Patent attributes
The invention relates to a method for digitally processing a signal from an optoelectronic distributed measuring device based on Brillouin scattering, said device comprising a continuous light source (1), a coupler (2), an acousto-optic modulator (3), an optical fiber (5) to be tested so that it emits in return a signal by spontaneous Brillouin backscattering at a frequency νF equal to νp−νBz, where νBz is the Brillouin frequency to be measured at every point z of said optical fiber (5), a local oscillator (16) emitting another light signal intended to be mixed with said return signal emitted by Brillouin backscattering by said optical fiber (5) to be tested, a detection module (9) able to detect said Brillouin shift frequency νBz at every point z of said optical fiber and a processing module for linking this Brillouin shift frequency νBz at every point z of said optical fiber to a temperature value and a strain value. According to the invention, the local oscillator (16) comprises a reference optical fiber (18) having a Brillouin frequency identical or close to that of the optical fiber (5) to be tested, said reference optical fiber (18) emitting a signal by spontaneous Brillouin backscattering, in response to said continuous light signal emitted in said second arm by said light source (1), said Brillouin backscattering signal being emitted at a frequency νOL=ν0−νBRef, where νBRef is the Brillouin frequency of the reference fiber without strain and at a reference temperature.
