We present a 3D label-free refractive index (RI) imaging technique
based on single-exposure intensity diffraction tomography (sIDT) using
a color-multiplexed illumination scheme. In our method, the chromatic
light-emitting diodes (LEDs) corresponding R/G/B channels in an
annular programmable ring provide oblique illumination geometry that
precisely matches the objective’s numerical aperture. A color
intensity image encoding the scattering field of the specimen from
different directions is captured, and monochromatic intensity images
concerning three color channels are separated and then used to recover
the 3D RI distribution of the object following the process of IDT. In
addition, the axial chromatic dispersion of focal lengths at different
wavelengths introduced by the chromatic aberration of the objective
lens and the spatial position misalignment of the ring LED source in
the imaging system’s transfer functions modeling are both corrected to
significantly reduce the artifacts in the slice-based deconvolution
procedure for the reconstruction of 3D RI distribution. Experimental
results on MCF-7, Spirulina algae, and living Caenorhabditis elegans samples demonstrate the reliable
performance of the sIDT method in label-free, high-throughput, and
real-time (∼24 fps) 3D volumetric biological imaging applications.