光盘信息符散斑图的统计特性研究

提出了一种用激光散斑测量光盘信息符统计特性的方法.利用散斑统计理论中衍射散斑场的平均对比度与散射屏表面粗糙度近似成线性关系,把光盘等效为弱散射屏,对未刻录、刻录及存在缺陷的CD-R光盘不同区域形成的衍射散斑图进行了对比研究.实验结果表明,该方法具有可量化、全场测量的优点,能够表征光盘信息符的某些统计特性,这为测量光盘刻录质量提供了一种新的方法和途径.     

脉冲相干激光雷达的散斑成像模型及其散斑噪声压缩

推导了脉冲相干激光雷达的散斑成像模型,证明了脉冲相干激光雷达图像中散斑噪声的乘法性质。根据其统计规律,提出一种新的用于散斑噪声压缩的并行加权均值多方向形态滤波算法。模拟结果表明此算法既有 地压缩了散斑噪声又保持了图像的几何结构,并且通过比较,证明其优于Safa的多方向形态滤波算法。     

相干激光雷达图像散斑噪声抑制算法

提出了一种新的用于散斑噪声抑制的非线性加权均值多方向形态滤波算法。运用此算法和先前提出的散斑噪声抑制算法以及小波软阈值算法和Lee滤波算法一并对相干激光雷达图像进行了噪声抑制处理，并且对处理的结果进行了比较，证明了本算法的进步，即在不降低噪声抑制能力的前提下，较好地保持了图像边缘。     

Algorithm for dynamic Speckle pattern processing

In this paper we present a new algorithm for determining surface activity by processing speckle pattern images recorded with a CCD camera. Surface activity can be produced by motility or small displacements among other causes, and is manifested as a change in the pattern recorded in the camera with reference to a static background pattern. This intensity variation is considered to be a small perturbation compared with the mean intensity. Based on a perturbative method we obtain an equation with which we can infer information about the dynamic behavior of the surface that generates the speckle pattern. We define an activity index based on our algorithm that can be easily compared with the outcomes from other algorithms. It is shown experimentally that this index evolves in time in the same way as the Inertia Moment method, however our algorithm is based on direct processing of speckle patterns without the need for other kinds of post-processes (like THSP and co-occurrence matrix), making it a viable real-time method. We also show how this algorithm compares with several other algorithms when applied to calibration experiments. From these results we conclude that our algorithm offer qualitative and quantitative advantages over current methods.     

激光散斑图样的光流场分析研究

提出了一种基于动态图像处理的新的电子散斑计量方法－光流场分析法，从新的角度出发讨论了运用图像序列分析的概念秋解决散斑图样测量的可行性和简便性。并且解决了当散斑图像不满足进行光流场分析的约束条件时的测量问题，即通过多通道的图像处理方法来改变图像连续特性，从而扩大了测量范围。     

基于自相关函数的激光散斑统计半径的测量

为了测量激光散斑的统计半径,运用统计光学理论推导了二维近场散斑光强的归一化自相关函数,并提出了通过求解散斑图像自相关拟合函数的系数来计算激光散斑统计半径的一种测量方法,利用该测量方法编制的测量软件可以方便地计算出激光散斑的统计半径.通过对尺寸已知的模拟散斑的测量,测量结果与实际尺寸相吻合,证实了该测量方法的可行性.     

部分相干离焦散斑照相的统计理论

运用散斑统计理论，探讨了部分相干离焦散斑照相的统计规律，指出了影响条纹质量的各种因素，并给出了实验验证。     

斜入射引入动态多重散射机制的激光散斑抑制

散斑抑制一直是激光显示技术的研究热点。对激光光束经SiO₂溶液所形成散斑的特性分析,建立了多重散射与散斑颗粒大小的联系。结合动态光散射理论,提出利用斜入射引入动态多重散射机制的激光散斑抑制方法,并构建由静态散射片和装有粒径为300 nm、摩尔浓度为3.0×10-4 μm-3的SiO₂悬浮液的光通管组成的散斑抑制装置,将其置入激光显示系统的光源部分。针对光束以不同入射角进入SiO₂悬浮液对散斑图像对比度影响进行了系统实验分析。结果表明,光束以约8°进入SiO₂悬浮液能将散斑图像的对比度从0.43降低至0.067。通过该方法实现了散斑颗粒的空间平均和散斑图像的时间平均,提高了散斑抑制的效果。散斑抑制单元无需振动装置且便于集成到激光投影系统中,不仅提高了系统的可靠性也减小了成本。     

基于图像熵的各向异性扩散相干斑噪声抑制

本文提出了一种基于图像熵的各向异性扩散滤波方法. 该方法使用图像熵作为边缘检测算子, 避免了由于均值和方差等统计量的估计带来的误差, 提高了边缘检测能力. 试验结果表明该方法能够获得比传统方法更好的相干斑噪声抑制效果. 关键词： 相干斑抑制 各向异性扩散 图像熵 合成孔径雷达     

内窥式散斑类共聚焦系统层析能力分析

本文研究了内窥式散斑类共聚焦系统(Endoscope-based speckle quasi-confocal system,EBSQCS)的层析能力。从散斑类共聚焦显微镜(Speckle quasi-confocal microscope,SQCM)成像原理出发,详细分析了内窥镜光学结构对散斑类共聚焦显微镜散斑场波动的影响规律,推导了内窥镜光学结构与内窥式散斑类共聚焦系统轴向分辨力的关系。实验测得了基于光纤束的内窥式散斑类共聚焦系统的轴向分辨力曲线。选用放大倍率4倍,光纤直径5μm的内窥镜系统的内窥式散斑类共聚焦系统轴向分辨力曲线的全峰半高是散斑类共聚焦显微镜的2.3倍,与理论计算值相符。实验结果表明内窥式散斑类共聚焦系统具有很好的轴向层析能力。     

