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题名:
大气湍流短曝光成像过程模拟
作者: 王立瑾
学位类别: 硕士
答辩日期: 2007-06-06
授予单位: 中国科学院光电技术研究所
授予地点: 光电技术研究所
导师: 廖胜
关键词: 大气湍流 ; 随机相位屏 ; 短曝光像 ; 长曝光像 ; 大气相干长度 ; 数值模拟 ; 实验室模拟
其他题名: Simulation of short exposure imaging through atmospheric turbulence
学位专业: 物理电子学
中文摘要: 本文主要对大气湍流短曝光成像过程进行模拟研究。模拟方法采用数值模拟和在实验室搭建仿真平台两种方法进行模拟,可以任意设定各种实验参数,得到各种大气湍流条件下目标的成像。 首先介绍了大气湍流的性质,接着研究了大气湍流随机相位屏的数值模拟方法。本文主要对比研究了傅立叶变换法和Zernike多项式法这两种数值模拟方法的特点。通过比较模拟相位屏的相位结构函数和理论值的符合度验证了相位屏的统计特性,并利用长曝光传递函数计算大气相干长度r0。研究结果表明用傅立叶变换法和Zernike多项式法模拟的大气湍流相位屏符合Kolmogorov谱的统计特性。但傅立叶变换法模拟的大气湍流相位屏的相位结构函数存在明显的低频空间频率成分不足,在高频部分比较吻合,r0值与设计值相比偏大,通过三层相位屏叠加和在大尺寸相位屏上截取的方法能有效的改善;Zernike多项式法模拟的大气湍流相位屏的相位结构函数存在明显的高频空间频率成分不足,而在低频部分比较吻合,r0值与设计值相比偏小,高频不足可以用增加Zernike多项式的阶数来加以改善,但同时计算量也会大幅增加。 本文详细介绍了使用激光散斑法和刻蚀法制作随机相位屏的方法,并搭建了大气湍流实验室模拟仿真装置,该模拟系统能够实现不同大气湍流强度下多帧短曝光像的连续采集。成像实验表明,两种方法生成的相位屏都能得到较好的短曝光像。由于激光散斑法制作的随机相位屏的透过性不高,导致相位屏叠加后图像强度较弱,以至于被噪声淹没,而刻蚀法制作的随机相位屏具有较好的透过率。在实验室仿真平台上使用的是三块使用干法刻蚀制作的随机相位屏,基底材料是熔石英。使用步进电机控制三层相位屏的步进步数和方向。在实验室里得到多帧短曝光像后叠加从而得到长曝光像,根据长曝光传递函数计算了三层相位屏的等效大气相干长度r0。整个模拟装置结构简单并且易于操作。通过仿真,只需调整少数的实验器件,就能够实现不同强度的大气湍流模拟。
英文摘要: This paper concentrates on the simulation of short exposure imaging through atmospheric turbulence. Numerical simulation and laboratory simulation is for simulation methods. Can be arbitrary set of experimental parameters, all kinds of atmospheric turbulence under conditions of the imaging target. First, the character of atmospheric turbulence is presented. Then two numerical simulation methods about simulating phase screen disturbed by atmospheric turbulence are compared. In the paper, using the Fourier transform method and Zernike polynomial method. Accuracy of PS is determined by comparing the phase structure function and theoretical results, and calculating r0 is through optical transform function of long exposure and phase structure function. The analysis shows that the Fourier transform method and Zernike polynomials simulation of atmospheric turbulence phase screen is correct. But low spatial frequency components of PS generated by Fourier Transform significantly deviate from theory value, while three PSs put together phase structure function has a much improvement, the result r0 is bigger than the theory value; and high spatial frequency components of PS generated by Zernike polynomial significantly deviate from theory value, and relatively low frequency of agreement, the result r0 is smaller than the theory value, high frequency can be used to increase less than Zernike polynomial order to be improved, but at the same time computation will substantially increase. This paper describes the use of laser speckle and lithography production phase screen, erection of atmospheric turbulence laboratory simulation device. The system can simulate different atmospheric turbulence intensity multi-frame short exposure image continuous acquisition. Imaging experiments show that both methods generate the phase screen can be better as a short exposure. But the transmission of the phase screen produced by laser speckle is not high, leading to the phase screen superimposed image intensity after weaker noise is so inundated, and the production method of etching phase screen has good transmittance. In laboratory simulation platform used by the three PSs is the use of dry etching produced by the phase screen, the basement is fused silica material. Stepper motor control the three PSs at different steps, different directions of rotation. In the laboratory to be multi-frame short exposure after the stack so as to be long-exposure images. According to long-exposure calculation of the transfer function of the three-phase-screen equivalent of atmospheric coherence length r0. Simulation of the entire structure is simple and easy to operate. The simulation, only a few adjustments to the experimental device, we will be able to achieve different degrees of atmospheric turbulence.
语种: 中文
内容类型: 学位论文
URI标识: http://ir.ioe.ac.cn/handle/181551/257
Appears in Collections:光电技术研究所博硕士论文_学位论文

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Recommended Citation:
王立瑾. 大气湍流短曝光成像过程模拟[D]. 光电技术研究所. 中国科学院光电技术研究所. 2007.
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