High-resolution distributed temperature sensing with the multiphoton-timing technique

Abstract

We report on a multiphoton-timing distributed temperature sensor (DTS) based on the concept of distributed anti-Stokes Raman thermometry. The sensor combines the advantage of very high spatial resolution (40 cm) with moderate measurement times. In 5 min it is possible to determine the temperature of as many as 4000 points along an optical fiber with an accuracy Δ T < 2 °C. The new feature of the DTS system is the combination of a fast single-photon avalanche diode with specially designed real-time signal-processing electronics. We discuss various parameters that affect the operation of analog and photon-timing DTS systems. Particular emphasis is put on the consequences of the nonideal behavior of sensor components and the corresponding correction procedures.

Empirical mode decomposition based dynamic error correction in SS covered 62.5/125µm optical fiber based distributed temperature sensor

“…Generally, theoretically and experimentally obtained values of R are different from each other because of the non-ideal performance of various components of the system and it finally results in highly erroneous temperature measurement. To compensate such error, a reference value of Raman ratio computed for the calibration zone is utilized [6]. This calibration zone is chosen from the sensing fiber itself and is kept at some constant known reference temperature ( say, θ).…”

“…However, as the fiber length increases, the error in temperature measurement increases. The main reason for the increase in this type of error is the difference in attenuation offered by the sensing fiber to optical AS and St signals [6,7]. Since the optical wavelengths of AS and St are at 1018 nm and 1109 nm respectively, lower wavelength signal (AS) experiences higher attenuation at a given fiber length compared to the higher wavelength signal (St).…”

“…Since the optical wavelengths of AS and St are at 1018 nm and 1109 nm respectively, lower wavelength signal (AS) experiences higher attenuation at a given fiber length compared to the higher wavelength signal (St). This leads to variation in the Raman ratio with a distance which is not actually caused by temperature effects and thus causes an error in the measurement of temperature profile along the fiber length [6,9].…”

“…These schemes include the use of Rayleigh in place of St signal [10], loop back [6] and double-ended (DE) configuration [11] where both ends of sensing fiber are accessed by the OFDTS. Lee [7] and Suh and Lee [12] suggested the schemes based on the use of two laser sources.…”

“…Generally, in OFDTS the calibration zone has to be kept at a constant temperature bath [6] that requires additional heating arrangement, temperature controller and other related hardware which add complexity to OFDTS. In this paper, the proposed technique avoids the need of a constant temperature bath which reduces complexity of the system.…”