多模光纤扩展光源抑制干涉仪相干噪声的研究  

Coherent Noise Suppression with Multimode Fiber Extended Light Source for Interferometer

作　　者：张徐 鲁棋 公维超 徐天柱[1,3] 王微微 孙莹[1,3] 刘世杰 Zhang Xu;Lu Qi;Gong Weichao;Xu Tianzhu;Wang Weiwei;Sun Ying;Liu Shijie(Precision Optical Manufacturing and Testing Center,Shanghai Institute of Optics and Fine Mechanics,Chinese Academy of Sciences,Shanghai 201800,China;University of Chinese Academy of Sciences,Beijing 100049,China;China-Russian Belt and Road Joint Laboratory on Laser Science,Shanghai 201800,China)

机构地区：[1]中国科学院上海光学精密机械研究所精密光学制造与检测中心,上海201800 [2]中国科学院大学,北京100049 [3]中国-俄罗斯激光科学“一带一路”联合实验室,上海201800

出　　处：《中国激光》2024年第6期179-188,共10页Chinese Journal of Lasers

基　　金：国家重点研发计划(2020YFA0714500,2022YFE0204800);中国科学院国际合作项目(181231KYSB20200040,2023VMB0008)。

摘　　要：激光干涉仪中光学元件表面划痕和灰尘等会在干涉图中形成衍射环状相干噪声,极大影响测量精度。为了消除此类相干噪声,提出了一种基于多模光纤耦合角度变化的扩展光源方法,控制平行光束经过旋转毛玻璃耦合进入多模光纤的角度,达到抑制散斑和相干噪声的效果。通过理论推导和仿真模型构建,基于纤芯直径为1 mm的多模光纤扩展光源,在直径为25.4 mm的泰曼-格林干涉仪上进行了实验验证。结果表明:通过改变入射角度可以控制扩展光源的形态,在-3°~2°的入射角度范围内,干涉仪的信噪比最大值与正入射时相比提高了40.3%,此时入射角度处于纤端光斑形态发生变化的临界角度与正入射角度中间,且该临界值与理论推导和仿真结果一致。实验证明了所提方法可以抑制干涉仪的相干噪声。Objective Defects such as scratches and dust on the surfaces of optical components in interferometers can generate diffraction ring coherent noise in interferograms,which can significantly affect measurement accuracy.To address this issue,this study introduces an extended-light-source method in which the coupling angle of a multimode fiber is altered.By controlling the coupling angle of the multimode fiber after the parallel beam passes through the rotating frosted glass,the proposed method effectively minimizes the effects of scattering and coherent noise.This approach provides a valuable contribution to the theory of extended light sources based on multimode fibers.The derivation and validation of the range of fiber incident angles at the location exhibiting the strongest signal-tonoise ratio(SNR)of the interferometric signal offer important guidance for installing and calibrating interferometers and other optical instruments utilizing this light-source configuration.Methods In this study,the objectives of eliminating coherent noise and improving the SNR of interference fringes in a composite extended source based on multimode fibers are explained.With a change in the coupling angle in the multimode fiber,the shape and size of the light beam emitted from the fiber end change accordingly.When the coupling fiber angle is adjusted,the free degree of the composite-light-source speckle increases,leading to a decrease in system speckle contrast.However,the size of the extended source affects the contrast of the interference fringes.Based on the formula for obtaining the interferometric SNR,it is known that changes in the scattering contrast and interference fringe contrast affect the SNR of the entire extended light source.In this study,the critical incident angle at which the light beam emitted from the fiber end becomes a hollow beam is derived through calculations.The Zemax OpticStudio software is used to simulate the fiber-end optical field.In the non-sequential mode,a Gaussian light source is set to enter at dif

关 键 词：光纤光学 干涉测量 扩展光源 相干噪声 信噪比 

分 类 号：O436.1[机械工程—光学工程] TN206[理学—光学]