Pixelated Carrier Phase-Shifting Shearography Using Spatiotemporal Low-Pass Filtering Algorithm

• Published in: Sensors (Basel, Switzerland) Switzerland), 2019-11, Vol.19 (23), p.5185
• Main Authors: Yan, Peizheng, Liu, Xiangwei, Wu, Shuangle, Sun, Fangyuan, Zhao, Qihan, Wang, Yonghong
• Format: Article
• Language: English
• Subjects: Algorithms; Deformation; Domains; Fourier transforms; Interferometry; Low pass filters; Noise; Nondestructive testing; Shearography
• ISSN: 1424-8220; 1424-8220
• DOI: 10.3390/s19235185

Shearography has been widely used in non-destructive testing due to its advantages in providing full-field, high precision, real-time measurement. The study presents a pixelated carrier phase-shifting shearography using a pixelated micropolarizer array. Based on the shearography, a series of shearograms are captured and phase maps corresponding to deformation are measured dynamically and continuously. Using the proposed spatiotemporal filtering algorithm in the complex domain, the set of phase maps are simultaneously low-pass filtered in the spatial and temporal domains, resulting in better phase quality than spatial low-pass filtering. By accumulating the temporally adjacent phase, the phase corresponding to large deformation can be evaluated; thus, large deformations can be accurately measured and protected from speckle noise, allowing internal defects to be easily identified. The capability of the proposed shearography is described by theoretical discussions and experiments.