光纤傅里叶变换光谱仪干涉图的对称化处理

Processing of Interferogram Symmetrization in Optical Fiber Fourier Spectrometer

偏离中心条纹的抽样以及光纤干涉仪的缺陷引起光纤傅里叶变换光谱仪(FFTS)输出的干涉图不对称,导致由傅里叶余弦变换计算得到的光谱带有相位误差,影响光谱的线型。文章首次将卷积方法应用到光纤傅里叶变换光谱仪中干涉图的对称化处理,利用干涉图的中心部分计算出相位误差,通过傅里叶变换得到了对称化处理函数,用卷积运算在时域完成了光谱的相位误差校正。实验研究表明,在FFTS中该方法能在时域有效地实现干涉图对称化,校正了光谱的相位误差。该方法不仅克服了双边干涉图的缺点,而且校正的结果有较高的准确度。

The asymmetry of an interferogram is caused by off-center sampling or defects in the fiber interferometer, and the spectra from Fourier cosine transformations of one-sided interferogram have phase errors. A method was firstly applied to symmetrizing interferogram by using the convolution technique in optical fiber Fourier spectrometer （FFTS）. The phase error can be derived from the central portion of the interferograrm. Syrmnetrization function was obtained from the Fourier transform of the phase error. Thus in spatial domain the syrmnetrization function convolved with original interferogram, and the spectra with correction of phase errors resulted from the syrmnetrized interferogram. Experimental study shows that the method efficiently corrects the phase error in FFTS. The method not only overcomes the disadvantages of two-sided interferogram, but also has better accuracy of the results.