Speckle Interferometry in harsh environments: design considerations and successful examples
Speckle Interferometry in harsh environments: design considerations and successful examples
复制标题
恶劣环境下的散斑干涉测量：设计考虑和成功案例
DOI：
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发表时间：
2018
期刊：
影响因子：
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通讯作者：
D. Willemann
中科院分区：
文献类型：
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作者：
A. Albertazzi;M. Viotti;F. Silva;C. Veiga;E. S. Barrera;M. Benedet;A. Fantin;D. Willemann
机械振动、空气和热不稳定性是最令人不安的因素之一，这些因素使得在恶劣环境中难以或不可能成功进行散斑干涉测量。通常，它们会破坏干扰信号，或者至少会显著降低干扰信号质量，从而将测量不确定性提高到不可接受的水平。了解干扰剂对散斑干涉测量的影响是找到在恶劣环境中进行有效测量的策略的第一步。在不利条件下成功测量有三种主要策略：隔离、鲁棒性和两者兼而有之。所谓隔离，我们指的是避免干扰因素对散斑干涉仪和被测对象的作用的方法。鲁棒性是指使用鲁棒的机械设计、鲁棒的光学技术、鲁棒的数据简化算法和/或不太受机械、热或空气不稳定性干扰的鲁棒配置。紧凑性、高刚度、坚固的机械设计和有效的夹紧系统是非常重要的考虑因素，可以最大限度地减少机械振动的影响。单次测量和平均也是最大限度地减少机械振动以及空气和热不稳定性的负面影响的强大策略。防护罩是减少空气不稳定性影响的有用解决方案，但有时对实现实验室外的热稳定性无效。稳健的光学技术可能是减少热膨胀效应的最有效方法。本文介绍了这些概念，并讨论了四个散斑干涉系统的作者开发和成功地使用在恶劣的环境中：消色差散斑干涉仪，使用衍射光学元件，已被应用于管道中的残余应力的原位测量。第二和第三系统是用于复合材料管的接头的粘附的现场测试的紧凑且可附接的剪切仪系统。最后，第四个系统是一个配置的剪切系统，使用两个光圈，以产生载波条纹的测量从一个单一的图像为每个加载阶段。
Mechanical vibrations, air and thermal instabilities are among the most disturbing agents that make difficult or impossible a successful speckle interferometry measurement in harsh environments. Usually, they destroy the interference signal or, at least, dramatically reduce the interference signal quality, what raises the measurement uncertainty to unacceptable levels. Understanding the effects of disturbing agents on speckle interferometry is a first step towards finding strategies to perform effective measurements in harsh environments. There are three main strategies to successfully measure under unfavorable conditions: isolation, robustness and both. By isolation, we mean ways to avoid the action of the disturbing agents on the speckle interferometer and on the measurand. By robustness, we mean using a robust mechanical design, a robust optical technique, a robust data reduction algorithm and/or a robust configuration that is not much disturbed by mechanical, thermal or air instabilities. Compactness, high stiffness, robust mechanical design and an effective clamping system are very important considerations to minimize the influence of mechanical vibrations. One-shot measurement and averaging are also robust strategies to minimize the negative effects of mechanical vibrations as well as air and thermal instabilities. Protective enclosures are useful solutions for reducing air instabilities effects, but sometimes ineffective for achieving thermal stability outside the lab. Robust optical techniques are perhaps the most effective way to reduce the effects of thermal dilatation. The paper describes these concepts and discusses four speckle interferometry systems developed and successfully used by the authors in harsh environments: An achromatic speckle interferometer, using a diffractive optical element, was developed and has been applied to in-situ measure of residual stresses in pipelines. The second and third systems are compact and attachable shearography systems for in-field testing of the adhesion of joints of composite material pipes. Finally, the fourth system is a configuration of a shearography system using two apertures to produce carrier fringes for the measurement from a single image for each loading stage.