TEMPERATURE MEASURING METHOD USING OPTICAL FIBER

摘要

PURPOSE:To make the measuring distance long and to make it possible to perform highly accurate measurement by utilizing the relationship between the spectral width of Brillouin gain and temperature in the Brillouin scattering phenomenon generated in an optical fiber. CONSTITUTION:First signal light S1 from a first light source 1 is coupled into an optical fiber 3 to be measured through a multiplexing/splitting device 4. Meanwhile, second signal light S2 from a second light source 2 is coupled into the optical fiber to be measured 3 through a terminal 3-2 which is opposite to a terminal 3-1 of the fiber 3. The relative frequency difference f between the light frequency f1 of the light S1 which generates Brillouin phenomenon and the light frequency f2 of the light S2 is continuously or discretely changed. The intensity of the light S2 is observed by using a photodetector 5. The spectrum of the Brillouin gain is obtained based on the relationship between the intensity of the amplified light and f. The spectral width of the Brillouin gain is linearly changed with the temperature. The highly accurate temperature measurement can be performed, and the long-distance measurement can be performed with the single-mode light characterized by a large amount of attenuation.