Conventional DTS
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The major phenomenon behind the technology is Raman scattering, by the interaction between an injected laser light and the molecules inside of the sensing fiber. The generated Raman Stokes and anti-Stokes backscattering components are separated by an optical filter and converted to electrical signals by optical detectors. Due to the weakness of backscattered light intensities, the system requires longer processing time (seconds to minutes depending on the application) for better resolution, which is the major difference from conventional electronic temperature sensors.
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DTS Layout 
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How to measure?
Temperature |
The temperature profile is calculated from back scattered light intensity ratio between Stokes and anti-Stokes components utilizing the known temperature of the Reference Fiber located inside of the DTS controller.
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Distance |
The distance of a temperature profile along the fiber is calculated by the round trip time of the back scattered light pulse.
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