Spatial Resolution Improvement of Distributed Raman Temperature Measurement System

Ensuring the synchronization of backscattered Raman light and improving the sampling rate are of great importance to improve the spatial resolution of a distributed Raman temperature measurement system. To keep the synchronization of the Anti-Stokes and Stokes light and improve the sampling rate, four effective methods are proposed in this paper. First, the asynchrony caused by the difference in the hardware is eliminated by attaching a fiber to the pigtail of APD, which detects the earlier arriving signal. Next, the data acquisition card chooses different sampling rates for the Anti-Stokes and Stokes light according to the velocity of propagation. Then, a new algorithm is adopted to decrease the difference in the fiber position between the Anti-Stokes and Stokes signals. Finally, the optical switch with different length of pigtails is applied to improve the sampling rate without upgrading the hardware of data acquisition card. By theoretical analysis and experimental simulation, the proposed measures in this paper can improve the spatial resolution effectively.