频闪散斑照相法

本文讨论了频闪散斑照相法的基本原理,给出了简谐振动和非简谐周期振动散斑图的全场分析的平均光强分布和条纹可见度的解析式.理论和实验表明频闪散斑法较之时间平均散斑法有着明显的优点.     

线性相关计算形成数字剪切散斑相关条纹图

本文提出了用线性关计算法形成数字剪切散斑干涉纹的新方法，从理论分析和实验研究均证明，用该方法所获得的数字剪切散斑相关条纹图在图象监视器上易于观盾，条纹图象光强无直流分量影响且可见度较减模式要高，该新方法的采用为今后的条纹图象分析了奠定了基础。     

线性相关计算法形成数字剪切散斑相关条纹图

本文提出了用线性相关计算法形成数字剪切散斑干涉条纹的新方法,从理论分析和实验研究均证明,用该方法所获得的数字剪切散斑相关条纹图在图象监视器上易于观看,条纹图象光强无直流分量影响且可见度较减模式要高,该新方法的采用为今后的条纹图象分析奠定了基础。     

剪切散斑干涉术的统计分析

本文用统计光学方法分析了剪切散斑图的成象过程;散斑图的频谱分布以及全场滤波干涉条纹的形成.发现剪切散斑干涉条纹不仅与三维位移微分有关,而且与面内位移量有关.在此基础上又讨论了影响干涉条纹质量的有关因素,并作了实验验证.     

基于Gabor滤波的散斑条纹图平滑方法

提出了一种基于伽博(Gabor)滤波的散斑条纹图平滑方法.通过加窗傅里叶运算提取散斑条纹图的条纹频率和条纹梯度方向,并利用它们确定具有频率和方向选择性的Gabor滤波器对散斑条纹图进行Gabor滤波.数值模拟和实验结果表明,该方法在滤除散斑噪声的同时能够有效的保留散斑条纹图的条纹结构,为从单幅散斑条纹图中进一步提取条纹相位场奠定了良好的基础.     

数值孔径与数字剪切散斑干涉条纹亮度的关系

分析了数字剪切散斑干涉条纹图的形成理论，并获得了条纹亮度与摄象机数值孔径等参数的精确关系式，从理论分析和实验验证均得出在采用小的摄象机数值孔径和３ｍＷ Ｈｅ－Ｎｅ激光器的情况下，仍可获得比较满意的数字剪切散斑干涉条纹图，理论工作及其结论对于进行数字剪切散斑干涉实验的最佳参数选择具有指导作用。     

基于改进旋滤波的电子散斑干涉图滤波方法

电子散斑干涉术条纹图在成像时不可避免地受散斑噪声调制,去除噪声是散斑干涉条纹处理的一项重要任务。利用散斑条纹图的方向性,提出一种基于模糊方向的旋滤波:在当前点的领域内定义4个模糊方向窗口,将传统旋滤波的一维、精确方向窗口的确定,转变为模糊方向窗口的确定;在确定的窗口内进行低通滤波时,采用自适应加权均值滤波代替传统的中值滤波。利用该方法分别处理模拟散斑条纹图和实验所得的真实条纹图,并与传统旋滤波、双边滤波和小波丢弃子带方法比较。实验结果表明,该改进算法在滤除散斑条纹图噪声的同时,有效保护了条纹的细节信息。     

高斯光束照射下的等倾双光束干涉

根据等倾干涉原理，对高斯光束经薄膜反射后的光强、可见度、条纹分布进行了理论分析，讨论了入射角对光强、可见度分布的影响，相位角对条纹可见度的影响.数值模拟计算表明：沿着垂直于光传播方向的平面，反射光束叠加区域为一圆斑，随着入射角的增大，可见度逐渐减小，光强分布偏离了高斯分布，光斑变大，峰值减小.干涉条纹在空间的分布类似于平面波的薄膜等倾干涉，主要由入射角及薄膜厚度决定.     