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。     

天文望远镜像差对斑点成像技术的影响

着重研究了采用斑点成像技术处理天文望远镜图像时,光学系统固定像差对图像恢复结果的影响。在详细研究各种恢复天文图像振幅和相位的理论和方法的基础上,建立了一个包括Labeyrie振幅恢复方法和KnoxThompson相位重构方法的恢复扩展目标的斑点成像处理模型,分析了光学系统固定像差对系统传递函数相位分布和目标相位重构的影响：天文目标通过大气成像,固定像差将会被淹没在大气湍流随机起伏中,像差对相位重构没有显著影响。处理图像结果表明,斑点成像技术能同时消除大气湍流和望远镜系统固定像差的影响,得到高分辨力的扩展目标图像。还提出了一种消除光学系统像差的方法。     

高速动态非接触激光光学法测量光纤外径

光纤拉丝过程中必须对纤丝外径进行精密测控,但是通常用于圆柱形物体动态非接触测量的方法(如相关光通量比较法、电压鉴别法、补偿光通量法等等)精度太低,测量范围难适于光纤测量。本文介绍了四种测量高速运动的光纤外径很有效的非接触式激光光学测量方法:1.前向光散射法。它测量的是激光束射到光纤上的散射角和散射条纹;2.后向光散射法。它测量后向散射条纹的间隔; 3.直接衍射法。它测量激光束直射到光纤上产生的衍射图象;4.计量光脉冲法。它测量与光纤外径有关的光脉冲效。文中还对此四种方法进行了讨论。     

Speckle statistical properties of Gaussian beam from a semi-rough target in the atmospheric turbulence

Based on extended Huygens–Fresnel principle and Goodman model for target surface, analytic expression is developed for the mutual coherent function (MCF) of a reflected Gaussian-beam from a semi-rough target in single-pass atmospheric turbulence. Then according to the MCF we derive expression about the mean intensity and average speckle size at the receiver. The analysis indicates that the mean intensity is closely related to the ratio of root mean square (rms) height to the lateral correlation length; in addition, the speckle size is associated with turbulence strength and roughness of target. Our results agree with well-known the limiting cases of perfectly smooth and Lambertian target.     

Statistical Properties of Laser Speckles Generated from Far Rough Surfaces

The statistical properties of speckle patterns generated from far rough surfaces, under illumination of a Gaussian beam, are investigated. The surface roughness dependence of the first- and second-order moments of intensity is theoretically investigated, and their analytical expressions have been derived and presented. The analysis indicates that the mean intensity distribution on the receiver plane is closely related to the ratio of the lateral correlation length to the surface root mean square (rms) height. On the other hand, the speckle size and the correlation degree of the speckle intensities are found to be independent of the parameter characterizing the roughness of a surface, and are only determined by the laser beam waist.     

基于图像处理技术的数字散斑照相

提出一种新的数字散斑照相计量方法,该方法研究将ＣＣＤ和计算机相结合,在自然光照下了对被测量物体照相,通过一种快的图像处理,直接提取物体变形信息。突破光测的激光照明及傅里叶变换模式,实现光测量技术真正自动化。     

Robustness of Objective and Subjective Speckle Patterns in the Speckle Strain Gauge

The robustness to rigid body object motions of three optical systems used in the speckle strain gauge were experimentally investigated and compared with analytical results of the correlation. It was found that an out-of-plane motion of the object damaged the reliability of the strain measure when recording the objective speckle patterns while subjective speckle patterns were more robust. Besides out-of-plane object motions, the robustness of a free-space geometry and an afocal imaging configuration are approximately the same, while a telecentric imaging system is more robust to rigid body motions but more sensitive to deformation gradients (basically in-plane rotation and tilt). Results from a measurement of the relaxation in a lead-tin alloy used in organ pipes is also presented.Presented at 1996 International Workshop on Interferometry (IWI ‘96), August 27-29, Wako, Saitama, Japan.     

时间序列动态散斑相关跟踪测量原理及其应用

在对散斑场的特性进行研究与分析的基础上,提出了时间序列动态散斑相关跟踪测量法,它弥补了一般散斑相关法不适合大变形测量的缺点,扩大了散斑相关法的应用范围.运用这种方法不仅可以测量大动态范围的面内变形,而且可以测量分析面内动态变形过程和变形速度.     

Speckle correlation for the analysis of random processes at rough surfaces

The importance of technological processes like corrosion, ablation or deposition causes interest in the quantitative monitoring of changes at rough surfaces. Thus, there is a need for effective methods to measure the statistical parameters characterizing changes in the profile or the material composition of such objects. The speckle field scattered from the surface is used as information carrier and its change is measured by correlation. This is realized by sophisticated data acquisition and digital processing techniques. An important issue is the interpretation of the correlation output in terms of statistical parameters describing the surface change. For many random surfaces a geometrical relation between surface profile and optical phase proves satisfactory. This allows to determine the standard deviation of the profile change. For a verification, speckle decorrelation in model surfaces of known deviation is measured. The paper introduces the speckle correlation concept, outlines some history and current setups and describes methods for data evaluation. The reliability of the quantitative interpretation of the speckle decorrelation is demonstrated. The method is illustrated by studies of metal corrosion and material removal in the cleaning of historical objects by laser ablation.