- Apr 24, 2018 -
The basic principle of the optical fiber sensor is to send the light signal from the light source into the modulator through the optical fiber, so that the parameters to be measured interact with the light entering the modulation region, resulting in the optical properties of the light (such as the intensity, wavelength, frequency, phase of the light). The polarization state is changed and becomes the modulated signal source. The measured parameters are obtained after demodulation after the optical fiber is fed into the photodetector.
Sensors are developing in the direction of sensitive, accurate, adaptable, small and intelligent. In this process, the new members of the sensor family of fiber sensors are popular. Fiber has a lot of excellent properties, such as the ability to resist electromagnetic and atomic radiation interference, thin, soft, light weight, mechanical properties; insulation, no The electrical properties of induction; water resistance, high temperature resistance, and corrosion resistance, etc. it can play an ear and eye role in places (such as high temperature areas) or harmful areas (such as nuclear radiation areas), and can also transcend human physiological boundaries and receive external information that is not felt by the senses.
The basic principle of the optical fiber sensor is to send light from the light source into the modulator through the optical fiber so that the parameters to be measured interact with the light entering the modulation region, resulting in the optical properties of the light (such as the intensity, wavelength, frequency, phase of the light, etc. The change of polarization state is called modulated signal light, and the measurement is completed by using the influence of the measured on the transmission characteristics of the light.
There are two measuring principles for optical fiber sensors:
The working principle is based on the optical modulation effect of the optical fiber , that is , the optical fiber ' s optical characteristics such as temperature , pressure , electric field , magnetic field and so on are changed when the external environment factors such as temperature , pressure , electric field , magnetic field and so on are changed .
Therefore, if we can measure the change of optical phase and intensity through the fiber, we can know the change of measured physical quantity. This kind of sensor is also called sensitive element type or function type optical fiber sensor. The laser point light beam diffuses into parallel waves, and the spectrometer is divided into two channels, one is the reference light path, the other is the measuring light path. The external parameters (temperature, pressure, vibration, etc.) cause the change of optical fiber length and the optical phase change of the phase, thus produce different number of interference fringes. Counting the mode movement of the optical fiber, we can measure the temperature or pressure.
Second, the principle of structured optical fiber sensor. The structured optical fiber sensor is a measurement system composed of optical detection element (sensing element), optical fiber transmission circuit and measuring circuit. Optical fiber is only used as the transmission medium of light, so it is also called optical fiber sensor of light transmission type or non-function type.
Fiber optic sensors are widely used. The famous sensor line Shopping Mall Baieng Network has imported from Canada an optical fiber displacement sensor, FODfor hard-to-reach locations and dangerous environments such as measurement in explosive materials, with high accuracy and safety equipment built in for medical applications. With high accuracy and good reliability, FOT-M, a fiber optic strain sensor for monitoring civil engineering applications such as dams, bridges, tunnels and other structures, is SFO-W.
Optical fiber has many excellent properties, such as: resistance to electromagnetic and atomic radiation interference, fine diameter, soft quality, light weight mechanical properties; insulation, non-inductive electrical properties; water resistance, high temperature resistance, corrosion resistance, chemical properties, etc. It can act as a human ear and eye in areas that are not accessible or harmful to human beings (such as nuclear radiation zones), and it can transcend human physiological boundaries and receive outside information that is not perceived by human senses.
The characteristics of optical fiber sensors:
1. Because prism is used in reflector, its detection performance is higher and more reliable than that of general reflective light control sensor.
2. Compared with the separate optical control sensor, the circuit connection is simpler and easier.
3. Mother button embedded design, installation is more simple.
The advantage of optical fiber sensor is that compared with traditional sensors, optical fiber sensor uses light as the carrier of sensitive information and optical fiber as the medium for transmitting sensitive information. It has the characteristics of optical fiber and optical measurement, and has a series of unique advantages. It has good electrical insulation, strong resistance to electromagnetic interference, non-invasive, high sensitivity, easy to realize long-distance monitoring of measured signal, corrosion resistance, explosion-proof, flexible optical path, easy to connect with computer.
The sensor is moving in the direction of sensitivity, precision, adaptability, small size and intelligence. It can act as a human ear and eye in places that are not accessible to people (such as high temperatures or areas that are harmful to people, such as nuclear radiation). It also transcends the physical boundaries of human beings and receives external information that their senses do not perceive.