Ultra-fast Scalable OCT Systems based on a New Photon Detector

光学相干层析成像（OCT）系统具有更高的成像速度，具有显著的诊断价值， 因为它们允许增加的视场、减少的测量时间、改进的分辨率 通过减少运动伪影和支持功能成像（如OCT血管造影术）来提高水平。因此，我们认为， 提高成像速度而不增加较高成本的负担是本发明的最终目标之一。 下一代OCT系统虽然A扫描速率超过几十MHz的超快OCT系统 已经证明，这种系统的广泛临床应用的主要障碍是它们的显著性， 这是因为它们依赖于超快激光器和探测器。 并行SS-OCT系统一直被认为是降低超快速OCT成本的最佳解决方案 系统，因为激光扫描速率和检测器带宽都可以通过增加数量来缩小 平行渠道。然而，为了实现高灵敏度而平衡检测的需要限制了本发明的范围。 并行通道的数量减少到少数，并且使得这样的系统没有吸引力。主要的限制是 平衡检测，要求每个检测器上的功率均衡具有严格的容差 汇率此外，在该方法中实现散粒噪声限制的灵敏度需要每个检测器的大的参考功率 随着信道数量的增加，这可能会增加到非常大的激光功率。 Mohseni的研究小组最近发表了基于一种名为电子注入（EI）的新探测器的结果 表明，散粒噪声限制的灵敏度~105 dB，可以实现不平衡的检测第一 时间此外，散粒噪声限制性能所需的参考功率约为 比传统的探测器低。基于这些发现，本项目假设 利用这种新的EI探测器可以实现具有散粒噪声限制灵敏度的并行SS-OCT系统; 并行OCT是高度可扩展的，并且可以通过简单地增加低速扫描速率来增强到多MHz扫描速率。 通道和使用传统的低速扫频源。这一假设将在 具体目的如下：（1）建立一个16路并行OCT系统 通道的基础上EI检测器，并在散粒噪声有限的灵敏度。(2)扩大系统规模 到64个并行通道，每个通道以100 MHz工作，每秒可进行3.2兆A扫描，同时使用 传统的扫频源在50 KHz的扫频速率，只需要几毫瓦的激光功率。 如果这项探索性研究达到了计划的目标，它为低成本超快速OCT和 系统以及具有潜在的前所未有的扫描速度的OCT系统。队员们 过去，我制作了具有数千个元件的EI探测器的大型阵列，并且熟悉工业 临床局限性。如果成功，该项目将使并行SS-OCT具有超过1000个并行通道， 未来，和前所未有的速度接近100千兆体素/秒。

Optical coherence tomography (OCT) systems with higher imaging speed have a significant diagnostic value, since they allow increased field of view, reduced measurement time, improved resolution down to the cellular level by reducing motion artifacts, and supporting functional imaging such as OCT angiography. Therefore, increasing the imaging speed without increasing the burden of higher costs is one of the ultimate goals of the next generation OCT systems. While ultra-fast OCT systems with A-scan rates exceeding tens of MHz have been demonstrated, a major roadblock in widespread clinical application of such systems is their significant cost due to their reliance on ultra-fast lasers and detectors. Parallel SS-OCT systems have long been considered the best solution to reduce the cost of ultra-fast OCT systems, since both the laser swept rate and detector bandwidth can be scaled down by increasing the number of parallel channels. However, the need for balanced detection for achieving high sensitivity has limited the number of parallel channels to a handful, and rendering such systems unattractive. The main limitation is the balanced detection, which requires stringent tolerances for the equalization of the power across each detector pair. Also, achieving shot-noise limited sensitivity in this method requires a large reference power per detector that could add up, as the number of channels grows, to a prohibitively large laser power. Mohseni's research group recently published results based on a new detector called Electron Injection (EI) showed that shot-noise limited sensitivity of ~105 dB could be achieved without balanced detection for the first time. Additionally, the required reference power for shot-noise limited performance was about three orders of magnitude lower than the conventional detectors. Based on these findings, this project hypothesize that a parallel SS-OCT system with shot-noise limited sensitivity can be made using the new EI detector; and that the parallel OCT is highly scalable and can be augmented to Multi-MHz scan rate by simply adding low-speed channels and using a conventional low-speed swept source. This hypothesis will be addressed in the experiments organized in the following Specific Aims: (1) to build a parallel OCT system with 16 parallel channels based on EI detectors, and operating at the shot-noise limited sensitivity. (2) to scale up the system to 64 parallel channels, each operating at 100 MHz, leading to 3.2 Mega A-scans per second, while using a conventional swept-source at 50 KHz swept rate and requiring only a few mW of laser power. Should this exploratory study achieve the planned goals, it paves the way for both low-cost ultra-fast OCT systems and also OCT systems with potentially unprecedented scanning speeds. The team members have made large arrays of EI detectors with thousands of elements in the past and are familiar with the industrial and clinical limitations. If success, this project enables parallel SS-OCT with over 1000 parallel channels in the future, and unprecedented speeds approaching 100 Giga-voxels/second.