Research Of Fiber Sensor Measure Method Based On Dsp

This paper presents a new type of optical fiber Bragg grating sensor. This system takes the optical fiber Bragg grating as the sensing components. When the fiber grating is under the pressure or the external temperature changes, the center wavelength will have an offset. The size of the central wavelength offset is related with the exerted pressure and the external temperature, of which the information is hidden in the variation of reflected wavelength. Therefore, it has the characteristics of wavelength coding. The purpose of this paper is to demodulate the offset of FBG center wavelength, through which we could obtain the size of the exerted pressure and the variation of the external temperature.The innovation of this paper is to add the FFP filter when the laser is build. In order to have higher precision and temperature with the modulator, DSP is used as the signal processing tool. The structure of the FFP is piezoelectric ceramic, and when the voltage is loaded on it, the central wavelength of the FFP will have an offset. DA outputs analog signals to modulate the FFP, which is operated by DSP. And it must make sure that DA outputs analog signals to modulate the FFP, which is operated by DSP. It must make sure that the central wavelength range of FFP could cover the bandwidth of the FBG. Frequency-doubled effect will appear when FFP central wavelength and FBG central wavelength overlap. At this time, the central wavelength of FFP is just the central wavelength of FBG. The relationship between the external force or variation of temperature and the FBG central wavelength can be obtained through FFP characteristic curve. Thus the optical fiber Bragg grating sensor system based on TMS320F2812 is designed. It has excellent anti-interference characteristics, high sensitivity advantage and anti-corrosion advantage, etc. However, other sensors don't have such characteristics. Nowadays, optical fiber grating sensor has become the important research direction.At first, this paper introduces the principle of optical fiber Bragg grating sensor and general demodulation scheme which include optical fiber Bragg grating sensor principle, matching grating method, non-equilibrium Mach-Zehnder interfering method as well as tunable FP filtering demodulation method, etc. Secondary, it presents the design and research of FBG sensing system, which includes the overall design scheme, system principle and analysis and then it brings forward the experimental optical devices and characteristic. It introduces system's hardware design and software design. This hardware design includes DSP system structure which introduces the properties of DSP and DSP overall design scheme. This software design includes relevant algorithm, FIR filters, AD subroutines, DA subroutines and computation of amplitude and phase. Then, an experiment and its result are given that concern the experiment device and experimental analysis. And the relationship between different external force and the central wavelength of FBG is obtained; the wavelength is demodulated by the optical fiber sensor based on DSP and with this relationship the external force is obtained. At last, this paper is summarized and the follow-up work is looked forward.