What is fiber optic temperature measurement? What is the dis

Fiber optic temperature measurement technology is a new technology that has been developed in the last more than 10 years. At present, the temperature measurement technology of fiber is still in the stage of research, development and practical application. Some of its excellent characteristics have been gradually revealed in some occasions where temperature measurement is difficult to solve by traditional methods. Temperature measurement is carried out on target objects which may cause large measurement errors and even can not work normally by means of common temperature measuring instruments. For example, the high frequency melting of metal and vulcanization of rubber, the temperature measurement of microwave oven during the baking process of wood and fabric, food and medicine. Optical fiber temperature measurement technology has an absolute advantage in these areas.

The principle of optical fiber temperature sensing is mainly based on the optical time domain reflection principle of optical fiber and the temperature effect of backscattering Raman scattering of optical fiber. When a light pulse is injected into the fiber from one end of the fiber, the optical pulse propagates along the optical fiber. As the inner wall of the fiber is similar to a mirror, the light pulse is reflected at every point in the transmission. A small part of the reflection is reflected in the reflection, and the direction is just opposite to the direction of the incident light. The intensity of the reflected light is related to the temperature of the reflection point in the light. The higher the temperature of the reflection point, the greater the intensity of the reflected light. That is to say, the intensity of the reflected light can reflect the temperature of the reflection point. Using this phenomenon, if we can measure the intensity of the reflected light, we can calculate the temperature of the reflection point, which is the basic principle of measuring the temperature by using the optical fiber.

The distributed optical fiber temperature sensing is to use the whole fiber as the sensor, and every point on the fiber temperature measuring fiber has the function of "transmission" and "sense". In the distributed optical fiber temperature sensing system, when a strong pulse laser signal is transmitted in the optical fiber, each point in the fiber produces extremely weak backscattering to the laser signal. According to the wavelength of the scattered optical signal, it can be divided into Rayleigh scattering, Raman scattering and Brillouin scattering. The intensity of the Raman scattering signal is correlated with the temperature of the point. The temperature information of the point is obtained by detecting the light intensity of the scattered light signal of each point, and then the temperature distribution on the whole fiber is obtained.