Patent ID: 7215416
Filing Date: 2007-05-08
Classification: G01D,G01K

Abstract:
1. A method of determining temperature along a fiber optic distributed temperature sensor, comprising the steps of: a) providing optical energy into one end Y of a fiber optic distributed temperature sensor and transmitting in the forward direction; b) measuring the backscattered signal at Stokes wavelength, Sy; c) measuring the backscattered signal at anti-Stokes wavelength, Ay; d) providing optical energy into the other end Z of the fiber optic distributed temperature sensor and transmitting in the reverse direction; e) measuring the backscattered signal at the Stokes wavelength, Sz; f) measuring the backscattered signal at the anti-Stokes wavelength, Az; g) determining the difference between the backscattered signal at the Stokes wavelength in the forward and the reverse directions for any given point i along the sensor, Ds; h) determining the difference between the backscattered signal at the anti-Stokes wavelength in the forward and the reverse directions for the given point i along the sensor, Da; i) determining the incremental value at a distance for the difference between the backscattered signal at the Stokes wavelength in the forward and the reverse directions for the given point i along the sensor, Δs; j) determining the incremental value at a distance for the difference between the backscattered signal at the anti-Stokes wavelength in the forward and the reverse directions for the given point i along the sensor, Δa; k) correcting the backscattered signal at the Stokes wavelength at the given point i by  or  for the forward and reverse directions, respectively; l) correcting the backscattered signal at the anti-Stokes wavelength at the given point i by  or  for the forward and reverse directions, respectively; and m) determining the temperature using the corrected signals at the Stokes wavelength (S) and the anti-Stokes wavelength (A).