Fresnel波带片的衍射场

本文从Ｈｕｙｇｅｎｓ－Ｆｒｅｓｎｅｌ原理的表式出发，用Ｆｏｕｒｉｅｒ－Ｂｅｓｓｅｌ变换讨论Ｆｒｅｓｎｅｌ波带片衍射场的特征，可以很自然地得到波带片的一系列焦点位置，求得焦平面上复振幅及光强的分布     

软X射线Bragg-Fresnel二维聚焦镜的设计理论和方法

Ｘ射线Ｂｒａｇｇ－Ｆｒｅｓｎｅｌ元件是近十年发展起来的一种用于Ｘ射线波段的新型光学元件。本文介绍一种具有二维聚焦效能的Ｂｒａｇｇ－Ｆｒｅｓｎｅｌ元件的设计理论和方法。设计中采用衍射理论并用Ｃ语言编制计算机程序系统对衍射图形进行设计。对于使用波长１３．８ｎｍ，入射角５°，使用焦距２００ｍｍ的使用条件，设计结果为３５Ｍｏ／Ｓｉ双层多层膜，周期厚度７．１４ｎｍ，理论反射率约为６０％；衍射图形共４００个环带，最内环半宽度５２．５μｍ，最外环宽度１．３μｍ。     

关于临界角法菲涅耳公式简化理论处理的新方法

本文研究了光束入射角位于临界角附近的Ｆｒｅｓｎｅｌ公式的简化处理，并导出临界角法光学调焦误差表达式，展开了讨论与分析。     

超导Fresnel公式及其应用

本引入两个位函数Пｓ和Пｓ＾＊，导出了超导的导波方程及其在谱域中的表达式，推导和扩充了Ｆｒｅｓｎｅｌ’ｓ公式的内容，使之成为研究超导体界面电磁特性的有力的数学工具，并用它对ＳＩＳ结构和ＩＳＩ结构进行了讨论，求解了常规金属在高低温下的表面阻抗及超导体的表面阻抗。     

处理金属闪耀光栅的多次基尔霍夫积分法

在散射场「通过菲涅耳（Ｆｒｅｓｎｅｌ）反射系数决定于入射场」的边界条件铁定理及等效场原理的支持下,完善了金属闪耀光栅的多次基尔霍夫（Ｋｉｃｈｈｏｆｆ）积分方法;并以利特罗（Ｌｉｔｔｒｏｗ）安装及固定偏向角安装的理想金属导体闪耀光栅对不同波长平面电磁波衍射效率的计算实例,探讨了此方法的稳定性与自洽性。     

Single-atom-response to a Partially Coherent Intense Laser Field

Ｓｉｎｇｌｅ┐ａｔｏｍ┐ｒｅｓｐｏｎｓｅｔｏａＰａｒｔｉａｌｙＣｏｈｅｒｅｎｔＩｎｔｅｎｓｅＬａｓｅｒＦｉｅｌｄＨＵＳｕｘｉｎｇＸＵＺｈｉｚｈａｎ（ＳｈａｎｇｈａｉＩｎｓｔｉｔｕｔｅｏｆＯｐｔｉｃｓａｎｄＦｉｎｅＭｅｃｈａｎｉｃｓ，ＣｈｉｎｅｓｅＡｃ...     

Excitation Intensity Dependence of Free-exciton Transitions in GaN Grown by Low-pressure Metalorganic Chemical Vapor Deposition

ＥｘｃｉｔａｔｉｏｎＩｎｔｅｎｓｉｔｙＤｅｐｅｎｄｅｎｃｅｏｆＦｒｅ┐ｅｘｃｉｔｏｎＴｒａｎｓｉｔｉｏｎｓｉｎＧａＮＧｒｏｗｎｂｙＬｏｗ┐ｐｒｅｓｕｒｅＭｅｔａｌｏｒｇａｎｉｃＣｈｅｍｉｃａｌＶａｐｏｒＤｅｐｏｓｉｔｉｏｎＧ．Ｄ．Ｃｈｅｎ（Ｄｅｐａｒ...     

A Simpler and More Precise Data Processing Method of SPIDER and Its Apparatus Design

1　Ｉｎｔｒｏｄｕｃｔｉｏｎ　　Ｔｈｅｍｅｔｈｏｄｓｔｈａｔｃａｎｍｅａｓｕｒｅｔｈｅｐｈａｓｅａｎｄｔｈｅ ｐｕｌｓｅｄｕｒａｔｉｏｎｍａｉｎｌｙｉｎｃｌｕｄｅｔｈｅＦＲＯＧ[1] (ｆｒｅｑｕｅｎｃｙ -ｒｅｓｏｌｖｅｄｏｐｔｉｃａｌｇａｔｉｎｇ)ａｎｄｔｈｅＳＰＩＤＥＲ[2 ] (ｓｐｅｃｔｒａｌ ｐｈａｓｅｉｎｔｅｒｆｅｒｏｍｅｔｒｙｆｏｒｄｉｒｅｃｔｅｌｅｃｔｒｉｃ ｆｉｅｌｄｒｅｃｏｎｓｔｒｕｃｔｉｏｎ) .ＦＲＯＧ[1] ｕｓｅｓｔｈｅｕｎｋｎｏｗｎｐｕｌｓｅｉｔｓｅｌｆａｓａｔｉｍｅ ｄｅｌａｙｅｄ ｇａ…     

