The theory of the boundary diffraction wave for wedge diffraction

A new potential function, line integration which gives the edge diffracted fields, is constructed for wedge diffraction by using the method of modified theory of physical optics. The surface integrals are transformed into line integrals by the technique of asymptotic reduction. As an application of the novel potential function, the diffracted field is obtained for the geometry of a wedge for arbitrary incidence of plane waves.     

Quantum theory of light diffraction

At present, the theory of light diffraction only has the simple wave-optical approach. In this paper, we study light diffraction with the relativistic quantum theory approach. We find that the slit length, slit width, slit thickness and wavelength of light affect the diffraction intensity and form of diffraction pattern. However, the effect of slit thickness on the diffraction pattern cannot be explained by wave-optical approach, but it can be explained in quantum theory. We compare the theoretical results with single- and multiple-slits experimental data, and find the theoretical results are in accordance with the experimental data. In addition, we give some theory predictions. We think all new predictions will be tested by the light diffraction experiment.     

Modified diffraction theory of Kirchhoff

The diffraction theory of Kirchhoff is reinterpreted and a new form of a surface diffraction integral is developed by using the axioms of the modified theory of physical optics, which leads to the exact scattered fields by conducting bodies. The new integral is arranged according to the interpretation of Young, and the diffracted waves are expressed in terms of a line integral. The method is applied to the diffraction problem by a semi-infinite edge contour.     

基于一致性几何绕射理论的曲面表面绕射声场解

提出了一种基于一致性几何绕射理论的理想刚性光滑曲面表面绕射声场高频近似计算方法。分别以圆球和无限长圆柱为例,计算了其表面绕射声场,并将计算结果与解析解进行了比较。结果表明,该方法具有计算简单明确,物理概念清晰,计算结果精确的特点。     

Uniform line integral representation of edge-diffracted fields

A uniform line integral representation is derived for edge-diffracted fields by using the modified theory of physical optics and uniform asymptotic evaluation methods. The method is applied to the problem of diffraction of plane waves by a semi-infinite edge, which creates tip-diffracted fields with edge-diffracted waves. The uniform diffracted fields are plotted and examined numerically.     

Wave optical theory of in-focus Lorentz microscopy

The purpose of this paper is to evaluate the significance of Foucault-type electron micrographs of thin ferromagnetic films, taking wave optical effects into account. The film is considered as a pure phase object and the diffraction pattern is determined exactly for an extremely collimated incident beam. The illumination on the photographic plate is then evaluated when the diffraction pattern is cut by a knife edge, as a function of the position of the knife edge.     

5 × 5 Spot array based on two crossed single-groove gratings

Compared to the reported 5?×?5 spot arrays, we propose a way of generating a 5?×?5 spot array with much higher efficiency and better uniformity by using two crossed single-groove gratings. Normally, a single-groove grating cannot generate a 1?×?5 equal-intensity array by employing traditional Fourier optics theory. In this letter, we will show by vector diffraction theory that when the period of a single-groove grating is more than twice that of the incident wavelength, it may generate a 1?×?5 equal-intensity array. Based on this discovery, we expand the 1?×?5 array into a 5?×?5 spot array straightforwardly by using two crossed single-groove gratings. The dependence on the refractive index for producing a 1?×?5 equal-intensity array is interesting and we explain the phenomenon from the perspective of energy distribution by the simplified modal method.     

颗粒层状结构对散射特性及激光粒度测量的影响

根据Aden-Kerker理论,对双层颗粒前向散射特性进行了研究。在此基础上,分别用衍射理论、Mie理论和Aden-Kerker理论计算了散射系数矩阵并采用非独立模式算法进行反演。数值计算结果表明,双层颗粒的散射光强由颗粒折射率和内外径决定,在实际的激光前向散射粒度测量中,如果沿用Fraunhofer衍射理论或Mie理论计算系数矩阵,在测量双层颗粒时,反演结果会有一定的误差。相比于Mie理论,衍射理论的反演误差更大。     

Scattering of inhomogeneous plane waves by a truncated cylindrical cap

Scattered fields of the inhomogeneous plane waves from a truncated cylindrical cap are obtained. Also the uniform diffracted fields are performed in terms of the Fresnel functions. Reflected and diffracted fields are obtained by using the physical optics and the geometrical theory of diffraction methods, respectively. All the mentioned results are plotted numerically for various numerical parameters.     

角谱理论用于衍射光学元件数字仿真

本文采用衍射角谱理论对衍射光学元件的光场分布进行数字计算。该理论包括两种表达方式:既可用含有传递函数的等式表达,也可用含有点扩散函数的等式表达。这两种计算方法在本质上是一致的。然而,在MATLAB计算过程中,它们又具有不同的适用条件,通过分析,将它们分为近场算法和远场算法,并且展示了它们的计算实例。结果表明,在标量衍射理论成立的条件下,不改变衍射元件抽样间隔和抽样点数,利用这两种算法能够快速、准确计算不同位置处的衍射图样。该方法对衍射光学元件像面光场分布的精确计算具有重要的意义。     

Uniform theory for the diffraction of evanescent plane waves

A uniform diffracted field is obtained in terms of Fresnel functions with complex argument by subtracting the unit step function from the Fresnel integral. The method is applied to the problem of diffraction of inhomogeneous plane waves by a perfectly conducting half-plane and wedge. The results are plotted numerically and compared with results reported in the literature.     

