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Research On Fiber Bragg Grating Sensing Technology And High Speed Demodulation Method In Special Environment

Posted on:2020-07-05Degree:DoctorType:Dissertation
Country:ChinaCandidate:J WangFull Text:PDF
GTID:1488306131967869Subject:Optical Engineering
Abstract/Summary:PDF Full Text Request
Aiming at the engineering application demand of fiber Bragg grating(FBG),the research of FBG sensing technology and high-speed demodulation method in special environment is carried out.A high-speed and high-resolution demodulation method of FBG based on optical real-time delay microwave phase detection(OTTD-MPD)is proposed.The real-time phase detection method in microwave photonics is applied to FBG demodulation.A full plating process is proposed for engineering applications in special environments.A FBG packaging method realizes All-metal Non-gelatinized Anti-chirp(AM-NG-AC)packaging of FBG sensors at full temperature(-192?140 ?).Research on special environment length detection method based on FBG is carried out.According to FBG length detection theory,two FBG-based cutter wear detection sensors and cutter wear demodulation system for shield machine with different application backgrounds are developed.Real-time multi-channel detection of cutter wear;Research on special environment bending detection method based on FBG was carried out.According to FBG bending detection theory,a new type of fiber Bragg grating-optical coherence tomography(FBG-OCT)catheter based on embedded semi-sectional stress tube was designed for real-time restoration and reconstruction of intravascular OCT three-dimensional morphology.The main work of this paper is as follows:1.The related theories of FBG demodulation,especially those of high-speed and high-resolution demodulation,are systematically studied.Based on Microwave Photonics and dispersion delay theory,an OTTD-MPD method is proposed to realize fast and high resolution demodulation of FBG.The experimental results show that when the group velocity dispersion of OTTD-MPD demodulation system is 79.5 ps/nm and the frequency of RF local oscillator signal is 40 GHz,the measurement resolution of FBG demodulation is 0.8 pm and the demodulation rate is over 10K/s.2.The all-metal non-gelatinized anti-chirp packaging FBG method for special applications is systematically studied.Electroless plating and evaporative plating were used to metallize FBG.The experimental results show that the encapsulated all-metal non-gelatinized anti-chirp packaging structure based on aluminum substrate not only realizes FBG protective packaging,but also achieves the temperature sensitivity of30.8pm/? after encapsulation,achieves anti-chirp and 0.3pm/? low temperature repeatability stability under liquid nitrogen conditions.3.The research of FBG-based special environment length detection method is carried out,and the theoretical model and analysis method of FBG-based length detection are established.However,combining the advantages of FBG power detection and wavelength encoding,a FBGA cutter wear detection scheme for shield machine is proposed,which reduces the detection requirements of reflective spectrum power.At the same time,FBGA not only meets the requirements of wear accuracy,but also achieves wear measurement in a large temperature range.The CFBG method uses a single optical fiber and the sensor is small in size.It is suitable for small cutter wear detection of shield machine.It achieves 1 mm detection accuracy and 20?80? wear end temperature range.The FBGA sensor method can meet the needs of 1 mm detection accuracy of main propulsion cutter head and 20?200? wear end temperature range,and can adapt to the temperature sudden change caused by hard geology.4.The research of bending detection method in special environment based on FBG is carried out,and the theoretical model and analysis method of bending detection based on FBG are established.According to the theory of FBG bending detection,a new type of FBG-OCT catheter was developed.The three-dimensional morphology of vascular prosthesis with bending information was reconstructed in the vascular prosthesis restoration experiment.The three-dimensional morphology of OCT in blood vessel with a bending radius of more than 200 mm and a rotating speed of 100r/s was restored.
Keywords/Search Tags:Fiber Bragg Grating Demodulation, Microwave Photonics, Dispersion Delay Ring, Fiber Bragg Grating Length Detection, Fiber Bragg Grating Bending Detection, Shield Wear Detection, Intravascular Optical Coherent Tomography
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