Applied Science Innovations, Inc. proposes a new tool of 3D optical coherence tomography (OCT) for cellular level imaging at video frame rates and dramatically reduced probe cross-section. Existing commercial OCT tools are focused in ophthalmology, where examination is external to the eye, the size of the probe is not important, and cellular level resolution is not required. The patent-pending 3D OCT will provide three-dimensional imaging in scattering media with improved resolution, depth of field, and minimal mechanical adjustment. The proposed approach is based on novel probe designs, original coherence scanning, and advanced signal processing. The flexible imaging probe will have dramatically reduced cross-section, compared to the existing systems, enabling the first "3D camera through a needle" for functional imagery, including in-vivo histological examination. Phase I has demonstrated the proof of concept by theoretical studies and implementation of a limited experimental prototype. First generation packaged prototype will be developed in Phase II of the project and delivered to NASA Glenn Research Center for evaluation and field tests. Commercial applications are envisioned in NASA's future space missions, biomedical imaging, and industrial inspection.