Design And Implement On Parallel Demodulation System Of Fiber Bragg Grating

In the second half of the 20th century, the information technology and sensing technology which especially take fiber optic communications and fiber optic sensing technology as representatives have been extremely improved, and greatly promoted the progress of human society. As a passive filter, Fiber Bragg Grating (FBG) has a series of advantages, for instance, it is small in size, small fusion loss, completely compatible in fiber and capable of being buried in smart materials, furthermore, its resonant wavelength is sensitive to changes in the external environment such as temperature, strain, refractive index, the concentration. Therefore, FBG has a wide range of applications in the fields of fiber optical communications and fiber optic sensing.FBG sensor demodulation system usually costs account for the majority of the cost of the whole system. However, it often determines the accuracy of the entire system. At present, due to difficulties caused by wavelength coding signal demodulation, system costs are too high in general areas to accept. Therefore, the way of demodulating wavelength coding signal of FBG is the key of application of FBG sensing technology.This paper presents a design of multi-channel parallel FBG demodulation system. Because the system can scan for multiple fibers at the same time and each fiber can be used as several fiber grating sensors in the way of WDM (wave division multiplication). As result, the system can demodulate almost 100 FBG sensors at one time, which can meet the demands of Real-time monitoring in sensor network of large projects.Papers detail an embedded FBG parallel demodulation system design, including optical facet, hardware and software designs. The facet of optical design has two aspects. First, using broadband optical source and tunable F-P filter we make narrowband scanning source, which is used as an incentive optical signal of FBG. Second, using the signal-3dB coupler we divide incentive optical signal into sub-ray beams, meanwhile we place incentive signal into the sensing fiber and make the reflected modulated light signals be coupled into PD (photo detector), after these processes the photoelectric conversion is completed. Furthermore, every fiber is equipped with a PD respectively, so using this kind of hardware redundancy we can ensure the system has a parallel demodulation capability. In the hardware design, the synchrony of hardware modules is controlled by specific hardware circuit, and the MCU (main control unit) is ARM9 processor chip-- Samsung S3C2410, which is used to control...