Dynamic full-field swept-source optical coherence tomography for high-resolution, long-depth, and intratissue-activity imaging

Optical coherence tomography (OCT) may use a high-numerical-aperture objective to achieve high lateral resolution. However, its practical imaging depth range is limited by the depth of focus (DOF). Although computational refocusing can potentially provide sharp images outside the DOF, signal reduction by the confocal effect still limits the imaging depth in practice in point-scanning OCT. In addition, standard OCT cannot visualize intra-tissue activities. To overcome these limitations, we demonstrated a dynamic spatially-coherent full-field OCT (dynamic SC-FFOCT). This modality uses computational refocusing to extend the imaging depth, and a repetitive acquisition protocol for dynamic OCT imaging that visualizes intra-tissue activities. In addition, a repetitive acquisition protocol was designed to visualize intra-tissue activities (i.e., dynamic OCT imaging). The in-focus lateral resolution is 1.4 μm, and the axial resolution is 6.5 μm (in air) at full-width at half-maximum intensity. Three-dimensional structure and the dynamic OCT imaging using SC-FFOCT with computational refocusing was applied to human breast adenocarcinoma spheroids (MCF-7 cell line). Volumetric dynamic imaging with high lateral resolution was demonstrated over the full depth of the spheroid.