Experimental Study on Flashlamp Pumped Nd~(3+)∶KGd(WO_4)_2 Laser

1　Ｉｎｔｒｏｄｕｃｔｉｏｎ　　Ｔｈｅｒａｐｉｄｄｅｖｅｌｏｐｍｅｎｔｏｆｈｉｇｈ ｐｏｗｅｒｄｉｏｄｅｌａｓｅｒｓｈａｓｒｅｓｕｌｔｅｄｉｎｔｈｅｓｅａｒｃｈｆｏｒｍｏｒｅｅｆｆｉｃｉｅｎｔｓｏｌｉｄ ｓｔａｔｅｌａｓｅｒｍａｔｅｒｉａｌｓｆｏｒｖａｒｉｏｕｓａｐｐｌｉｃａｔｉｏｎｓ.Ｔｈｅｌａｓｅｒｅｍｉｓｓｉｏｎｆｒｏｍｔｈｅ4Ｆ3 / 2 4Ｉ11/ 2 ｔｒａｎｓｉｔｉｏｎｏｆＮｄ3 + ｉｏｎｓｈａｓｂｅｅｎｏｂｓｅｒｖｅｄｉｎａｖａｒｉｅｔｙｏｆＮｄ ｄｏｐｅｄｃｒｙｓｔａｌｓｕｓｉｎｇｆｌａｓｈｌａｍ…     

Studies on the SFD Properties of Nd_xGd_(1-x)Ca_4O(BO_3)_3 Solid-solution Crystal

1　Ｉｎｔｒｏｄｕｃｔｉｏｎ　　Ｉｎｔｈｅｐａｓｔｆｅｗｙｅａｒｓ,ｓｍａｌｌｓｉｚｅｄＳＦＤｌａｓｅｒｈａｓａｔｔｒａｃｔｅｄｇｒｅａｔａｔｔｅｎｔｉｏｎｓ.Ｌａｓｅｒｄｉｏｄｅ(ＬＤ)ｐｕｍｐｅｄｓｏｌｉｄｓｔａｔｅｌａｓｅｒｓｈａｖｅｂｅｅｎｆｏｕｎｄｖｅｒｙｕｓｅｆｕｌｉｎｔｈｅｆｉｅｌｄｓｏｆｍｉｌｉｔａｒｙ,ｉｎｄｕｓｔｒｙ,ｍｅｄｉｃａｌｔｒｅａｔｍｅｎｔａｎｄｓｃｉｅｎｔｉｆｉｃｒｅｓｅａｒｃｈｅｓｄｕｅｔｏｔｈｅａｄｖａｎｔａｇｅｓｏｆｈｉｇｈｓｔａｂｉｌｉｔｙ,ｃｏｍｐａｃｔｎｅｓｓ…     

一种菲涅尔全息图的快速算法

通过分析菲涅尔全息图计算模型,发现大量的平方运算和三角函数运算是计算速度的瓶颈,提出了一种菲涅尔全息图的快速计算方法.根据菲涅尔全息图的数学模型,利用三角函数的和差化积公式,将全息图的数学模型变换为由仅与水平或垂直方向有关的独立分量,通过四则运算来表示.在菲涅尔全息图的计算中,用少量的三角函数、平方运算和大量的四则运算代替原来大量的三角函数和平方运算,减少了全息图的运算量.实验表明,采用该算法后全息图的计算速度提高了9倍以上.     

X光能点、放大倍率及针孔尺寸对空间分辨的影响

X光针孔成像是惯性约束聚变(ICF)研究中重要的诊断方法,对其点扩散函数的计算可用于图像重建和系统空间分辨的判断。对菲涅耳衍射公式进行了化简,分析了X光能点、针孔尺寸及放大倍率对针孔点扩散函数的影响。实验在保证成像能获得足够高信噪比的条件下,通过模拟获得在最佳空间分辨时所要的针孔大小、放大倍率和X光能点等参数。在流体力学不稳定性的静态样品定标实验中,通过模拟获得了针孔的调制传递函数(MTF),结合实验测量的结果反推获得分幅相机本身的MTF值。同时采用测刀边函数的方法获得了分幅相机本身的刀边函数,进而得到相机在各空间频率下的MTF值。两种方法得到的分幅相机MTF值一致,验证了通过菲涅耳衍射模拟X光针孔成像的可行性。     

