Spatial Performance of Acousto-Ultrasonic Fiber Bragg Grating Sensor

In this letter, we present results for the spatial performance of a fiber Bragg grating (FBG) sensor to continuous-wave acousto-ultrasonic (AU) signals. The FBG AU sensor is an intensity sensor, using a transmit reflect detection system. The AU sensor was used to receive actively generated continuous-wave ultrasonic signals from a PZT transducer. We present results showing the received signal strength as a function of longitudinal, lateral, and angular separation in small aluminum panels. Measurements were taken for distances of less then 100 mm and at angles from 0 to 90° between the sensor and the transducer. These results show no direct dependence between the received signal strength and the spatial separation, in the range considered. Only variations due to interference were observed.