抑制移相干涉仪中相干噪声的多模光纤扩展光源研究  

Extended Light Source of Multimode Fibers for Suppressing Coherent Noise in Phase-Shift Interferometer

作　　者：胡晨辉 陈磊[1] 黄晨 马致遥 钱月 张喆 李若琨 郑东晖[1] Hu Chenhui;Chen Lei;Huang Chen;Ma Zhiyao;Qian Yue;Zhang Zhe;Li Ruokun;Zheng Donghui(School of Electronic and Optical Engineering,Nanjing University of Science and Technology,Nanjing 210094,Jiangsu,China)

机构地区：[1]南京理工大学电子工程与光电技术学院,江苏南京210094

出　　处：《光学学报》2022年第19期1-8,共8页Acta Optica Sinica

基　　金：国家自然科学基金(62005122,U1731115);江苏省自然科学基金(BK20200458);江苏省研究生科研与实践创新计划(KYCX20_0263)。

摘　　要：激光干涉仪中光学元件上的瑕疵、气泡和脏点等会在干涉图中引入类似“牛眼环”的相干噪声。为解决这一问题,提出一种基于多模光纤扩展光源的相干噪声抑制方法。该方法利用扩展光源抑制相干噪声,选择最优多模光纤纤芯保证良好的干涉条纹对比度,并使用复合散斑抑制技术,通过多模光纤和旋转毛玻璃减小散斑对比度,抑制多模光纤模式干涉产生的散斑噪声。在直径为300 mm的干涉仪中进行了仿真分析与实验验证,结果表明:在直径为300 mm的菲佐立式平面干涉仪,腔长为500 mm,相机曝光时间为5 ms的条件下,将该光源系统中多模光纤纤芯直径范围控制在0.52~1.70 mm范围内,可以保证干涉条纹对比度大于0.75;干涉仪最终成像的散斑对比度维持在0.04左右,最小可以达到0.044;多模光纤扩展光源进一步提高了光源的均匀性,干涉仪中成像背景更均匀。实验证明了所提方法可以有效抑制干涉图中的相干噪声。The defects, bubbles, and dirty spots in the optical elements of a laser interferometer introduce coherent noise similar to the "bull’s eye ring" into the interferogram. To solve this problem, a coherent noise suppression method based on an extended light source of multimode fibers is proposed. The proposed method uses the extended light source to suppress coherent noise and selects the optimal multimode fiber core to ensure a favorable interference fringe contrast. Then, a composite speckle suppression technique is employed, and the speckle contrast is reduced by introducing the multimode fibers and rotating ground glass to suppress the speckle noise generated by the mode interference of the multimode fibers.Simulation analysis and experimental verification are carried out in an interferometer with a diameter of 300 mm. The following observations can be made from the results. Under the conditions of a vertical planar Fizeau interferometer with a diameter of 300 mm, a cavity length of 500 mm, and a camera exposure time of 5 ms, an interference fringe contrast higher than 0. 75 can be ensured by keeping the core diameter of the multimode fibers in the proposed light source system between 0. 52 mm and 1. 70 mm. The speckle contrast of the final image obtained by the interferometer is maintained at about 0. 04, with a minimum of 0. 044. The extended light source of multimode fibers further improves the uniformity of the light source, contributing to a more uniform imaging background in the interferometer. The experiment proves that the proposed method can effectively suppress the coherence noise in the interferogram.

关 键 词：光纤光学 干涉测量 菲佐干涉仪 扩展光源 相干噪声 散斑 信噪比 

分 类 号：O436.1[机械工程—光学工程] TN206[理学—光学]