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在分析两路反馈外腔结构自混合干涉(SMI)模型的基础上,对两路自混合干涉信号的处理方法进行了理论分析和仿真验证。在弱反馈水平下,利用希尔伯特变换原理实现了两路合成信号相位的重构,并对合成信号相位分解得到了两路外腔反射体位移的波形,最大误差小于1.5rad。在对含噪的两路自混合干涉信号进行预处理时,采用小波软阈值和集合经验模态分解(EEMD)相结合的算法,达到了良好的去噪效果。
Based on the analysis of self-mixing interference (SMI) model of two feedback external cavity structures, theoretical analysis and simulation verification of the two-way self-mixing interference signal processing method are carried out. Under the weak feedback level, the phase reconstruction of the two composite signals was realized by the Hilbert transform principle. The phase displacement of the two outer cavity reflectors was obtained by the phase decomposition of the composite signal. The maximum error was less than 1.5 rad. In the pretreatment of the noisy two-way self-mixing interference signals, a combination of the wavelet soft threshold and the set empirical mode decomposition (EEMD) is used to achieve a good denoising effect.