环形器噪声对激光干涉测量系统影响分析

Analysis of Effect of Circulator Noise on Laser Interferometry System

本文提出一种光学环形器噪声评价指标,介绍激光外差干涉原理。通过建立典型环形器在激光干涉系统位移测量中的噪声传递模型并结合环形器的噪声来源,分析和论证环形器非线性误差系数与杂散光相位对系统位移测量误差的影响,提出以环形器方向性为环形器噪声评价指标的误差评价方法,通过数值仿真验证其适用性。针对环形器噪声的主要来源,基于理论分析模型设计并研制一种点衍射空间光环形器。搭建验证系统并与商用典型环形器进行对比,点衍射空间光环形器方向性达到129 dB,较商用典型环形器提高66 dB,实现较高精度的目标位移测量。

In this paper,we propose an evaluation index for optical circulator noise and explained the principle of laser heterodyne interference.Then,we establish a noise transfer model for a typical circulator in the displacement measurement by laser interferometry systems.In addition,in combination with the noise source of the circulator,we demonstrate the influence of the nonlinear error coefficient of the circulator and the phase of stray light on the displacement measurement error.Furthermore,we propose an error evaluation method with the circulator directivity as the noise evaluation index and verified its applicability by numerical simulation.Aiming at the main source of noise of the circulator,a kind of point diffraction spatial optical circulator is designed and developed based on theoretical analysis model.This circulator has a directivity of 129 dB,the directivity of circulator is 66 dB higher than that of typical commercial circulator,thus achieving high-precision measurement of target displacement.