Accurate Modeling and Design of Graded-Index Fiber Probes for Optical Coherence Tomography Using the Beam Propagation Method
Accurate Modeling and Design of Graded-Index Fiber Probes for Optical Coherence Tomography Using the Beam Propagation Method
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DOI：
10.1109/jphot.2013.2250939
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发表时间：
2013-03
影响因子：
2.4
通讯作者：
D. Lorenser;Xiaojie Yang;D. Sampson
中科院分区：
文献类型：
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作者：
D. Lorenser;Xiaojie Yang;D. Sampson
用于感测和生物医学成像应用（诸如光学相干断层扫描（OCT））的光纤探头经常采用梯度折射率（GRIN）光纤的区段来重新聚焦来自输送光纤的发散光。这种GRIN光纤微透镜通常具有引起聚焦输出光束的显著失真的像差。基于高斯光束的ABCD矩阵变换的当前设计方法不能模拟这种效应，因此不足以分析和设计需要衍射限制输出光束的高性能探头。我们演示了使用光束传播法（BPM）来分析GRIN透镜光纤中的光束畸变，这些光束畸变来自折射率分布，这些折射率分布表现出与理想的抛物线形状或工件（如波纹或中心凹陷）的偏差。此外，我们证明了这种方法的权力，探索新的探头设计，将梯度折射率相位掩模产生波前形状的输出光束与扩展的焦深（DOF）。我们目前的结果，使用我们的方法是在良好的协议与实验数据。BPM能够使用具有任意折射率分布的非理想或定制工程GRIN光纤精确模拟光纤探针，这对于设计用于生物医学应用的高性能光纤微成像系统非常重要。
Fiber-optic probes for sensing and biomedical imaging applications such as optical coherence tomography (OCT) frequently employ sections of graded-index (GRIN) fiber to re-focus the diverging light from the delivery fiber. Such GRIN fiber microlenses often possess aberrations that cause significant distortions of the focused output beam. Current design methods based on ABCD matrix transformations of Gaussian beams cannot model such effects and are therefore inadequate for the analysis and design of high-performance probes that require diffraction-limited output beams. We demonstrate use of the beam propagation method (BPM) to analyze beam distortion in GRIN-lensed fibers resulting from index profiles that exhibit a deviation from the ideal parabolic shape or artifacts such as ripples or a central dip. Furthermore, we demonstrate the power of this method for exploring novel probe designs that incorporate GRIN phase masks to generate wavefront-shaped output beams with extended depth-of-focus (DOF). We present results using our method that are in good agreement with experimental data. The BPM enables accurate simulation of fiber probes using non-ideal or custom-engineered GRIN fibers with arbitrary refractive index profiles, which is important in the design of high-performance fiber-based micro-imaging systems for biomedical applications.