Fig. 1. Schematic diagram of ultrasonic signal detection by optical fiber sensor

Fig. 2. Interferometry scheme for multi-channel sensing

Fig. 3. Power spectral density obtained for each channel of interferometer

Fig. 4. Experimental results

Fig. 5. Directivity of optical fiber ultrasonic sensor

Fig. 6. Schematic diagram of internal position placement of optical fiber sensor for transformer PD monitoring

Fig. 7. Detection results of simulated partial discharge signals by three fiber optic sensors

Fig. 8. Experimental setup used to implement AE source scanning

Fig. 9. Normalized results of acoustic signal detected by sensor during test along x axis

Fig. 10. TOA measurement of AE sources at different positions