【作者】 童桂；

【导师】 廖文和；

【作者基本信息】 南京航空航天大学 ， 航空宇航制造工程， 2007， 博士

【摘要】 随着自适应光学技术在人眼波前像差校正领域中的成功应用,人类多年来首次获得了活体人眼视网膜细胞级别的生理组织图像,这给诊断多种眼底疾病带来了新的契机。MEMs技术的发展日新月异,新的波前探测和波前校正设备不断出现,低成本、小体积的微型自适应光学系统开始被眼科影像科研工作者考虑和研究。本文通过建立一基于HS波前传感器和微机械薄膜变形镜的眼出射波前像差微型自适应光学校正系统,分析和优化其中包含的关键技术,从而提高了整个自适应光学系统的波前校正性能。论文的主要工作内容包括:1.研究了现有人眼眼底视网膜观测的主要技术设备及其局限性;自适应光学对成像系统像质改善的研究和自适应光学技术设备的发展水平;基于自适应光学技术的人眼波前像差校正及其视网膜细胞组织观察的国内国外的研究现状;根据上述内容分析,提出本文的课题来源和具体研究内容。2.研究了人眼眼球及视网膜组织细胞的生理结构,定义了人眼出射波前像差,综合分析了Zernike多项式的性质特征;建立了基于正交归一化Zernike多项式的人眼波前像差理论描述模型;首次系统分析了Zernike模式像差对成像系统像质的影响分析,建立了基于调制传递函数和斯特利尔比与低阶、高阶和组合模式波前像差之间的对应关系模型。3.深入研究了自适应光学系统中波前传感器、HS波前传感器的波前探测原理和理论模型,包括光斑质心定位及其斜率探测误差;建立了基于HS波前传感器的Zernike模式复原模型,提出了基于Gram-Schmidt正交变换和Householder正交变换的波前模式复原算法,在此基础上总结提出了模式正交变换对于波前模式复原结果的影响;首次提出了一种新的基于HS传感器斜率探测噪声的最优复原模式算法,并分析了其相关影响因素,并实际验证了最优模式对于HS波前传感器模式复原性能的提升。4.深入研究了波前校正器、分立致动式变形镜和整体致动式变形镜的结构和性能差别;建立了一种采用微机械薄膜变形镜的自适应光学系统模型,对其影响函数进行特征描述;在利用微机械薄膜变形镜进行波前模式复原校正中,首次提出了两种开环波前模式校正(主成分分析、模拟退火)和一种改进的闭环实时模式校正算法(改进的奇异值分解),进一步提升了波前校正器的畸变波前校正性能;最后研究了基于微机械薄膜变形镜的自适应光学系统模式空间分辨能力。5.采用了基于自适应光学视网膜显微成像系统模块化设计的设计方法;针对视网膜显微成像系统中各模块的性能指标依次进行研究,提出了其设计参数及功能结构;建立了自适应光学系统的主要功能模块和波前像差校正工作流程,实现其核心器件的控制通讯和数据传输。6.首次建立了一套基于微机械薄膜变形镜和HS波前传感器的自适应光学试验测试平台和软件控制系统,实现了基于Zernike多项式的波前模式复原探测和校正并加以优化;分别利用光学测试镜片、模拟眼和活体兔眼引入畸变波前像差,并进行测试系统的模式复原,从而分析微型自适应光学系统对波前像差的校正性能。原型系统参数和实验结论对整个项目的临床产品化有着重要意义。更多还原

【Abstract】 Problems on retinal imaging of human eye are attached importance to the field of ophthalmologic video at all time, and its solution is probitious to the advanced diagnosis on the fundus ailments. Along with the successful application to the wavefront aberrations correction of the human eye, the cellular images of the fundus retina were acquired by the scholars many years later, which provided the new moment for the diagnosis on the fundus sicknesses. Technologies of MEMs (Micro Electro Mechanical system) were changing with each passing day, and modern devices being used in wavefront sensing and wavefront correction came forth incessantly. Low-cost, little-size settings of adaptive optics gradually are taken into account and investigated by the professionals in the field of ophthalmologic video. In the paper, a minitype system of adaptive optics based on the HS(Hartmann-Shack) wavefront sensor and Micromachined membrane deformable mirror was builded, and the included key technologies were analyzed and optimized in order to improve the correction capability of the whole adaptive optics equipment. The mostly content is as follows:1) The in-existence devices being used into the retinal imaging of human eye and their limitions were expatiated, and the imaging qualify of imaging devices that was increased by adaptive optics and the development level of devices and Technologies about adaptive optics were did. Finally, the status in quo of wavefront aberration correction by adaptive optics and fundus cellular observation in inner and outer nation were summarized.2) The histiocytic structures of human eye and its retina pictured, and the exit wavefront aberration was defined and the characteristics of Zernike polynomials were analyzed. With Zernike polynomials theorical modal description of wavefront aberration of human eye was put forward, then influence on the imaging qualify by Zernike modal aberration were discussed,which contents involved the relation between the MTF(Modulated Transfer Function),SR(Strehl Ratio) and the low order, high order modal aberraion.3) The types of wavefront sensor in the adaptive optics were enumerated and priciples and theotical models of HS sensor were introduced, which contents involved into location of center of mass of spot and the error of slope sensing. In the modal reconstruction of HS sensor, at first the modal based on Gram-Schimit and Householder decoupling transforming were put award, and as a result influence of decoupling modes on the modal reconstruction was discussed. Finally, a new optimal modes of slope sensing error of HS sensor was brought forward, and its advanced capacity was verified by the simulation.4) The type of wavefront correctors were introdued, and the strcuture and performance of schism actuators deformable mirrors and whole actuators mirrors were compared. The Micromachined Membrane deformable mirror and its influence function were described characteristicly, with which the modal reconstruction and correction can be achieved. In this paper two new approaches were introduced: one was principal component analysis ,and the other was simulation annealing, then their results of aberrated wavefront correction were given. Finally, the space resolution of the little-size adaptive optics was discussed5)Modularization designing of retinal microscopy based on the AO(Adaptive optics) were built, and performance parameters of its components were analyzed, then designing parameters and function configurations were created.data transfer and control communication of AO were set up among devices..6) In order to verify the performance of wavefront correction of above adaptive optics, the experimental adaptive optics setting was build. With a optical test lens and artifical simulation eye the correction capability to aberrated wavefront was validated, and final results were reported and analyzed.更多还原