基于多光束数字全息干涉技术的曲表面动态三维变形测量方法研究

How to measure dynamic three-dimensional deformation accurately is a key issue in the research of dynamics characterization of materials and structures.The traditional measurement method is to use the contact sensor and full-field information can not be achieved.Optical measurement techniques have the advantage of being full-field and non-contact and provides a new way for studying this issue. While the application of optical measurement techniques in materials testing and research has already achieved some acceptance in research and industry, its application to curved components has been limited, the main reason for this is that we can not ignore the influence of the sensitivity vector caused by the geometry on measuring three-dimensional deformation of the curved surface. This requires that the geometry and consequently the local variation of the sensitivity vector should be taken into consideration if deformations in three dimensions have to be measured on curved surface. To solve this problem， a novel non-contact measurement system that combines multi-beam digital holographic interferometry and high-speed digital image acquisition technology is proposed for dynamic three-dimensional deformation measurement on curved surface.The measurement system is based on the principle of the recording of four holograms in one digital image and independently digital reconstruction of the corresponding phase maps,Simultaneous measurement of the geometry and three-dimensional deformation can be achieved, therefore, it is suitable for a variety of transient deformation or periodical deformation measurement.This will provide a reliable experimental testing tool for the study of dynamics characterization materials and structures.

如何精确测量动态三维变形是进行动力学特性研究时的一个关键问题，传统的测量方法依靠接触式的传感器无法得到全场信息，光学测量技术具有非接触、全场测量的特点，这为研究这一问题提供了新的途径。尽管光学测量技术在材料试验和研究中已经得到了广泛的应用，然而针对曲表面试件的应用至今尚不够完善，其主要原因是不能忽略因几何形状而引起的灵敏度矢量变化所带来的影响。这就要求我们在测量三维变形的同时，还必须考虑曲表面几何形状的影响。针对这一问题，本项目利用基于多光束数字全息干涉的测量技术和高速数字图像采集技术相结合，建立一种新的能够满足曲表面动态三维变形非接触、高分辨和全场测量的光学测量系统以及编制相应的处理软件。该测量系统采用将四幅全息图同时记录于一幅数字图像中并独立重构各自相位的技术，可实现形貌与三维变形的同时测量，能够适用于各种瞬态或者周期性变形测量，为动力学特性分析提供可靠的实验测试手段。

如何精确测量三维变形是进行材料和结构力学特性研究时的一个关键问题，相关测量技术的研究已经越来越受到国内外学者的重视。针对曲表面试件的应用尚不够完善，其主要原因是不能忽略因几何形状而引起的灵敏度矢量变化所带来的影响。针对这一问题，本项目基于多光束数字全息干涉测量技术，建立一种新的能够满足曲表面三维变形非接触、高分辨和全场测量的光学测量系统以及编制相应的处理程序。该测量系统基于测量形貌的双波长方法和测量三维变形的不共面三光束方法原理，可实现形貌与三维变形的同时测量。针对多光束数字全息干涉相位图中散斑噪声严重的问题，提出了运用复相位技术和三维质量导向相位解包裹技术解决，获得了高质量的连续相位图。为适应不同的实验条件拓展测量范围，开展了非对称物光照射光路的多光束数字全息干涉测量系统研究，改进光路设计提高了测量精度。一系列的实验结果验证了测量系统的可靠性和准确性，通过与有限元模拟结果的对比得出测量的面内位移和离面位移相对误差小于10%，有利于其在实际工程中的推广应用，为材料和结构力学特性分析提供可靠的实验测试手段。