Light conductor hydrophone working on Mach=Zehnder principle - has one optical fibre holding polarisation forming measuring system and another forming reference system fixed to carrier and operated by coherent light

摘要

The sections (13, 14) of the carrier (10) supporting the respective optical fibres (11, 12) have differing elasticity. A 2 by 2 coupler (15) connects the fibre input ends to a laser diode (16). The output ends of the fibres are combined by a 3 by 3 coupler (17) with all three outputs leading to an evaluating unit (18). The latter provides two characteristic curves of the interferometer phase shifted by 90 deg. so that the reception function of the hydrophone is not limited to the linear part of the sinusoidal output signals. ADVANTAGE - Higher sensitivity with simplified construction.