Multiple self-mixing interference based on phase modulation and demodulation for vibration measurement

• Published in: Applied optics. Optical technology and biomedical optics 2017-02, Vol.56 (4), p.1006
• Main Authors: Jiang, Chunlei, Wen, Xin, Yin, Shuxin, Liu, Yunfei
• Format: Article
• Language: English
• ISSN: 2155-3165
• DOI: 10.1364/AO.56.001006

In this paper, a high-precision and effective method of multiple self-mixing interference (MSMI) modulation and demodulation is proposed. The MSMI signal is sinusoidal modulated by an electro-optic modulator. Then, the four-quadrant integral technique is used to demodulate the modulated MSMI signal and reconstruct displacement of the vibration object. The four-quadrant integral technique is within a modulation period; the signal is integrated four times; the integral system is operated by simple linear operations and can obtain the phase. This method not only can demodulate sinusoidal vibration but also can reconstruct an arbitrary wave. At the same time, without increasing the hardware equipment and the complexity of the algorithm, the measurement accuracy of MSMI is doubled that of self-mixing interference. The simulation tests and experimental measurements are confirmed by conducting a series of experiments.