Application of F&C-Jiajun optical fiber sensor
Over the years, sensors have developed in the direction of sensitivity, precision, adaptability, small size and intelligence. In this process, fiber optic sensors, a new member of the sensor family, are favored. Optical fiber has many excellent properties, such as: Anti-electromagnetic interference and atomic radiation performance, fine diameter, soft, light weight mechanical properties, insulation, non-inductive electrical properties, water resistance, high temperature resistance, corrosion resistance of chemical properties, etc., it can be in the place where people can not reach (such as high temperature area), or harmful to people in the area (such as nuclear radiation area), play a role of human eyes and ears, but also beyond the human physiological boundaries. Receiving external information that is not perceived by the human senses.
Optical fiber sensor is a new technology that has emerged in recent years, which can be used to measure a variety of physical quantities, such as sound field, electric field, pressure, temperature, angular velocity, acceleration, etc., and can also complete measurement tasks that are difficult to complete with existing measurement technologies. In small Spaces, in strong electromagnetic interference and high voltage environments, fiber optic sensors have shown unique capabilities. At present, there are more than 70 kinds of optical fiber sensors, which are roughly divided into optical fiber itself sensors and sensors that use optical fiber.
The so-called sensor of the optical fiber itself is that the optical fiber itself directly receives the external measurement. The external physical quantity to be measured can cause changes in the length, refractive index and diameter of the measuring arm, so that the light transmitted in the fiber changes in amplitude, phase, frequency, polarization and so on. The light transmitted by the measuring arm interferes (compares) with the reference light of the reference arm, so that the phase (or amplitude) of the output light changes, according to which the measured change can be detected. The phase transmitted in optical fiber is highly sensitive to external influences, and the physical quantity corresponding to a small phase change of 10 to the minus 4 radians can be detected by interference technology. Using the fiber’s winding and low loss, it is possible to disk a very long fiber into a small diameter fiber ring to increase the utilization length and obtain higher sensitivity.
Optical fiber acoustic sensor is a kind of sensor that uses the optical fiber itself. When the optical fiber is subjected to a very small external force, it will be slightly curved, and its light transmission capacity will change greatly. Sound is a kind of mechanical wave, its effect on the optical fiber is to force the optical fiber and produce bending, through bending can get the strength of the sound. Compared with laser gyro, fiber optic gyro has high sensitivity, small size and low cost, and can be used in high-performance inertial navigation systems of aircraft, ships and missiles. The diagram shows the principle of a fiber optic sensor turbine flowmeter.
Another large category of optical fiber sensors is the use of optical fiber sensors. Its structure is roughly as follows: the sensor is located at the end of the optical fiber, which is just the transmission line of the light, and the physical quantity to be measured is transformed into the amplitude, phase or amplitude change of the light. In this sensor system, conventional sensors and optical fibers are combined. The introduction of optical fiber makes it possible to realize the probe telemetry. This optical fiber transmission sensor has a wide range of applications and is easy to use, but the accuracy is slightly lower than the first type of sensor.