【作者】 梁春；

【导师】 廖文和；

【作者基本信息】 南京航空航天大学 ， 机械工程， 2009， 博士

【摘要】 自适应光学是近年来发展迅速的一门新兴技术,在天文观测和激光导星等领域得到广泛应用。伴随微加工技术的发展,微小型、低成本的自适应光学系统开始出现,应用范围开始从星载相机、望远镜系统、激光核聚变等领域扩展到眼科医疗等民用项目中,其中,基于人眼波前像差测量与校正的视网膜细胞显微成像系统是研究的热点。论文系统研究了基于自适应光学的人眼波前像差测量、复原中的关键技术,建立了一套高精度的人眼波前像差重构方法,成功应用于活体人眼视网膜细胞观测系统中,有效提高了自适应光学系统的像差测量校正性能,实现了对人眼波前像差的实时测量与校正,并获得了高分辨率的视网膜图片。论文的主要内容如下:1.系统叙述了人眼视网膜组织细胞的生理结构,分析了人眼成像的光学原理,在人眼光学模型的基础上给出眼波前像差的数学表达模型,并采用像质评价标准对人眼像差对成像质量的影响进行了计算和评价。2.系统研究了Hartmann-Shack波前传感器的探测原理和理论模型,对传感器的结构、工作原理和影响探测精度的装配误差进行了系统分析,在此基础上推导出利用激光点光源,自基准标定传感器结构参数的新方法,解决了该参数无法直接测量的难题。3.深入研究人眼像差波前复原中的关键技术。包括人眼像差测量中入瞳激光安全功率计算;激光散斑形成原理及利用旋转散射体抑制人眼像差测量中散斑的技术;复原模式对人眼波前像差重建的影响。4.在分析人眼像差光斑图特点基础上,研究出一套基于形态法滤波,光斑动态跟踪光斑定位,区域迭代质心计算的自适应光斑质心计算方法,经实际使用证明,该方法具有较强抗噪能力,能有效提高光斑识别率与质心探测精度,并在一定程度上扩大了传感器应用范围。5.建立国内首套基于微机械薄膜变形镜的小型化、低成本人眼视网膜细胞成像系统,系统包括一套以自适应光学系统为基础的光学平台和与之配套的控制软件系统。该系统具有像差测量,变形镜影响函数标定,闭环校正、视网膜细胞成像等功能,此外软件还对闭环校正中的参数设置进行了优化,可以匹配瞳孔实现免散瞳像差校正。6.对搭建的自适应光学系统进行了像差测量、校正能力的验证,在对模拟眼、活体兔眼、以及猪眼视网膜的像差测量校正实验基础上,最终对活体人眼分别进行了像差测量、校正和视网膜成像,成功获得了清晰的视网膜细胞分布图像。更多还原

【Abstract】 As an emerging technology which is growing rapidly in recent years, adaptive optics has been extensively used in the fields of astronomical observations and laser-guide-star (LGS). With the development of micromachining technology, adaptive optics system of micro-miniature and low cost appears. The application of this technology extended from areas of satellite-borne camera, telescope system and laser nuclear fusion to the civilian projects, such as Ophthalmic Medical items. One of the hotspots among is the imaging system of retina cell based on the measurement and correction of wavefront aberration. In this paper, the measurement and correction of wavefront aberration, based on adaptive optics, has been researched systematically as the key technology. A high-precision wavefront aberration reconstruction method which has successfully applied in the human retina cells imaging system was found, and it effectively improved the measurement and aberration correction performance of the adaptive optics system. Real-time measurement and aberration correction in human eye was realized and got a clear picture of the retinal cells.The content of this paper mainly includes:1. It described the physiology structure of human retina, analyzed the principle of imaging of human eyes and the influence of imaging quality through the mathematical model of wavefront aberration.2. Based on the research of principle of detection and theoretical model of Hartmann-Shark wavefront sensor, it analyzed the structure, operation and assembly error which has influences on detection accuracy. A new self-reference method is given in this paper to calibrate the parameter of Hartmann-Shark wavefront sensor with point light source .3. The key techniques are analyzed in depth, include: the maximum permissible exposure calculation of laser used to measure wavefront aberration of human eyes, formation principle of laser speckle and the technique for reducing speckle by using rotating diffuser, the influence of mode selection on reconstructing wavefront aberration of human eyes.4. A new adaptive method is given to estimate the centroid of images after analyzing spot pattern characteristics of human eye aberration. This method is based on the morphological filter, dynamic tracing of spot window, and iterative approximation algorithm. The experimental results show that the method is with strong anti-noise ability, and obviously improves the spot recognition rate and centroid detection accuracy, which effectively extends the applicability of Hartmann-Shack wavefront sensor.5. Based on micromachined membrane deformable mirror(MMDM), a miniaturized and low-cost human retina cell imaging system was first built in China, including a set of optical platform based on adaptive optical system and a software control system accompanying. The functions of software control system consist aberration measurement, calibration of influence function of deformable mirror, closed-loop feed back correction and retina cell imaging. In addition, the preferences were optimized in aberration correction in order to match the different size of pupil, which makes it possible to operate with dilation-free.6. We tested the ability of aberration measurement and correction about the adaptive optics system, and do the experiments of aberration measurement and correction with model eyes, rabbit eyes and pig retina. Human eyes have been tested finally after analysis and conclusion. Clear retina cell images were acquired successfully.更多还原