对激光自混合干涉式位移测量原理进行了数值模拟和实验研究。首先,从三镜法布里-珀罗腔理论出发,得到了基于半导体激光自混合干涉原理的位移测量模型,在此基础上对多种波形调制外反射体位移情况下激光自混合干涉信号进行了理论分析,证实信号倾斜方向发生反转的间隔条纹数目对应反射体位移的幅值范围;反射体有半个波长的位移,信号即输出一个完整的条纹;反馈强度的增加将增大输出条纹的倾斜。对信号倾斜现象进一步分析发现,当反射体位移减小时,信号向左倾斜,反之向右。造成信号倾斜的原因是由于高反馈强度下引起的非线性相位调制了输出信号强度。这些结论同样适用于任意波形调制的反射体位移。实验测试结果同理论分析吻合较好。

According to the theory of laser oscillation cavity with three mirrors, a model for displacement measurement using self-mixing interference of semiconductor laser is established in this paper. Using this model the signals of the self-mixing interference due to an external reflector modulated by different waves are theoretically studied. It is shown that the fringe number of output signal, with which the signal changes orientation, is determined by displacement of the reflector. When the reflector moves half wavelength, the signal outputs a whole fringe. Increasing the feedback intensity will enhance the fringe inclination. When the reflector moves smaller, the signals incline on left. When the reflector moves larger, the signals incline on right. The reason of the fringe inclination results from the nonlinear phase in signal intensity impacted by feedback. Above conclusions are the same with arbitrary wave driving reflector. Experimental results are well agreement with theoretical conclusions.