DISTRIBUTED SENSING APPARATUS

摘要

The current invention is applicable to an optical fibre based distributed sensing system that operates according to the non-linear process of Stimulated Brillouin Scattering (SBS). Such a sensing system that is based upon the Brillouin Optical Time Domain Analysis (BOTDA) technique relies upon the interaction between two lightwaves that have an optical frequency difference that lies in the microwave region. It is important that this frequency difference is tunable and stable, and that at least one of the lightwaves can be pulsed. The current invention describes a system that is capable of achieving these objectives, and can launch both lightwaves into one end of a single optical fibre (that operates as the distributed sensing medium) with minimum loss.