人眼像差哈特曼测量仪的重复性测试

人眼像差哈特曼测量仪利用 Hartmann-Shack 波前传感器探测波前,并用 Zernike 多项式实现波前的重建。测试结果的重复性对该仪器来说是至关重要的。此仪器对模拟人眼静态像差和活体人眼动态像差分别进行单帧采集和连续采集,所得的模拟人眼静态像差 Zernike 系数的标准偏差的最大值,PV 与 RMS 依次为 0.016?,0.061?和 0.006?;活体人眼动态像差 Zernike 系数的标准偏差的最大值,PV 与 RMS 依次为 0.045?,0.167? 和 0.030?,这些指标都小于 ?/5,表明该仪器具有较高的重复性。     

人眼不同瞳孔直径波前像差特性分析

采用Hartmann-Shack人眼像差仪,测量了人眼在3.1mm,5.2mm和6mm瞳孔直径下的波前像差。波前像差的RMS值表明,随着瞳孔直径的增大,人眼各阶波前像差均随着增大。与瞳孔直径为3.1mm时相比,瞳孔直径为6mm和5.2mm时,Zernike2-10阶波前像差的RMS值分别增大1.2-7.7倍和1.1-4.8倍。用调制传递函数(MTF)和Strehl比评价了高阶波前像差对成像质量的影响,结果表明,大瞳孔高阶波前像差对成像质量的影响大于小瞳孔;在3.1mm,5.2mm和6mm瞳孔直径下,欲达到衍射极限的Strehl比率,分别需要矫正Zernike波前像差前2-4阶、前3-6阶和前5-7阶,需矫正的像差阶数随瞳孔直径的增大而增加。     

高级像差对人眼成像质量和视觉的影响

定量地研究高级像差对人眼成像质量和视觉的影响对人眼像差矫正具有重要的实验和临床意义.利用Hartmann-Shack波前传感器人眼像差仪测量了正常人眼6mm瞳孔的波前像差,由波前像差计算出人眼光学系统的光学调制传递函数MTF和Strehl比率,并由MTF和视网膜空间像调制度AIM曲线计算出人眼视锐度和对比敏感度函数CSF.根据MTF和Strehl比率分析了高级像差对人眼成像质量的影响,根据视锐度和对比敏感度函数CSF分析了高级波像差对视觉的影响.研究表明Zernik前6级像差对人眼成像质量和视觉的影响是不可忽略的,更高级的像差对人眼成像质量和视觉的影响较小,甚至可以忽略.对Zemik前6级像差进行矫正,可以得到相当好的视觉.     

泽尼克像差组合对人眼光学质量的影响

基于人眼光学质量客观评价标准区域调制传递函数（AreaMTF）、斯特列尔比（SRX）和同心相对瞳孔平面（PFWc），分析了波前像差RMS为0．25μm时泽尼克像差项组合对人眼光学质量的影响。C4（离焦）与C12（球差）等组合后，像差比例在1．33到4．90的范围内AreaMTF和SRX有极大值；C6（三叶草）与C7（彗差）等组合后，像差比例在0．20到1．00的范围内它们有极小值。二阶像差（离焦和像散）组合时，C4（离焦）起着主导作用。三阶像差（彗差和三叶草）组合时，SRX和PFWc值的变化范围均较大，分别为0．066到0．228和0．048到0．656。     

衍射精密测量系统中的像差分析

本文以细丝直径衍射测量系统为例，分析讨论了各种像差对测量精度的影响，从而为衍射测量物镜的像差校指明方向。     

镜头像差知多少?

镜头像差包括球差、彗差、像散、场曲、色差与畸变,这些对初学者来说既熟悉又陌生--常听到影友们说这个镜头畸变严重或那个镜头有明显像场弯曲等,又囿于难以弄懂理论书籍中复杂的公式推导,故对自己手中的镜头是否存有像差,是否会影响拍摄而有点不放心.下面是笔者将像差、色差与畸变作尽可能通俗的描述,旨在帮助初学者能客观地评估自己的镜头,在使用中能扬长避短.     

