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全息术解析光波干涉与衍射现象在现代光学中，全息术是一种基于光波干涉与衍射现象的高级光学技术。
通过使用全息术，可以将光波的相位和振幅信息完整地记录下来，并在后续的观察中进行重建。
全息术被广泛应用于三维成像、图像存储和显示等领域，为我们带来了许多重要的科学和技术进展。
光波干涉是指两个或多个光波的相遇产生的现象。
当两个光波的相位相同或相差等于2π的整数倍时，它们会互相增强，形成亮纹。
相反，当两个光波的相位相差等于(2n+1)π时，它们会互相抵消，形成暗纹。
在全息术中，通过将这种相位差信息记录下来，我们可以在后续的观察中还原出原始光波的全息图像。
光波衍射是指光波在通过孔隙或物体边缘时出现偏折和扩散的现象。
当光波通过一个窄的缝隙或孔洞时，它会向四周扩散，形成衍射图样。
这种扩散效应使得我们能够观察到物体的微小细节。
在全息术中，通过记录光波的衍射图样，我们能够在后续的观察中还原出物体的全息图像。
全息术的基本原理是将物体的光波信息通过干涉或衍射的方式记录在一块光敏介质上。
当这块光敏介质被光照射时，光波的相位和振幅信息将被记录下来。
在全息图形成之后，我们可以使用与原始光波相同的光束照射到全息图上，通过光的干涉或衍射效应，将记录下来的光波信息重建出来。
全息术有两种主要类型，即传统全息术和数字全息术。
传统全息术使用光敏材料作为记录介质，需要使用化学处理才能在干净的环境中观察到全息图像。
而数字全息术使用数字摄像机记录光波信息，并通过计算机处理和重建图像。
数字全息术具有实时处理和方便传输的优势，逐渐成为全息术的主流技术。
除了用于成像和显示，全息术还被应用于光学存储领域。
全息光盘是一种使用全息术记录和读取数据的介质。
与传统光盘相比，全息光盘能够存储更多的数据，并且具有更快的读取速度。
这使得全息光盘在信息存储和大容量数据传输方面具有巨大的潜力。
全息术的发展不仅推动了光学技术的进步，也为科学研究和工程实践带来了许多机遇。
它在医学成像、材料研究、人工智能等方面的应用也在不断拓展。
第三章确定应力强度因子叠加法及组合法第1节概述1、应力强度因子求解的重要性应力强度因子是线弹性条件下计算带裂纹结构剩余强度和裂纹扩展寿命必不可少的基本控制参量。
由于应力强度因子在裂纹体分析中的中心地位，它的求解自断裂力学问世以来就受到了高度的重视，迄今为止，已经产生了众多的方法。
应力强度因子与裂纹几何和荷载形式有关，两者的组合可以派生出许多种情况，从而使应力强度因子的求解变得很复杂。
2、常用应力强度因子求解方法常用的应力强度因子计算方法有两大类：一)理论计算方法1）解析法复变函数法、保角变换法等特点：计算精确，但适用范围窄2)数值法有限元素法、边界元法、无网格法等特点：适用范围宽，但计算效率较差3)半解析—半数值方法边界配置法等特点：适用范围比解析法宽，计算效率比数值法高二) 实验方法电阻应变片法、光弹性法、全息干涉法、散斑干涉法等3、应力强度因子一般描述形式应力强度因子可以描述为：K a=βσπ3-1-1I式中, σ是远离裂纹处的名义应力, a是裂纹尺寸。
因子β是裂纹几何形状、结构几何形状载荷形式以及边界条件等的函数, β是无量纲的。
对于无限大板, 中心穿透裂纹, 远处均匀受拉（单向或双向），应力强度因子为:=σπ3-1-2K aI其中a为半裂纹长度。
即在此情况下, β=1, 从而, 可以将β看作是一修正系数, 它使实际应力强度因子与无限大板的中心裂纹有关。
第2节叠加法1、叠加原理由于线弹性断裂力学方法建立在弹性基础上, 故可用线性累加每种类型载荷所产生的应力强度因子来确定一种以上的载荷对裂纹尖端应力场的影响。
在相同几何形状的情况下, 累加应力强度因子解的过程称为叠加原理。
造成同一开裂方式的应力强度因子求和过程的唯一限制是应力强度因子必须以相同的几何形状(包括裂纹几何形状)为前提。
——如果结构在几种或者特殊荷载作用下，产生了复合裂纹，则各型应力强度因子是在将荷载分解后各型裂纹问题的应力强度因子本身的叠加。
全息干涉术的原理和应用引言:全息干涉术是一种特殊的光学技术，借助光波的干涉原理，可以记录并再现物体的三维图像。
它具有广泛的应用领域，如娱乐、科学、医学等。
本文将介绍全息干涉术的原理和应用。
一、全息干涉术的原理全息干涉术基于光的两个主要特性：波动性和干涉性。
当一束光通过透明介质后，分为两部分：直射光和透过介质表面反射后进入物体再反射回来的光。
这两束光相互干涉形成干涉条纹，记录下来的全息图像就是干涉条纹的模样。
全息干涉术的关键在于使用一个参考光波和一个照明光波。
参考光波是一束与照明光波相干的平行光，它通过物体并和物体反射出来的光相交。
当参考光波和物体反射光波相遇时，会发生干涉现象。
通过调节参考光波的相位差，我们可以记录下完整的干涉图像。
二、全息干涉术的应用1. 三维图像展示全息干涉术可以将物体的完整三维信息记录下来，并通过光的干涉现象再现出来。
这种技术被广泛应用于三维图像展示，如全息照片、全息电影等。
观看者可以从不同角度欣赏到物体的真实外观，增强了视觉体验。
2. 医学和生物学全息干涉术在医学和生物学领域有重要应用。
它可以帮助医生和研究人员观察细胞、纤维和其他微小结构，以便更好地理解它们的形态和功能。
通过全息干涉术，可以捕捉到细胞的三维形状和细节，从而提供更准确的诊断和治疗。
3. 材料科学全息干涉术在材料科学中也有着重要的应用。
它可以帮助科学家们研究材料的内部结构和性能。
通过记录材料的干涉图像，可以获取材料的隐含信息，比如应力分布、形变等。
这对于材料设计和评估非常有价值。
4. 安全技术全息干涉术在安全技术领域也有广泛应用。
比如，全息干涉术可以用于防伪技术，将难以复制的图案和信息记录在光敏材料上，以保证产品的真实性。
此外，全息干涉术还可以用于指纹识别和虹膜识别等生物识别技术中，提高安全性和准确性。
总结:全息干涉术作为一种基于光的干涉现象的技术，具有广泛的应用领域。
它的原理是利用两束相干光的干涉现象记录物体的三维信息，并可以再现出真实的图像。
全息干涉与散斑干涉技术综述报告全息干涉无损检测技术是无损检测技术中的一个新分支，它是20世纪60年代末期发展起来的，是全息干涉计量技术的重要应用。
我们知道结构在外力的作用下，将产生表面变形。
若结构存在缺陷，则对应缺陷表面部位的表面变形与结构无缺陷部位的表面变形是不同的。
这是因为缺陷的存在，使得缺陷部位的结构的刚度、强度、热传导系数等物理量均发生变化的结果。
因而缺陷部位的局部变形与结构的整体变形就不一样。
应用全息干涉计量技术就可以把这种不同表面的变形转换为光强表示的干涉条纹由感光介质记录下来。
而激光散斑技术是在激光全息实验中，我们观察被激光所照射的试件表面，就可以看到上面有无数的小斑点，因而观察不到条纹，因此在前期，散斑是被看作是噪声来对待的，直到随着人们对全息干涉技术的进一步了解，才发现虽然这些斑点的大小位置都是随机分布的，但所有的斑点综合是符合统计规律的，在同样的照射和记录条件下，一个漫反射表面对应着一个确定的散斑场，即散斑与形成散斑的物体表面是一一对应的。