基于散斑相位条纹方向的自适应正弦/余弦滤波

结合正弦/余弦(sin/cos)滤波技术提出了依据散斑相位条纹图的条纹方向自动选取滤波窗口大小的自适应滤波法。通过计算散斑包裹相位条纹图的条纹方向,依据相位条纹方向自动选择合适的滤波窗口,对散斑包裹相位图的sin和cos变换图同时进行自适应均值滤波,再通过四象限反正切算法得到包裹相位条纹图。实验结果表明,该滤波法能有效保护条纹相位跳变信息,对于条纹密度变化较大且形状复杂的散斑包裹相位图,仍能进行有效的条纹滤波处理,滤波后的相位条纹图更逼近于原始条纹走向。     

基于统计滤波的单幅散斑条纹图的相位恢复技术

基于统计信号处理技术的贝叶斯（Bayes）估计原理，提出一种新的滤波方法。该方法能有效减少散斑条纹图中的噪声，而且仅用一幅散区斑条纹图就能获得准确的条纹相位分布，通过实例说明了该方法的处理过程。     

A review of phase unwrapping techniques in fringe analysis

There has been an increasing interest in the automation of fringe analysis over the last decade. In recent years a number of researchers have addressed the problem of automatic phase unwrapping in fringe analysis. The advent of phase stepping and the development of FFT techniques has moved the emphasis in automated techniques away from fringe tracking and towards fringe counting or scanning approaches, but a major difficulty with such scanning techniques has been their susceptibility to noise. However, several alternative noise-immune phase unwrapping strategies have been proposed, but these approaches have not addressed the problems caused by large scale discontinuities such as those produced by aliasing. Other methods have been developed which confront this last difficulty. This paper gives an overview of the phase unwrapping problem and describes fringe tracking, fringe scanning, noise-immune and region processing techniques that have been developed in the search for the fully automated solution.     

Application of the FFT method for the quantitative extraction of information from high-resolution interferometric and photoelastic data

This paper describes the application of a digital Fourier transform to phase encoded intensity distribution. Attention is drawn to a method of extracting quantitative information automatically from the interferometric fringe data. To achieve this, a set of carrier fringes has been added to interferometric fringe data. This has made it possible to form a phase map using a FFT (fast Fourier transform) algorithm. A minimum spanning tree (MST) phase unwrapping strategy has been used to create a contiguous map of the whole fringe field. Finally, the measurement parameter related to the fringe field has been calculated from one single image. Experimental results are given for the burner flames, a compressible flow and photoelastic fringe data. It has been shown that the methods developed have the potential for use as reflection analysis systems suitable for applications to non-stationary objects and complicated fringe fields.     

散斑错位干涉术条纹的形成与特性分析

通过相关计算及滤波分析,建立了散斑错位干涉术条纹强度的统计分布,从而得到了这类条纹更为一般的特征属性.     

Time evolution of diffusion fringes in the Christiansen effect

When laser radiation is allowed to fall at the diffusion region separating two liquids in a Christiansen filter, a new fringe pattern appears. We termed it as “diffusion fringes”. In the present work, we have studied this interference fringe pattern and its time evolution. It has been observed that there is a definite co-relation between the shape of the fringe pattern and the width of the diffusion region. The time evolution of this fringe patterns indicates that as diffusion region increases the circular fringe becomes elliptical and finally straight. It is believed that a detailed investigation of these diffusion fringes will throw much needed light not only on the theory of the Christiansen effect but also on the rate of diffusion between two molecules.     

Fringe projection profilometry based on complementary color-encoded fringe patterns

3D measurement techniques based on color-encoded fringe pattern projection have been widely used in various fields of engineering recently. There is one problem that the surface color of measured object may interfere with the color of projected fringe pattern. To solve this problem, a novel method based on complementary color-encoded fringe projection is proposed. Two color-encoded fringe patterns whose fringe colors are complementary are designed. The first pattern is with the sinusoidal fringe embedding into the green color channel which is used to evaluate phases by Fourier transform method. The fringe color of the captured image is established with the help of the complementary color fringe pattern, which is based on the feature of color complementation. Thus, the influence brought by the color of object surface can be eliminated, and decoding errors can be further reduced. Experiment results indicate that the proposed method is valid and can be applied to the measured colorful objects.     

