Kang Jiqiang, Feng Pingping, Li Bowen, Zhang Chi, Wei Xiaoming, Lam Edmund Y, Tsia Kevin K, Wong Kenneth K Y
Opt Express. 2018 Sep 17;26(19):24928-24939. doi: 10.1364/OE.26.024928.
Imaging speed and range are two important parameters for optical coherence tomography (OCT). A conventional video-rate centimeter-range OCT requires an optical source with hundreds of kHz repetition rate and needs the support of broadband detectors and electronics (>1 GHz). In this paper, a type of video-rate centimeter-range OCT system is proposed and demonstrated based on dual optical frequency combs by leveraging electro-optic modulators. The repetition rate difference between dual combs, i.e. the A-scan rate of dual-comb OCT, can be adjusted within 0~6 MHz. By down-converting the interference signal from optical domain to radio-frequency domain through dual comb beating, the down-converted bandwidth of the interference signal is less than 22.5 MHz which is at least two orders of magnitude lower than that in conventional OCT systems. A LabVIEW program is developed for video-rate operation, and the centimeter imaging depth is proved by using 10 pieces of 1-mm thick glass stacked as the sample. The effective beating bandwidth between two optical comb sources is 7 nm corresponding to ~108 comb lines, and the axial resolution of the dual-comb OCT is 158 µm. Dual optical frequency combs provide a promising solution to relax the detection bandwidth requirement in fast long-range OCT systems.
成像速度和范围是光学相干断层扫描（OCT）的两个重要参数。传统的视频速率厘米范围OCT需要具有数百kHz重复率的光源，并且需要宽带探测器和电子设备（>1 GHz）的支持。本文提出并演示了一种基于双光学频率梳，利用电光调制器的视频速率厘米范围OCT系统。双梳之间的重复率差异，即双梳OCT的A扫描速率，可以在06 MHz范围内调整。通过双梳拍频将干涉信号从光域下变频到射频域，干涉信号的下变频带宽小于22.5 MHz，这比传统OCT系统中的带宽至少低两个数量级。开发了一个用于视频速率操作的LabVIEW程序，并通过使用10片1毫米厚的玻璃堆叠作为样品来证明厘米级成像深度。两个光学梳状源之间的有效拍频带宽为7 nm，对应于108条梳状线，双梳OCT的轴向分辨率为158 µm。双光学频率梳为放宽快速长距离OCT系统中的检测带宽要求提供了一个有前景的解决方案。
