Ultrasonic Imaging of Seismic Physical Models Using Fiber Bragg Grating Fabry–Perot Probe

Abstract

A fiber-optic sensor has been proposed and demonstrated for the ultrasonic wave (UW) imaging of seismic physical models. The sensor probe comprises a fiber Bragg grating Fabry–Perot (FBG-FP) mounted inside the tip of an aluminum cone, which focuses the UW effectively into the fiber. The FBG-FP probe possesses an excellent UW sensitivity because of the narrow-band notches on the top of the reflection spectrum caused by the FP interference. A spectral band-side filter technique is used to measure the UW signal. Because of the symmetrical structure of the sensor, it provides a directional UW detection with a high-signal-to-noise ratio. As expected, the two-dimensional images of the four physical models are reconstructed by the fast scanning of the sensor.