Abstract Due to the speckle effect in the laser self-mixing interference (SMI), the signal amplitude will fluctuate greatly, which will affect the measurement accuracy and range. The angle measurement method based on speckle affected SMI signal is presented. The high frequency and low frequency noises in SMI signal can be filtered out simultaneously by variable mode decomposition. The envelope of SMI signal is calculated by Hilbert transform and the envelope signal is used to normalize the speckle affected SMI signal. The angle is calculated indirectly according to displacement measurement results obtained by fringe counting method. The experimental results show that the relative error of angle is ± 2% with the angle measurement range of 1°.

中文翻译：

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基于散斑影响的激光自混合干涉信号的角度测量方法

摘要 由于激光自混合干涉（SMI）中的散斑效应，信号幅度会出现较大波动，从而影响测量精度和量程。提出了基于散斑影响SMI信号的角度测量方法。变模分解可以同时滤除SMI信号中的高频和低频噪声。SMI信号的包络通过希尔伯特变换计算得到，包络信号用于归一化受散斑影响的SMI信号。根据条纹计数法获得的位移测量结果间接计算角度。实验结果表明，角度测量范围为1°时，角度相对误差为±2%。