Advances, applications and prospects of laser thermography nondestructive testing and evaluation: a review

Laser Thermography has emerged as a pivotal infrared thermography non-destructive testing method, offering remote, high-precision inspection with flexible spatial-temporal excitation. This paper comprehensively reviews laser thermography, including its heat wave inspection mechanism, technique advances, multiple industrial applications, and future intersections and prospects. First, the heat transfer principles of thermography are analysed, emphasising defect detection via thermal wave propagation, imaging metrics, and critical methodological factors. Next, the development, advantages, and limitations of laser thermography from aspects of spatial modulation and time-frequency modulation are analysed, followed by the corresponding post-inspection image processing. The review further explores industrial applications across aerospace, energy, and manufacturing sectors, highlighting its efficacy in detecting cracks, delaminations, and material degradation at different scales. Finally, the future trends are discussed, as well as their intersection with infrared-based holography and hyperspectral testing to create novel inspection complementation & applications. By synthesising technical insights and practical case studies, this work bridges knowledge gaps among manufacturers, designers, and researchers engaged in laser thermography for damage inspection, health monitoring, and integrity evaluation. It establishes a unified reference framework to accelerate the transition from laboratory validation to practical inspection application solutions.