High-speed full-range spectral-domain correlation mapping optical coherence tomography

We present a full range spectral-domain correlation mapping optical coherence tomography (cm-OCT) method to obtain complex conjugate free, full-range correlation mapping angiography. The mirror image elimination is based on linear phase modulation of B-frames by introducing a slight off-set of the probe beam with respect to the lateral scanning fast mirror's pivot axis. An algorithm that exploits Hilbert transform to obtain complex-conjugate free image in conjunction with the cm-OCT algorithm is used to obtain full-range imaging of microcirculation within tissue beds in vivo. The proposed system is based on a high speed spectrometer at 92kHz with a modified scanning protocol to achieve higher acquisition speed to render cmOCT images with high-speed and wide scan range. The estimated sensitivity of the system was around 105dB near the zero-delay line with similar to 13dB roll-off from 0.5mm to 3mm imaging-depth position. The estimated axial and lateral resolutions are 12 mu m and 25 mu m, respectively. A direct consequence of this complex conjugate artifact elimination is the enhanced flow imaging sensitivity for deep tissue imaging application by doubling the imaging depth. In turn, this also provides additional flexibility to explore the most sensible measurement range near the zero-delay line.