Principle of Distributed Temperature Sensing :-
When a light source is incident on the optical fiber, it is scattered by the fiber glass molecules as it propagates down the fiber and exchange molecules with lattice vibration. As the light scattered down the fiber optical cable nearly all the scattered light has a wavelength identical to the incident light, called Rayleigh scattering. A small amount of the scattered light has a different wavelength called Raman scattering which produce stokes signal and anti-stokes signal, is reflected back to transmitted end where it is analyzed. The difference between intensities of backscattered anti stokes and stokes signals gives the measure of temperature at point.
Measurement of arrival time of backscattered light to the transmitting end enables to find location of temperature reading, phenomena known as Optical Time Domain Reflectometry.
Principle of Distributed Bragg Sensing:-
The FBG sensing element is made up of periodic changes in the core of a single mode optical fiber caused by UV light exposure. The FBG functions as a partial mirror. Light with a range of wavelengths will generally pass through the FBG, but one specific wavelength will reflect back. The reflected wavelength is determined by the initial optical characteristics of the FBG embedded during the manufacturing process. These optical characteristics of the FBG are directly related to temperature and strain. Changes in one or more parameters will result in a shifted wavelength being reflected back to the reading unit. The temperature or strain FBG can be measured by determining the shift from the initial wavelength.
Principle of Fluorescence Decay Sensing :-
The working principle is based on Fluorescence Lifetime or Time Decay of a Rare-Earth Fluorescence Sensor formed on the tip of the Optical Fiber. The other end of the fiber is attached to a light source which is used to excite the Fluorescent material. When the sensitive Fluorescence material is stimulated by a Pulsed Light Source, electrons inside the material absorbs photons, causing electrons to move from low to high state of excitation. After excitation, the excited fluorescent material tends to return from its peak state to ground state by emitting light photon. This time taken to reach to the ground state from excited state is dependent on the ambient temperature and thus temperature is deduced by forming a relation between Time Decay and Temperature.
Fsenz is Organised and Managed by Tempsens Instruments (I) Pvt. Ltd. is one of the largest solution providers for Thermal and Cable Products. The manufacturing facilities are based in India, Germany, and Indonesia. It’s a part of Pyrotech Group, which was established by four technocrats in 1976 at Udaipur, Rajasthan with the first product as Thermocouple and RTD.
