Spatio-temporal optical coherence imaging and tomography for in vivo applications

Strong scattering in biological tissues limits the achievable imaging depth and produces noiseboth coherent and incoherentthat impairs contrast in volumetric in vivo reconstructions. By dynamically tailoring spatial and temporal coherence to suppress scattered photons, spatio-temporal optical coherence imaging (STOC) enables high-contrast, high-resolution in vivo visualization, with direct applications in ophthalmic diagnostics and complex tissue imaging.

The primary aim of this work is to formalize and validate the theoretical foundations and practical implementations of STOC and its three-dimensional volumetric extension, spatio-temporal optical coherence tomography (STOC-T). Specifically, the study seeks to demonstrate their ability to enhance imaging performance in scattering media, benchmark against current optical coherence methods, and assess their readiness for clinical application.

This work mainly reviews advances in spatio-temporal optical coherence imaging and tomography, and includes an original description of filtering multiply scattered signals derived from a generalized diffraction model, showing that application of STOC-T obeys the first Born approximation.

Spatio-temporal optical coherence Imaging and tomography markedly improved image fidelity in highly scattering media, demonstrated by enhanced fringe contrast and reduced incoherent background across phantoms and biological tissues. STOC-T achieved high-resolution, high-contrast in vivo visualization of challenging structures, including retinal layers and choroidal microvasculature, with markedly improved delineation compared with conventional coherence imaging. Quantitatively, STOC-T extended effective imaging depth while preserving lateral resolution ( $\sim 5\mu m$ ) and exhibited coherence noise suppression and high phase stability. Performance metrics revealed contrast improvements in retinal ganglion cell soma imaging, with shot-noise-limited sensitivity attainable under appropriate conditions. Practical limitations such as high data volume, camera bandwidth demands, and computational load were identified, alongside potential pathways for further enhancement through optimized phase coding and adaptive acquisition strategies.

Spatio-temporal optical coherence imaging and tomography enable high-contrast, deep volumetric imaging with improved resolution by combining phase modulation, spectral sweeping, and coherence control. Validated in vivo, it resolves fine retinal/choroidal structures beyond conventional OCT limitations. Its simple hardware and computational emphasis position it for clinical translation, despite challenges in data volume and acquisition demands.