Backscattering

When the medium, where the scattering phenomenon occurs, is homogenous, only a forward scattered beam is allowed. However, in an inhomogeneous medium like the optical fibers, and due to its variations in density and composition and in this way, some photons return toward the light source producing backscattering. This backscattered part of light is used generally to get information about the change in fibre properties directly related to the change in the environmental medium.