FTIR单边干涉图相位校正技术的研究与改进

基于傅里叶变换红外光谱仪干涉图的单边过零采样和非对称性,对相位校正技术进行研究和改进。针对Mertz乘积法对切趾函数的匹配性要求高,干涉图非对称切趾旁瓣抑制效果差、光谱分辨率低的缺点,综合Mertz法和Forman法的特点提出一种改进的相位校正方法。采用对称化方法将单边干涉图变换为双边干涉图、对称切趾、傅里叶变换重建功率谱,并采用对称化的双边干涉图傅里叶变换求取高分辨率的相位谱,提高相位校正的精度。通过仿真分析了非对称窗函数较对称窗函数有比较宽的主瓣宽度、高的旁瓣幅值,分辨率降低;实验验证该改进的相位校正方法功率谱误差小、计算量少,且光谱分辨率比较高,达到2cm-1。

Phase correction technology research and improvement based on single-sided interferograms in FTIR

In the Fourier transform infrared spectrometers the interferograms are usually sampled by the means of the single-side beyond zero path difference and the interferograms are asymmetric. These phase-corrected technologies are researched and improved in the present paper. In the Mertz method which requires apodization to be higher, the interferograms are apodized by these asymmetric windows so that the width of the main lobe increases and spectral resolution reduced. In order to solve these problems, a method which combines the Mertz and Forman methods is presented in the paper. In the method a double-side interferogram is constructed by the mirrored processing of the single-side interferogram beyond zero path difference, followed by the symmetric apodization, fast Fourier transform (FFT) to rebuild spectrum. And in the method high resolution phase spectrum is computed by the symmetrization of double-side interfergram to improve the phase-correction accuracy. In the experiment, these asymmetric window functions have the lower resolution compared with these symmetric window functions. And the spectrum which is acquired by the improved phase corrected method is compared with the spectra which are acquired by the Mertz and Forman methods, and the improved method has less error than Mertz, less computation than Forman, and the spectral resolution achieved 2 cm(-1).