基于B样条的拉曼光谱基线校正方法

Baseline Correction Method for Raman Spectroscopy Based on B-Spline Fitting

基线漂移是光谱检测仪器普遍存在的现象,会对光谱信号的特征提取带来十分不利的影响,而基线校正是解决该问题的重要手段,也是拉曼光谱信号预处理的重要组成部分。基线校正的原理一般是通过拟合基线的方法来去除光谱信号中的基线漂移。传统的基线校正方法是利用多项式拟合的方法对拉曼光谱信号的基线进行拟合的,但是该方法容易出现过拟合和欠拟合现象,且拟合阶数难以确定。针对传统方法的缺点进行了改进,利用B样条方法对拉曼光谱信号的基线进行拟合,发挥B样条低阶光滑的优点,能够有效地克服多项式方法的缺陷。在实验中,利用该方法对孔雀石绿、罗丹明B的拉曼光谱信号进行了基线校正,观察并比较该方法和传统方法的校正结果。实验结果表明,该方法能够有效地消除拉曼光谱信号的基线漂移,在基线漂移较小和较大的位置,可以采用相同的拟合阶数,不会出现欠拟合和过拟合的现象,获得了良好的基线校正效果,为进一步分析光谱数据提供准确可靠的信息。

Baseline drift is a widespread phenomenon in modern spectroscopy instrumentation,which would bring a very negative impact to the feature extraction of spectrum signal,and the baseline correction method is an important means to solve the prob-lem,which is also the important part of Raman signal preprocessing.The general principle of baseline drift elimination is using the fitting method to the fit the baseline.The traditional fitting method is polynomial fitting,but this method is prone to over-fitting and under-fitting,and the fitting order is difficult to be determined.In this paper,the traditional method is improved;the B-spline fitting method is used to approach the baseline of Raman signal through constant iteration.The advantages of B-spline, namely low-order and smoothness,can help the method overcome the shortcomings of polynomial method.In the experiments, the Raman signal of malachite green and rhodamine B were detected,and then the proposed method and traditional method were applied to perform baseline correction.Experimental results showed that the proposed method can eliminate the Raman signal baseline drift effectively without over- and under-fitting,and the same order can be used in both positions where large or small baseline drift occurred.Therefore,the proposed method provided more accurate and reliable information for the further analysis of spectral data.