在一定范围内，散斑场的运动是和物体表面上各点的运动一一对应的，这就启发人们根据散斑运动检测，来获得物体表面运动的信息，从而计算位移、应变和应力等一些力学量。
因此全息和激光散斑方法由于其固有的高灵敏度，在非破坏性测试领域发现了越来越多的应用。
可探测到表面及地下的裂缝、空洞、脱层和分层等缺陷。
由于这些方法测量了在外部加载或其他条件的影响下，在这三个维度下研究对象的变形，它们也可以用于质量控制，也可以用于设计阶段。
激光散斑的方法，还利用了电子检测和处理的发展(称为电视全息术)，并可用于实时定量评价。
本综述报告主要介绍利用光纤光刻技术，对全息和激光散斑测量方法进行了全面的研究，这两种方法都适用于焊接、复合材料的检验。
IntroductionHolography is a two step process of recording a wavefrontand then reconstructing the wave. While Holography is oftenused to obtain the recreations of beautiful 3-dimensional scenes,there are several engineering applications, the most common andimportant one being Holographic Non-Destructive Testing . Thisis accomplished with holographic interferometry, whereininterferometry is carried out with holographically generatedwavefronts .A speckle pattern is generated when an object with a roughsurface is illuminated with a highly coherent source of lightsuch as laser. Initially this speckle noise was considered asthe bane of holographers, until it was realized that these specklescarry information about the surface that produce them. Again,as in the case of holography, the combination of interferometric concepts with speckle pattern correlation gave rise to speckle interferometry . The developments in electronic detection and processing further added wings to laser speckle methods giving rise to Electronic Speckle Pattern Interferometry (ESPI), or “TV Holography”. This paper describes a brief outline of holographic and speckle methods for Non-Destructive Testing applications, wherein the deformations of an object under load are measured in a non-contact way. Measurement of surface shapes using contouring and derivatives of displacement using Shearography are also presented.1.HolographyThe schematic for recording a hologram is shown in Fig.1. The light from a laser is split into two beams. One beam illuminates the object and the other beam is used as a reference. At the recording plane, an interference of theFig. 1 : Experimental arrangement for recording a hologram. wavefront scattered by the object with the reference wavefront takes place. A recording is made on a high resolution photographic plate. The developed plate, now called a “Hologram”, when illuminated by the reference wave, reconstructs the object wave. There are several recording geometries such as in-line, off-axis, image plane, Fourier Transform, reflection and rainbow holograms. The theory behind the recording and reconstruction of object wavefront is well documented .1.1Holographic Interferometry (HI)While holography is used to obtain recreations of beautiful 3-D scenes, most engineering applications of holography make use of its ability to record slightly different scenes and display the minute differences between them. This technique is called Holographic Interferometry (HI). Herewe deal with Interference of two waves of which atleast one of the waves is generated holographically.Methods of Holography