Distributed optical fiber Raman temperature system with an optical fiber ring
For restraining the temperature excursion accumulation and the anti-Stokes back-scattering intermingling with the Rayleigh back-scattering,an optical fiber sampling ring was set after an inswept death section of the sensing optical fiber.The anti-Stokes back-scattering was demodulated by Rayleigh back-scattering and the fiber's temperature was calculated by the sampling ring,which advanced the temperature precision and stability of the system.A 10 ns,100 mW,1.55 μm pulse laser,a 15 dB gain of EDFA,two high sensitive and low noise APD,two100M14bitA/D and two DSP chips using for 2~(12)~2~(13) digital average form the experimental system.The spatial resolution of 1 m and temperature resolution of 0.03 ℃ were achieved using these techniques.