Precise, rugged spectrum-based calibration of distributed anti-Stokes Raman thermometry systems

We report the development of a rugged calibration method based on the measurement of the spectral response of a distributed anti-Stokes Raman thermometry (DART) system. Due to the presence of a high level of Rayleigh scattered signal in the Stokes channel, we find that the temperature measurement may be more precise if we use the Rayleigh signal as reference for the anti-Stokes thermometry. Moreover, we find that the temperature measurement needs to be calibrated for the loss spectrum of the optical components used in the system. Based on such an algorithm, we have demonstrated a prototype which is capable of sensing temperatures up to 90°C with an accuracy of 2°C over distances up to 6.5 km with 8 m spatial resolution.