Fringe removal algorithms for atomic absorption images: A survey

The fringe noises disrupt the precise measurement of the atom distribution in the process of the absorption images. The fringe removal algorithms have been proposed to reconstruct the ideal reference images of the absorption images to remove the fringe noises. However, the focus of these fringe removal algorithms is the association of the fringe removal performance with the physical systems, leaving the gap to analyze the workflows of different fringe removal algorithms. This survey reviews the fringe removal algorithms and classifies them into two categories: the image-decomposition based methods and the deep-learning based methods. Then this survey draws the workflow details of two classical fringe removal algorithms, and conducts experiments on the absDL ultracold image dataset. Experiments show that the singular value decomposition (SVD) method achieves outstanding performance, and the U-net method succeeds in implying the image inpainting idea. The main contribution of this survey is the interpretation of the fringe removal algorithms, which may help readers have a better understanding of the research status. Codes in this survey are available at https://github.com/leigaoyi/Atomic_Fringe_Denoise.     

Consideration of Fractional Fringe Method on the Basis of the Least Squares Method

The traditional fractional fringe method has been applied to measure 1-dimensional size of a block gauge using multiple wavelengths. Recently, similar methods have been used in pattern interferometry and also in pattern projection profilometry. However, the technique does not seem to be based on a well-established principle. In this paper, the fractional fringe method is formulated on the basis of the least squares method and on its basis effects of errors in fractional fringes and wavelengths are analyzed and the effective selection of wavelengths is considered.     

基于CCD采集的Mach-Zehnder干涉条纹图的处理算法

Mach-Zehnder干涉仪适用于研究气体密度迅速变化的状态。由于气体折射率的变化与其密度的变化成正比,而折射率的变化将使通过气体的光线有不同的光程,因此可通过干涉臂变化对干涉条纹图像效果的影响得到气体密度。实测中,采用图像采集卡和CCD来接收Mach-Zehnder干涉仪产生的条纹图像,再通过计算机对条纹图像的条纹间距进行处理,从而得到气体密度的变化状态。从光干涉理论出发,对Mach-Zehnder干涉条纹图像特征进行了分析,建立了Mach-Zehnder干涉条纹的数学模型,并根据此模型设计了处理Mach-Zehnder干涉条纹图像的算法。算法包括图像的预处理(即图像的噪声提取)、图像的二值化及图像的细化。     

Time-average hologram interferometry of periodic,non-cosinusoidal vibrations

In the present paper, the method of time-average hologram interferometry has been applied to study periodic, non-cosinusoidal vibrations represented by a Jacobian elliptic function. For such vibrations the characteristic fringe function has been evaluated by making use of an equation derived from considerations of the effect of motion on coherence. Techniques of holographic addition and subtraction and extended pulse stroboscopic holography have been applied to analyze these vibrations in detail. Graphical representation of the fringe irradiance distributions in the reconstructed image is given in all the cases.     

Experimental observation of a strange temporal oscillation of X‐ray Pendellösung fringes

As a strange property not explained by existing theories, it has been known from experiment that X‐ray moiré and Pendellösung interference fringes show a small spatial oscillation in the beam path in free space that the diffraction image carrying those fringes is propagated after emerging from the crystal. In connection with the investigation into this strange fringe oscillation, it has been found, by an experiment successively recording Pendellösung‐fringe topographs using an X‐ray CCD camera, that X‐ray Pendellösung fringes also show a small temporal oscillation. Characteristics of this temporal Pendellösung‐fringe oscillation, namely irregularities in the fringe profile, the manner of fringe oscillation and a reciprocal correlation between oscillation amplitude and fringe contrast, are shown to be very similar to those of the previously reported spatial oscillation of moiré and Pendellösung fringes. Therefore this temporal oscillation is supposed to have the same origin as the spatial oscillation, revealing another section of the same phenomenon. This discovery of the temporal oscillation advances a step nearer to the full understanding of this strange phenomenon, while disclosing a new property of Pendellösung fringes. As well as the above, a three‐dimensional profile representation (surface plot) is given of the image of Pendellösung fringes, to make it clear that unidentified fine intensity modulations, called subfringes in this paper, are produced superposed on the main fringe system. Overall inspection of the intensity profiles of the fringe‐imaged topographs suggests that temporal intensity oscillations also occur on a more global scale than the extension of individual fringes, as an unidentified action of the wavefield.