Heterodyne swept-source optical coherence tomography for complete complex conjugate ambiguity removal
Heterodyne swept-source optical coherence tomography for complete complex conjugate ambiguity removal
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DOI：
10.1117/1.2136147
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发表时间：
2005-11-01
影响因子：
3.5
通讯作者：
Izatt, JA
中科院分区：
文献类型：
--
作者：
Davis, AM;Choma, MA;Izatt, JA
傅立叶域(FD)技术在光学相干层析成像(OCT)中受到越来越多的关注。这主要是因为它们的灵敏度比传统的时域技术高出两到三个数量级。FDOCT图像受两个主要伪影来源的影响。首先，由于实值光谱干涉信号的傅里叶变换是厄米对称的，所以产生了复共轭模糊。这种模糊性导致在样品和参考反射器之间的正和负光程长度差处的反射器的人为叠加。其次，非干涉项和样本自相关项出现在DC处，遮挡了零光程差的反射面。我们证明了扫频源OCT(SSOCT)中的外差检测能够解决复共轭模糊，并去除非干涉和自相关伪影。我们还证明了当样本移位到大的路径长度差时，频移解复共轭模糊度避免了SSOCT中有限的源线宽引起的衰落。我们描述了一种高效的外差式SSOCT设计，能够补偿移频元件的功率损耗。最后，我们展示了这项技术，结合波数触发和电子解调，用于活体成像人类眼前节。(C)2005年光学仪器工程师学会。
Fourier domain (FD) techniques have increasingly gained attention in optical coherence tomography (OCT). This is primarily due to their demonstrated sensitivity of two to three orders of magnitude over conventional time-domain techniques. FDOCT images are subject to two primary sources of artifacts. First, a complex conjugate ambiguity arises because the Fourier transform of the real-valued spectral interferometric signal is Hermitian symmetric. This ambiguity leads to artifactual superposition of reflectors at positive and negative pathlength differences between the sample and reference reflectors. Second, noninterferometric and sample autocorrelation terms appear at dc, obscuring reflectors at zero pathlength difference. We show that heterodyne detection in swept-source OCT (SSOCT) enables the resolution of complex conjugate ambiguity and the removal of noninterferometric and autocorrelation artifacts. We also show that complex conjugate ambiguity resolution via frequency shifting circumvents falloff induced by finite source linewidth in SSOCT when samples are shifted to large pathlength differences. We describe an efficient heterodyne SSOCT design that enables compensation of power losses from frequency-shifting elements. Last, we demonstrate this technique, coupled with wavenumber triggering and electronic demodulation, for in vivo imaging of the human anterior eye segment. (C) 2005 Society of Photo-Optical Instrumentation Engineers.