同轴非相干相移数字全息显微成像特性研究

发布时间：2018-10-10 18:53

【摘要】：数字全息术诞生于上世纪60年代,因具有同时获取样品相位和振幅的优点,可应用于振动测量、三维形貌测量和相位检测等领域。但数字全息对光源高度相干性的要求使其应用推广受到局限。近年来,随着实用化、商品化的高速率空间光调制器的推广,基于空间光调制器(Spatial Light Modulator,SLM)的非相干数字全息术受到科研工作者的极大关注。它可以在非相干光源照明下实现待测物体的三维空间信息记录且无需任何扫描设备和移动部件,克服了激光数字全息对系统稳定性要求高的弊端,具有结构简单、重建灵活、可与任何成熟的光学系统匹配的优点,有很高的学术研究和实际应用价值。本文在分析非相干数字全息成像原理的基础上,给出了点扩散函数、横向放大率及重建距离等数学表达式,并探讨了影响系统成像分辨率的因素,运用MATLAB软件编程完成仿真模拟,验证了其三维成像特性;通过优化系统结构参数,得到了高质量的重建像;在此基础上,搭建了反射式和透射式全息显微成像记录系统,验证了其三维显微成像特性;进一步研究了SLM像素复用方式对成像质量的影响;最后,利用SLM实现螺旋相位调制,并在计算机上仿真,验证了螺旋相位调制的非相干数字全息系统可实现图像边缘对比增强的特性,分析了不同拓扑荷值对重建像质量的影响。论文主要从以下四方面进行研究:(1)在介绍传统光学全息记录和重建的基础上,论述数字全息的基本原理;介绍和比较常用的全息图数值重建算法,重点对角谱衍射算法进行分析;概述了数字全息的优点及应用;对比同轴与离轴全息的特点;对同轴全息相移技术进行详细地阐述。(2)以非相干数字全息理论为依据,从波动光学角度推导了基于SLM的同轴非相干数字全息记录光路的点扩散函数(Point Spread Function,PSF),得到系统的横向放大率及全息重建距离的数学表达式,分析影响重建像分辨率的因素。利用计算机对具有不同位置信息的“S”、“L”、“M”字母进行仿真模拟,验证该系统的三维成像特性;对USAF分辨率板进行拍摄,得到了高质量重建像。(3)搭建基于SLM的同轴非相干相移数字全息显微系统,对USAF分辨板进行拍摄,获得了与传统宽场显微镜相同的分辨率;利用透射式全息显微光路对植物细胞成像,验证了其可用于生物细胞观察的特性,并对20μm的针孔进行拍摄,进一步研究了SLM像素复用方式对成像质量的影响;利用反射式全息显微光路对尺寸为300μm 500μm单颗粒金刚钻成像,得到了不同焦平面的最佳重建像,验证了其三维显微成像特性。(4)利用SLM实现螺旋相位调制,在计算机上仿真模拟,验证了螺旋相位调制的非相干数字全息系统可实现图像边缘提取的特性,对20μm针孔进行实验,对比了SLM分别加载双透镜相位掩模和双透镜螺旋相位掩模的重建像,分析了不同拓扑荷数对重建像质量的影响。
[Abstract]:Digital holography was born in 1960s. It can be used in vibration measurement, three-dimensional topography measurement and phase detection because of the advantages of simultaneously obtaining the phase and amplitude of the sample. However, the application of digital holography is limited by the requirement of high coherence of light source. In recent years, with the popularization of commercialized high rate spatial light modulator, incoherent digital holography based on spatial light modulator (Spatial Light Modulator,SLM) has attracted great attention of researchers. It can realize the three-dimensional spatial information recording of the object to be tested under the illumination of incoherent light source without any scanning equipment and moving parts. It overcomes the disadvantages of laser digital holography which requires high stability of the system, and has simple structure and flexible reconstruction. It has the advantages of matching with any mature optical system and has high academic research and practical application value. Based on the analysis of the principle of incoherent digital holographic imaging, the mathematical expressions of point diffusion function, transverse magnification and reconstruction distance are given, and the factors influencing the imaging resolution of the system are discussed. MATLAB software is used to complete the simulation and verify its three-dimensional imaging characteristics. By optimizing the system structure parameters, a high-quality reconstruction image is obtained. On this basis, a reflection and transmission holographic microscopic imaging recording system is built. The effect of SLM pixel multiplexing on imaging quality is further studied. Finally, the spiral phase modulation is realized by SLM and simulated on a computer. It is verified that the incoherent digital holographic system with helical phase modulation can enhance the image edge, and the effect of different topologies on the quality of reconstructed image is analyzed. This paper mainly studies the following four aspects: (1) on the basis of introducing the traditional optical holographic recording and reconstruction, the basic principle of digital holography is discussed, and the commonly used holographic numerical reconstruction algorithm is introduced and compared. Emphasis is placed on the analysis of the diagonal spectrum diffraction algorithm; the advantages and applications of digital holography are summarized; the characteristics of coaxial and off-axis holography are compared; the phase shift technique of coaxial holography is described in detail. (2) based on the theory of incoherent digital holography, The point diffusion function (Point Spread Function,PSF) of coaxial incoherent digital holographic recording optical path based on SLM is derived from the viewpoint of wave optics. The mathematical expressions of transverse magnification and holographic reconstruction distance of the system are obtained, and the factors affecting the resolution of reconstructed image are analyzed. The computer is used to simulate the letters "S", "L" and "M" with different position information, to verify the three-dimensional imaging characteristics of the system, and to photograph the USAF resolution board. The high quality reconstructed image is obtained. (3) the coaxial incoherent phase-shift digital holographic microscope system based on SLM is built and the USAF resolution plate is photographed and the resolution is the same as that of the traditional wide-field microscope. The plant cells were imaged by the transmission holographic microscopic light path, the characteristics of which could be used for biological cell observation were verified, and the pinhole of 20 渭 m was photographed. The effect of SLM pixel multiplexing on the imaging quality was further studied. The best reconstruction image of different focal plane is obtained by using the reflective holographic micro-optical path pair of 300 渭 m 500 渭 m single particle diamond. (4) the helical phase modulation is realized by SLM, and the simulation is carried out on a computer. The incoherent digital holographic system with helical phase modulation is proved to be able to detect the edge of the image. The experiment of 20 渭 m pinhole is carried out, and the reconstruction images of the double lens phase mask and the double lens spiral phase mask loaded by SLM are compared, respectively. The effect of different topological charge numbers on the quality of reconstructed image is analyzed.
【学位授予单位】：郑州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O438.1

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