Everything in nature is closely related to temperature. Since Galileo invented the thermometer, people began to use temperature to measure.
Temperature sensors are the earliest developed and most widely used sensors. But the sensor that really turns the temperature into an electrical signal was invented by the German physicist Saibei, the later thermocouple sensor. After 50 years, Siemens in Germany invented the platinum resistance thermometer. With the support of semiconductor technology, this century has developed a variety of temperature sensors including semiconductor thermocouple sensors. Correspondingly, based on the interaction law between waves and matter, acoustic temperature sensors, infrared sensors, and microwave sensors have been developed.
Since the advent of optical fiber in the 1970s, with the development of laser technology, optical fiber has been proved to have a series of advantages in theory and practice. The application of optical fiber in the field of sensing technology has also received increasing attention. With the development of science and technology, many fiber optic temperature sensors have emerged, and it is expected that in the wave of new technological revolution, fiber optic temperature sensors will be widely used and play more roles.
The basic working principle of the fiber optic temperature sensor is that the light from the light source is sent to the modulator through the optical fiber, and the temperature of the parameter to be measured interacts with the light entering the modulation zone to cause optical properties of the light (such as the intensity and wavelength of the light). Change in frequency, phase, etc., called modulated signal light. After being sent to the photodetector through the optical fiber, after demodulation, the measured parameters are obtained.
There are many types of fiber optic temperature sensors, which can be divided into functional and transmission types according to their working principles. The functional optical fiber temperature sensor measures the temperature by using various characteristics (phase, polarization, intensity, etc.) of the optical fiber as a function of temperature. Although these sensors have the characteristics of transmission and sense, they also increase the sensitivity and desensitization.
The fiber of the transmission type fiber temperature sensor only serves as an optical signal transmission to avoid the complicated environment of the temperature measurement area. The modulation function of the object to be measured is realized by sensitive components of other physical properties. Such sensors, due to the presence of optical fibers, have optical coupling problems with the sensing head, increase the complexity of the system, and are sensitive to interference such as mechanical vibration.
A variety of fiber optic temperature sensors have been developed.
The following is a brief introduction to the research status of several major fiber-optic temperature sensors. Among them are fiber-optic interference temperature sensors, semiconductor absorption fiber temperature sensors, and fiber grating temperature sensors.
Since its inception, fiber optic temperature sensors have been used in power systems, construction, chemical, aerospace, medical, and marine development, and have achieved a large number of reliable application results. Its application is a field that is in the ascendant and has a very broad development prospect. So far, there have been many related researches at home and abroad, although there have been great developments in sensitivity, measurement range and resolution, but I believe that With the deepening of research, according to the specific application purpose, there will be more and more higher precision, simpler structure, lower cost, more practical solutions, and further promote the development of temperature sensors.
