基于适度光反馈自混合干涉技术的振动测量

光反馈自混合干涉技术是一种新浮现的有别于传统双光束干涉的一类新的测试技术。为了在适度光反馈下进行振动的精密测量,提出了一种基于适度光反馈自混合干涉技术的振动测量方法。经对光反馈自混合干涉信号条纹分析,发现通过选定合适的光反馈水平及激光器线宽展宽因数,可以得到锯齿干涉条纹。这种干涉信号不仅包含振动幅度信息也包含振动方向信息。该振动测量方法利用锯齿干涉条纹的特点,首先通过条纹记数实现大范围振幅粗测,具有半波长位移分辨力;然后基于适度光反馈下小数条纹的特点,给出了小于半波长位移测量的线性表达式,从而实现位移的精测。仿真计算表明,该方法可以实现大量程高分辨力振动位移测量,在叠加20 dB的噪声下,振幅测量相对误差平均为0.5%。

Vibration Menasurement Based on Moderate Optical Feedback Self-Mixing Interference

Optical feedback self-mixing interferometry is an emerging sensing and measurement technique,which is quite different with traditional double-beam interferometry.To perform precision vibration measurement under the condition of moderate optical feedback,a vibration measurement method is proposed based on moderate optical feedback self-mixing interference.Based on the analysis of the optical feedback self-mixing inteference signal fringes,it is found that saw-like fringes in the self-mixing signal waveforms can be observed by properly choosing the optical feedback level and line width enhancement factor of semiconductor laser.With the saw-like fringe not only the vibration amplitude can be measured,but the movement direction can also be determined.The proposed measurement is based on the analysis of saw-like fringes with the following two steps.Firstly,rough measurement of displacement is carried out by counting the fringe numbers with the resolution of half wavelength.Then based on the studies of fractional fringe structure under modulate optical feedback,a linear formula for displacement within half wavelength is derived,and precise displacement measurement is realized.Computer simulations show that the proposed technology is able to achieve high-resolution and large-range measurement of vibration amplitude.