宽带FBG与自相关算法提高CCD解调精度的研究
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摘要
为提高光纤光栅解调算法的精度,设计了3 d B带宽在1~3 nm之间的宽带布拉格光栅与自相关算法解调系统,使用线阵CCD检测光谱,进行波长寻峰分析与实验验证。线阵CCD离散像素点之间波长间距固定,宽带布拉格光栅可得到更多有效像素数据点;自相关算法只考虑传感测量时光谱的偏移程度,可抵消背景噪声,消除光栅刻写或封装过程中操作不当引起光谱异常的影响,从而提高光栅中心波长解调精度。温度测量结果表明,使用自相关算法解调啁啾光栅与宽带光栅,误差较高斯算法分别减少54.05%和40.87%,此算法可以使啁啾光栅达到正常光栅的解调精度。并且,使用宽带光栅的解调误差仅为啁啾光栅的50%。
In order to improve the demodulation accuracy of fiber grating,a broadband Fiber Bragg Grating( FBG) with a 3 d B bandwidth within 1 ~ 3 nm and self-correlation algorithm demodulation system are designed. A linear array CCD sensor is used to detect grating spectrum and tested in the wavelength peak finding experiment. Wavelength spacing between pixels is fixed in a CCD sensor,so higher bandwidth FBG can get more effective pixels,and self-correlation algorithm only demodulates the excursion of spectrum in sensing and testing,thus,background noise is offset and spectral anomaly caused by writing or packaging improperly is eliminated. The precision of the grating center wavelength demodulation is improved. Experimental results show that using self-correlation algorithm demodulate broadband FBG and chirp FBG,the error is respectively 54. 05% and 40. 87% lower than Gauss algorithm. Self-correlation algorithm can make the chirped grating reach the demodulation accuracy of normal grating. Also the error of broadband FBG is only 50% of chirp FBG error.
In order to improve the demodulation accuracy of fiber grating,a broadband Fiber Bragg Grating( FBG) with a 3 d B bandwidth within 1 ~ 3 nm and self-correlation algorithm demodulation system are designed. A linear array CCD sensor is used to detect grating spectrum and tested in the wavelength peak finding experiment. Wavelength spacing between pixels is fixed in a CCD sensor,so higher bandwidth FBG can get more effective pixels,and self-correlation algorithm only demodulates the excursion of spectrum in sensing and testing,thus,background noise is offset and spectral anomaly caused by writing or packaging improperly is eliminated. The precision of the grating center wavelength demodulation is improved. Experimental results show that using self-correlation algorithm demodulate broadband FBG and chirp FBG,the error is respectively 54. 05% and 40. 87% lower than Gauss algorithm. Self-correlation algorithm can make the chirped grating reach the demodulation accuracy of normal grating. Also the error of broadband FBG is only 50% of chirp FBG error.
引文
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[2]ZHANG Faxiang,LV Jingsheng,JIANG Shaodong,et al.High sensitive anti-shock fiber grating micro vibration sensor[J].Infrared and Laser Engineering,2016,45(8):61-66.(in Chinese)张发祥,吕京生,姜邵栋,等.高灵敏抗冲击光纤光栅微振动传感器[J].红外与激光工程,2016,45(8):61-66.
[3]WANG Guina,ZENG Jie,MU Hao,et al.Optimization of fiber Bragg grating sensing network[J].Laser&Infrared,2015,45(1):66-69.(in Chinese)王桂娜,曾捷,穆昊,等.光纤光栅传感网络的优化研究[J].激光与红外,2015,45(1):66-69.
[4]LIU Feng,ZHU Lianqing,LOU Xiaoping,et al.Signal distortion analysis of fiber grating line array detector demodulation system[J].Laser&Infrared,2014,44(10):1119-1122.(in Chinese)刘锋,祝连庆,娄小平,等.光纤光栅线阵探测器解调系统信号失真分析[J].激光与红外,2014,44(10):1119-1122.
[5]ZHANG Dengpan,WANG Jin,WANG Yongjie.Realtime calibration method based on FBGA fiber grating demodulation system[J].Laser&Infrared,2015,45(7):825-829.(in Chinese)张登攀,王8),王永杰.基于FBGA光纤光栅解调系统的实时校准方法[J].激光与红外,2015,45(7):825-829.
[6]Wu M,Xiong Y,Ren N,et al.Design of FBG demodulation system based on arrayed waveguide grating[J].International Journal of Smart Home,2016,10(7):21-28.
[7]Huang W,Zhang W,Zhen T,et al.A cross-correlation method in wavelet domain for demodulation of FBG-FP satic-strain sensors[J].IEEE Photonics Technology Letters,2014,26(16):1597-1600.
[8]Huang W,Zhen T,Zhang W,et al.A high-resolution demodulation algorithm for FBG-FP static-strain sensors based on the hilbert transform and cross third-order cumulant[J].Sensors,2015,15(5):9928-9941.
[9]Harasim D,Gulbahar Y.Improvement of FBG peak wavelength demodulation using digital signal processing algorithms[C]//XXXVI Symposium on Photonics Applications in Astronomy.International Society for Optics and Photonics,2015:966212.
[10]Chen J,Shi F Q,Lei X,et al.A wide-range demodulation method for FBG sensor[J].Microwave&Optical Technology Letters,2016,58(10):2416-2419.
[11]Xiong Y L,Ren N K,Wu M Z,et al.Sensitivity-enhanced FBG demodulation system with multi-sideband filtering method[J].Optics Communications,2017,382:246-252.
[12]LI Zhengying,ZHOU Zude,TONG Xinglin,et al.Study on high-speed and high-capacity fiber grating demodulator[J].Acta Optica Sinica,2012,32(3):52-57.(in Chinese)李政颖,周祖德,童杏林,等.高速大容量光纤光栅解调仪的研究[J].光学学报,2012,32(3):52-57.
[13]HU Chenyuan.High-speed fiber grating sensing network high-speed demodulation method and key technology research[D].Wuhan:Wuhan University of Technology,2015.(in Chinese)胡宸源.大容量光纤光栅传感网络高速解调方法及关键技术研究[D].武汉:武汉理工大学,2015.