Brillouin back-scattering

Fig. 9.1 Schematic representation of a Brillouin spectrometer for measurements in three different scattering geometries back-scattering (180°), 90R scattering and 90A scattering (beam path defined by shutters and mirrors). The laser power can be modu-...

Fig. 9.2 Typical scattering geometries used for Brillouin spectroscopy, (a) 90N-scattering geometry (b) 90A-scattering geometry (c) a combination of the 90A- and the 90R-scatter-ing geometry (d) back scattering geometry.

As a matter of fact, three different scattering processes may occur in an optical fibre sensor, generating a back propagating light that can be exploited to receive information on the local properties of the fibre and consequently on the surrounding environment Rayleigh, Raman, and Brillouin scattering. 

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