本文關(guān)鍵詞：光纖光柵傳感OFDR解調(diào)關(guān)鍵技術(shù)研究　出處：《電子科技大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 光頻域反射儀 線性掃頻激光器 非線性調(diào)諧補(bǔ)償 光纖光柵傳感

【摘要】：光纖光柵傳感因波長編碼、測量范圍廣、抗電磁干擾、長期穩(wěn)定性好、耐腐蝕,尤其是能陣列復(fù)用等優(yōu)點(diǎn),在工程結(jié)構(gòu)、石油化工、電力系統(tǒng)等諸多領(lǐng)域的監(jiān)測中有著十分廣泛的應(yīng)用,是目前最為成熟的光纖傳感器。但受光源譜寬與傳感器帶寬的限制,無法實(shí)現(xiàn)高密度傳感器陣列復(fù)用。將光頻域反射計(jì)(OFDR)技術(shù)應(yīng)用于光纖光柵傳感解調(diào)是實(shí)現(xiàn)高密度陣列復(fù)用最為有效的方法。針對(duì)高密度光纖光柵傳感系統(tǒng),論文主要對(duì)OFDR的光源特性、光路結(jié)構(gòu)及解調(diào)算法中的關(guān)鍵技術(shù)進(jìn)行了研究。論文主要研究工作如下:1.闡述了OFDR的基本原理,推導(dǎo)了OFDR的理論模型,對(duì)影響其動(dòng)態(tài)范圍、空間分辨率的各種因素進(jìn)行了分析和討論。建立了相位噪聲理論模型,仿真分析了其在不同的光源相干長度和連接器反射率下對(duì)拍頻信號(hào)的影響。進(jìn)一步討論了OFDR系統(tǒng)抑制光譜偏振衰落的方法。2.開展了光纖光柵傳感系統(tǒng)OFDR解調(diào)算法設(shè)計(jì)與特性分析。對(duì)影響拍頻信號(hào)的非線性調(diào)諧效應(yīng)進(jìn)行了分析,并總結(jié)了其補(bǔ)償方法。通過理論推導(dǎo),討論了輔助干涉儀觸發(fā)采樣法中調(diào)諧光源掃頻速率與光路時(shí)延間的匹配條件。3.仿真分析驗(yàn)證了非均勻傅里葉變換(NUFFT)和三次樣條插值算法能夠消除非線性調(diào)諧效應(yīng),改善系統(tǒng)空間分辨率,并提出采用加漢明(hamming)窗FFT的三次樣條插值法,減小信號(hào)能量的擴(kuò)散,進(jìn)一步提高系統(tǒng)空間分辨率。4.開展了高密度光纖光柵傳感OFDR解調(diào)實(shí)驗(yàn)。一方面,編寫了基于NUFFT和加窗三次樣條插值補(bǔ)償算法的信號(hào)處理軟件,實(shí)現(xiàn)空間分辨率1cm的OFDR系統(tǒng)。另一方面,進(jìn)一步編寫了光纖光柵波長偏移量的解調(diào)算法,并開展了溫度解調(diào)實(shí)驗(yàn)。OFDR系統(tǒng)成功解調(diào)了不同溫度下光纖光柵的波長偏移量,通過與光譜分析儀實(shí)際測試結(jié)果對(duì)比,驗(yàn)證了解調(diào)算法的正確性。在4個(gè)波長一致、間隔為15cm弱反射的光纖光柵傳感器陣列上,不增敏的情況下,獲得溫度靈敏系數(shù)9.83/Cpm?。實(shí)驗(yàn)結(jié)果表明該OFDR系統(tǒng)能夠應(yīng)用于高密度光纖光柵傳感的解調(diào)。
[Abstract]:Fiber Bragg grating (FBG) sensing has many advantages such as wavelength coding, wide measurement range, anti-electromagnetic interference, good long-term stability, corrosion resistance, especially the ability of array reuse, etc., in engineering structure, petrochemical industry. Power system and other fields of monitoring have a very wide range of applications, is the most mature optical fiber sensor, but limited by the spectral width of light source and sensor bandwidth. Unable to implement high density sensor array multiplexing. OFDR (Optical Frequency Domain reflectometer). Fiber Bragg grating sensing demodulation is the most effective method to realize high density array multiplexing. This paper mainly studies the characteristics of OFDR light source, optical circuit structure and the key technology of demodulation algorithm. The main research work of this paper is as follows: 1. The basic principle of OFDR is expounded. The theoretical model of OFDR is derived, and the factors affecting its dynamic range and spatial resolution are analyzed and discussed, and the theoretical model of phase noise is established. The effects of coherent length of light source and reflectivity of connector on the beat frequency signal are simulated and analyzed. The method of suppressing spectral polarization fading in OFDR system is further discussed. 2. Fiber Bragg grating sensing system is developed. Design and characteristic analysis of OFDR demodulation algorithm. The nonlinear tuning effect affecting beat frequency signal is analyzed. And summarized its compensation method. Through the theoretical derivation. The matching conditions between the frequency sweep rate of the tuned light source and the optical path delay in the trigger sampling method of the auxiliary interferometer are discussed. 3. The simulation results verify the nonuniform Fourier transform (NUFFT). And cubic spline interpolation algorithm can eliminate the nonlinear tuning effect. The spatial resolution of the system is improved and the cubic spline interpolation method with hamming window FFT is proposed to reduce the diffusion of signal energy. Further improve the system spatial resolution. 4. The high-density fiber grating sensing OFDR demodulation experiment is carried out. On the one hand. The signal processing software based on NUFFT and cubic spline interpolation compensation algorithm is developed to realize the OFDR system with spatial resolution of 1cm. Furthermore, the demodulation algorithm of wavelength offset of fiber grating is compiled, and the temperature demodulation experiment. OFDR system successfully demodulates the wavelength offset of fiber grating at different temperature. The correctness of the demodulation algorithm is verified by comparing with the actual test results of the spectrum analyzer. In the case of four fiber Bragg grating sensor arrays with the same wavelength and 15cm interval weak reflection, the sensitivity is not increased. The temperature sensitivity coefficient is 9.83% Cpm? The experimental results show that the OFDR system can be applied to demodulation of high density fiber grating sensor.
【學(xué)位授予單位】：電子科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TN761;TN253

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本文編號(hào)：1407925