用菲涅耳衍射理论分析双光栅成像效应

从理论上对双光栅成像效应现象进行研究,分别从菲涅耳衍射理论和平面透射光栅的菲涅耳衍射公式出发,分析了物光波经过两个平行放置的平面透射光栅组成的系统衍射后的复振幅分布。分析结果表明,在理想状态下,当两个光栅的放置位置满足一定条件时,在第二个光栅后面可以观察到一个清晰的原物体图像。理论分析解释了两个光栅在双光栅成像效应中的作用,得到了双光栅成像效应发生时,两个光栅的空间频率、衍射光级数以及光栅放置位置之间的关系式,这与实验所得结果相一致。     

环形光栅的菲涅耳衍射

在圆孔的菲涅耳衍射的基础上 ,讨论环形光栅的菲涅耳衍射 ,并给出了计算机仿真结果     

菲涅耳圆孔衍射的解析处理

推导了傍轴条件下菲涅耳圆孔衍射场的级数解,进而讨论了一些具有重要理论和实验意义的问题。     

平面透射光栅的菲涅耳衍射

从标量场的菲涅耳衍射理论出发,研究了球面波入射平面透射光栅的衍射场,导出菲涅耳衍射场的复振幅分布,并得到光栅菲涅耳衍射角的计算公式．结果表明,在理想情况下菲涅耳衍射的每一级衍射波都是一个球面波;在对菲涅耳衍射角进行新的定义后,衍射角的计算仍然可以采用夫琅禾费衍射的光栅方程．     

菲涅耳圆孔衍射的解析处理

推导了傍轴条件下菲涅耳圆孔衍射场的级数解,进而讨论了一些具有重要理论和实验意义的问题．     

基于菲涅耳衍射的无透镜相干衍射成像

相干衍射成像是一种新型的无透镜成像技术,在光学测量、显微成像和自适应光学等领域有重要应用．本文提出一种基于单幅菲涅耳衍射强度图样的无透镜相干衍射成像方法;该方法采用特殊设计的卷积可解阵列抽样屏,通过对抽样物波的菲涅耳衍射强度图样进行非迭代的逆菲涅耳变换和滤波等数字处理实现被测物波复振幅信息的恢复,最后通过数字衍射得到物体的数字再现像．文中对抽样孔径、衍射距离、图像传感器尺寸等参数对再现像的影响进行了理论分析和模拟实验研究．发现在针孔大小和记录孔径大小一定的条件下,存在一个最佳的衍射距离;衍射距离过大会给重建图样带来噪声,衍射距离过小则会使再现象的分辨率降低．文中还对抽样针孔大小对系统成像分辨率的影响进行了分析,为进一步开展相关实验研究和应用提供了理论依据．     

验证菲涅耳圆孔衍射中的一个重要结论

验证菲涅耳圆孔衍射中的一个重要结论温淑珍（黑龙江绥化师专）在菲涅耳圆孔衍射中，如图１，圆孔ＣＣ’露出的波阵面，在与点光源Ｐ０处同一轴上的Ｐ点引起的光振动的振幅”’为其中山和山分别为波阵面上相对于ＰＯ和Ｐ所作的第一个和最后一个菲涅耳半波带单独对该点引起...     

菲涅耳轴上衍射场的计算

给出了一种计算菲涅耳衍射的方法,它既能比较精确地计算轴上的衍射场,也能用来近似地估算轴外的衍射场。     

菲涅耳型衍射光学元件的研究

本文在衍射理论基础上,深入分析了菲涅耳型衍射光学元件的特性,针对连续及二元浮雕结构,建立了位相深度因子(M),波长匹配系数(α)与衍射效率的关系式,对影响衍射效率的因素进行了讨论.研究了设计与工艺的匹配问题,建立了数值孔径,最小特征尺寸与衍射效率的关系,为不同波段衍射光学元件的应用,及设计和评价衍射光学元件提供了有效的理论方法.本文最后举例分析了用于白光波前传感器中的小数值孔径微透镜列阵的性能,并对衍射效率及传递函数两个综合指标进行了测量.     

部分相干光照明下光栅的塔尔博特效应

首先利用部分相干光理论详细地分析了在部分相干光照明下光栅的菲涅耳衍射,给出了观察面上衍射光强分布的一般公式,并就光源的发光面积对光栅塔尔博特效应的影响进行了讨论,得到了光栅衍射光强的分布随着照明光源的发光尺寸的增加而逐渐变得平滑这一结论．并且,当光源发光尺寸增加到毫米量级时,光栅的塔尔博特效应将完全消失。在实验上埘不同发光尺寸的扩展作相干光源照明光栅时的菲涅耳衍射光强进行了测量,实验结果与理论分析得出的结论相符合。     

Fresnel diffraction of truncated Gaussian beam

We study the Fresnel diffraction of Gaussian beam truncated by one circular aperture, and give the general analytic expression of the Fresnel diffraction of truncated Gaussian beam denoted by Bessel functions. Then the characteristic of the axial diffraction fluctuation and the influence of the caliber of the circular aperture and the wave waist of Gaussian beam on the diffraction distributions are discussed, respectively. Through the numerical calculations, the characteristics of the transverse diffraction are presented and the relationship of the fluctuation of the transverse diffraction profile and the position of the axial point is shown. The physical origin of the fluctuation of Fresnel diffraction intensities of truncated Gaussian beam is expressed in terms of Fresnel half-zone theory. These phenomena and the conclusions are important for the measurement of the parameters of the beam and its applications.     

An indirect algorithm of Fresnel diffraction

An indirect algorithm for Fresnel diffraction calculation at any distance is presented in this paper. Using this indirect algorithm, the Fresnel diffraction on a near plane can be realized in two steps, the first is to acquire the diffractive field on a far field and the second is to obtain the diffractive field on a near plane using an inverse Fresnel integral. Compared with conventional algorithms, this algorithm is valid at any range of distance. The sampling theorem, as the basis of this indirect algorithm, is discussed in detail. Theoretical calculations show good agreements with experimental results.     

Angular criterion to distinguish between Fraunhofer and Fresnel diffraction

The distinction between Fresnel and Fraunhofer diffraction is an essential condition for the accurate analysis of diffracting structures. In this paper we propose a criterion based on the angle subtended by the first minimum of the diffraction pattern from the centre of the diffracting aperture. The determination of the minimum of the diffraction pattern is the crucial point to assure the accuracy of the criterion. Therefore, the applicability of adequate thresholds for detection is discussed. The criterion is also generalized by expressing it in terms of the number of Fresnel zones delimited by the aperture. Simulations are reported to illustrate the feasibility of the criterion.     

菲涅耳衍射的数值计算

利用Mathematica软件分别计算了单缝衍射及双缝衍射的光强分布,成功解决了菲涅耳衍射的计算这一较难问题,并得到了双缝衍射向杨氏双逢干涉过渡的具体条件,完成了实验室内难以完成的任务.