“The fiber optic sensor consists of a light source, an incident fiber, an exit fiber, an optical modulator, a photodetector, and a demodulator. The basic principle is that the light of the light source is sent to the modulation area through the incident optical fiber, and the light interacts with the external measured parameters in the modulation area, so that the optical properties (such as intensity, wavelength, frequency, phase, partial normality, etc.) change and become The modulated signal light is then sent to the photodetector and demodulator through the output fiber to obtain the measured parameters.
The fiber optic sensor consists of a light source, an incident fiber, an exit fiber, an optical modulator, a photodetector, and a demodulator. The basic principle is that the light of the light source is sent to the modulation area through the incident optical fiber, and the light interacts with the external measured parameters in the modulation area, so that the optical properties (such as intensity, wavelength, frequency, phase, partial normality, etc.) change and become The modulated signal light is then sent to the photodetector and demodulator through the output fiber to obtain the measured parameters.
Optical fiber sensors can be divided into two categories according to the sensing principle: one is a light-transmitting (non-functional) sensor, and the other is a sensing (functional) sensor. In the light-transmitting optical fiber sensor, the optical fiber is only used as the transmission medium of light, and the sensing of the measured signal is completed by other sensitive components. A modulator is a sensitive element of spectral changes or other properties.
In the sensing fiber optic sensor, the optical fiber is both sensitive to the measured signal and the transmission of the optical signal, and the “sensing” and “transmission” of the signal are combined into one, so the optical fiber in this type of sensor is continuous. Due to the different roles played by the optical fibers in these two sensors, the requirements for the optical fibers are also different.
In the light-transmitting sensor, the optical fiber only plays the role of transmitting light, and the communication optical fiber or even the ordinary multi-mode optical fiber can meet the requirements, and the sensitive element can be realized by flexibly selecting high-quality materials, so the sensitivity of this type of sensor can be made It is very high, but requires more optical coupling devices and the structure is more complicated.
The structure of the sensing fiber optic sensor is relatively simple, and some coupling devices can be used less, but the requirements for the optical fiber are high, and special optical fibers that are sensitive to the measured signal and have good transmission characteristics are often used. So far, the former is mostly used in practice, but with the improvement of the optical fiber manufacturing process, the sensing optical fiber sensor will also be widely used.
According to the principle of light being modulated in the optical fiber, the optical fiber sensor can be divided into: intensity modulation type, phase modulation type, polarization state modulation type, frequency modulation type, wavelength modulation type, etc. So far, optical fiber sensors can measure more than 70 kinds of physical quantities.
Compared with traditional sensors, fiber optic sensors have unique advantages:
(1) High sensitivity
Since light is an electromagnetic wave with a very short wavelength, its optical length is obtained from the phase of the light.Taking the fiber interferometer as an example, due to the small diameter of the fiber used, its optical length will change when it is subjected to a small external mechanical force or temperature change, resulting in a large phase change.
Assuming that a 10-meter fiber is used, a change of 1°C causes a phase change of 1000ard. If the minimum phase change that can be detected is 0.01ard, then the minimum temperature change that can be measured is 10°C, which shows its high sensitivity.
(2) Anti-electromagnetic interference, electrical insulation, corrosion resistance, intrinsic safety
Since the optical fiber sensor uses light waves to transmit information, and the optical fiber is an electrically insulating, corrosion-resistant transmission medium, and is safe and reliable, it can be easily and effectively used in various large-scale electromechanical, petrochemical, mines, etc. flammable, explosive and other harsh environments.
(3) Fast measurement speed
Light travels the fastest and can transmit two-dimensional information, so it can be used for high-speed measurements. The analysis of radar and other signals requires a very high detection rate, which is difficult to achieve by applying Electronic methods, but can be solved by using high-speed spectrum analysis of the diffraction phenomenon of light.
(4) Large information capacity
The measured signal takes light waves as the carrier, and the frequency of light is extremely high, and the frequency band accommodated is very wide, and the same optical fiber can transmit multiple signals.
(5) Suitable for harsh environments
Optical fiber is a dielectric, resistant to high voltage, corrosion, and electromagnetic interference, and can be used in harsh environments that other sensors are not suitable for. In addition, the optical fiber sensor also has the characteristics of light weight, small size, flexibility, wide range of measurement objects, good reusability, and low cost.
Fiber Optic Temperature Sensors – FOT-L-SD and Fiber Optic Temperature Sensors – FOT-L-BA are a class of fiber optic temperature sensors ideal for measuring temperature in extreme environments, including cryogenic, nuclear, microwave, and high-intensity RF etc. The FOT-L combines all the good features you would expect from an ideal sensor body. As a result, these sensors provide highly accurate and reliable temperature measurements even in extreme temperatures and adverse environments.
The main features of both FOT-L temperature sensors are their complete immunity to EMI and RFI, their small size, built-in safety features for hazardous environments, high temperature resistance, corrosion resistance and high accuracy. Based on fiber optic technology, sensors are inherently immune to EMI and RFI. The light sensor is electronically inactive, so it neither emits nor is affected by any type of EM radiation, be it microwave, RF, or NMR.
Fiber Optic Pressure Sensor -FOP-M260, FOP-M260 fiber optic pressure sensor is a small volume, high precision sensor designed for the medical field. Completely immune to electromagnetic interference and completely intrinsically safe to the human body. Widely used in cardiovascular, gastroenterology, pharmacology and other medical fields.
Optical fiber pressure sensor FOP-M260 specific parameters:
Pressure range: 300mmHg~300mmHg
System accuracy: ±3mmHg
Sensitivity thermal effect:
Pressure resistance: 4500mmHg
Wire Sheath: Nylon sheath, outer diameter 0.9mm
Top terminal: bare unprotected/with protection/protected with gel/customized
Standard sensor length: 2m
Connector: SCAI, SCAI is a SCA connector with intelligent chip communication calibration data connected to the signal reading module.
The Links: 2DI75M-050 DSEI2X61-10B