干涉成像光谱仪切趾函数对复原光谱的影响分析

EFFECTS OF APODIZATION FUNCTIONS OF IMAGING FOURIER TRANSFORM SPECTROMETER ON RECONSTRUCTED SPECTRUM

随着搭载干涉成像光谱仪HJY20-1-A的我国环境与减灾遥感卫星HJ-1A即将发射,我国干涉光谱成像研究也从实验室开始走向实用化.在干涉光谱成像过程中,切趾函数处理是干涉成像光谱仪光谱复原过程中的一个重要环节,对复原光谱的精度有着极其重要的影响.根据HJY20-1-A的参数设置,文中首先模拟了24种典型地物对应于HJY20-1-A和其它最大光程差设置的干涉成像光谱仪数据,在不同切趾函数作用下的复原光谱,结果表明Hann ing函数是其中最有效、最为稳定的切趾函数,同时发现切趾函数的应用虽然可以提高复原光谱的精度,但与真实光谱仍存在一定差距,尤其对应HJY20-1-A,复原光谱的精度更加有限.在以上分析基础上,提出了基于仪器线型函数标准化的光谱复原改进算法,实验结果证实了该方法可以显著提高复原光谱精度,尤其适用于最大光程差较小的空间调制型干涉成像光谱仪.最后,就HJY20-1-A复原光谱对3种典型植被指数求解,进一步证明了该方法的有效性.

The imaging Fourier transform spectrometer （IFIS） HJY20-1-A onboard China small satellite ＂HJ-1A＂ will be launched soon. As a new and challenging type of imaging spectrometer, its successful launch implies IFTS will play an important role in hyperspectral remote sensing applications, in which apodization function is an important part of interferogram pre-processing, and it has a powerful effect on the accuracy of reconstructed spectra. Hence, it is necessary to analyze the effect of apodization functions on reconstructed spectra. The reconstructed spectra of 24 kinds of typical surface objects were simulated under four different apodization functions and four different max optical path differences （one for HJY20-1-A） in this paper. Results shows that 1 ）Hanning function is the most stable and efficient apodization function; 2） although the accuracy of reconstructed spectrum is improved by apodization functions, the accuracy is not very high, especially for HJY20-1- A. Finally, an improved algorithm based on the standardization of the instrument line shape function （ILS） was proposed, the reconstructed spectrum by this algorithm was gained with higher accuracy. For reconstructed spectra with HJY20-1-A, three typical vegetation indices were calculated. The calculated results agrees with those obtained by the real spectra.