Yi Luying, Sun Liqun, Ming Xianshun, Zou Mingli
Tsinghua University, State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instruments, Beijing, China.
Biomed Opt Express. 2018 Oct 1;9(10):5071-5083. doi: 10.1364/BOE.9.005071.
To achieve full-depth spectral domain optical coherence tomography in the case of strong environmental disturbance, the iterative phase-shifting (IPS) method and modified dispersion-coded (MDC) method are proposed in this work. In IPS, the precise amount of phase shift is retrieved by iteration, and the direction of the phase shift is determined by dispersion compensation. Conjugate mirror items and noise can be simultaneously eliminated by two captured interferograms, whereas only one of them can be removed in the traditional phase-shift method with two interferograms. In MDC, they are removed through dispersion compensation and signal extraction with a single interferogram. Full-depth images of a glass slide, an onion, and a live fish eye are obtained by the two methods. The advantages and disadvantages of each method are analyzed and compared. IPS is found to be more effective for removing conjugate artifacts, whereas MDC is more conducive to real-time imaging. For a 2 mm × 3.6 mm image of a fish eye (200 depth scans and 1200 spectral sampling points per depth scan), the mirror image artifact is reduced by 28.55 dB in MDC and 41.53 dB in IPS. Processing times are 5.1 seconds (20 iterations) for the IPS method and 0.91 seconds for MDC.
为了在强环境干扰情况下实现全深度光谱域光学相干断层扫描，本文提出了迭代相移（IPS）方法和改进的色散编码（MDC）方法。在IPS中，通过迭代获取精确的相移量，并通过色散补偿确定相移方向。共轭镜项和噪声可以通过两张采集到的干涉图同时消除，而在传统的双干涉图相移方法中只能消除其中之一。在MDC中，通过色散补偿和单干涉图的信号提取来消除它们。通过这两种方法获得了载玻片、洋葱和活鱼眼的全深度图像。分析并比较了每种方法的优缺点。发现IPS在去除共轭伪像方面更有效，而MDC更有利于实时成像。对于鱼眼的2mm×3.6mm图像（200次深度扫描，每次深度扫描1200个光谱采样点），MDC中的镜像伪像降低了28.55dB，IPS中降低了41.53dB。IPS方法的处理时间为5.1秒（20次迭代），MDC为0.91秒。
