AP Sensing offers a broad range of trainings to help customers and partners understand DTS technology and get a comprehensive system overview. This includes many practical tips for the installation and commissioning.
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About DTS Technology
Distributed Temperature Sensing (DTS) principle
AP Sensing’s distributed temperature sensing instruments are based on the proven Raman Optical Time Domain Reflectometry (OTDR) technology. An optical laser pulse propagating through the fiber gets partially scattered back to the transmitting end, where it is analyzed. The backscattered light consists of different spectral components:
- Rayleigh Backscattering
- Brillouin Backscattering
- Raman Backscattering
The Raman backscattering
The Raman backscattering intensity depends on temperature and can be used as a measure for the temperature along the fiber. The Raman backscattered light has two components above and below the incident light: the Raman Stokes and Raman Anti-Stokes peak.
The backscattered light is spread across a range of wavelengths. Some of these wavelengths are affected by temperature changes while others are less affected. Using a very accurate detector the difference in the signal strength is measured and the temperature is derived from these measurement results.
Because the light propagation speed in an optical fiber is well known, the distance can be determined from the round trip delay time of the returning backscattered light. The exact position of the temperature reading is determined by measuring the arrival time of the returning light pulse similar to a radar echo showing the distance to a car or plane.
About the Raman Effect
Sir Chandrasekhara Venkata Raman, an Indian physicist, discovered the effects of light scattering in 1928. At the age of 42 he won the Nobel Prize for his work and today the result is known as the Raman effect.
It took several decades until technology companies, such as Agilent Technologies, were able to exploit the Raman effect and take it out of the research labs and put it into practice in reliable test and measurement instruments.
DTS Technology Today
The use of passive optical fibers as distributed temperature sensors is considered a powerful way to monitor temperature over long distances and in harsh environments:
- dirt and dust
- humidity
- corrosive conditions
- strong electromagnetic fields
- extreme temperatures
Under such conditions conventional detection technologies often fail to offer a reliable and cost effective solution.
With a continous - linear - fiber optical temperature sensor there is no need to install multiple conventional punctual sensors. The fiber optical sensor leaves no area unmonitored, and in effect monitors thousends of temperature points simultaneously.
