视网膜细胞显微镜波前重建技术研究

发布时间：2018-08-06 18:05

【摘要】： 高分辨率视网膜图像能够为视网膜疾病的早期诊断、治疗、人眼视觉的科学研究提供重要依据。但人眼作为光学系统,其系统内部存在的低阶和高阶像差,使得对视网膜的成像很难达到衍射极限水平,采用常规成像方法无法得到高分辨率视网膜图像。近几年发展起来的自适应光学技术,使观察细胞级别的视网膜图像成为可能。论文以基于自适应光学技术的视网膜细胞显微镜开发为背景,对人眼视网膜成像系统中的关键技术之一——像差重建进行了深入的研究。论文的主要内容如下: 1、论述了人眼的基本结构视网膜成像特点以及人眼波前像差的定义和成因,建立了基于正交归一化Zernike多项式表达人眼波前像差的理论模型。 2、研究了利用Hartmann-Shack波前传感器进行像差测量的原理,在对光斑图像预处理的基础上,提出了利用六角点原理确定子光斑的方法,实现了子光斑及其质心的准确定位。 3、重点研究了基于Zernike模式的波前重建算法,研究了基于最小二乘准则的直接法方程组基于Gram-Schmidt正交变换基于Householder变换基于奇异值分解在内的四种模式重建方法,通过理论分析以及仿真实验证明,各算法精度相当,能够满足人眼波前重建的精度要求。但基于奇异值分解的模式算法由于其理论简单,计算步骤较少,易于编程等优点作为人眼波前像差重建算法性能更优。 4、分析了基于Zernike多项式模式进行波前重建的误差问题,讨论了模式重建过程中截断误差混淆误差以及耦合系数与重建项数的关系,并以此为依据选择人眼波前像差重建过程中Zernike多项式的最优项数。在上述基础上,开发了人眼波前像差测量及重建模块,实现了人眼像差的准确测量和重建,为人眼视网膜成像系统中后续的像差循环矫正提供了像差数据,经实际运用,满足了视网膜细胞显微镜对视网膜细胞成像的要求。
[Abstract]:High resolution retinal images can provide important basis for the early diagnosis, treatment and human visual science research of retinal diseases. However, as an optical system, the human eye has low order and high order aberrations in the system, which makes it difficult to reach the diffraction limit level for retinal imaging, and high resolution retinal images can not be obtained by conventional imaging methods. Adaptive optics has been developed in recent years to make it possible to observe retinal images at cell level. Based on the development of retinal cell microscope based on adaptive optics, aberration reconstruction, one of the key techniques in human retinal imaging system, is studied in this paper. The main contents of this paper are as follows: 1. The basic structure of the human eye is discussed. The characteristics of retinal imaging and the definition and cause of human eye wavefront aberration, A theoretical model for the expression of wavefront aberration based on orthogonal normalized Zernike polynomial is established. 2. The principle of aberration measurement using Hartmann-Shack wavefront sensor is studied. A method of determining sub-spot by using the principle of hexagonal point is put forward, and the accurate location of the sub-spot and its centroid is realized. 3. The algorithm of wavefront reconstruction based on Zernike mode is studied emphatically. The direct equations based on the least square criterion are studied. Based on Gram-Schmidt orthogonal transformation? Based on Householder transform? Four methods of pattern reconstruction based on singular value decomposition (SVD) show that the accuracy of each algorithm is the same and can meet the precision requirements of wavefront reconstruction through theoretical analysis and simulation experiments. However, because of its simple theory and less calculation steps, the model algorithm based on singular value decomposition (SVD), The advantage of easy programming is that the performance of wavefront aberration reconstruction algorithm is better. 4. The error problem of wavefront reconstruction based on Zernike polynomial model is analyzed, and the truncation error in the process of pattern reconstruction is discussed. The relationship between the confusion error and the coupling coefficient and the number of reconstructed terms is used as the basis to select the optimal term number of Zernike polynomials in the process of wavefront aberration reconstruction. On the basis of the above, the module of human eye wavefront aberration measurement and reconstruction is developed, which realizes the accurate measurement and reconstruction of human eye aberration, and provides aberration data for subsequent aberration circulatory correction in human retinal imaging system. It meets the requirements of retinal cell microscopy for retinal cell imaging.
【学位授予单位】：南京航空航天大学
【学位级别】：硕士
【学位授予年份】：2010
【分类号】：TP391.7;R774.1

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