The fiber optic probe hydrophone

Abstract

We present a new type of hydrophone based on a fiber-optic sensor principle for shock wave and ultrasonic measurements in water. Its detection mechanism is based on the change of the optical reflection coefficient at the end surface of a glass fiber in water by pressure signals. The relation between the intensity of the reflected light and the water pressure is defined by material constants so that calibration by reference is not necessary. Shock wave measurements were made with the fiber optic probe hydrophone and compared with the results obtained by PVDF membrane and needle hydrophones. Important advantages are high resolution in space and time, a reproducible response also to negative pressure signals with high accuracy, high cavitation threshold, large bandwidth (>1 GHz), ideal electromagnetic shielding, high deterioration resistance and simple calibration control.