Science knowledge - optical fiber sensing, fiber Bragg grating, fiber grating sensor
Fiber Optic Sensing Technology
As the fiber not only as a light transmission medium, and light waves in optical fiber transmission when the characterization of light wave characteristic parameters (amplitude, phase, polarization, wavelength, etc.) due to external factors (such as temperature, pressure, magnetic field, electric field, displacement, etc.) the role of the change directly or indirectly, which can be used as a fiber optic sensor to detect a variety of components to be measured (physical, chemical, volume and biomass), which is the basic principle of optical fiber sensors.
Classification of fiber-optic sensing technology
Optical fiber sensors can be divided into sensor type (intrinsic type) and transmission light type (non-intrinsic type) two categories. Use of external factors change the characteristics of optical fiber parameters, which were measured against external factors and data transmission, known as the sensing fiber optic sensor, it has a sensor in-one features, information access and transmission are among the fiber. Optical fiber sensor transmission is measured using other sensitive components of the characteristic quantities, the optical data transmission, it is characterized by full use of existing sensors, easy to expand the applications. These two types of fiber-optic sensor system can be further divided into light stress, phase modulation, polarization modulation and wavelength modulation of several forms.
The characteristics of optical fiber sensors
1, anti-electromagnetic interference, electrical insulation, corrosion resistance, intrinsic safety.
2, high sensitivity.
3, light weight, small size, deflection.
4, extensive measurement object.
5, little effect on measured media, can be used for aerospace composite materials.
6, to facilitate reuse, easy to form a network.
7, integrated cost-effective.
Fiber Bragg Grating
Optical fiber core refractive index grating is periodic perturbation by the permanent fiber formed of a passive device, it will be a specific wavelength of incident light in the light of some or all of the reflection.
Fiber Bragg Grating Sensor
Fiber grating by stretching and compression, or change the temperature can change the grating period and effective refractive index in order to change the reflection wavelength of FBG purpose. Reflection wavelength and the strain, temperature, pressure, a linear relationship between physical quantities, according to these characteristics, can be made into fiber grating strain, temperature, pressure, acceleration and other sensors.
Fiber Bragg Grating Technology
FBG sensors are very extensive, and particularly suited to strong electromagnetic fields, corrosion and other harsh or unusual environments. His main application is as follows:
1 Civil Engineering: such as bridges, dams, Andi, a large steel structure such as health and safety monitoring
2 aerospace industry: as the plane pressure, temperature, vibration, fuel level and other indicators to monitor
3 ship shipping: If the ship's damage assessment and early warning
4 power industry: As the fiber Bragg grating sensors are not subject to electromagnetic fields, it is particularly suitable for monitoring the temperature of the power system
5 petrochemical industry: fiber grating nature of security, especially for petrochemical plants, oil fields in the temperature, liquid level control, etc.
NMR 6, remote machine on the ground temperature, the heart can be an efficient measurement
7 Application of the nuclear industry: waste stations to monitor the situation, monitoring the situation of the reactor building, etc.
8 FBG hydrophone can also be applied to the robot arm, sensing, security identification system
