平行四边形孔的夫琅和费衍射

在普物光学实验中,一般观察圆孔、单缝、多缝等规则孔径的夫琅和费衍射,并根据衍射图样与波长、孔径之间的定量关系可测定孔径的大小,如图孔的直径,狭缝的宽度,光栅常数等。但是复杂一些的微孔由于制作上和解释其衍射现象上的困难未被列入实验教学。     

衍射条纹的图形显示

根据衍射光强相对分布 ,用计算机作图的方法显示了单缝和圆孔夫琅和费衍射条纹的图形。     

光栅衍射的层次教学

光栅衍射的教学是工科大学物理教学中的一个难点,通过从衍射的光强分布的角度,组织了一个由单缝衍射到双缝衍射、到多缝衍射、再将双缝干涉和光栅衍射作一比较这样一个循序渐进的层次教学,更好地让学生理解光栅衍射.     

多缝衍射中缺级现象的演示

普通物理光学课在讲解多缝夫琅和费衍射时,阐述单缝衍射因子和缝间干涉因子的作用以及缺级概念都是十分重要的。以往,只是借助于间距固定的双缝和多缝来演示上述的概念,虽然对理解这些问题有所帮助,但只是停留在静态现象的观察,不能显示出随常数d(d=a b)的改变,衍射图样动态变化的过程。我们用自己制作的可调间距的双     

光栅衍射中缝间干涉因子作用的计算机模拟

根据惠更斯-菲涅耳原理,从光栅衍射的形成机制出发,探讨了缝间干涉因子的作用。应用matlab程序,模拟了在改变缝数、波长和光栅常数时,缝间多光束干涉条纹的相应变化。该计算机仿真方法,有助于学生理解光栅衍射过程、特征和规律。     

圆孔衍射中心显现亮暗斑的实验设计与实施

根据半波带法的理论推导,发现了在圆孔衍射实验中难以观察到衍射图样中心为暗斑的原因,并利用几何画板软件进行了模拟实验,快速找出了合理的实验参量.根据这些参量,采用简单的实验器材在课堂上为学生演示出了丰富的衍射现象.     

用计算机研究光的多缝衍射

依据光栅衍射理论，利用计算机的计算功能和作图功能对光的多缝衍射实验进行了模拟．由于采用了面向对象的编程语言C＋＋，使得软件的使用非常简单，只要任意设定实验的参数，计算机就会快速地绘出各种复杂的衍射图线，并准确地再现光栅衍射的现象及规律．便于对光的干涉和衍射现象进行深入的研究。     

平行光的菲涅耳圆孔衍射的实验研究

通过实验观察到衍射图样的中心可亮可暗,并用"菲涅耳半周期带"原理加以分析、解释,通过分析总结出圆孔衍射图样的中心光强的变化规律,完善圆孔衍射的实验研究.     

互补Sierpinski地毯光栅夫琅和费衍射现象的研究

利用菲涅耳 基尔霍夫光栅衍射原理和傅里叶分析方法，对具有分形结构互补Sierpinski地毯光栅的夫琅和费衍射现象进行了探讨。导出了观察平面上的频谱函数、振幅函数以及光强函数。运用MATLAB软件对该光栅的衍射现象进行了仿真，并绘制出其幅 频特性曲线。结果表明，在各阶光栅的衍射图样中，幅度较大的部分主要集中在接收屏的中心区域，而在偏离中心的区域内，幅度值较小，在较远区域幅度值趋近于零，这说明获得的衍射图样不仅具有衍射光的基本特性，而且都呈现出明显的分形特征。     

谱线不等高对光栅常数测量的影响

分光计测光栅常数实验的基本操作之一就是调节谱线等高,即要调节光栅刻痕与转轴平行。本文对谱线不等高对光栅常数测量的影响,给出一定量公式,导出方法物理意义明晰,计算简洁。首先以单缝衍射为例,说明狭缝与线光源不平行时,衍射图样的变化。图1是单缝夫琅和费衍射装置图。三个     

点衍射干涉仪中小孔衍射波面误差分析

针孔或光纤直径的大小是影响点衍射干涉仪检测精度的重要因素,在实际检测中须根据检测任务的精度要求来选择小孔的尺寸.基于标量衍射理论,仿真计算了小孔尺寸引起的衍射波面相对标准球面偏离的误差.结果表明,当小孔直径为2.5μm,数值孔径(NA)为0.3时,与小孔有关的光学系统误差峰值(PV)约为0.07 nm.仿真方法和计算结果为针对各种高精度面形检测任务而设计点衍射干涉仪和分析其精度提供了理论和数据参考.     

