宽带FBG与自相关算法提高CCD解调精度的研究

为提高光纤光栅解调算法的精度,设计了3 dB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%。

Research on demodulation precision of CCD improved by broadband FBG and self-correlation algorithm

In order to improve the demodulation accuracy of fiber grating,a broadband Fiber Bragg Grating(FBG) with a 3 dB 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.