Multimode fiber-optic hydrophone based on a schlieren technique

A multimode fiber-optic hydrophone is described which is based upon a schlieren acoustooptic intensity modulation mechanism. Computer modeling of critical device parameters was experimentally verified and used to indicate ultimate attainable device performance. The device was shown to be able to detect the Knudsen noise level for frequencies up to 1 kHz, to have a dynamic range of 125 dB, to have an omnidirectional receiving response, and to be able to detect displacements as small as 3.4 x 10(-3) A. The device is not susceptible to phase noise, is relatively insensitive to static pressure head variations and is electrically passive.