  Optical diffraction tomography (ODT) provides three-dimensional refractive
index (RI) tomograms of a transparent microscopic object. However, because of
the finite numerical aperture of objective lenses, ODT has the limited access
to diffracted light and suffers from poor spatial resolution, particularly
along the axial direction. To overcome the limitation of the quality of RI
tomography, we present an algorithm that accurately reconstructs RI tomography
using preliminary information that the RI values of a specimen are discrete and
uniform. Through simulations and experiments on various samples, including
microspheres, red blood cells, and water droplets, we show that the proposed
method can precisely reconstruct RI tomograms of samples with discrete and
uniform RI values in the presence of the missing information and noise.
