Pressure sensitive fibre=optic sensor e.g. hydrophone - has reacting fibre in series with optical delay line with light source coupled to one end of light path

摘要

The sensor has a light path formed by a pressure-sensitive optical fibre (25) in series with at least one optical delay line (26). A light source (11) is coupled to one end of the light path with the propagation times for the light through the pressure-sensitive optical fibre (25) and the optical delay line (26) being equal. Pref. the light source (11) comprises a semiconductor laser, which is coupled to a beam splitter (20), with two inputs and outputs (21...24), two of which are coupled via the optical path, the remaining output being coupled to a photodetector (17). The light is pref. transmitted in both directions along the optical path to set up interference in the beam splitter with the photodetector (17) monitoring variations in this interference. The sensor can be used as a fibre-optic hydrophone.