  We demonstrate a motion-free intensity diffraction tomography technique that
enables direct inversion of 3D phase and absorption from intensity-only
measurements for weakly scattering samples. We derive a novel linear forward
model, featuring slice-wise phase and absorption transfer functions using
angled illumination. This new framework facilitates flexible and efficient data
acquisition, enabling arbitrary sampling of the illumination angles. The
reconstruction algorithm performs 3D synthetic aperture using a robust,
computation and memory efficient slice-wise deconvolution to achieve resolution
up to the incoherent limit. We demonstrate our technique with thick biological
samples having both sparse 3D structures and dense cell clusters. We further
investigate the limitation of our technique when imaging strongly scattering
samples. Imaging performance and the influence of multiple scattering is
evaluated using a 3D sample consisting of stacked phase and absorption
resolution targets. This computational microscopy system is directly built on a
standard commercial microscope with a simple LED array source add-on, and
promises broad applications by leveraging the ubiquitous microscopy platforms
with minimal hardware modifications.
