Auto-correction method for differential attenuation in a fiber-optic distributed-temperature sensor

A novel method to improve the accuracy of fiber-optic distributed-temperature measurements derived from Raman backscatterings is presented. This method utilizes two light sources with different wavelengths, such that the wavelength of the primary source's return anti-Stokes component overlaps with the incident wavelength of the secondary light source to cancel out the nonidentical attenuations generated by the wavelength differences between Stokes and anti-Stokes. The concept is successfully verified by the experimental results obtained from several sample fibers. The correction can be made automatically and continuously without any interruptions during the whole measurement periods.