Iyer Rishyashring R, Yang Lingxiao, Sorrells Janet E, Chaney Eric J, Spillman Darold R, Boppart Stephen A
APL Photonics. 2024 Jul 1;9(7):076114. doi: 10.1063/5.0207414. Epub 2024 Jul 23.
The applications of ultrafast optics to biomedical microscopy have expanded rapidly in recent years, including interferometric techniques like optical coherence tomography and microscopy (OCT/OCM). The advances of ultra-high resolution OCT and the inclusion of OCT/OCM in multimodal systems combined with multiphoton microscopy have marked a transition from using pseudo-continuous broadband sources, such as superluminescent diodes, to ultrafast supercontinuum optical sources. We report anomalies in the dispersion profiles of low-coherence ultrafast pulses through long and non-identical arms of a Michelson interferometer that are well beyond group delay or third-order dispersions. This chromatic anomaly worsens the observed axial resolution and causes fringe artifacts in the reconstructed tomograms in OCT/OCM using traditional algorithms. We present DISpersion COmpensation Techniques for Evident Chromatic Anomalies (DISCOTECA) as a universal solution to address the problem of chromatic dispersion mismatch in interferometry, especially with ultrafast sources. First, we demonstrate the origin of these artifacts through the self-phase modulation of ultrafast pulses due to focusing elements in the beam path. Next, we present three solution paradigms for DISCOTECA: optical, optoelectronic, and computational, along with quantitative comparisons to traditional methods to highlight the improvements to the dynamic range and axial profile. We explain the piecewise reconstruction of the phase mismatch between the arms of the spectral-domain interferometer using a modified short-term Fourier transform algorithm inspired by spectroscopic OCT. Finally, we present a decision-making guide for evaluating the utility of DISCOTECA in interferometry and for the artifact-free reconstruction of OCT images using an ultrafast supercontinuum source for biomedical applications.
近年来，超快光学在生物医学显微镜中的应用迅速扩展，包括光学相干断层扫描和显微镜（OCT/OCM）等干涉技术。超高分辨率OCT的进展以及OCT/OCM在与多光子显微镜相结合的多模态系统中的应用，标志着从使用伪连续宽带光源（如超发光二极管）向超快超连续光源的转变。我们报告了通过迈克尔逊干涉仪的长且不相同的臂的低相干超快脉冲的色散分布异常，这些异常远远超出了群延迟或三阶色散。这种色散异常会恶化观察到的轴向分辨率，并在使用传统算法的OCT/OCM重建断层图像中产生条纹伪影。我们提出了用于明显色散异常的色散补偿技术（DISCOTECA），作为解决干涉测量中色散失配问题的通用解决方案，特别是对于超快光源。首先，我们通过光束路径中的聚焦元件对超快脉冲的自相位调制来证明这些伪影的起源。接下来，我们介绍了DISCOTECA的三种解决方案范式：光学、光电和计算范式，并与传统方法进行了定量比较，以突出对动态范围和轴向轮廓的改进。我们使用受光谱OCT启发的改进的短时傅里叶变换算法解释了光谱域干涉仪臂之间相位失配的分段重建。最后，我们提出了一个决策指南，用于评估DISCOTECA在干涉测量中的效用，以及使用超快超连续光源进行生物医学应用的OCT图像无伪影重建。
