Applications of a fast FBG interrogation system for real-time thermal and structural monitoring

Fiber Bragg Gratings sensors (FBGs) are nowadays widely employed in several fields, ranging from structural monitoring to medical applications, thanks to their ability to provide good metrological performance and to guarantee intrinsic safety and immunity to electromagnetic fields. Currently, FBG applications are not only limited by the cost and complexity of the interrogation system but also by the measurement process that requires a demanding post-processing thus relegating the sensor usage to the monitoring of static or quasi-static quantities. This paper addresses the problem of real-time measurements with FBG sensors and describes an interrogation system based on a fast FBG analyzer and on a processing algorithm devised for real-time measurements. The proposed interrogation system can process up to 2500 optical spectral per second and can detect the position of the optical peak with a resolution as small as 1 pm. The system is of potential interest for applications where the acquisition rate is critical and the processing must be performed in real-time, such as for temperature sensing during thermal ablation, strain sensing for weight in motion applications (WEVI) or to perform modal analysis of structures finalized to structural health monitoring (SHM).