8 May 2014 Line field off axis swept source OCT utilizing digital refocusing
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OCT is a promising tool for performing fast and cheap noninvasive biopsies. High speed imaging helps to reduce motion artifacts that cause decreased sensitivity and resolution. Using a point scanning configuration one is ultimately limited in sensitivity. Therefore parallel configurations are a potentially attractive solution to further enhance the speed capabilities of future OCT systems. Even more, if full field configurations are employed one can exploit the intrinsic phase correlation over the field of view for digital wavefront correction techniques. Full field OCT has nevertheless limitations concerning the missing confocal gating. The sensitivity is decreased in the presence of specular reflexes from optical interfaces, furthermore light scattering cross talk between pixel causes additional signal degradation. A good compromise between parallel detection capabilities and confocal gating seems therefore line field OCT. We built a bench top line field system employing a frequency swept source enabling 2D/3D imaging at up to 200 kA-scans/s with an axial resolution of 8μm and a depth range of 3.53mm in air. To prevent specular reflexes reaching the line scan camera, an off axis configuration of the optical path together with spatial filters placed in conjugate planes of the system was used. Geometrical optics based digital refocusing through the full depth range was shown on a sample target containing FeO particles, on a biological sample and in vivo. Furthermore, we assessed the regime where line field has an advantage over point scanning OCT in terms of sensitivity.
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Daniel Fechtig, Daniel Fechtig, Abhishek Kumar, Abhishek Kumar, Branislav Grajciar, Branislav Grajciar, Amardeep S. G. Singh, Amardeep S. G. Singh, Wolfgang Drexler, Wolfgang Drexler, Rainer A. Leitgeb, Rainer A. Leitgeb, "Line field off axis swept source OCT utilizing digital refocusing", Proc. SPIE 9129, Biophotonics: Photonic Solutions for Better Health Care IV, 91293S (8 May 2014); doi: 10.1117/12.2052195; https://doi.org/10.1117/12.2052195

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