单边干涉图相位校正技术与关键问题

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Forman卷积法干涉图相位校正方法进行分析和改进。针对Forman卷积法相位校正过程中需卷积运算,硬件实现难的问题,应用三个快速傅里叶变换(FFT)运算实现线性卷积,节省运算时间。并通过仿真分析了小双边数据量、切趾函数、多次相位校正等对干涉图相位校正效果的影响。在以500K的红外黑体为辐射源,获取红外光谱范围的大气吸收谱实验中,通过HgCdTe点探测器获取单边过零干涉图,采用改进的Forman法对干涉图进行相位校正和光谱重建,经标定、归一化后的复原光谱,光谱分辨率为4cm-1,波长误差比较小,有比较高的准确度。

Correcting Method of Asymmetric Single-Side Interferogram and Analyzation of Key Problems

In the Fourier transform infrared spectrometers,the interferograms are usually sampled by means of the single-side beyond zero path difference and the interferograms are asymmetric.In order to realize the Fourier cosine transform and truly rebuild the spectrum,the phase-corrected technologies of Forman is researched and improved.In the Forman method,the convolution is used in several times so that the operation is complication and it is difficult to realize by the hardware circuits.The linear convolution is realized though three fast fourier transform(FFT) operation to reduce the quantity of computation.It is found that quantity of the short double-side data,apodization function and the times of phase correction affect the result of the corrected interferograms in the experiment.The 500 K infrared blackbody is used as the radiant source to achieve the absorption spectrum of the atmosphere in the infrared range.The single-side beyond zero interferograms is achieved by the HgCdTe dot diode detection.The interferograms are corrected and rebuilded by the improved Forman method.The spectral resolution of the rebuild absorption spectrum is 4 cm-1 and the wavenumber error is little.which show the higher accuracy of spectrometers.