载波电子散斑干涉频谱旁瓣中心偏移的克服方法

Methods to Overcome Frequency Spectrum Side Band′s Center Excursion of CESPI

详细分析了利用快速傅里叶变换相位解调法处理载波电子散斑干涉(CESPI)相关条纹图时产生频谱旁瓣中心偏移的原因及其影响.为了消除该频谱旁瓣中心偏移产生的转动量误差,借助一幅变形前载波相关条纹图,并结合频域同态滤波技术,设计了两种新的图像处理方法——形貌相减消差法和旁瓣共轭消差法.理论分析与实验结果表明:这两种方法均能有效地消除零频偏移产生的测量误差,提高测量精度;旁瓣共轭消差法还具有程序简单、操作方便的优点.

When FFT was adopted to deal with CESPI correlation fringe figure it would cause frequency spectrum side band′s center excursion.The causations and influence were analyzed in detail.In order to avoid rotation amount error,two methods which included appearance subtraction method and conjugated side band method were designed.The methods were supported by a piece of CESPI correlation fringe figure before deformation and combined with frequency domain homomorphic filtering.The results of theory analysis and experiments indicated that the methods could eliminate the measurement error caused by frequency spectrum side band′s center excursion entirely and improve measuring accuracy.Furthermore,conjugated side band method had the advantages including simple procedure and easy operation.