正弦相位调制型激光自混合干涉仪的实时位移测量技术

Implementation of Real-Time Displacement Precision Measurement Technology for Sinusoidal Phase-Shifting Laser Self-Mixing Interferometer

采用正弦相位调制技术与时域解调相位方法相结合,提高激光自混合干涉仪在大量程位移测量中实时测量的准确度和速度。通过在激光器外腔中放置的电光晶体调制器对光束进行正弦相位调制,采用时域解调相位方法解调干涉信号相位。同时满足了大量程位移测量过程中的速度要求以及实现干涉仪位移测量的实时性。实验上,用PI公司高分辨率的商用电动位移平台标定的结果验证了该正弦相位调制激光自混合干涉仪在百毫米级大尺度位移测量中可达到小于0.5μm的位移测量误差。对干涉仪在实时位移测量中的影响测量速度的因素进行了分析,得出了本干涉仪的测速上限。

In order to improve the measurement accuracy and realize the real-time mesurement speed of the laser self-mixing interferometer in a large range of displacement, advanced sinusoidal phase-shifting technique and the time-domain phase demodulation method are adopted. The electro-optic crystal modulator is used to realize the sinusoidal phase-shifting on the laser beam in the external cavity and the interference signal＇s phase will be demodulated by the time-domain phase demodulation method. By combining the two together, it can meet the speed requirement in a wide range of displacement measurement process and implement the interferometer＇s real-time measurement requirement at the same time. Experimentally, PI＇s high-precision commercial electric displacement platform calibration results verified the sinusoidal phase modulation laser seif-mixing interferometer＇s displacement measurement precision can reach less than O. 5 ~m in the hundred mm large-scale displacement measuring process. In addition, the factors affecting the interferometer＇s measurement speed in the real-time displacement measurement process is analyzed and the maximum speed of our system is obtained.