Guided wave imaging of composite plates using passive acquisitions by fiber Bragg gratings.

In this paper, imaging results of defects in composite plates using guided wave-based algorithms, such as delay and sum and Excitelet, are presented. Those algorithms are applied to passive data for which the signal corresponding to each emitter-receiver couple is recovered as a result of the cross correlation of the ambient noise measured simultaneously by the two sensors. The transition to passive imaging allows the use of lighter sensors that are unable to emit ultrasonic waves, such as fiber Bragg gratings (FBGs) sensors on optical fibers, which are used in this study.