Fiber Optic Pyrometer uses a polymer temperature-sensitive material that matches the refractive index of the optical fiber to coat the outside of two fused optical fibers so that light energy is input from one optical fiber and the reflective surface is output from the other optical fiber. A new type of temperature-sensitive material is affected by temperature, the refractive index changes, so the output optical power is a function of temperature. Its physical essence is to use the characteristic parameters of the light wave transmitted in the optical fiber, such as amplitude, phase, polarization state, wavelength and mode, etc., which are sensitive to external environmental factors such as temperature, pressure, radiation, etc. Fiber Optic Pyrometer is a non-contact temperature measurement.

One, the application of Fiber Optic Pyrometer

There are many types of fiber optic pyrometers. In addition to the fluorescence and distributed fiber temperature sensors described above, there are fiber grating temperature sensors, interferometric fiber temperature sensors, and fiber optic temperature sensors based on bending loss. Due to their many types, applications The development is also very extensive, for example, applied to the power system, construction industry, aerospace industry, marine development and so on.

2. Classification of Fiber Optic Pyrometer

1. Distributed optical fiber pyrometer

Distributed Fiber Optic Pyrometer is usually used in a system for detecting spatial temperature distribution. Its principle was first proposed in 1981, and after the experiment of scientists, this technology was finally developed. The development of this sensor principle is based on the research of three sensors, namely Rayleigh scattering, Brillouin scattering, and Raman scattering. Great progress has been made in the research of Rayleigh scattering (OTDR) and Brillouin scattering (OTDR). Therefore, future sensor research hotspots will be placed on the research of new distributed optical fiber sensors based on Raman scattering (OTDR) on.

Recently, Gunes Yilmaz, Turkey, developed a distributed optical fiber pyrometer. The temperature resolution of this sensor is 1℃ and the spatial resolution is 1.23m. In my country, many universities have also launched research on distributed optical fiber temperature sensors. For example, the China Jiliang University invented a coal mine temperature detection sensor system in 1997. The detection temperature is -49℃～150℃ and the temperature resolution is 0.1. ℃.

2. Fluorescence Fiber Optic Pyrometer

The current hot research is aimed at the optical fiber fluorescence temperature sensor, which uses the characteristic of fluorescent materials to emit light to detect the temperature of the light-emitting area. Such fluorescent materials usually emit light when they are stimulated by ultraviolet or infrared rays. The emitted light parameters and temperature are inevitable. Therefore, the temperature can be tested by detecting the fluorescence intensity.

Universities all over the world have designed such sensors. For example, Seoul University in South Korea found that a 10cm double-doped fiber has a temperature index of 20℃～290℃ for the fluorescence intensity reflected at 915nm; Tsinghua University in my country Borrowing semiconductor GaAs raw materials to absorb light, and based on the principle that light changes with temperature, a fluorescent Fiber Optic Pyrometer with a temperature range of 0℃～160℃ has been developed.