English to French Tech/Engineering Physics

The intensity of the optical pulse determines the dynamic range of the measurement, that is, the ability to determine the location of ever smaller reflection sites.

The location information of the disturbance may be determined from a range dependent timing of changes in the temporal speckle patterns. The changes in the temporal speckle patterns arise from changes in the refractive index of the fibre along its length caused by the disturbance. The disturbance may be, or may produce, a pressure wave such as an acoustic wave, or a temperature variation.

The direction information may be determined from a comparison of the temporal speckle patterns at a range specific timing for two polarisation eigenmodes. The range specific timing corresponds to a specific location along the fibre.