High-Performance Rotational Shearography System Based on Dove Prism for Nondestructive Testing

Abstract

Digital shearography (DS) is a nondestructive testing method that provides full-field measurement, with its sensitive direction closely related to shearing direction and its sensitivity related to the shearing amount. Conventional single-direction DS carries the risk of missed detection of defects, while conventional two- or multidirectional DS struggles to balance both rapid measurement and high-quality measurement results. To avoid missed detection of defects and achieve high-performance measurement, we have designed a novel rotational shearography system that can perform defect detection with just a single temporal phase shift (TPS). The system introduces rotational shearing amount using a dove prism (D), effectively preventing missed detections caused by the insensitivity of defect shapes to the shearing direction. A 4f system is embedded in the measurement system to overcome the limitations imposed by optical components on the field of view (FOV), allowing the system to work in a large range of FOV. We constructed an experimental setup to evaluate the performance of the proposed system. The measurement results not only demonstrate the system’s applicability for various loading conditions and defect shapes but also verify its feasibility in both large and tiny FOV measurements.