基于激光自混调频特性的振动测量方法

Vibration Measurement Method Based on Laser Self-Mixing Frequency Modulation Characteristics

基于激光自混合干涉的振动重构方法需估算光反馈水平因子以及线宽增强因子,目标振动导致光反馈水平变化,引入较大的测量误差。为提高测振精度和鲁棒性,本文提出一种基于自混合干涉调频特性的振动重构算法,利用全光纤马赫-曾德尔干涉仪获得自混合干涉调频信号,解算出激光器的瞬时频率,并联合调幅信号相位实现对目标振动信息重构。该方法无需估算光反馈水平因子以及线宽增强因子,极大地简化了测量光路与解算模型,在保证测量精度的同时降低了振动信息提取过程的复杂性。数值仿真表明,在适度光反馈的条件下,该算法在振幅为2~100μm的测量范围内具有良好的线性度。实验结果显示,在1.6~8.3μm的测量范围内,重复测量标准差低于15 nm,非线性误差为0.78%。

The vibration reconstruction method based on laser self-mixing interference needs to estimate the optical feedback level factor and the line-width enhancement factor.In order to improve the precision and robustness of vibration measurement,a vibration reconstruction algorithm based on the frequency modulation characteristics of self-mixed interferometer is proposed.The all-fiber Mach-Zehnder interferometer is used to obtain the frequency-modulated signal of self-mixing interferometer,and the instantaneous frequency of the laser is calculated.This method does not need to estimate the optical feedback level factor and the line-width enhancement factor,greatly simplifies the measurement optical path and the solution model,and reduces the complexity of the vibration information extraction while ensuring the measurement accuracy.Numerical simulation shows that the proposed algorithm has good linearity in the measuring range from 2μm to 100μm amplitude with moderate optical feedback level.Experimental results show that the standard deviation of repeated measurements is less than 15 nm and the non-linear error is 0.78%in the range of 1.6μm to 8.3μm amplitude.