焦位置处有较大的冷反射信号，而长焦位置处的冷反射信号则较弱。本变焦光学系统在不同焦距位置处具有不同的畸变量。本文建立了一种变焦光学系统径向畸变模型，为具体实现图像畸变校正奠定了理论基础。
其他摘要	Infrared systems operating in midwave infrared are used in many applications. In zoom systems, the wide field of view is used for observing a large scene area for possible targets of interest, and the narrow field of view is used for close-up identification of the target of interest. Large zoom ratio means the zoom system has a greater range of observation and a higher accuracy of identification, and so there is a significant need to design an infrared zoom system with a large zoom ratio. In order to achieve a large zoom ratio, the mechanically compensated zoom type of two sets of two components linked together is presented in this paper. Compared with the other two mechanically compensated zoom type, we can found that this type is suitable to design the zoom system with a large zoom ratio. With the mechanically compensated zoom type of two sets of two components linked together, we designed the ideal optical system. By primary aberration theory, original structure of the actual optical system was obtained. Then, the actual optical system was designed by computer optimization. Focal length range of the system is -10mm~-300mm; spectral band is 3.7um~-4.8um; F∕number is 2. The actual zoom system consists of eight elements, made from silicon and germanium. There are four aspheric surfaces utilized for compactness in order to achieve the desired optical performance. The zoom curves are smooth and the moving distances are short. Root mean square radius of the spot is less than the size of pixel of the detector over the full zoom range. The modulation transfer function value of the system in the cutoff frequency is more than 0.29 over the entire zoom range. The zoom system has high image quality. Tolerance analysis of the optical system shows that the system is suitable for manufacturing. The zoom optical system work with a cooled detector, and the detector would see itself, it is named narcissus effect. A method of quantitative analysis of the narcissus effect is presented in this paper. Then, we calculated the intensity of narcissus effect over the entire zoom range. There is a larger intensity of narcissus effect in the short focal length position, and in the long focal length position, the intensity of narcissus effect is small. There are different amounts of distortion in different focal length positions. A radial distortion model for zoom optical system is presented in this paper, and it is prepared for distortion correction.
语种	中文
文献类型	学位论文
条目标识符	http://ir.ciomp.ac.cn/handle/181722/41509
专题	中科院长春光机所知识产出
推荐引用方式 GB/T 7714	周昊. 高变焦比中波红外连续变焦光学系统研究[D]. 中国科学院大学,2014.

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