基于二维频域分析的空间外差干涉图降噪研究

    Noise reduction of spatial heterodyne interferogram based on two-dimensional frequency domain analysis

    • 摘要: 空间外差光谱技术是一种新型傅里叶变换光谱技术,因其高灵敏度、高分辨率特征,被广泛应用于大气遥感等领域。通过空间外差光谱仪获得的干涉图数据常常会伴随噪声干扰,使测量结果出现误差。基于此,提出了一种基于二维频域滤波的空间外差干涉图降噪方法,通过分析实测钾灯二维频谱图与仿真理想二维频谱图的特点,引入阈值数据构造特定滤波器,分离有效信号和噪声信号,并通过与降噪前后的干涉图平均光谱的对比,对处理方法的应用效果进行评价。将本文方法应用于钾灯(准单色光)和氙灯、水汽(连续光)3种光源干涉图的降噪处理,结果显示,钾灯干涉图降噪后,其变换光谱中特征峰凸显且周围的噪声明显减少;氙灯、水汽干涉图降噪后干涉图中的暗斑得到抑制,非均匀性得到改善,选取3行校正前后的光谱与平均光谱比较,均方根误差分别下降80.61%、76.21%、78.45%和78.59%、80.04%、87.72%;峰值信噪比分别提高了44.74%、38.58%、41.03%和39.10%、41.98%、54.59%。对比旋滤波算法和小波算法处理效果,氙灯的均方根误差优化了68.08%、54.36%,峰值信噪比优化了27.84%、16.32%;相应的水汽的值为78.79%、80.40%和38.83%、41.56%。处理降噪效果明显,说明本文算法在实现空间外差光谱数据降噪应用上具有可行性。

       

      Abstract: Spatial heterodyne spectroscopy is a new Fourier transform spectroscopy technique, which is widely used in the field of atmospheric remote sensing because of its high sensitivity and high resolution. The interferogram data obtained by the space heterodyne spectrometer is often accompanied by noise interference, which makes the measurement results appear to be wrong. Based on this, we proposed a spatial heterodyne interferogram noise reduction method based on 2D frequency domain filtering. By analyzing the characteristics of measured 2D spectrum diagram of potassium lamp and the simulated ideal 2D spectrum diagram, the threshold data was introduced to construct a specific filter, so as to separate the effective signal and the noise signal, and compare with the average spectral data of the interferogram before and after noise reduction. The application effect of the treatment method was evaluated. The proposed method in this paper was applied to the noise reduction processing of the interferograms from 3 light sources: potassium lamp (quasi-monochromatic light), xenon lamp, and water vapor (continuous light). The results show that after noise reduction of the potassium lamp interferogram, the characteristic peaks in its transformed spectrum are highlighted and the surrounding noise is significantly reduced. After noise reduction of the xenon lamp and water vapor interferograms, the dark spots in the interferograms are suppressed and the non-uniformity is improved. By comparing the spectra of 3 rows before and after correction with the average spectrum, the root mean square errors decreased by 80.61%, 76.21%, 78.45% and 78.59%, 80.04%, 87.72%, respectively; the peak signal-to-noise ratios increased by 44.74%, 38.58%, 41.03% and 39.10%, 41.98%, 54.59%, respectively. Compared with the results of the rotation filtering algorithm and the wavelet algorithm, the root mean square error of the xenon lamp is optimized by 68.08% and 54.36%, and the peak signal-to-noise ratio is optimized by 27.84% and 16.32%. The corresponding values for water vapor are 78.79%, 80.40% and 38.83%, 41.56%. The noise reduction effect is obvious, indicating that the algorithm proposed is feasible for the application of noise reduction in space heterodyne spectral data.

       

    /

    返回文章
    返回