基于正弦相位调制的光纤干涉位移测量系统研究

针对全光纤干涉仪工作距离短、测量范围小等问题，提出了一种基于正弦相位调制的全光纤干涉系统，在参考臂通过电光调制器引入的调制参考光，与探头接收到的目标反射光产生干涉。根据锁相放大原理从干涉信号中提取出正交分量后，首先建立由正交分量构成的观测模型，通过卡尔曼滤波对正交分量的幅值和偏置进行迭代估计和修正，降低由相位延迟、调制深度漂移、寄生干扰等导致的幅值漂移和附加偏置；然后利用反正切法对反射光与参考光之间的相位差进行解调。开展了模拟干涉信号的相位解算仿真模拟和位移测量实验。仿真和实验验证了该算法解算相位的有效性。结果表明，该位移测量系统的工作距离可达到20 cm，测量精度为10 nm。

Study on all-fiber sinusoidal phase modulation interferometer for displacement measurement

To solve the short working distance and small measurement range of all-fiber interferometer, we proposed an all-fiber interferometry system based on sinusoidal phase modulation. An electro-optical modulator is combined in reference arm to generate modulated reference beam, which interferes with the target reflected beam received by the collimator. After extracting orthogonal components from interference signals according to phase-locked amplification principle, an observation model composed of orthogonal components is first established. The amplitude and bias of the orthogonal components are iteratively estimated and corrected by Kalman filtering to reduce the amplitude drift and additional bias caused by phase delay, modulation depth drift, parasitic interference, etc. Then the inverse tangent method is used to demodulate the phase difference between the reflected light and the reference light. The phase solution simulation and displacement measurement experiments of analog interference signals are carried out. Simulation and experiment verify the validity of the proposed method. The experimental results show that the displacement measurement system can achieve a working range of 20 cm and a measurement accuracy of 10 nm.