Fiber optic temperature sensor, Intelligent monitoring system, Distributed fiber optic manufacturer in China
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Overview of Fiber Optic Temperature Measurement
1、 What is fiber optic temperature measurement
Fiber optic temperature measurement is a technology that uses optical fibers as sensing elements for temperature measurement. Fiber optic, also known as optical fiber, is a commonly used cylindrical dielectric waveguide material. The essence of fiber optic sensing technology is to detect targets by using light as the measured carrier through fiber optic communication.
Fiber optic temperature measurement technology has multiple types. Point based temperature measurement is the deployment of a single temperature probe in certain key areas of the system for measurement.
1. Fluorescent fiber optic temperature sensing technology is a technique that involves coating a fluorescent substance on the end of a fiber optic cable. By measuring the decay time of fluorescence energy and utilizing the temperature correlation of the intrinsic afterglow time of the fluorescent substance, the temperature value of the measured point can be obtained. It is suitable for a temperature range of -50-200 ℃ and has an accuracy of about ± 1 ℃. It is mainly used for temperature measurement inside electrical equipment and has the characteristics of small size, easy integration, reliable performance, resistance to electromagnetic interference, good insulation performance, convenient installation, and flexible networking.
2. Gallium arsenide fiber temperature measurement technology embeds gallium arsenide crystal material into the far end of the fiber as a temperature probe, injects incident light into the near end device of the fiber, and obtains the temperature parameters at the probe by analyzing the spectrum of the reflected light. Its advantage is that the probe temperature is obtained through absolute spectral measurement, without involving on-site calibration. The probe has good universality, and the sensing distance can exceed 500m. The light source life and online detection long-term stability exceed 30 years, but the cost is high.
3. Fiber Bragg Grating Measurement
The single point temperature measurement is connected in series along the propagation direction of the optical fiber to form a measurement method that covers multi-point temperature detection. For example, in a temperature measurement system with multiple fiber Bragg gratings connected in series, several Bragg fiber Bragg gratings with different center wavelengths are formed by exposure and etching through ultraviolet radiation along the longitudinal direction of the optical fiber. When the ambient temperature of the fiber Bragg grating changes, the wavelength of the grating reflection signal also changes. This system has a small probe volume, an appropriate bending of the optical path, resistance to electromagnetic radiation, and is easy to telemetry. However, the mechanical strength of the fiber Bragg grating is low, and it is easily damaged in complex working conditions. The sensitivity of wavelength demodulation is also a problem. The wavelength drift of reflected light caused by a temperature rise of tens of degrees does not exceed 1nm. Fully distributed measurement refers to the use of optical fibers as both a channel for transmitting optical signals and a temperature sensitive material for conducting temperature changes. By deploying a monitoring device and a sensing fiber, the monitoring cost per unit fiber length can be reduced as the sensing distance increases. It is a highly promising engineering temperature measurement solution.
2、 Why use fiber optic temperature measurement
（1） Advantages in special environments
Anti electromagnetic interference
In some environments with strong electromagnetic interference, such as around high-voltage equipment in power systems, near large motors, or in places with dense electronic equipment, traditional temperature sensors based on electrical signal measurements (such as thermocouples, thermistors, etc.) will be affected by electromagnetic interference, resulting in inaccurate measurements or even inability to function properly. Fiber optic itself is an optical medium, and light waves do not generate electromagnetic interference, nor are they afraid of electromagnetic interference. Therefore, fiber optic temperature measurement technology can accurately measure temperature in such strong electromagnetic interference environments, ensuring the reliability and stability of measurement results.
Intrinsic safety
In flammable and explosive environments, such as oil and gas storage sites in the petrochemical industry and underground coal mines, traditional electrical temperature sensors may generate electrical sparks due to their working principle involving electrical signals, which can cause serious safety accidents such as explosions or fires. Fiber optic is made of insulating materials such as glass or plastic, which are not charged and do not generate electrical sparks during the measurement process. Therefore, fiber optic temperature measurement technology has inherent safety characteristics and can safely measure temperature in these hazardous environments, effectively ensuring the safety of personnel and equipment.
Corrosion resistance
In some harsh chemical environments, such as chemical production workshops and equipment monitoring in marine environments, the air may contain corrosive gases or liquids, which can corrode traditional metal temperature sensors and affect their service life and measurement accuracy. Fiber optic materials have good corrosion resistance and can work stably in such harsh chemical environments for a long time, ensuring the accuracy and continuity of temperature measurement.
（2） Advantages in measuring characteristics
High precision and high sensitivity
Fiber optic temperature measurement technology can achieve high-precision temperature measurement and meet the requirements for temperature measurement accuracy in various complex environments. For example, in scientific research experiments that are highly sensitive to temperature changes, or in temperature monitoring of electronic chips, even small temperature changes can have a significant impact on experimental results or equipment performance. Fiber optic temperature measurement technology can accurately capture these subtle temperature changes. Its high sensitivity also enables it to quickly respond to temperature changes and provide timely feedback on temperature information, which is crucial in some application scenarios that require high temperature response speed, such as temperature monitoring in certain chemical reaction processes.
Long distance monitoring and multi-point measurement
Fiber optic can achieve continuous temperature monitoring for tens or even hundreds of kilometers, and through a distributed fiber optic temperature measurement system, temperature monitoring at multiple points can also be achieved simultaneously. This characteristic is of great significance in some large-scale infrastructure construction and industrial production processes. For example, in long-distance oil pipeline monitoring, optical fibers can be laid along the pipeline to monitor the temperature of multiple points throughout the pipeline at once, and timely detect temperature anomalies caused by leaks, blockages, or external environmental influences in the pipeline; In temperature management of large buildings, optical fibers can also be used to monitor temperature at different locations inside the building, achieving efficient energy management and equipment maintenance.
（3） Other advantages
Can be linked with other systems
The fiber optic temperature measurement system can be linked with fire protection, alarm systems, etc. When an abnormal temperature rise is detected, the alarm system can be triggered in a timely manner to notify relevant personnel to take measures. At the same time, temperature information can also be provided to the fire protection system for early warning and prevention before a fire occurs. For example, in densely populated and cargo concentrated places such as large shopping malls and warehouses, the linkage between fiber optic temperature measurement and fire alarm systems can effectively improve fire safety levels and reduce losses from fire accidents.
Convenient data transmission and analysis
Fiber optic can not only serve as a temperature sensor, but also as a medium for temperature measurement and transmission, enabling remote data transmission and facilitating users to remotely view and manipulate measurement results. And it can analyze the collected temperature data for easy troubleshooting. In some remote monitoring or large-scale device monitoring networks, the convenience of data transmission and analysis can greatly improve management efficiency, reduce maintenance costs, and timely detect and handle potential problems.
