Researchers at the U.S. Naval Research Laboratory (NRL), Optical Sciences Division, in collaboration with the laboratory’s Material Science Division, for the first time have demonstrated successful detection of acoustic emission from cracks in riveted lap joints using a distributed feedback fiber laser-acoustic emission sensor. “An automated, in-situ structural health monitoring (SHM) system, capable of monitoring key structural parameters such as temperature, strain, impacts and cracks, and capable of reliably detecting damage well before reaching a critical level is needed to increase safety and readiness while lowering operational cost of Navy platforms” said Dr. Geoffrey Cranch, research physicist, Optical Sciences Division. “At present, none of the services are using in-situ technologies to manage the structural health of their assets.” To accomplish this goal, sensors that can detect acoustic emission signatures associated with crack initiation and growth, in near real-time, are required. Such a sensor must be smaller and lighter than existing electrical equivalents, possess comparable or improved sensitivity, be easily multiplexed, and achieve all of these components with a small system footprint and high reliability.