Diffraction management

By using the diffraction properties of waveguide arrays, we propose a scheme to produce structures with designed diffraction. We fabricated arrays with reduced, canceled, and even reversed diffraction. Results of experiments with such waveguides are presented and compared with the predictions made by coupled-mode theory.     

Diffraction theory of quasicrystals

The diffraction problem of quasicrystals is solved with the aid of shift operators, s _q(x, y, z) (q = x, y, z). Starting from certain sets of latent lattices which have to be optimized according to chemical composition, density, and diffraction pictures, it is shown that periodic structures are determined by as many parameters as the number of independent positions. Furthermore, the Fourier coefficients (Fc's) are strictly periodic. Structure factors are given by sums of products of Bessel functions (Bfs). The amplitudes of Fc's enter the arguments of Bf's, while their phases determine phase factors. The diffraction pictures show periodic properties, as far as the orders of Bf's and Fc's are concerned. This periodicity is violated only by the arguments of Bf's. Hence direct calculation of phases of reflections with certain ambiguities is possible. Quasicrystals are characterized by incommensurate modulations with an infinite number of possible Fc's which can not be derived from diffraction patterns. This difficulty is overcome by the observation of extinction rules, limiting the number of reflections observed. The orders of Fc's, Bf's respectively, entering the sum mentioned above, are correlated by convolution properties in diffraction. Taking into account their periodicities and the existence of sets of latent lattices, regularities in the diffraction pattern result which are briefly discussed.     

Basics of X-ray Diffraction

X-ray diffraction (XRD) is the most comprehensive tool to identify minerals in complex mineral assemblages. The method is briefly described with special emphasis on clay and ceramics. As an example, an investigation of graphite-containing pottery sherds by XRD is presented. By comparing the measured XRD data with the patterns simulated by the Rietveld method, the graphite content of such samples could be determined.     

Spectral Theory of Diffraction

In this paper we present an overview of the spectral domain approach for solving a variety of high frequency diffraction problems. We demonstrate via a number of examples that the fields derived from the use of the Spectral Theory of Diffraction (STD) remain uniformly valid for all observation angles, including the shadow boundary, the reflection boundary and the caustic direction where the conventional Geometrical Theory of Diffraction (GTD) breaks down. Furthermore, we show how the accuracy of STD can be improved and its range extended by combining it with integral equation methods in the spectral domain. This work was supported in part by U.S. Army Research Grant DAHC04-74-G0113 and in part by Office of Naval Research Grant N00014-75-C-0293.     

Diffraction of oriented nano-peapods

This paper presents an investigation of the structural properties of oriented A@SWNT peapods, where A represents any molecular species organized on a 1D cristalline chain inside the single wall nanotubes (SWNT). This study is based on the use of diffraction methods applied to the case of oriented A@SWNT samples. Two preferential orientations of tubes are considered, 1D (fiber) and 2D (pellet) both having an axial symmetry. We show that even in the case of samples presenting a very large mosaic, information about the correlation state between C₆₀ chains and about the C₆₀ polymerization, can be obtained provided that pertinent scans are performed. These are longitudinal scans along and perpendicularly to the symmetry axis accompanied by convenient constant Q scans. Detailed diffraction patterns are simulated in the case of a 2D oriented sample of C₆₀@SWNT peapods (`bucky paper').     

衍射光学透镜的设计

介绍一种衍射光学透镜的通用设计方法，它适用于大的相对孔径和任意的物像共轭距离，同时考虑了透镜基板厚度的影响．设计的结果，用激光写入法加工成透镜，其成像质量达到衍射极限．     

Diffraction of bending waves

This paper is a discussion of the theory of diffraction and scattering of bending waves by mass-impedance loadings of an infinite plane plate. Emphasis is placed on the case of heavy loadings, at which deflexions of the plate are precluded and the scattering is the strongest possible. Examples treated in detail include the diffraction grating, diffraction by a semi-infinite rib, and diffraction by a comb of semi-inifinite ribs.