Blatter Cedric, Grajciar Branislav, Eigenwillig Christoph M, Wieser Wolfgang, Biedermann Benjamin R, Huber Robert, Leitgeb Rainer A
Group of Biomedical Optics, Center of Medical Physics and Biomedical Engineering, Medical University Vienna, Waehringerstrasse 13, 1090 Vienna, Austria.
Opt Express. 2011 Jun 20;19(13):12141-55. doi: 10.1364/OE.19.012141.
We present a Bessel beam illumination FDOCT setup using a FDML Swept Source at 1300 nm with up to 440 kHz A-scan rate, and discuss its advantages for structural and functional imaging of highly scattering samples. An extended focus is achieved due to the Bessel beam that preserves its lateral extend over a large depth range. Furthermore, Bessel beams exhibit a self-reconstruction property that allows imaging even behind obstacles such as hairs on skin. Decoupling the illumination from the gaussian detection increases the global sensitivity and enables dark field imaging. Dark field imaging is useful to avoid strong reflexes from the sample surface that adversely affect the sensitivity due to the limited dynamic range of high speed 8 bit acquisition cards. In addition the possibility of contrasting capillaries with high sensitivity is shown, using inter-B-scan speckle variance analysis. We demonstrate intrinsic advantages of the extended focus configuration, in particular the reduction of the phase decorrelation effect below vessels leading to improved axial vessel definition.
我们展示了一种使用1300nm的FDML扫频光源、A扫描速率高达440kHz的贝塞尔光束照明频域光学相干断层扫描（FDOCT）装置，并讨论了其在高散射样本的结构和功能成像方面的优势。由于贝塞尔光束在大深度范围内保持其横向扩展，因此实现了扩展焦深。此外，贝塞尔光束具有自重建特性，即使在诸如皮肤上的毛发等障碍物后面也能成像。将照明与高斯检测解耦可提高整体灵敏度并实现暗场成像。暗场成像有助于避免样本表面的强反射，由于高速8位采集卡的动态范围有限，这些反射会对灵敏度产生不利影响。此外，利用B扫描间散斑方差分析展示了以高灵敏度对比毛细血管的可能性。我们展示了扩展焦深配置的固有优势，特别是减少了血管下方的相位去相关效应，从而改善了轴向血管清晰度。
