Few-Mode Optical Coherence Tomography (FM-OCT)

光学相干层析成像（OCT）是一种成像技术，它允许红外光穿透散射光的材料，从而获得3D图像。这是一种非侵入性技术，可以对2-3mm深度的组织进行3D可视化。图像的分辨率是MRI、CT、超声的100 ~ 1000倍。OCT是眼科重要的诊断方法，其横向分辨率高，可以区分层数和测量厚度。OCT也被研究作为糖尿病性青光眼、心血管疾病、非黑色素瘤皮肤癌、前列腺癌和食道问题等疾病的诊断工具。然而，传统OCT在某些方面对疾病管理施加了重大限制，例如对比度有限，难以检测所有方向的血流或3D粒子运动。然而，一些眼部疾病涉及细胞簇的形成和/或眼内侧血流量的改变。眼睛内3D血流的测量可用于其他神经血管疾病的早期诊断，如阿尔茨海默病。我们的实验室已经演示了使用多模光纤（FMF）的OCT，可以收集比传统使用单模光纤收集更多的光。FMF与模态特定光子灯（MSPL）耦合，用于模态解复用。它们一起产生同时的OCT图像，每个图像都是从组织（和光纤）内不同的传播模式获得的。这些模式的实时图像处理可以提高对小于分辨率的颗粒的灵敏度，并允许在表面平面上进行精确的流量测量。通过这项工作，我们计划使MSPL适应OCT波长，并在幻影和生物组织上展示新的FM-OCT。几个加拿大和美国的工业合作伙伴进行了接触，并表现出极大的兴趣推动这项技术进一步超越其概念验证。

Optical coherence tomography (OCT) is an imaging technique that allows infrared light to penetrate a material that scatters the light to obtain a 3D image. It is a non-invasive technology that allows the 3D visualization of tissues at a depth of 2-3mm. The resolution of the images is 100 to 1000 times higher than MRI, CT, and ultrasound. OCT is an important diagnostic method in ophthalmology, thanks to the high transverse resolution where layers can be differentiated and thickness measured. OCT is also investigated as a diagnostic tool for diseases such as diabetic glaucoma, cardiovascular disorders, non-melanoma skin cancer, prostate cancer and esophageal problems. Yet, some aspects of conventional OCT impose significant limitations on disease management, such as limited contrast, difficulty in detecting blood flow in all orientations, or 3D particle motion. However, some ocular diseases involve the formation of cell clusters and/or changes in lateral blood flow in the eye. The measurement of 3D blood flow in the eye could be used for early diagnosis of other neurovascular diseases, such as Alzheimer's disease. Our laboratory has demonstrated OCT with a few mode fiber (FMF) allowing the collection of more light than traditionally collected using a single mode fiber. The FMF is coupled to a modally-specific photonic lantern (MSPL) for mode demiultiplexing. Together, they yield simultaneous OCT images, each acquired from a different propagation mode within tissues (and fiber optics). Real-time image processing of these modes allows increased sensitivity to particles smaller than the resolution, and allow for precise flow measurement in the en face plane. Through this work, we plan to adapt the MSPL to OCT wavelengths and demonstrate the new FM-OCT on phantoms and biological tissues. Several canadian and american industrial partners were approached, and showed great interest in pushing this technology further than its proof-of-concept.