  Polarimetric imaging provides valuable insights into the polarization state
of light interacting with a sample. It can infer crucial birefringence
properties of bio-specimens without using any labels, thereby facilitating the
diagnosis of diseases such as cancer and osteoarthritis. In this study, we
present a novel polarimetric coded ptychography (pol-CP) approach that enables
high-resolution, high-throughput gigapixel birefringence imaging on a chip. Our
platform deviates from traditional lens-based polarization systems by employing
an integrated polarimetric coded sensor for lensless coherent diffraction
imaging. Utilizing Jones calculus, we quantitatively determine the
birefringence retardance and orientation information of bio-specimens from the
recovered images. Our portable pol-CP prototype can resolve the 435-nm
linewidth on the resolution target and the imaging field of view for a single
acquisition is limited only by the detector size of 41^2. The prototype allows
for the acquisition of gigapixel birefringence images with a 180-mm^2 field of
view in ~3.5 minutes, a performance that rivals high-end whole slide scanner
but a small fraction of the cost. To demonstrate its biomedical applications,
we perform high-throughput imaging of malaria-infected blood smears, locating
parasites using birefringence contrast. We also generate birefringence maps of
label-free thyroid smears to identify thyroid follicles. Notably, the recovered
birefringence maps emphasize the same regions as autofluorescence images,
underscoring the potential for rapid on-site evaluation of label-free biopsies.
Our approach provides a turnkey and portable solution for lensless polarimetric
analysis on a chip, with promising applications in disease diagnosis, crystal
screening, and label-free chemical imaging, particularly in
resource-constrained environments.
