人工晶体前移与人眼屈光调节关系的研究

基于Hwey-LanLiou眼模型,采用ZEMAX光学设计软件实现光线追迹的方法研究了人工晶体在眼内的前移与人眼屈光调节之间的关系.结果表明：人工晶体每前移一定的距离,人眼所获得的屈光调节量不恒定;调节量大小依赖于眼轴长度和所需植入的人工晶体,特别是眼轴长度;对于不同眼轴长度术眼中的人工晶体前移,人眼所获得的屈光调节量与眼轴长度呈负相关.     

不同因素对可调节人工晶体屈光调节力的影响

首先以Hwey-Lan Liou眼模型为基础，根据等效性原则，保持该眼模型中自然晶状体屈光度不变，对无穷远点成像。然后利用ZEMAX实现光线追迹的方法，将自然晶状体替换为可调节人工晶状体（accommodative intraocular lens，AIOL），结合对人眼成像质量影响的分析，研究了AIOL在眼内的移动度、材料、中心厚度、结构、光学面非球面性等因素对其屈光调节力的影响。结果表明:AIOL移动度对其调节力贡献最大,材料、中心厚度、结构对调节力基本无影响；具有非球面光学面的AIOL调节力相对较大。     

偏心和倾斜光学系统初级象差理论的研究

在共轴光学系统波象差的基础上,推导出了光学元件的偏心和倾斜分别对主要象差的影响.得出了除了球差外,每一种象差由于偏心和倾斜都引入了它同种类的象差;小量的偏心和倾斜并不改变系统的球差的结论;如果球差并不为零,将会产生与象高无关的彗差,即轴向彗差等等.     

具有层状晶状体的人眼模型的光学性质

为了更加符合眼睛的解剖学结构,用建立的层状结构晶状体模型代替了Hway-Lan Liou眼模型中的折射率连续变化的晶状体模型。从而建立了新的眼睛模型。在这个新的层状晶状体模型中,最外层前后表面的非球面系数与解剖学数据相符。由于层状结构使光线追迹具有特殊性。因此用C语言编制了光线追迹程序,并对此眼睛模型的光学性质进行了研究。结果表明,晶状体层数较少时,眼睛的球差曲线出现翼状结构．即层状晶状体的引入使眼睛具有多焦性．并对这种现象进行了解释;具有层状结构晶状体的眼睛和具有折射率连续变化的晶状体的眼睛能够给出等价的球差结果。     

二次曲面前房型有晶体眼人工晶体的球差矫正特性分析

为探究二次曲面前房型有晶体眼人工晶体的球差矫正特性,进行了球面和二次曲面有晶体眼人工晶体的设计,并利用像差理论对二者的球差矫正特性进行了研究.基于R.Navarro等人提出的模型眼得到屈光不正眼模型,利用ZEMAX光学软件分别设计了可矫正屈光不正人眼的球面与二次曲面前房型有晶体眼人工晶体.通过对光学传递函数和Zernike球差系数的比较,以及对Seidel球差分布系数的计算分析发现:在保证屈光不正矫正至正常水平的前提下,较之传统球面人工晶体,二次曲面的引入仅对远视眼的球差有矫正作用,并使光学传递函数显著改善|而对近视眼而言,二次曲面人工晶体的球差矫正效果与球面人工晶体相当.这一结论对前房型有晶体眼人工晶体的设计和应用具有重要的理论指导意义.     

二次曲面前房型有晶体眼人工晶体的球差矫正特性分析

为探究二次曲面前房型有晶体眼人工晶体的球差矫正特性,进行了球面和二次曲面有晶体眼人工晶体的设计,并利用像差理论对二者的球差矫正特性进行了研究.基于R.Navarro等人提出的模型眼得到屈光不正眼模型,利用ZEMAX光学软件分别设计了可矫正屈光不正人眼的球面与二次曲面前房型有晶体眼人工晶体.通过对光学传递函数和Zernike球差系数的比较,以及对Seidel球差分布系数的计算分析发现:在保证屈光不正矫正至正常水平的前提下,较之传统球面人工晶体,二次曲面的引入仅对远视眼的球差有矫正作用,并使光学传递函数显著改善|而对近视眼而言,二次曲面人工晶体的球差矫正效果与球面人工晶体相当.这一结论对前房型有晶体眼人工晶体的设计和应用具有重要的理论指导意义.     

