Introduction to the Principles of Fiber Optic Temperature Measurement: Fluorescent Fiber Optic Temperature Measurement, Distributed Fiber Optic Temperature Measurement, and Fiber Bragg Grating Temperature Measurement

There are three methods for fiber optic temperature measurement, namely fluorescence fiber optic temperature measurement, distributed fiber optic temperature measurement, and fiber optic grating temperature measurement. The price of each temperature measurement system varies depending on the application environment and the configuration of the fiber optic distance system device. You need to consult us for detailed information.

Principle of Fluorescent Fiber Temperature Measurement

Coating fluorescent material on the end of the optical fiber, after being excited by a certain wavelength of light, the fluorescent material is stimulated to emit fluorescent energy. Due to the exponential decay of stimulated radiation energy, the time constant of decay varies depending on temperature. By measuring the decay time, the temperature of the measurement point can be obtained.

The principle of distributed fiber optic temperature measurement

The principle of a distributed fiber optic temperature measurement system is that as the temperature of the detection point changes, the intensity of Raman scattered light scattered in the opposite direction in the fiber optic also changes after applying a pulse laser. Then, these scattered light are filtered and converted into electrical signals. This process converts the optical signal into an electrical signal, amplifies the electrical signal, and then converts it through the system to output data through a signal processor. The scattering velocity of Raman scattered light waves is constant, and the location of monitoring points is calculated by calculating the time it takes for the scattered waves to return. When a certain pulse laser is applied in the optical fiber, the laser photons have energy. After interacting with molecules, the molecules are excited and release a certain amount of energy. The energy difference between them causes a change in the frequency of the released photons. By sensing the change in this energy, the signal changes are displayed, and the temperature change at the monitoring point is calculated.

Principle of Fiber Bragg Grating Temperature Sensor

A sensor that detects temperature by detecting the central wavelength shift of the light signal reflected by an internal sensitive element - a fiber optic grating. Installation structures with different packaging options such as surface, embedded, and immersion. Due to the fact that fiber optic grating temperature sensors use light waves to transmit information, and optical fibers are electrically insulated and corrosion-resistant transmission media, they are not afraid of strong electromagnetic interference. This makes them convenient and effective for monitoring in various large-scale electromechanical, petrochemical, metallurgical high-pressure, strong electromagnetic interference, flammable, explosive, and corrosive environments, with high reliability and stability. In addition, the measurement results of fiber optic grating temperature sensors have good repeatability, making it easy to form various forms of fiber optic sensing networks and can be used for absolute measurement of external parameters. Multiple gratings can also be written into a single optical fiber to form a sensing array, achieving quasi distributed measurement.

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