冲击噪声对多普勒差分干涉仪相位反演精度影响分析及校正方法

Analysis of Influence of Spike on Phase Retrieval Accuracy of Doppler Asymmetric Spatial Heterodyne Spectrometer and Correction Method

多普勒差分干涉仪通过测量干涉条纹的相位变化反演大气风速,由于CCD探测器会受到宇宙射线干扰和CCD自身存在的热像元,干涉图上会形成位置和强度随机的冲击噪声,严重影响风速反演精度.本文探讨了冲击噪声各参数对多普勒差分干涉仪相位反演精度的理论影响,并对冲击噪声进行修正,针对干涉图冲击噪声的特点,基于多普勒差分干涉仪相位反演模型,建立了相位误差与冲击噪声特征参数之间的理论模型,分析指出冲击噪声的强度、位置、峰宽对相位反演精度影响规律,并利用实验数据进行验证.结果表明,相位反演误差随冲击噪声的位置呈周期性变化,与冲击噪声强度和峰宽呈正相关.提出一种最近邻比较与加窗中值滤波结合的干涉数据冲击噪声校正算法,能够有效修正冲击噪声点,且不会对原始干涉数据产生影响,校正后冲击噪声引起的相位误差减小90%以上,有助于提高后续干涉数据处理的精度.

The doppler asymmetric spatial heterodyne interferometer can be used to retrieve the atmospheric wind speed by measuring the phase frequency shift of interference fringes.Because of the interference from cosmic rays and“hot pixels”in CCD,some spikes that have random location and intensity occur on the interferogram.The presence of such spikes can seriously affect the accuracy of wind speed retrieval.In this paper,the theoretical influence of various parameters of spike on the phase inversion accuracy of doppler asymmetric spatial heterodyne interferometer is discussed,and the spike correction method is proposed.Based on the characteristics of the spike and the phase retrieval model of doppler asymmetric spatial heterodyne interferometer,a theoretical model between the phase error and the intensity and position of the spike is established.The influence of the intensity,position and width of the spike on the phase retrieval accuracy is analyzed and verified by experiments.The results show that the phase retrieval error varies periodically with the position of the spike,and is positively correlated with the intensity and peak width of spike.A new method of spike correction based on nearest neighbor comparison and windowed median filter is proposed.The new method can effectively correct the spike without affecting the original interference data.The phase error caused by the spike after correction is reduced by more than 90%,which will help to improve the accuracy of subsequent interference data processing.