| Fiber bragg grating is a kind of passive component with good performance, being widely applied in communication, sense and other areas. Quartz fiber grating sensor has the advantages of anti-electromagnetic interference, high sensitivity, well linearity, wavelength coding and realizable accurate distributed sensor, which can be used in the sensing measurement of stress, temperature, electric current, accelerated speed and other physical parameter. At present, it has been widely used in civil engineer, oil exploitation, military, aerospace and other areas.In making fiber bragg grating, usually the protective layer will be eliminated, resulting in the huge decrease of mechanical strength. Therefore, as the fiber bragg grating being used as sense, it should be equipped with good packaging protection. The ordinary organic polymer covercoating and macromolecule glue coating are equipped with the disadvantages of easily ageing, creep deformation and easily emerging relative displacement, leading to the inaccurate measurement, largely limiting the application of optical fiber and grating. Based on such a condition, a variety of packaging technique appearance, among them the metal packaging has advantages of stable and strong, good ductility, high temperature resistance, good weldability and so on, becoming the new hotspot of fiber encapsulation.Based on the analysis of fiber bragg grating sensor principle, the article use the mode theory to deduce the mathmatic mode of temperature and strain transducer, proving theorical basis for the packaging design of fiber bragg grating sensor. Then on the basis of comparative analyzing heat evaporate coating, chemical coating, sputtering coating, electroplating, ion plating and other traditional fiber bragg grating sensor coating method's advantages and disadvantages, the article applies magnetron sputter plating to realize the coating technique of FBG sensor, elaborating the coating theory in detail and realized the control process of FBG magnetron sputter plating coating, finishing the coating to FBG the different metals such as copper, thin with contrallable coat thickness.Secondly, the article has researched about temperature and strain response characteristic towards the fiber bragg grating sensor after being coated. The coated temperature responsive has increased from 10.1pm/℃to 11.3 pm/℃,the sensitivity has increased by 11.2%. Its temperature sensitivity has improved while the strain character has no difference. Besides that, on the basis of the analysis of various fiber bragg grating sensor signal demodulation method, the article apply long period fiber grating filter to design signal demodulation proposal. In the demodulating system, double traverse demodulation has been applied, one is to use the sensor signal of LPFG filtering, another is to refer to photosignal, reducing the illuminant jitter and the affect brought by the noises of illuminant and other systems.Finally, the light sensor signalsafter demodulation has been dealt with photoelectric translating, signal amplification and vertical filtering, besides that, the STC12C4052AD singlechip has been used to realize the treatment of analog signal to digital signal. In addition, the temperature information has used the LCD 1602 to display, make a convinience for human-machine communication. Among them, the addition of DS18B20 chip's temperature comparison mode provides rather accurate real-time temperature signal for system, further improved the reliability for system. In the ending of the article, relating to the hardware circuit, it has finished the modular write of related softwares, perfecting the fiber bragg grating temperature sensor demodulation system.Being teseted, the design in the article is equipped with the advantages of strong practicability,easy demodulation schedule and accurately. Besides that, the system parameter can meet the requirements of practicle projects such as the temperature test of transformer substation, under the shaft and so on. |
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