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In the late 1970s, optical fiber sensing technology emerged rapidly along with the development of optical fiber communication technology. In the past 20 years, fiber grating has been rapidly developed as a kind of micro-optical component, which has made the development of fiber-optic sensing technology a qualitative leap. In the aerospace field, the use of various sensors is extremely intensive. But its sensitivity, volume and weight have high requirements.
For the structure of an aircraft, fiber cable，the health development monitoring system requires a large number of sensors, so the size and weight of the sensors become more important. Especially when advanced aircraft are in flight, traditional sensor network technology can no longer meet our development needs for real-time and accurate monitoring of atmospheric data. In addition, the aircraft will be affected by extremely harsh flight environment (including high temperature, strong magnetic field, etc.) during the flight. The existing traditional electric sensors are easily restricted by environmental factors and cannot work normally in extreme flight environments, which will inevitably affect the safety of the aircraft and cause catastrophic accidents. The fiber grating sensor, because of its light weight, small size, high temperature resistance, corrosion resistance, anti-electromagnetic interference, etc., can largely overcome the influence of environmental factors, can accurately monitor various parameters of the aircraft structure, and make timely judgments. prevent accidents. The wide application of fiber grating sensing technology in the aerospace field will play an important role in promoting the development of aerospace.
2. principles of Fiber Bragg Grating Sensing Technology
The optical fiber sensor is a periodic distribution structure of refractive index formed in the fiber core using ultraviolet exposure technology. When a certain bandwidth of light enters the optical fiber sensor through the circulator, because the optical fiber sensor has wavelength selectivity, it can only make a specific wavelength The light is reflected, and then the wavelength change of the reflected light is measured by a demodulator or spectrometer.Microarray ， The change in the period of the fiber grating and the effective refractive index n eff will affect the reflection spectrum of the fiber grating. Any physical process that changes these two parameters will cause the shift of the grating Bouguer wavelength. There is the following relationship between them and the wavelength change ∆λ B
The sensing process based on optical fiber sensor is the influence of external physical parameters on the period or effective refractive index of the optical fiber sensor, which causes the drift of the center wavelength of the emitted light.
Compared with traditional Chinese electrical sensors, fiber grating temperature sensors have the following advantages:
(1) The sensor probe has simple structure, small size and light weight, and can measure the strain and structural damage of the structure.
3. There is natural compatibility with optical fiber, easy to connect with optical fiber, low loss, good spectral characteristics and high reliability.
The fiber grating detector is non-conductive, has little impact on the measured medium, and has the characteristics of anti-corrosion and anti-electromagnetic interference, and is suitable for working in harsh environments.
(4) Lightweight and soft, multiple gratings can be written in one optical fiber to form a sensing array.
(5) Sensor multiplexing is a unique technology of optical fiber sensor, which can measure the distribution field along the optical fiber laying path.
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