Consideration is given to a new optical-fibre technique for the measurement of the spatial distribution of physical fields (e.g. magnetic field, electric field, temperature, mechanical stress, etc.). The technique relies upon the time-resolution of light backscattered from a pulse propagating in a monomode optical fibre to measure the spatial distribution of the fibre's polarization properties. These properties are modified by the field under investigation.
A. J. Rogers, A. J. Rogers,
"Polarization-Optical Time Domain Reflectometry", Proc. SPIE 0236, 1980 European Conf on Optical Systems and Applications, (15 May 1981); doi: 10.1117/12.959037; https://doi.org/10.1117/12.959037