DA-OCT presents an attractive solution to image deeper into highly scattering tissue, exposing morphology otherwise undetected using conventional OCT. Based on the principles of multispectral multiple-scattering low-coherence Interferometry (ms2/LCI), DA-OCT uses spatial and coherence gating to restrict the detected photon paths of forward-scattered light to accept a more significant proportion of quasiballistic signal penetrating several mm into tissue.
DA-OCT improves upon ms2/LCI by selecting a shallower focal zone (∼0.75-1.5 mm deep). This difference, coupled with a 100x faster scanning speed, shifts the detection priority from multiply scattered to ballistic light. As a result of this unique scanning geometry, DA-OCT suffers a ~9-fold decreased depth of focus compared to conventional OCT. We exploit this using a dynamic focus-tracking method to both extend image penetration and improve the overall imaging performance of OCT in turbid media.
Featured Publications for DA-OCT:
Jelly, Evan, et al. “Deep imaging with 1.3 μm dual-Axis optical coherence tomography and an enhanced depth of focus.” Biomedical Optics Express 12.2 (2021): 7689–7702.
Zhao, Yang, et al. "Dual-axis optical coherence tomography for deep tissue imaging." Optics letters 42.12 (2017): 2302-2305.