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What is a fiber optic grating demodulator

What is a fiber optic grating demodulator

In many special occasions, fiber optic grating sensors have many characteristics that traditional sensors do not possess. Fiber Bragg Grating, as an intelligent sensor, has the advantages of small size, light weight, corrosion resistance, strong resistance to electromagnetic interference, easy integration, and simple structure. It can be buried inside the tested object and material to detect physical quantities such as pressure, temperature, stress, strain, flow rate, flow rate, and viscosity.

Fiber Bragg Grating (FBG) sensors have rapidly become excellent sensor components, capable of measuring various physical quantities such as temperature, strain, and pressure. It has the advantages of high sensitivity, no electromagnetic interference, good waterproof performance, small size, light weight, high reliability, and can be embedded in composite materials. FBG obtains sensing information by modulating the reflection center wavelength through external parameters. Therefore, the key to demodulation in FBG sensing systems is to measure the change in the center wavelength of its reflection peak.

At present, FBG center wavelength demodulation methods can be divided into two categories: (1) methods based on grating diffraction spectroscopy measurement or tunable laser scanning, such as using CCD detection, tunable filters, etc; (2) Using fixed filters, such as edge filtering method. The use of tunable lasers has problems such as slow detection speed and high system cost; The edge filtering method has problems such as inconvenient multi-point multiplexing and conflicting range and accuracy. The CCD detection method using planar or volume gratings has been widely used due to its advantages such as fast spectral detection speed, low system cost, and simple multi-point multiplexing.

Principle of Fiber Bragg Grating Demodulator

The core work of demodulation for fiber optic grating sensing signals is to read and transform the return values of different center wavelengths of the fiber optic grating, and then obtain the changes in external information. The light from a broadband light source is incident into the sensing fiber through a 50:50 coupler with a certain bandpass. There are multiple FBG sensors with different reflection center wavelengths in the sensing fiber, and FBG sensors with different reflection center wavelengths are reflected at wavelengths that meet the Bragg condition, while light transmission at wavelengths that do not meet the condition occurs. At this point, external parameters are modulated into the reflected wavelength and enter the demodulator through a coupler for demodulation. The demodulator used in this article is based on the principles of multi-level diffraction gratings and linear array infrared CCD. The optical path adopts the principle of transmission grating dispersion. The reflected spectrum is processed by dispersion and projected onto the photosensitive surface of the linear array photodetector. Therefore, the reflected spectrum is converted into electrical signals on different pixels of the linear array photodetector, which are used for subsequent demodulation.

Price of Fiber Bragg Grating Demodulator

1. Looking at fiber optic sensor brands, a good sensor brand will be promoted in the market, and over time, it will gradually become a brand. There is still a considerable gap between branded and non branded products in terms of after-sales and service. Brand products value reputation and reputation, so fiber optic sensor brands are still good.

2. Quality, a high-quality fiber Bragg grating demodulator is not comparable to other unbranded products in terms of user experience. A high-quality product is very strict in production, which will result in sales prices that cannot be compared with inferior products and will be slightly more expensive.

3. Search more, you can search for relevant fiber optic demodulator products online, learn more about the quotations provided by different fiber optic grating sensor companies, and choose a product that you think is suitable for your application range. The market is very large, so compare and find some more favorable products.

Fiber Bragg grating demodulators have a wide range of applications in fields such as power energy, petrochemicals, industrial and civil buildings, and other fields that require real-time temperature and stress monitoring. The use of fiber optic grating sensing technology can achieve long-distance measurement and monitoring, with the characteristics of wide measurement range, high accuracy, and high resolution. It has advantages in harsh environments with strong electromagnetic interference or flammable and explosive materials.
The industrialization and scale promotion of fiber optic sensors are adapting to the needs of national economic development. The research and industrialization of fiber optic sensor technology has become a sensor that is well applied in the power and other industries. Traditionally, fiber Bragg gratings are demodulated using spectrometers, monochromators, and wavelength meters. However, these demodulation systems have drawbacks such as high cost and large volume. Therefore, many simpler and more practical demodulation methods have been proposed. There are mainly interference demodulation technology, linear edge filtering technology, matched filtering demodulation technology, tunable filtering demodulation technology, etc. The interferometric demodulation technology has high measurement accuracy, but the measurement range is limited by the free spectral range of the interferometer. The testing range of linear edge filtering technology is inversely proportional to the resolution, while the matching filtering method is simple and practical, but the tuning range is small. The demodulation method based on tunable FP filters has advantages such as high sensitivity, high light energy utilization, simple operation, wide tuning range, and good system stability. A wavelength displacement monitoring system suitable for engineering applications.

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