偏心和倾斜光学系统的像差特性

运用一种新的分析偏心和倾斜光学系统初级像差特性的方法—矢量像差理论,分析了具有较大交叉倾斜角的平行平板光学系统和具有较大倾斜角的光楔光学系统的像差特性.通过ZEMAX光学设计软件像差分析功能中的垂轴像差曲线、场曲曲线和点列图加以比较,两者非常吻合,证明该理论可以对具有较大倾斜元件的非共轴光学系统设计起指导作用.     

非球面人工晶体设计及人眼瞳孔对其光学性能的影响

给出一种非球面人工晶体的设计方法。以Holladay角膜模型为基础,设定其球差大小为非球面人工晶体球差值,并在晶体位置发生移动及不同人眼瞳孔直径下,对所设计的非球面人工晶体光学性能与球面人工晶体进行对比分析。结果表明:当晶体植入人眼位置并且瞳孔直径相同时,设计的非球面人工晶体所在人眼光学系统的MTF,对比敏感度及离焦MTF的改善程度都明显优于传统的球面人工晶体,人眼成像质量均随人眼瞳孔直径的增大而下降;当晶体前移时,晶体所在人眼光学系统的MTF均随瞳孔直径的增大而下降,设计的非球面人工晶体仍表现出优于球面人工晶体的光学性能。     

倾斜偏心对同轴波导TEM模式性能的影响

采用CST微波工作室软件,数值模拟了内外导体轴线偏心对同轴波导TEM模式性能的影响。结果表明：随着倾斜偏心度的逐渐增大,倾斜偏心同轴波导的S21参数和电场的幅值减小,但减小的幅度不是很明显,不会影响同轴波导的正常工作。但是,当偏心度增大到1°时,同轴波导TEM模式的端口电场分布云图与无偏心相比发生了很大的变化,可能导致同轴波导不能正常工作。     

人眼的高级像差对视功能的影响

准确测量和分析人眼的高级像差有助于更好地改善视觉,具有重要的实验和临床意义。测量了实际人眼的波前像差,分析了高级像差对人眼视功能的影响。像差数据由哈特曼-夏克（Hartmann-Shack）波前传感器分别对不同瞳孔的人眼进行测量而获得,视功能的评价方法采用了调制传递函数（MTF）、对比敏感度函数（CSF）、斯特雷尔（Strehl）比率。由人眼的波前像差数据和视网膜空间像调制度（AIM）曲线直接给出了视锐度值与对比敏感度值。矫正了离焦与像散后．被测者的平均视锐度值达到了1．0,对比敏感度在低频（20c／mm）处约为52,高频（80c／mm）处约为1;矫正了前4阶像差后,平均视锐度值可提高到1．2,对比敏感度在低频（20c／mm）处提高到96,高频（80c／mm）处提高到7。实际人眼各不相同,达到理想成像需矫正高级像差的阶数也不同。矫正了前九阶像差后,均可达到理想成像,斯特雷尔比率值大于0．8。     

An anatomically accurate eye model with a shell-structure lens

A human eye model based on anatomically accurate eye model previously proposed by Liou, has been transformed into a new eye model, in which laminated structure of the lens is considered. The crystalline lens is presented in the form of hundreds of shells with rotational symmetry, and with constant index within each shell. The refractive index increases from the cortical shell to the inner one, according to the equation proposed by Smith G. et al. The anterior surface of the lens is prolate, whereas the posterior surface of the lens is oblate which is consistent with the anatomical data. A ray tracing procedure has been applied to study the refractive structure of the eye. The optical characters of the model have been studied. The reason that the wings occur on the spherical aberration curve has been given. And we found that the lens with gradient refractive index and lens with shell structure can give same longitudinal spherical aberration results.     

Effect of transition zone on wavefront aberration with treatment decentration after conventional refractive surgery

Based on the ablation profile of conventional refractive surgery, the influence of transition zone on induced wavefront aberrations with decentration, as well as laser oblique incidence, was studied. The results indicated that transition zone played a significantly important role in the influence of decentration on the postoperative aberrations. The induced coma increased rapidly with the increase of lateral translation of the centre of ablation. Furthermore, the induced spherical aberration increased theoretically as the translation increase and the sign of spherical aberration was usually positive for myopic correction. And yet it changed from positive to negative for hyperopic correction. In addition, the induced spherical aberration was related with the corrected refraction. As an important goal for refractive surgery, the optimal postoperative visual performance may be smoothly achieved by minimizing treatment decentration and optimizing transition zone in refractive surgery.     