Interferometry are classified as (i) Real-time HI, (ii) Double-Exposure HI, and (iii) Time average HI. In holographic interferometry, we record the holograms of the two states of an object under test, one without loading and one with loading. When such a doubly exposed hologram is reconstructed, we see the object superposed with a fringe pattern which depicts the deformation undergone by the object due to loading. The theory behind the fringe formation in HI is as follows [3]:Let the O1 and O2 represent the undeformed and deformed object waves, which are written asO1(x，y) = |O(x，y)| exp[-i Φ(x，y)] (1)O2(x，y) = |O(x，y)| exp[-i Φ(x，y) + δ] (2) where δis the phase change due to displacement or deformation of the object. The intensity due to superposition of these two waves isI(x，y) = |O1(x，y) + O(x，y)|2= O1O1* + O2O2* + O1O2* + O1* O2= I1 + I2+ 2I1I2Cos δ(3)where I1 and I2 are the intensities of O1 & O2. The Phase Difference δ is given byδ = (K2-K1).L (4)where K2 is the observation vector, K1 is the illumination vector and L is the displacement vector. Thus the evaluationof the phase δis gives the displacement. The fringes formed represent contours of constant displacement.1.2Holographic Non-Destructive Testing (HNDT)This powerful technique of Holographic interferometry, is an invaluable aid in Engineering design, Quality Control and Non-Destructive testing and Inspection. In HNDT, the object under study is subjected a very small stress or excitation and its behavior is studied using HI.The defects in the object can be spotted as an anomaly in the otherwise regular fringe pattern. HNDT is a highly sensitive, whole-field, non-contact technique and is applicable to objects of any shape and size. The types of excitation used for HNDT are mechanical, thermal, pneumatic or vibrational. Defects such as cracks, voids, debonds, delaminations, residual stress, imperfect fits, interior irregularities, inclusions could be seen. HNDT is applied to inspect the disbonds between the plies of an aircraft tyre, delamination of the composite material of a helicopter rotor blade, PCB inspection, rocket castings, pressure vessels, andso on.Use of double-pulsed laser makes HI more attractive for study of transients and impact loads. Fig.2 shows the double exposure hologram of a turbine blade subjected to an impact loading (recorded using a double-pulsed Ruby laser).Fig. 2 : Double-pulse hologram of a turbine blade impact loaded with a small metallic ball.Time average HI, wherein a hologram of a vibratingobject is recorded, provides information about the modes and the vibration amplitudes at various points on the object. Figs.3(a) and (b) show the time average holograms of a rectangular plate vibrating at 1826 Hz and 5478 Hz, from which the resonant mode patterns could be easily studied . In HNDT, this technique is used for study of vibrations of machinery, car doors, engines and gear boxes and to identify the points where they should be bolted to arrest