Fourier synthesis optical diffraction tomography for kilohertz rate volumetric imaging.

Many biological and soft matter processes occur at high speeds in complex three-dimensional (3D) environments, and developing imaging techniques capable of elucidating their dynamics is an outstanding challenge. Here, we introduce Fourier synthesis optical diffraction tomography (FS-ODT), a quantitative phase imaging approach capable of recording the 3D refractive index at kilohertz rates. FS-ODT introduces computational strategies that multiplex tens of illumination angles in a single tomogram, markedly increasing the volumetric imaging rate. We validate FS-ODT on samples of known composition, hindered diffusion of colloids in solution, and the motility of bacterial swimmers. We also integrate FS-ODT into a multimodal microscope combining refractive index imaging with multicolor structured illumination microscopy. FS-ODT is a promising approach for unlocking imaging regimes that have been little explored, including understanding the physical interactions of colloids and microswimmers with their 3D environment and the interplay between these stimuli and the molecular response of biological systems.