Adaptable switching schemes for time-encoded multichannel optical coherence tomography

Andreas Wartak; Florian Beer; Bernhard Baumann; Michael Pircher; Christoph K. Hitzenberger

doi:10.1117/1.JBO.23.5.056010

24 May 2018 Adaptable switching schemes for time-encoded multichannel optical coherence tomography

Andreas Wartak, Florian Beer, Bernhard Baumann, Michael Pircher, Christoph K. Hitzenberger

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Journal of Biomedical Optics, Vol. 23, Issue 5, 056010 (May 2018). https://doi.org/10.1117/1.JBO.23.5.056010

Abstract

We introduce the approach of variable time encoding for multichannel optical coherence tomography (OCT). High-speed fiber optical switches are applied for sequential sample arm switching to enable quasisimultaneous image acquisition from three different orientation angles. In comparison with previous multichannel OCT (using simultaneous sample illumination), time-encoded multichannel OCT has no need for division of illumination power among the respective channels to satisfy laser safety requirements. Especially for ophthalmic applications—in particular retinal imaging, which the presented prototype was developed for—this advantage strongly influences image quality through an enhanced sensitivity. Nevertheless, time encoding comes at the cost of a decrease in imaging speed due to sequential channel illumination. For the typical multichannel OCT modality Doppler OCT, this results in a reduction of the maximum unambiguously determinable Doppler velocity. However, we demonstrate that this drawback can be overcome by adaptation of the illumination channel switching scheme. Thus, a re-extension of the maximum unambiguously determinable Doppler frequency to the full A-scan rate of the tunable light source is presented. The performance of the technique is demonstrated by flow phantom experiments and measurements of retinal blood flow in the eyes of healthy human volunteers.

CC BY: © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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Andreas Wartak, Florian Beer, Bernhard Baumann, Michael Pircher, and Christoph K. Hitzenberger "Adaptable switching schemes for time-encoded multichannel optical coherence tomography," Journal of Biomedical Optics 23(5), 056010 (24 May 2018). https://doi.org/10.1117/1.JBO.23.5.056010

Received: 24 January 2018; Accepted: 30 April 2018; Published: 24 May 2018

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