应用反射型球面菲涅耳波带片的成像物镜设计

设计了一种应用球面菲涅耳波带反射面与非球面反射面结合的成像物镜。对球面结构的菲涅耳波带反射面进行分析,推导了球面菲涅耳波带反射面近似替代非球面的方法,采用单片球面菲涅耳波带反射面和三片非球面反射面设计成像物镜,在放大倍数100×、视场角120°、菲涅耳数2.5情况下,调制传递函数在放大成像侧可实现0.6 lp/mm的40%以上,畸变小于2.2%。该设计方法为菲涅耳波带片应用于可见光成像提供了参考,并随着菲涅耳器件加工技术的不断发展具有良好的应用前景。     

Relations between chirp transform and Fresnel diffraction, Wigner distribution function and a fast algorithm for chirp transform

Two physical interpretations of chirp transform related to Fresnel diffraction and Wigner distribution function are given.The chirp transform can be regarded as a Fresnel diffraction observed on a spherical tangent to the diffraction plane,or a rotation and stretching transformation of the Wigner distribution function space.A general fast algorithm for the numerical calculation of chirp transform is developed by employing two fast Fourier transform algorithms.The algorithm,by which a good evaluation can be achieved,unifies the calculations of Fresnel diffraction,arbitrary fractionalorder Fourier transforms and other scalar diffraction systems.The algorithm is used to calculate the Fourier transform of a Gaussian function and the Fourier transform,the Fresnel transform,the Fractional-order Fourier transforms of a rectangle function to evaluate the performance of this algorithm.The calculated results are in good agreement with the analytical results,both in the amplitude and phase.     

Beam spreading of truncated Gaussian beams in Kolmogorov turbulence

Based on the extended Huygens-Fresnel principle and the hard-edge aperture function expanded as the sum of finite-term complex Gaussian function, analytical expression for average intensity of truncated Gaussian beam in Kolmogorov turbulence is derived, and some limiting cases are discussed. The influences of many factors, such as Fresnel number, wavelength, truncation parameter and structure constant on beam spreading are studied with the help of the average intensity formula. We found that the peak value of average intensity decreases and the beam spot spreads with the decrease of Fresnel number. The change of peak intensity against Fresnel number is slower with large aperture than that with small aperture. When Fresnel number is not small enough the influence of turbulence on intensity profiles is so small that can be neglected if structure constant is small.     

Partially coherent Fresnel diffraction by a slit aperture. IV. Effect of the phase term in the coherence function

A formula was derived in paper 1 of the this series for investigating the Fresnel diffraction field of a slit aperture when the mutual coherence function of the illumination contains a quadratic phase term. That formula is applied to study the intensity distribution in the Fresnel diffraction field of a slit aperture illuminated by a quasi-monochromatic incoherent slit source. The phase term has a big effect on the features of Fresnel diffraction.     

Partially coherent Fresnel diffraction by a slit aperture. III. Fresnel diffraction patterns

The intensity distribution in the Fresnel diffraction pattern of a slit aperture illuminated with partially coherent light is obtained, as a function of the coherence condition across the aperture, by evaluating the formula developed in a previous paper. It is shown that the Fresnel diffraction pattern is affected by the coherence condition of illumination across the aperture and its form.     

Partially coherent Fresnel diffraction by a slit aperture. II. Axial intensity distributions

The general formula derived in a previous paper is applied to obtain the intensity distribution along the axis normal to a slit aperture in the Fresnel diffraction field when the spatial mutual coherence function of the illumination over the aperture takes three different forms of correlation. It is shown that the axial intensity distribution of Fresnel diffraction by the slit aperture is effectively influenced by the coherence condition across the diffracting aperture.     

A successive scattering methodology with application to two cylinders in the Fresnel region of each other

We present an efficient approach to compute the second-order scattering of an electromagnetic wave by two discrete scatterers in proximity to each other. Such a two-body system represents the simplest canonical arrangement to address near-field volume scattering phenomena in microwave remote sensing models of vegetation. Using an analytical wave-based approach, a successive scattering methodology is employed to derive the first interaction term in multiple scattering by two arbitrary scatterers in terms of their transition operators. The general formulation is applied to find the second-order bistatic scattering amplitude for a pair of finite length thin cylinders at arbitrary interaction distances using the exact Green's function. To improve computational efficiency, the solution is then specialized to the Fresnel region. These second-order bistatic scattering amplitude results are in agreement with the exact Green's function model when the scatterers are in the Fresnel region of each other. Additionally, it is demonstrated that using the far field approximation in the Fresnel region can yield significant deviations from the exact results. The Fresnel model, unlike the far field approximation, accurately predicts the scattering amplitude peak values and null locations, and is suited to fast solutions in realistic canopy simulations.     

光学系统像点附近的光强空间分布

根据准确的菲涅耳衍射振幅和光强解析表达式推导出光学系统像点队近的光强空间分布。与采用洛梅尔函数计算不同,文中使用常用的贝塞尔函数准确地计算了光强空间分布,从而使计算更容易、结果更直观。并对菲涅耳数这一物理概念进行了论述。