Patent ID: 7126680

Claim:
A method of determining temperature using a fiber optic distributed temperature sensor, comprising: a) providing an optical energy signal to a fiber optic distributed temperature sensor at a predetermined wavelength; b) receiving backscattered signal from the fiber optic distributed temperature sensor; c) measuring responses from the backscattered signal at Stokes wavelength and anti-Stokes wavelength of the predetermined wavelength; d) calculating the Stokes/anti-Stokes ratio (SAR) from the measured responses; e) providing an optical energy signal at the Stokes wavelength to the fiber optic distributed temperature sensor; f) receiving backscattered signal from the fiber optic distributed temperature sensor at the Stokes wavelength and measuring its intensity; g) providing an optical energy signal at the anti-Stokes wavelength to the fiber optic distributed temperature sensor; h) receiving backscattered signal from the fiber optic distributed temperature sensor at the anti-Stokes wavelength and measuring its intensity; i) calculating the attenuation ratio between the backscattered signal at the Stokes and anti-Stokes wavelengths at selected positions along the fiber optic distributed temperature sensor; j) repeating steps a through i at a different time; k) calculating the change in the attenuation ratio with time; l) calculating a corrected SAR by multiplying the SAR and the change in attenuation ratio with time; and m) using the corrected SAR to determine temperatures measured by the fiber optic distributed temperature sensor.