Specially profiled reflector for spherical front beams focusing

Focusing the power emitted from a source with spherical wave front by a specially profiled reflecting surface has been attempted using the simple ray tracing method. The reflector (mirror) surface profile that achieves such power redistribution is obtained from solving an ordinary first order differential equation using common numerical techniques. Furthermore, the proposed methodology can be useful to design complex reflectors for the electomagnatic and the acoustic systems, which finds broad engineering, industrial and biomedical applications.     

Internal distribution of radiation absorption in a semitransparent spherical particle

The internal distribution of spectral radiation absorption in a semitransparent spherical particle irradiated uniformly and isotropically is determined by the ray tracing method, and the detailed computation formulae for the internal spectral radiation absorption are deduced. The computed results show that the peak of internal volumetric spectral radiation absorption may locate at the interior shell of the particle. The dimensionless volumetric spectral radiation absorption is higher near the center for weakly absorbing or small spheres, but the dimensionless volumetric spectral radiation absorption is higher near the surface for strongly absorbing or large spheres. The corresponding physical interpretations of the internal spectral absorption distribution are given.     

人眼入射波前像差和出射波前像差的差异

利用临床采集的人眼波前像差、角膜地形图和眼轴数据,在光学软件Zemax中构建了60只个性化眼模型,得出在瞳孔直径为6mm和3mm时的入射波前像差和出射波前像差.在6mm瞳孔下,入射波前像差大小为3.753     

托卡马克等离子体LHCD与ECCD的协同作用

本文通过求解Fokker-Planck方程和射线追踪技术,详细研究了托卡马克等离子体中,低混杂波电流驱动(LHCD)与电子回旋波电流驱动(ECCD)的协同作用,结果表明,这种协同作用有利于用EC波驱动电流;捕获电子效应对电流驱动有一定影响,特别是O波弱场注入时,影响更为明显;驱动的电流对平衡磁场很敏感,磁场的大小也影响驱动电流的剖面。     

Spherical aberration and its correction using Lie algebraic methods

We discuss three methods to correct spherical aberration for a point to point imaging system. First, results obtained using Fermat’s principle and the ray tracing method are described briefly. Next, we obtain solutions using Lie algebraic techniques. Even though one cannot always obtain analytical results using this method, it is often more powerful than the first method. The result obtained with this approach is compared and found to agree with the exact result of the first method.     

Using a simple method: conversion of a Gaussian laser beam into a uniform beam

Spherical aberration phenomenon was used to convert the intensity profile of a Gaussian laser beam into a uniform beam profile. The measurements of the beam profile were obtained using a simple optical method.     

超短脉冲经过小数值口径透镜的聚焦特性

 从亥姆霍兹方程出发，考虑透镜的色差和球差，得到了超短脉冲经过小数值口径透镜后光场的解析表达式；利用数值模拟得到了旁轴焦平面和边缘焦平面上光场强度的时空分布，以及聚焦区域内轴上点的强度分布图，并分析了色差和球差的大小对它们的影响。由于通过透镜中心和边缘之间的大部分脉冲产生了干涉相消，因此在旁轴焦平面与边缘焦平面上都出现前、后两个峰值相差很大的脉冲，并且随着球差的增大，两峰值差更大了；聚焦区域内轴上点的强度分布基本是对称的，强度最大点不是出现在旁轴和边缘焦平面上，而是在它们之间的某个位置，并且随着球差的增加，该位置将向聚焦区域的边缘靠近。     

Intraocular lens design for treating high myopia based on individual eye model

In this research, we firstly design the phakic intraocular lens (PIOL) based on individual eye model with optical design software ZEMAX. The individual PIOL is designed to correct the defocus and astigmatism, and then we compare the PIOL power calculated from the individual eye model with that from the experiential formula. Close values of PIOL power are obtained between the individual eye model and the formula, but the suggested method has more accuracy with more functions. The impact of PIOL decentration on human eye is evaluated, including rotation decentration, flat axis decentration, steep axis decentration and axial movement of PIOL, which is impossible with traditional method. To control the PIOL decentration errors, we give the limit values of PIOL decentration for the specific eye in this study.