In this paper, a novel method for simultaneous measurement of rotation speed and vibration based on self-mixing speckle interference (SMSI) has been demonstrated. In view of the autocorrelation characteristic of SMSI, the time delay of laser incident during one rotation period is determined, and the rotation speed of the object is calculated according to the mathematical relationship. At the same time, the signal square-wave conversion and the global maximum fringe-counting method are proposed to measure the vibration displacement subject to the rotation. The theory and signal processing means are introduced in detail, and a series of experiments employing computer disk at different positions with various rotation speeds indicate that the proposed method achieves a simple, efficient, and accurate multi-parameter measurement.

In this paper, the self-mixing interference subject to weak optical feedback has been used to measure the damping vibration. By analyzing the spectrum of the signal, the damping coefficient can be extracted precisely from the nth-order Bessel functions, which are determined by the dominant harmonic order of the frequency spectrum. Theoretical derivation and signal processing are presented. Four kinds of vibrating targets with different damping coefficients are measured. Experimental results show that standard deviation and root mean square error of data are less than 0.2 and 0.1, respectively, which means fitted values are stable as well as having a very high fitting precision.

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