Optical Coherence Tomography for High‐Precision Industrial Inspection in Industry 4.0: Advances, Challenges, and Future Trends

ABSTRACT Non‐contact, high‐resolution imaging is critical in modern industrial environments, where complex and multilayered structures demand precise inspection without disrupting production. Optical coherence tomography (OCT), a non‐destructive, depth‐resolved imaging modality, has emerged as a transformative tool for real‐time visualization of internal features in advanced manufacturing processes. This review begins with the principles of OCT and provides a comprehensive analysis of its applications across key manufacturing sectors, including display inspection, thin‐film monitoring, microelectronics, printed circuit board (PCB) analysis, laser‐based manufacturing, and coating evaluation. For each domain, representative methods are examined for their effectiveness in detecting subsurface defects, measuring internal geometries, and supporting quality control. The role of OCT in industry is highlighted through comparisons with conventional inspection techniques. In addition, the review discusses current challenges across resolution, optical penetration and contrast, signal quality, system integration, hardware cost, throughput, and artificial intelligence (AI) and data infrastructure. It also highlights emerging advances in adaptive optics, multimodal and AI‐enhanced imaging, compact and portable OCT platforms, and next‐generation computational and data‐processing architectures for real‐time industrial deployment. By combining technical evaluation, comparative analysis, and future‐oriented perspectives, this review positions OCT as a core technology and foundational tool for next‐generation quality assurance in smart manufacturing and Industry 4.0 environments.