光刻物镜波像差绝对检测技术综述

光刻物镜是光刻机核心部件，其波像差大小决定着光刻机的分辨率和套刻精度。随着光刻机性能的逐步提升，光刻物镜波像差要求已经降低到0.5 nm (RMS)以下，这对波像差的检测是一个极大的挑战。现行的光刻物镜波像差检测方法 (如哈特曼法，剪切干涉法和点衍射法等)的检测精度往往受限于其系统误差，而绝对检测技术是一种能够将系统误差分离出来的技术，最终突破精度极限。本文回顾了光刻物镜系统波像差检测方法和波前绝对检测技术，详细梳理了绝对检测技术在不同波像差检测方法中的应用和研究进展，重点总结了绝对检测技术在不同波像差检测方法中的技术难点，同时结合这些难点，展望了光刻物镜波像差绝对检测技术的未来发展趋势。     

微分代在高阶复合几何像差-色像差分析中的应用

微分代数是计算机数值计算领域中的一种强有力的新型数学方法,它为任意高阶微分的计算提供了一种可达到机器精度的极为简便的手段.本文根据微分代数的基本原理,研究了它在高阶复合几何像差-色像差分析计算中的应用,得到了系统的任意阶传递性质的微分代数表示,并具体给出了一至三阶复合几何像差-色像差所对应的微分代数系数.文中还以一个轴上电位分布具有解析表达式的静电电子透镜为例,计算了它的一至三阶复合几何像差-色像差系数,并给出了一阶色差分布图形.     

光学系统设计中降低公差灵敏度的方法

基于初级像差理论提出了一种降低系统公差灵敏度的方法,即通过控制光学系统各元件表面的初级像差值以“小像差互补”达到像差平衡.首先阐明“小像差互补”含义,然后通过理论公式指出了初级像差与公差灵敏度的关系,最后举出一个航空相机光学系统的设计实例,通过对其“大像差互补”与“小像差互补”两种设计结果进行公差分析,结果表明利用“小...     

数码单反相机的像差校正分析

介绍数码单反相机的基本结构,利用光学成像原理,分析相机成像过程中产生的各种像差,分别讨论单色像差和复色像差的校正原理和方法。     

Corneal wave aberration from videokeratography: accuracy and limitations of the procedure

A procedure to calculate the wave aberration of the human cornea from its surface shape measured by videokeratography is presented. The wave aberration was calculated as the difference in optical path between the marginal rays and the chief ray refracted at the surface, for both on- and off-axis objects. The corneal shape elevation map was obtained from videokeratography and fitted to a Zernike polynomial expansion through a Gram-Schmidt orthogonalization. The wave aberration was obtained also as a Zernike polynomial representation. The accuracy of the procedure was analyzed. For calibrated reference surface elevations, a root-mean-square error (RMSE) of 1 to 2 microm for an aperture 4-6 mm in diameter was obtained, and the RMSE associated with the experimental errors and with the fitting method was 0.2 microm. The procedure permits estimation of the corneal wave aberration from videokeratoscopic data with an accuracy of 0.05-0.2 microm for a pupil 4-6 mm in diameter, rendering the method adequate for many applications.     

Effect of defocus on on-axis wave aberration of a centered optical system

We derive equations for defocus and primary spherical wave aberration coefficients caused by a shift in image plane of a perfect optical system. The spherical aberration equation is accurate at describing changes in the spherical aberration of an aberrated schematic eye.     

对Hartmann-Shack波前传感器平移误差的研究

Hartmann—Shack传感器的探测精度对于评价自适应光学系统的校正能力和光学检测精度都是十分重要的。通过对传感器的平移误差的理论分析和数据仿真来对传感器的系统精度进行研究，确定平移误差的最佳范围为残余像差与理论像差的均方根比值不大于0．5％。这为Hartmann—Shack传感器的装配提供了理论依据和技术指标。     