Multiplication rule for the Collins diffraction formula obtained by virtue of the Fresnel operator in quantum optics theory

By using the Fresnel operator we derive a multiplication rule for the Collins diffraction formula; the inverse of Collins diffraction integration can also be conveniently derived in this way in the context of quantum optics theory.     

Diffraction of homogeneous and inhomogeneous plane waves by a planar junction between perfectly conducting and impedance half-planes

The problem of diffraction of homogeneous and inhomogeneous plane waves at the discontinuity formed by perfectly conducting and impedance half-planes is examined by the method of modified theory of physical optics (MTPO). The MTPO integral of the reflected scattered waves by the perfectly conducting half-plane is reconstructed in order to include the effect of the diffracted wave coming from the edge of the impedance half-plane. The integrals are evaluated by a uniform asymptotic method. The results are plotted numerically and compared with the literature.     

Carbon nanocones: wall structure and morphology

Large-scale production of conical carbon nanostructures is possible through pyrolysis of hydrocarbons in a plasma torch process. The resulting carbon cones occur in five distinctly different forms, and disc-shaped particles are produced as well. The structure and properties of these carbon cones and discs have been relatively little explored until now. Here we characterize the structure of these particles using transmission electron microscopy, synchrotron x-ray and electron diffraction. The carbon nanocones are found to exhibit several interesting structural features; instead of having a uniform cross-section, the walls consist of a relatively thin inner graphite-like layer with a non-crystalline envelope, where the amount of the latter can be modified significantly by annealing. The cones appear with a well-defined faceting along the cone edge, demonstrating strict long-range atomic ordering; they also present occasional examples of symmetry breaking, such as two apexes appearing in the same carbon nanocone.     

Z-scan的基础理论及技术回顾

由Sheik-Bahe于1989年提出的Z-scan技术已经成为在非线性光学和材料科学领域里的一项非常有用的测量方法,它能简单而灵敏地测量非线性光折射率和吸收率.本文概要地讨论了Z-scan技术并介绍了它的最新进展,其中着重讨论了高斯分解法对此项技术的理论研究.     

反射型阶梯光栅的特性分析

衍射效率是评价二元光学器件质量性能的重要指标之一.针对反射性阶梯光栅,利用几何方法计算出斜入射情况下光束在台阶边缘的光程差的分布情况,根据多缝夫琅和费衍射推导出反射型阶梯光栅的衍射光强表达式.并在此基础上,讨论了台阶数N取2和N趋向于无穷两种极限情况下阶梯光栅光强公式的变化情况,得到区别于一般文献所表达的衍射效率公式.初步试验表明,反射型阶梯光栅的衍射效率与台阶数、蚀刻深度与入射波长的比值均有密切相关.     

自聚焦变栅距光栅设计、制作及特性研究

利用变栅距光栅的衍射光束自聚焦特性,设计和制作了变栅距透射光栅,并对其自聚焦特性进行了研究.采用变栅距光栅的自动生成宏文件程序,优化设计了变栅距光栅的栅距变化.采用光栅扫描电子束光刻的方法制作了中心线数为300 1/mm、适用于355 mm波长的自聚焦变栅距变狭缝光栅.使用三倍频Nd:YAG激光器,研究了制作的变栅距光栅的聚焦特性,并与对氦氖激光的聚焦特性进行了比较.结果表明,主动式设计的变栅距变狭缝自聚焦光栅可以大幅提高衍射光强度和分辨本领,具有重要的应用价值.     

Carbon nanocones: wall structure and morphology

Abstract

Large-scale production of conical carbon nanostructures is possible through pyrolysis of hydrocarbons in a plasma torch process. The resulting carbon cones occur in five distinctly different forms, and disc-shaped particles are produced as well. The structure and properties of these carbon cones and discs have been relatively little explored until now. Here we characterize the structure of these particles using transmission electron microscopy, synchrotron x-ray and electron diffraction. The carbon nanocones are found to exhibit several interesting structural features; instead of having a uniform cross-section, the walls consist of a relatively thin inner graphite-like layer with a non-crystalline envelope, where the amount of the latter can be modified significantly by annealing. The cones appear with a well-defined faceting along the cone edge, demonstrating strict long-range atomic ordering; they also present occasional examples of symmetry breaking, such as two apexes appearing in the same carbon nanocone.     

Optimal design method for multi-layer diffractive optical elements with consideration of antireflection coatings

An optimal design method for multi-layer diffractive optical elements (MLDOEs) is put forward with consideration of antireflection coatings in actual applications of hybrid optical systems. Taking this method into account for optimal design, it can ensure 100% diffraction efficiency at the designed wavelengths and maximum polychromatic integral diffraction efficiency over the whole waveband. In addition, it can be obtained not only for mechanical durability of soft polymers improvements but increase antireflection coatings functions for hybrid optical systems. Finally, an example for optimal design algorithm process and simulation of MLDOEs used in visible waveband is presented. The results show that this optimal method perfects the MLDOEs design on the basic theory with great practicability for MLDOEs design.     

Dislocations in the field theory of elastoplasticity

By means of linear theory of elastoplasticity, solutions are given for screw and edge dislocations situated in an isotropic solid. The force stresses, strain fields, displacements, distortions, dislocation densities and moment stresses are calculated. The force stresses, strain fields, displacements and distortions are devoid of singularities predicted by the classical elasticity. Using the so-called stress function method we found modified stress functions of screw and edge dislocations.