气体光谱分析应用中傅里叶变换红外光谱基线漂移分段比校正方法

Spectral Baseline Correction by Piecewise Dividing in Fourier Transform Infrared Gas Analysis

针对气体光谱分析应用中傅里叶变换红外光谱仪长时间连续工作时易出现光谱基线漂移、畸变问题,对红外光源温度波动及漂移、动镜倾斜、分束器性能变化以及检测器横向偏移对光谱基线的影响进行了仿真研究,结果表明光谱基线的漂移近似线性。基于此,本文提出分段比光谱基线漂移修正法SBCPD校正光谱基线。通过比较基线校正前后仿真光谱峰高变化、偏最小二乘(PLS)定量分析模型预测不确定度、油气探井气测录井在线基线校正性能,发现SBCPD性能优越,要优于传统的多项式拟合法及airPLS法。经检验,该方法性能稳定,计算量小,便于工程应用。

Aimed at the problem that baseline drift or distortion often appears in Fourier transform spectra after spectrometer has continuously worked for a long time, baseline variation caused by IR source temperature drift and fluetuation, tilt of moving mir- ror, performance parameter change of beam splitter and lateral shift of detector were studied by simulating using MATLAB. Simulation results show that spectral baseline drift is approximately linear. On this basis, a novel method named spectral baseline correction by piecewise dividing （SBCPD） is proposed to correct spectral baseline in the present work. By comparing peak height of simulated spectra, it was found that performance of SBCPD is better than that of common methods of polynomial fitting, air-PLS （adaptive iteratively reweighted Penalized Least Squares）. And the application in gas well-logging showed that prediction accuracy of SBCPD is also higher. Additionally, this method is reliable and of less calculation, and is suitable for engineering application.