Opt Lett. 2018 Apr 15;43(8):1782-1785. doi: 10.1364/OL.43.001782.
Extended-focus optical coherence tomography (xf-OCT) is a variant of optical coherence tomography (OCT) wherein the illumination and/or detection modes are engineered to provide a constant diffractionless lateral resolution over an extended depth of field (typically 3 to 10× the Rayleigh range). xf-OCT systems operating at 800 nm have been devised and used in the past to image brain structures at high-resolution in vivo, but are limited to ∼500 μm in penetration depth due to their short illumination wavelength. Here we present an xf-OCT system optimized to an image deeper within the cortex by using a longer illumination central wavelength of 1310 nm. The system offers a lateral resolution of 3 and 6.5 μm, over a depth of 900 μm and >1.5 mm using a 10× and 5× objective, respectively, in air. We characterize the system's resolution using microbeads embedded in PDMS and demonstrate its capabilities by imaging the cortical structure and microvasculature in anesthetized mice to a depth of ∼0.8 mm. Finally, we illustrate the difference in penetration depths obtainable with the new system and an xf-OCT system operating at 800 nm.
扩展焦点光学相干断层扫描（xf-OCT）是光学相干断层扫描（OCT）的一种变体，其中照明和/或检测模式经过设计，可在扩展景深（通常是瑞利范围的 3 到 10 倍）上提供恒定的无衍射横向分辨率。过去已经设计并使用了工作在 800nm 的 xf-OCT 系统来高分辨率地对活体大脑结构进行成像，但由于其短的照明波长，其穿透深度仅限于约 500μm。在这里，我们提出了一种优化的 xf-OCT 系统，通过使用 1310nm 的更长的照明中心波长，可在更深的皮层内进行成像。该系统在空气中使用 10×和 5×物镜时，分别在 900μm 的深度上提供 3μm 和 6.5μm 的横向分辨率和>1.5mm 的深度，我们使用嵌入 PDMS 中的微珠来表征系统的分辨率，并通过对麻醉小鼠的皮层结构和微血管进行成像来演示其功能，深度可达约 0.8mm。最后，我们说明了新系统和工作在 800nm 的 xf-OCT 系统可获得的穿透深度的差异。
