Utilization and advancement of laser ultrasound testing in assessment of aerospace composite characteristics: A review

Laser Ultrasonic Testing (LUT) holds great promise for industrial applications, particularly in Nondestructive Testing (NDT) of aerospace composites. It offers advantages such as non-contact, high-resolution, and real-time defect detection. Traditional NDT methods struggle with the complex shapes of structural parts and in-situ testing, limiting their detection efficiency and sensitivity. We review the principles of excitation, optical detection, and laser parameter selection for LUT. It also compares applicability of LUT with other NDT techniques. We discuss strengths and limitations of LUT in detecting defects, characterizing material properties, and monitoring the health of aerospace composites. LUT has proven effective in detecting defects in aerospace materials under extreme conditions such as high temperature and pressure during manufacturing and service. However, challenges remain in defect localization, rapid identification, signal extraction in noisy environments, and micro-defect characterization. Despite these limitations, LUT stands out for its non-contact real-time capabilities and its ability to detect defects in harsh industrial conditions. This paper enhances the understanding for potential and future development of LUT, including improvements in laser generators, non-contact inspection equipment, modular inspection device design, and high-accuracy real-time inspection technologies.