Development and application of ultrahigh-speed 2G-OCT system for 3d micro-vascular imaging

Abstract

Doppler optical coherence tomography (D-OCT) enables high resolution imaging of spatially-localized motion in the sample, especially in-vivo microvasculature imaging, utilizing the phase-resolved technique that is based on the detection of the phase shift between two temporally separated A-lines. To ensure correlation between the two phase measurements, conventional D-OCT over-samples in the transverse direction reducing the phase de-correlation due to the transverse displacement of the imaging beam at the expense of the imaging speed, i.e., frame rate. Recently several approaches such as optimization of beam scanning pattern in OFDI (optical frequency domain imaging) and dual beam scan using polarization multiplexing in SD-OCT (spectral-domain OCT) were demonstrated to address this issue. We present high-speed Doppler OFDI using frequency multiplexed dual beam illumination. The novel scheme provides a pair of spatially separated beams with an acousto-optic frequency shifter that illuminate the exactly same location on the sample with an adjustable time interval upon the imaging beam scan by the galvanometer. Since each beam is encoded with a distinct frequency shift, the two temporally separated beams are easily de-multiplexed in data processing. We demonstrate high-speed vasculature imaging of a mouse thigh, ankle and brain with 117 Fps imaging speed which could measure 3D image of micro-vascular structure in few seconds. This device could be applied on various research fields on medical treatment and diagnosis and biological research.