Xie Xin, Lee Cheok Peng, Li Junrui, Zhang Boyang, Yang Lianxiang
Optical Laboratory, Department of Mechanical Engineering, Oakland University, 2200 N. Squirrel Rd., Rochester, Michigan 48309, USA.
Ngee Ann Polytechnic, 535 Clementi Road, Singapore 599489, Singapore.
Rev Sci Instrum. 2016 Aug;87(8):083110. doi: 10.1063/1.4961473.
The selection of the direction of sensitivity for digital shearography is determined by its shearing direction. As a result, directionally shaped defects could be missed in non-destructive testing using a digital shearography system with only one shearing direction. This paper reports a polarized digital shearography system based on two Mach-Zehnder interferometers, which can create two orthogonal shearing directions and record shearograms in the two orthogonal directions simultaneously. The two shearograms are separated from each other by proper polarization design so that no cross interference occurs. The phase maps of the shearograms are generated by spatial phase shift methods through the introduction of different carrier frequencies in the two orthogonal shearograms and use of the Fourier transform method. This enabled simultaneous dual directional non-destructive testing during continuous loading. Theory derivation, spectrum analysis, and non-destructive testing application results are shown in detail.
数字剪切散斑干涉术灵敏度方向的选择由其剪切方向决定。因此，在使用只有一个剪切方向的数字剪切散斑干涉术系统进行无损检测时，可能会遗漏具有方向性的缺陷。本文报道了一种基于两个马赫-曾德尔干涉仪的偏振数字剪切散斑干涉术系统，该系统可以产生两个相互正交的剪切方向，并同时记录两个正交方向上的散斑图。通过适当的偏振设计，将两个散斑图彼此分离，从而不会发生交叉干扰。通过在两个正交散斑图中引入不同的载波频率并使用傅里叶变换方法，利用空间相移方法生成散斑图的相位图。这使得在连续加载过程中能够同时进行双方向无损检测。详细展示了理论推导、频谱分析和无损检测应用结果。
