空间外差光谱仪在研制加工过程中, 由于加工误差及胶合误差会使CCD接收到的干涉图存在光强分布不均匀现象, 降低了变换光谱的准确性。 基于对空间外差光谱仪干涉图光强非均匀性的产生机制与特点分析基础上, 提出了一种干涉图非均匀性校正方法, 该方法通过对实际干涉图进行单调分解、 分段归一化及重新组合过程求解出光强分布函数, 然后将变换光谱与光强分布函数倒数的傅里叶变换结果进行卷积来获得非均匀性校正后的光谱, 最后将校正光谱进行逆傅里叶变换从而实现干涉图的非均匀性校正。 将此方法应用于空间外差试验仪的近红外实测单色光干涉图的非均匀性校正, 结果显示, 该方法可以有效改善干涉图光强分布的非均匀性, 抑制变换光谱的边频信号, 通过与仿真的理想光谱对比, 1 571和1 572 nm光谱校正前后噪声的减小率分别达到40.7%和24%, 提高了光谱信噪比和准确性。

The intensity distribution is inhomogeneous in the interference pattern received with CCD because of the processing errors and agglutination errors produced during researching and processing of the spatial heterodyne spectrometer, which reduces the accuracy of the transform spectrum. An inhomogeneous correction method to interference pattern is proposed through analyzing producing mechanism and characteristics of the inhomogeneity existed in interference pattern intensity of spatial heterodyne spectrometer. According to the method, actual interference pattern was decomposed monotonously, piecewise normalized and recombined to solve light intensity distribution function; then the transform spectrum was convolved with Fourier transform result of the reverse light intensity distribution function to obtain inhomogenous correction spectrum; lastly the inverse Fourier transform was implemented to corrected spectrum to realize inhomogenous correction of interference pattern. The correction method could be used in measured monochromatic interference pattern of near infrared light in spatial heterodyne spectrometer. The results show that the method could effectively improve the homogeneity of interference pattern intensity distribution and inhibit edge frequency signal of transform spectrum. Compared with the simulated ideal spectrum, the noise in 1 571 nm spectrum reduces 40.7% while the noise in 1 572 nm spectrum reduces 24% with signal to noise and accuracy of the spectrum being increased.