the vibration and noise.Fig. 3 : (a) and (b) Time averaged hologram of a centrally clamped plate at (0,0) and (1,0) mode when vibrated at 1826 Hzand5478Hz respectively2 22 22. Electronic Speckle Pattern Interferometry(ESPI)Recent holographic applications in engineering use a video camera for image acquisition, which is coupled to a computer image processing system. This is termed as TV Holography, though technically called Electronic Speckle Pattern Interferometry (ESPI). The technique makes use of the speckle pattern produced when an object with a rough surface is illuminated with a laser [4-6]. The correlation between the speckle patterns, before and after an object is deformed, are carried out using image processing techniques. Figure 4 shows the schematic of an ESPI system. The object is illuminated by the light from a laser and is imaged by a CCD camera. An in-line reference beam, derived from the same laser, is added at the image plane. The specklecorrelation is carried out by storing an image while the object is in its initial state, and subtracting the subsequent frame fromthis stored frame, displaying the difference on the monitor. When the object is subjected to some loading or excitation, the correlated areas appear black while the uncorrelated areas would be bright, resulting in a fringe pattern. As in HI,the fringes represent contours of constantdisplacement of the object points.The fringe formation in ESPI is well documented . The intensity distributions I 1(x,y) and 12(x,y) recorded before and after the object displacement respectively can be written asFig. 5 : Measurement of Poisson’s ratioI I (x,y) = a 1 +a 2 + 2a 1a 2 cos(ϕ) (5) I 2(x,y) = a 1 +a 2 + 2a 1a 2cos(ϕ+δ) (6)Fig. 4 : Experimental arrangement for ESPIFig. 6 : (a) Delamination in a plate (b) Longitudinal crack in asteel weldmentwhere a 1 and a 2 are the amplitudes of the object and reference waves, δ is the phase difference between them and ϕ is the additional phase change introduced due to the objectmovement. The subtracted signal as displayed on the monitor is given by,I 1 - I 2 = 4 |a 1a 2 Sin[ϕ + (δ/2)] Sin (d/2)|(7)Thus we find the brightness is modulated by a sine factor of the phase. The brightness on the monitor is maximumFig. 7 : Fiber Optic Shearography systemwhen δ = (2m +1)π and zero when δ = 2m π, which producesa fringe pattern on the monitor. The phase change δ is given by equation [4], the same as in holography. Figure 5 shows such an interferogram obtained by ESPI with a plate subjected to four-point bending, from which the Poisson’s ratio of the material of the plate could be calculated directlyfrom the smaller angle between the asymptotes of the hyperbolic fringes [8]. Figure 6(a) shows the delamination between two plates bonded together, while Fig. 6(b) shows a longitudinal crack in a weldments [9].4. Shearography In Shearography, we generate correlation fringes which are contours of constant slope of the out-of-plane displacement of