【作者】 张芳；

【导师】 刘文耀；

【作者基本信息】 天津大学 ， 光学工程， 2009， 博士

【摘要】 电子散斑干涉测量技术(Electronic speckle pattern interferometry,简称ESPI)是一种全场非破坏性光学测量技术,广泛应用于粗糙表面的变形测量和无损检测。在应用该技术时,准确提取相位,对物体的位移、应变、振动等测量具有重要意义。目前最常用的相位提取方法是条纹中心线法和相移法,后者多用于静态测量,因其能够得到全场相位信息而备受关注。在利用条纹中心线法提取相位时,由于较强颗粒噪声的影响,条纹的可见度和分辨率很差,无法正确读取条纹信息,因此滤除条纹图中的噪声是正确判读条纹信息的关键。本文利用偏微分方程滤波方法和变分法滤除散斑噪声,深入研究了各种偏微分方程滤波模型和变分滤波模型对散斑干涉条纹图的滤波效果,分析各种模型滤波性能优劣的原因,在此基础上,提出基于条纹特征的、滤波性能更佳的偏微分方程滤波方法。对滤波后的条纹图进一步采取二值化、骨架线提取、条纹级数标定、插值一系列操作,得到物体的三维相位信息。在相移相位测量技术中,本文对相位图的生成方式、包裹相位图的滤波方法以及相位展开方法等关键技术进行了探讨和研究。由于电子散斑干涉测量技术具有实时显示、灵敏度高、全场测量等优点,该技术在工业无损检测中得到广泛的应用。本文利用电子错位散斑干涉方法,结合相移技术,搭建了一个小型化的错位相移无损检测系统,检测轮胎气泡缺陷。本文的创新性工作概括如下:(1)在散斑条纹图的滤波方面,改进了PM(Perona-Malik)变分滤波模型和总变分滤波模型。(2)提出了两个新的偏微分方程滤波模型:结合条纹的密度信息和其含有乘性噪声的特点,提出一种同态偏微分方程滤波方法;结合条纹的方向信息,提出一种基于条纹等值线和法向曲线的各向异性滤波模型,滤波效果良好。(3)在相位提取技术方面,将基于热传导方程的MBO(Merriman-Bence-Osher)方法引入条纹图二值化过程,并对其进行改进,二值化效果明显优于传统阈值方法;改进了最小二乘相位展开方法,提高了相位展开精度。(4)搭建了一个小型化的错位散斑相移轮胎气泡缺陷检测系统。对系统进行了总体设计,并获取了轮胎缺陷图片。系统可脱离防震台检测,切实可行。更多还原

【Abstract】 Electronic speckle pattern interferometry (ESPI) is a whole-field, nondestructive measurement technique, which is well-known for deformative and nondestructive measurement of coarse surface. As using this technique, accurate extraction of phase value is of fundamental importance for the successful measurement of displacement, strain and vibration. At present, two of the most comprehensive phase extraction techniques are the fringe-centerline method and the phase-shifting technology. The latter method is used for static measurement mainly, and is paid more attention because the whole-field phase information is available.As using fringe-centerline method to extract phase, the strong grain-shape random noise leads to heavy restrain to the fringe on visibility and resolving ability. It is difficult of accurate extraction of phase value from fringe patterns. Therefore, research on effectively filter to the fringe patterns is of fundamental importance for the development of ESPI. The partial differential equations (PDE) filter methods and the variational filter methods were used for noise reduction. We discussed the filter effect of various PDE filter models and variational filter models to ESPI fringe patterns, analyzed reasons of success or failure, and proposed more effective PDE filter models based on fringe features. After denoising, a series of operations, binarization, skeleton extraction, fringe order assignation and interpolation, were implemented and the three-dimension phase map was obtained. For phase-shifting technology, the generation modes for phase map, filter method for wrapped phase map and the phase unwrapped technique were studied.Owing to the prominent advantages, such as real-time display, high sensitivity and whole-field measure, ESPI is widely used in industrial nondestructive detection. Applying the electronic shearing speckle pattern interferometry (ESSPI) and the phase-shifting technology, a miniaturization shearing phase-shifting nondestructive detection system was set up for bubbles detection of tire.The major innovations achieved in the dissertation are as follows:(1) For noise reduction of ESPI fringe patterns, two variational filter models, i.e. PM variational model and total variational model, were improved.(2) Two new PDE filter models were presented. Considering the imfromation of fringe density and the feature of containing multiplicative noise, a homomorphic PDE filter method based on fringe orientation was proposed. And combining the isophote line and the normal curve, a new anisotropic PDE filter method was presented. The filter effect has been improved distinctly.(3) For phase extraction technology, the MBO algorithm based on the heat conduction equation was introduced for the binarization of fringe patterns for the first time, and the binarization effect by our improved algothm is better than that by those traditional threshold methods. Furthermore, the least-squares phase unwrapped method was reformed and the precision was improved.(4) A miniaturization shearing speckle phase-shifting system for bubbles detection of tire was set up. The overall design was made for the system and some images about tire defect were acquired. The system can not be quakeproof. The feasibility of the system was validated.更多还原