Development of internal defect detection equipment for composite materials based on shear speckle interference

To address the limitations of slow phase-shifting speed and low hardware integration in traditional composite defect detection systems, a portable device was developed that integrates a Wollaston prism shearing module with a high-speed liquid crystal phase retarder. The main contribution of this work is an improved real-time phase unwrapping process for shear speckle interferometry measurements, achieved by combining gradient-adaptive smoothing with graph-cut optimization and deploying it on an embedded GPU platform. Embedded software and GPU-accelerated algorithms were incorporated to enhance processing efficiency. An improved algorithm combining gradient-adaptive smoothing and graph-cut optimization was proposed for noise suppression in phase unwrapping, reducing the root mean square error (RMSE) by 27.34% to 33.20% under hybrid noise conditions and completing single-frame analysis within 0.36 s. Experimental validation using aluminum discs and composite specimens showed that the reliable detection of internal defects with a diameter of ≥2<i>m</i><i>m</i> under heat loading achieved 97% accuracy. The system's integrated hardware-software design achieves submillimeter resolution while maintaining field-deployable portability, fulfilling critical requirements for high-speed, high-sensitivity nondestructive testing in aerospace applications.