Spatial Phase-Shifting Shearography for Industrial In-Line Quality Control

Electronic Speckle Pattern Shearing Interferometry, also referred to as Shearography, is a non-destructive, contactless, area-based, and largely material-independent optical measurement method. Due to recent technological advancements, spatial phase-shifting Shearography enables video-rate measurements, limited only by the frame rate of the imaging camera. In contrast to temporal phase-shifting, this allows inline measurements in industrial environments, even under comparatively harsh conditions. In this work, we present a theoretical comparison of both phase-shifting approaches. In addition we demonstrate several application scenarios of spatial phase-shifting Shearography tailored to industrial deployment. Building upon a patented measurement system developed at Trier University of Applied Sciences and transferred to TENTA VISION GmbH, this contribution also summarises recent advances in automated shearographic data analysis using artificial intelligence. Results from previously published studies on unsupervised and automated labeling approaches are consolidated and discussed in the context of industrial integration. The combined perspective highlights strategies for reducing annotation effort and enabling scalable, robust defect detection within practical shearographic inspection workflows.