ABSTRACT
This chapter provides a description of the optical fibre hydrophone, which is a device for the measurement of underwater acoustic pressure signals. Optical fibre hydrophones form one of the most interesting and important case studies in the field of optical fibre sensors. There are several reasons for this. First, optical hydrophones were one of the very first optical fibre sensor technologies to be developed, in the late 1970s, and have a history of continuous development extending over more than 20 years. Second, because of this long history and significant levels of investment, they are one of the most well developed of all types of optical fibre sensor in terms of the performance achieved, the levels of multiplexing demonstrated and the harshness of the environments in which they have successfully operated. The hydrophone application is an area in which optical fibre sensors have demonstrated clear advantages over any other sensing approach. The development of the optical hydrophone has, therefore, had a significant impact on the development of optical fibre sensors, in general, and is a classic case study of a laser based optical sensing system.
