Do fiber optic temperature sensors require light

Fiber optic temperature sensor, Intelligent monitoring system, Distributed fiber optic manufacturer in China

Does fiber optic temperature sensors require light? This is a general question. Firstly, there are several types of fiber optic temperature sensors, such as fluorescence temperature sensors, distributed fiber optic temperature sensors, fiber Bragg grating temperature sensors, etc. Each type of temperature transmitter requires different types of light.

Principle of Fluorescent Fiber Optic Temperature Sensor

Within a certain temperature range, the fluorescence lifetime of any fluorescent substance exhibits a certain temperature correlation, and the principle of fluorescence lifetime temperature measurement is based on this temperature correlation. When light irradiates a fluorescent substance, its internal electrons gain energy to transition from the ground state to the excited state, and the radiation energy released from the excited state back to the ground state causes the fluorescent substance to emit fluorescence. The duration of fluorescence emission after the light is removed depends on the lifetime of the excited state, which is called fluorescence lifetime. Fluorescence lifetime has characteristics: the length of fluorescence lifetime is determined by the temperature. Fluorescent lifetime temperature sensors are temperature sensors based on this characteristic. Some rare earth fluorescent materials emit visible linear spectra, namely fluorescence and its afterglow, after being irradiated and excited by excitation light. If a certain parameter of fluorescence is modulated by temperature and their relationship exhibits monotonicity, this relationship can be used for temperature measurement.

Fiber optic temperature sensors can be divided into two categories: point type and distributed. As the name suggests, point type temperature sensors can only measure temperature information at a single specific location. Currently, there are mainly absorption type temperature sensors, fluorescence attenuation type fiber optic temperature sensors, fiber optic grating temperature sensors, etc. Compared with distributed temperature sensors, point type temperature sensors are technically simpler to implement and have higher sensitivity. However, when measuring temperatures in a large area, a large number of point type temperature sensors need to be installed, which limits practical production applications and also increases production costs. Distributed fiber optic temperature sensors lay temperature measurement optical cables in temperature measurement areas such as mines, highways, embankments, etc. They use the principle of optical time-domain reflection combined with the temperature effect of some scattered light to measure the temperature of the entire optical cable, and the measurement distance can reach hundreds of kilometers. At present, there are mainly distributed fiber Raman temperature measurement systems and distributed Brillouin temperature measurement systems, which are based on Raman scattering and Brillouin scattering effects in optical fibers, respectively. They have advantages such as high spatial resolution, high precision, and long-distance monitoring, and have been widely applied in fields such as petrochemicals, nuclear power plants, and bridge hazards. In addition to the advantages of electromagnetic interference resistance, intrinsic safety, lightning protection and explosion prevention that ordinary fiber optic sensors have.

The distributed fiber optic temperature measurement system also has the following advantages

Wide temperature measurement range, achieving distributed temperature monitoring

The distributed fiber optic temperature measurement system can obtain temperature information from thousands of measurement points on the entire optical cable in one measurement, truly realizing distributed monitoring with strong real-time performance, and monitoring distances of up to hundreds of kilometers.

Small size, easy to install, and variable shape

Fiber optic has a small volume and light weight, and can be wound into various shapes to ensure that the attenuation of the fiber is within an acceptable range. It is suitable for use in narrow spaces and placed in certain special test areas.
Simple structure and high cost-effectiveness

The system structure is simple and convenient to use. Simply lay the optical cable in the area to be tested to obtain temperature information in that area. Compared with point temperature sensors, it has a higher cost-effectiveness.