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提出了一种基于3×3耦合器的小型化单光栅纳米位移测量方法。基于激光多普勒效应与光纤耦合器散射矩阵理论,首次将3×3耦合器与计量光栅相结合,设计了一种对称式光路结构,利用所提出的新型相位解调算法实现纳米级精度的位移测量。方法具有结构简单、调节方便、对波长变化不敏感和能有效抑制空气扰动等特点,从而使得系统具有良好的稳定性。实验结果显示,3×3耦合器三路输出信号两-两产生的李萨育图形平滑清晰,相位差保持在120°左右,说明本方法具有较好的测量稳定性。数值仿真与理论分析具有较好的一致性,在同时存在相位和幅值误差的情况下可以实现8nm的测量精度。
A 3 × 3 coupler-based miniaturized single-grating nano-displacement measurement method is proposed. Based on the laser Doppler effect and the fiber coupler scattering matrix theory, the 3 × 3 coupler and the grating are combined for the first time to design a symmetrical optical path structure. The new phase demodulation algorithm is proposed to realize the nanometer-scale precision Displacement measurement. The method has the advantages of simple structure, convenient adjustment, insensitivity to wavelength variation and effective suppression of air disturbance, thereby making the system have good stability. The experimental results show that the Lissajous figures generated by the two-three output signal of the 3 × 3 coupler are smooth and clear, and the phase difference remains at about 120 °, indicating that the method has good measurement stability. The numerical simulation and theoretical analysis have good consistency, and the measurement accuracy of 8nm can be achieved under the condition that both the phase and the amplitude error exist simultaneously.