The principle, прымяненне, and advantages of distributed fiber optic sensors

Валаконна-аптычны датчык тэмпературы, Інтэлектуальная сістэма маніторынгу, Распаўсюджаны вытворца оптавалакна ў Кітаі

The principle and application fields of fiber optic sensors

The full English name of fiber optic sensor is Fiber Optical Sensor, abbreviated as FOS. In many aspects of modern society, there are broad application prospects and development prospects. In some related fields, various fiber optic sensors have been developed, including temperature, strain, pressure, liquid level, gas, fiber optic gyroscope, and other sensors. Fiber optic sensors use the transmitted light waves in optical fibers to sense changes in the external environment for monitoring. The working process of fiber optic sensors is that when the incident light source is transmitted from the fiber optic to the modulator, the optical parameters change due to changes in the external measured parameters, becoming modulated optical information. Затым, the modulated optical signal is detected by the photoelectric detection device, and the external parameters are obtained after being demodulated.

Тэхналогія размеркаванага валаконна-аптычнага зандзіравання

As a rapidly emerging high-tech sensing technology, the theoretical development and practical application of distributed fiber optic sensors are also constantly deepening. У цяперашні час, exploration and research on dam deformation and temperature monitoring are deepening, but these studies are often point based monitoring, and the distance between various sensors is large, and some places cannot be located, so timely and effective warning capabilities cannot be achieved. There are some traditional non-destructive methods for evaluating local rupture or damage and ensuring structural integrity in engineering structural safety monitoring or testing systems, such as electromagnetic methods, acoustic emission methods, ground penetrating radar systems, and erosion monitoring using inserted reference electrodes. These traditional diagnostic methods are susceptible to electromagnetic interference and have limitations in sensitivity and repeatability. In contrast, fiber optic sensors have advantages in long-term use and repeatability due to their resistance to electromagnetic interference, moisture, and erosion. Таму, fiber optic sensors have been used for safety monitoring in engineering buildings.

Distributed fiber optic sensing technology can use direct or indirect measurement methods to monitor embankments based on the desired target:

① Direct measurement is the placement of optical fibers directly inside the monitored object. With the deformation and temperature changes of the monitored object, the optical fibers obtain strain and temperature information, which is the strain situation and temperature distribution of the monitored object. The direct measurement method can effectively provide early warning of dam risks, but it is not conducive to long-term monitoring.

② Indirect measurement is the process of placing optical fibers on a certain support structure or using fiber optic sensor probes to convert the deformation and temperature of the monitored object into the corresponding parameter changes of the support structure or sensor, and then convert them into the strain and temperature of the optical fiber. By detecting the strain and temperature on the optical fiber, the deformation and temperature of the monitored object are indirectly obtained. The indirect measurement method can be used for long-term monitoring, but it requires the design of specialized support structures and requires that the changes in the support structures or sensors used correspond well with the strain and temperature of the optical fiber.

Application of Distributed Fiber Optic Sensors

Distributed fiber optic sensors not only have the advantages of fiber optic sensors, but also have the characteristics of distributed and long-distance monitoring. Currently, these types of sensors are mainly used for monitoring temperature and stress
Change. The specific applications include the following four aspects:

① In terms of tunnels and bridges. Due to the shortcomings of traditional sensing technologies, such as weak anti-interference ability, difficulty in achieving on-site non electrical, remote distributed, and large-scale monitoring. Таму, fiber optic sensing technology has become the preferred sensor for safety monitoring in these large-scale engineering projects.

② In terms of oil, gas, and pipelines.

Leakage monitoring of conveying pipelines or storage tanks, as well as temperature monitoring and fault location detection.

③ In terms of electricity and power plants.

Surface temperature monitoring and positioning of cables and wires, as well as fire monitoring and early warning in power plants and substations.

④ In terms of water conservancy and civil engineering. Temperature and strain testing of dams, embankments, embankments, and slopes, as well as structural displacement and strain monitoring and early warning of large buildings.

The advantages of fiber optic sensors

Fiber optic sensors have the characteristics of high sensitivity, anti-interference, невялікі памер, лёгкі вага, large dynamic range, and easy implementation of system telemetry and control. They can be used for monitoring in harsh and high-risk environments.
Specifically manifested as:

① The electrical insulation of fiber optic sensors ensures that there are no circuit safety issues with the sensing probe. Due to the fact that fiber optic sensors do not absorb electromagnetic radiation, the radiation will not cause reading confusion
Chaotic phenomenon.

② Fiber optic sensors have integration and small size. Most fiber optic sensors generate optical signals through fiber optic conduction to excite light sources, without the need for power supply. Even in harsh environments, they do not cause safety issues such as circuits.

③ Fiber optic components themselves are both detection and transmission components, capable of achieving telemetry functions. The measured object can be at a certain distance from the sensor, and the fiber optic sensor has a large measurement range, satisfactory accuracy, and simplified calibration. Fiber optic sensors can be classified into different types of sensors based on different classification methods, and each type also exhibits different characteristics.

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