an object under study . In this technique, one speckle field is made to interfere with the same speckle field, but sheared with respect to it. The subtractive correlation of the speckle patterns of the deformed and undeformed yields the derivatives of the displacement profile. Figure 7 shows the schematic of a fiber optic Shearography system. A double image of the laser illuminated object is made on the CCD camera. A small shear is introduced between the two images by tilting one of the mirrors. Incorporation of fiber optics makes the system very compactand the technique applicable to objects at inaccessible locations. Shearography is a very useful tool in experimental stress analysis and NDT as well. With the use of phase shifting techniques, the fringe patterns can also be automatically processed by the computer to obtainquantitative 3-dimensional plots . Figure 8 shows the results of an NDT application of Shearography to detect delamination in glass fiber reinforcedplastic (GFRP). The GFRP specimens were prepared withunidirectional glass fiber mat and epoxy resin with and without programmed defects. The defects were introduced by placing a thin Teflon film of 10 mm diameter and thickness 0.23mm between the layers of glass fiber mat during the lamination. Four layers of Glass fiber mat were used to make the laminate. The specimens were made in the form of circular diaphragm. The diaphragm was clamped along the edgesanFig. 8 : Slope fringes obtained on a circular GFRP specimen which was (a) Defect free (b) Having a programmed delaminationloaded mechanically at the center. The optical configuration of Fig. 8 was used, which is sensitive to the slope of the out- of-plane displacement. Figure 8(a) shows the fringes obtained with a defect-free specimen, while Fig. 8(b) shows the fringeswhen a delamination was introduced between the third and fourth layers. The defect site could be easily seen as a localized fringe. 全息无损检测主要还是采用全息干涉计量技术的三种方法进行，即实时全息干涉法，两次曝光全息法和时间平均全息干涉法。
《信息光学》课程教学大纲一、课程基本信息二、课程简介信息光学是应用光学、计算机和信息科学相结合而发展起来的一门新的光学学科，是信息科学的一个重要组成部分，也是现代光学的核心。
本课程主要介绍信息光学的基础理论及相关的应用，内容涉及二维傅里叶分析、标量衍射理论、光学成像系统的频率特性、部分相干理论、光学全息照相、空间滤波、相干光学处理、非相干光学处理、信息光学在计量学和光通信中的应用等。
三、课程目标本课程是光电信息科学与工程专业的主要专业课程之一，设置本课程的目的是让学生掌握信息光学的基本概念、基础理论及光信息处理的基本方法，了解光信息处理的发展近况和运用前景。
为今后从事光信息方面的生产，科研和教学工作打下基础。
四、教学内容及要求第一章信息光学概述（2学时）1.信息光学的基本内容和发展方向2.光波的数学描述和基本概念3.相干光和非相干光4.从信息论看光波的衍射要求：1.了解信息光学的内容和发展方向2.掌握相干光和非相干光的特点3.掌握从信息论的观点看光波的衍射。
重点：空间频率，等相位面。
从信息光学看衍射的基本观点。
难点：空间频率，光波的数学描述。
第二章二维傅里叶分析（8+2学时）1．光学常用的几种非初等函数2．卷积与相关3．傅里叶变换的基本概念4．线性系统分析5．二维采样定理要求：1．了解光学中常用非初等函数的定义、性质，熟悉它们的图像及在光学中的作用2．了解卷积与相关的定义及基本性质3．熟悉傅里叶变换的基本原理，性质和几何意义4．熟悉系统的基本概念及线性系统分析的基本理论5．了解二维采样定理及其应用6．本章强调概念的物理意义理解，以定性和应用为主。
避免与《信号与系统》课程重复。
重点：δ函数的意义和运算特性，傅里叶变换性质、定理，相关和卷积的意义及运算，线性空间不变系统的特性。
难点：卷积，傅里叶变换、系统分析。
第三章标量衍射理论（6+2学时）1．基尔霍夫衍射理论2．菲涅耳衍射和夫琅和费衍射3．夫琅和费衍射计算实例4．菲涅尔衍射计算实例5．衍射的巴俾涅原理要求：1．了解基尔霍夫衍射理论2．熟悉菲涅耳- 基尔霍夫衍射公式及其物理意义3．熟悉菲涅耳衍射与夫琅和费衍射4．掌握常见夫琅和费衍射光场的分析与计算5．了解菲涅耳衍射光场的分析和计算6．了解巴俾涅原理及其应用重点：如何用二维傅里叶变换来分析和计算夫琅和费衍射。
