摘要
光学相干层析成像(OCT)能通过微型光纤探头实现人体内部组织和器官的三维结构或功能成像,在生物医学成像领域具有重要应用。本课题组提出并改进了基于大纤芯光纤的微型探头,同时通过调制大纤芯光纤的模式能量分布、模式相位差、模式干涉场的放大方式以及模式数量实现了出射光束的调控和成像性能的优化,以期同时获得较高的横向分辨率、较长的焦深和工作距以及较好的轴向光强均匀性。本文提出了相应的快速仿真方法,解决了模式数量多、模式干涉场复杂情况下探头参数的优化问题。仿真和实验显示,基于大纤芯光纤的探头能实现2~3.8倍的焦深拓展和2.1倍的工作距拓展,且在成像效果上相对于传统光纤探头有显著提升。由于具有尺寸小、成像质量好、结构牢固的优点,基于大纤芯光纤的探头在OCT内窥成像尤其是窄小空间内的高分辨率成像方面具有巨大的应用潜力。
Objective Developing a fiber probe with a high lateral resolution,long depth of focus,long working distance,and uniform axial light intensity is essential for endoscopic optical coherence tomography(OCT).Traditional beam shaping components,such as axicon lens and binary-phase mask,were minimized and adapted to miniature fiber probes for optimized output beams,but with a short working distance and reduced depth of focus gain compared to their bulk-optic counterparts.Alternatively,pure fiber techniques that simply splice fibers in series were proposed and demonstrated a significant enhancement in the imaging quality.The first demonstration of the concept suggested a phase mask consisting of a short section of overfilled graded-index fiber(Lorenser,2012).However,the most recent progress indicated that using a step-index large core fiber as a coaxially focused multimode beam generator(Yin,2017)or a high-efficient fiberbased filter(Ding,2018)would be advantageous in terms of easy fabrication and increased depth of focus gain.However,full optimization of such probes is not straightforward,where the difficulty originates from the complexity of the light field by multimode interference and the arrangement flexibility of fiber components.Therefore,this study presents systematic research on the optimization of large core fiber probes.We discuss key design considerations for selecting fiber optics for mode excitation,number of modes,beam expansion method,and selecting the lens-free mode or spatial filter mode.We hope that our findings can be essential in designing the ultrathin fiber probe with improved performance for OCT imaging.Methods A unified equation quantifying the depth of focus gain was first deduced by comparing the Gaussian beam with the same minimal beam diameter.Then,the fiber mode theory was applied to demonstrate the light field manipulated by the large core fiber.The tunning length of the large core fiber was determined by its re-imaging property and modal dispersion.According to the relative position of th
作者
邱建榕
杨晨
章程
孟佳
韩涛
钱黄河
陈沛哲
杨璐
刘智毅
丁志华
Qiu Jianrong;Yang Chen;Zhang Cheng;Meng Jia;Han Tao;Qian Huanghe;Chen Peizhe;Yang Lu;Liu Zhiyi;Ding Zhihua(State Key Laboratory of Modern Optical Instrumentation,College of Optical Science and Engineering,Zhejiang University,Hangzhou 310027,Zhejiang,China)
出处
《中国激光》
EI
CAS
CSCD
北大核心
2022年第20期62-77,共16页
Chinese Journal of Lasers
基金
国家自然科学基金(62035011,11974310,31927801,61905214)
国家重点研发计划(2017YFA0700501,2019YFE0113700)
浙江省自然科学基金(LR20F050001)
中央高校基本科研业务费专项资金(2020XZZX005-07)。
关键词
光纤光学
光学相干层析成像
光纤探头
优化
大纤芯光纤
fiber optics
optical coherence tomography
fiber probe
optimization
large core fiber