Calculation of retinal image quality for polychromatic light

Although the retinal image is typically polychromatic, few studies have examined polychromatic image quality in the human eye. We begin with a conceptual framework including the formulation of a psychophysical linking hypothesis that underlies the utility of image quality metrics based on the polychromatic point-spread function. We then outline strategies for computing polychromatic point-spread functions of the eye when monochromatic aberrations are known for only a single wavelength. Implementation problems and solutions for this strategy are described. Polychromatic image quality is largely unaffected by wavelength-dependent diffraction and higher-order chromatic aberration. However, accuracy is found to depend critically upon spectral sampling. Using typical aberrations from the Indiana Aberration Study, we assessed through-focus image quality for model eyes with and without chromatic aberrations using a polychromatic metric called the visual Strehl ratio. In the presence of typical levels of monochromatic aberrations, the effect of longitudinal chromatic aberration is greatly reduced. The effect of typical levels of transverse chromatic aberration is virtually eliminated in the presence of longitudinal chromatic aberration and monochromatic aberrations. Clinical value and limitations of the method are discussed.     

High-resolution retinal imaging with micro adaptive optics system

Based on the dynamic characteristics of human eye aberration, a microadaptive optics retina imaging system set is established for real-time wavefront measurement and correction. This paper analyzes the working principles of a 127-unit Hartmann-Shack wavefront sensor and a 37-channel micromachine membrane deformable mirror adopted in the system. The proposed system achieves wavefront reconstruction through the adaptive centroid detection method and the mode reconstruction algorithm of Zernike polynomials, so that human eye aberration can be measured accurately. Meanwhile, according to the adaptive optics aberration correction control model, a closed-loop iterative aberration correction algorithm based on Smith control is presented to realize efficient and real-time correction of human eye aberration with different characteristics, and characteristics of the time domain of the system are also optimized. According to the experiment results tested on a USAF 1951 standard resolution target and a living human retina (subject ZHY), the resolution of the system can reach 3.6?LP/mm, and the human eye wavefront aberration of 0.728λ (λ=785?nm) can be corrected to 0.081λ in root mean square (RMS) so as to achieve the diffraction limit (Strehl ratio is 0.866), then high-resolution retina images are obtained.     

Wide-field compensation of monochromatic eye aberrations: expected performance and design trade-offs

The optical quality of the human eye varies across the visual field. Hence an exact compensation of the eye aberration for a given field point can give rise to a less-than-optimum compensation in neighboring field regions. We have studied some aspects of this problem and present here an approach to design wide-field (< 10 degrees) optically thin correcting elements, e.g., phase plates, deformable mirrors, and liquid-crystal displays. Their expected performance is assessed using actual eye aberration data. Particular attention is given to the design of elements providing a minimum averaged rms residual aberration and those providing a nearly uniform rms residual aberration across a given field.     

Dynamic eye model for adaptive optics testing

An artificial dynamic eye model is proposed. The prototype enabled us to introduce temporal variations in defocus and spherical aberration, resembling those typically found in the human eye. The eye model consisted of a meniscus lens together with a modal liquid crystal lens with controllable focus. A diffuser placed at a fixed distance from the lenses acted as the artificial retina. Developed software allowed the user to precisely control the dynamic generation of aberrations. In addition, different refractive errors could simultaneously be emulated by varying the distance between the components of the model. The artificial eye was first used as a dynamic generator of both spherical aberration and defocus, imitating the behavior of a real eye. The artificial eye was implemented in an adaptive optics system designed for the human eye. The system incorporated an electrostatic deformable mirror and a Hartmann-Shack wavefront sensor. Results with and without real time closed-loop aberration correction were obtained. The use of the dynamic artificial eye could be quite useful for testing and evaluating adaptive optics instruments for ophthalmic applications.     

Spherical aberration gauge for human vision

Spherical aberration affects vision in varying degrees depending on pupil size, accommodation, individual eye characteristics, and interpretations by the brain. We developed a spherical aberration gauge to help evaluate the correction potential of spherical aberration in human vision. Variable aberration levels are achieved with laterally shifted polynomial plates from which a user selects a setting that provides the best vision. The aberration is mapped into the pupil of the eye using a simple telescope. Calibration data are given.