Lower-limit type trigonometric apodization function of Fourier transform spectrometer and efficient spectrum restoring method thereof

Abstract

The invention relates to an efficient spectrum restoring method. The restoring method includes: firstly, performing zero-passage single-side sampling and single-side zero fill on an interference pattern and performing short double-side sample and double-side zero fill on the interference pattern; secondly, leading the zero-passage single-side data performed with zero fill and the short double-side data performed with zero fill to form a sequence of complex numbers, wherein the zero-passage single-side data are a real part, and the short double-side data are an imaginary part; then performing apodization on the sequence of complex numbers through the lower-limit type trigonometric apodization function, and then performing fast Fourier transformation; and finally performing spectrum phase correction according to the property of the conjugate symmetrical sequence of complex numbers so as to obtain accurate spectrum distribution.

Description

technical field [0001] The invention relates to a new interferogram apodization function and its efficient spectral restoration method. Background technique [0002] In the actual measurement of the interferogram of a Fourier transform spectrometer, generally sampling to a finite maximum optical path difference L actually means forcing the interferogram function to drop suddenly to zero starting from this point and thereafter, which leads to the interferogram A sharp discontinuity occurs there, which causes "perturbations" of the transformed spectrum in a rather large wavenumber range, ie side lobes. In order to suppress the influence of side lobes on spectral distortion, the triangular apodization function can be used to weight the interferogram to alleviate the discontinuity at the extreme optical path difference L. [0003] In addition, ideally, the interferogram is symmetrical about the zero optical path difference, but due to the difficulty of detecting the interferenc...

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Problems solved by technology

It can be seen that in the existing phase error correction method of the product method, for the interferogram suitable for triangular apodization function weighting, in order to reduce the error caused by the short bilateral interferogram data being used twice and suppress the side lobe, it is necessary Using the Mertz apodization function and the triangular apodization function to perform two apodization processes respectively, the calculation amount is large and the efficiency is low;

[0032] In addition, the Mertz apodization function is used to weight the zero-crossing unilateral interferogram to reduce the error caused by using the short bilateral interferogram data twice. This method has obvious disadvantages: when the phase error does not meet the condition of slowly changing with the wave number When , the asymmetry of the interferogram is relatively serious. At this time, this weighting method not only cannot weaken the asymmetry, but will aggravate the asymmetry, failing to achieve the expected weighting effect, resulting in spectral distortion and low calculation accuracy.

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