  Optical coherence tomography (OCT) has seen widespread success as an in vivo
clinical diagnostic 3D imaging modality, impacting areas including
ophthalmology, cardiology, and gastroenterology. Despite its many advantages,
such as high sensitivity, speed, and depth penetration, OCT suffers from
several shortcomings that ultimately limit its utility as a 3D microscopy tool,
such as its pervasive coherent speckle noise and poor lateral resolution
required to maintain millimeter-scale imaging depths. Here, we present 3D
optical coherence refraction tomography (OCRT), a computational extension of
OCT which synthesizes an incoherent contrast mechanism by combining multiple
OCT volumes, acquired across two rotation axes, to form a resolution-enhanced,
speckle-reduced, refraction-corrected 3D reconstruction. Our label-free
computational 3D microscope features a novel optical design incorporating a
parabolic mirror to enable the capture of 5D plenoptic datasets, consisting of
millimetric 3D fields of view over up to $\pm75^\circ$ without moving the
sample. We demonstrate that 3D OCRT reveals 3D features unobserved by
conventional OCT in fruit fly, zebrafish, and mouse samples.
