Merkle Conrad William, Chong Shau Poh, Kho Aaron Michael, Zhu Jun, Dubra Alfredo, Srinivasan Vivek Jay
Opt Lett. 2018 Jan 15;43(2):198-201. doi: 10.1364/OL.43.000198.
Most flying-spot optical coherence tomography and optical coherence microscopy (OCM) systems use a symmetric confocal geometry, where the detection path retraces the illumination path starting from and ending with the spatial mode of a single-mode optical fiber. Here we describe a visible light OCM instrument that breaks this symmetry to improve transverse resolution without sacrificing collection efficiency in scattering tissue. This was achieved by overfilling a water immersion objective on the illumination path while maintaining a conventional Gaussian mode detection path (1/e intensity diameter ∼0.82 Airy disks), enabling ∼1.1 μm full width at half-maximum (FWHM) transverse resolution. At the same time, a ∼0.9 μm FWHM axial resolution in tissue, achieved by a broadband visible light source, enabled femtoliter volume resolution. We characterized this instrument according to paraxial coherent microscopy theory and, finally, used it to image the meningeal layers, intravascular red blood cell-free layer, and myelinated axons in the mouse neocortex in vivo through the thinned skull.
大多数飞点光学相干断层扫描和光学相干显微镜（OCM）系统采用对称共焦几何结构，其中检测路径会追溯照明路径，从单模光纤的空间模式开始并以其结束。在此，我们描述了一种可见光OCM仪器，它打破了这种对称性，以在不牺牲散射组织中采集效率的情况下提高横向分辨率。这是通过在照明路径上过度填充水浸物镜，同时保持传统的高斯模式检测路径（1/e强度直径约为0.82个艾里斑）来实现的，从而实现了约1.1μm的半高宽（FWHM）横向分辨率。同时，通过宽带可见光源在组织中实现了约0.9μm的FWHM轴向分辨率，实现了飞升量级的体积分辨率。我们根据傍轴相干显微镜理论对该仪器进行了表征，最后，通过变薄的颅骨在体内对小鼠新皮层中的脑膜层、血管内无红细胞层和有髓轴突进行了成像。
