Improved sensitivity roll-off in dual reference, buffered spectral-domain optical coherence tomography.

TL;DR: In this paper, a spectral-domain optical coherence tomography (SD-OCT) system operating at a center wavelength of 1300nm was proposed to image swine colon ex vivo and duodenum in vivo.

Abstract: Significance: While spectral-domain optical coherence tomography (SD-OCT) is a preferred form of OCT imaging, sensitivity roll-off limits its applicability for certain biomedical imaging applications. Aim: The aim of this work is to extend the imaging range of conventional SD-OCT systems for imaging large luminal organs such as the gastrointestinal tract. Approach: We present an SD-OCT system operating at a center wavelength of 1300 nm that uses two delayed reference arms to reduce sensitivity roll-off and an optical switch and a fiber optic delay line to ensure that the interference spectra are acquired from the same sample time window. Result: The proposed system was used to image swine colon ex vivo and duodenum in vivo, demonstrating improved image quality due to a ∼14  dB increase in sensitivity at the edges of the ranging depth. Conclusion: The proposed system requires modest hardware implementation and is compatible with catheter-based endoscopic helical scanning with enhanced sensitivity for the samples at a distance of ∼6  mm from the zero delay point.