  Conventional imaging systems can only capture light intensity. Meanwhile, the
lost phase information may be critical for a variety of applications such as
label-free microscopy and optical metrology. Existing phase retrieval
techniques typically require a bulky setup, multi-frame measurements, or prior
information of the target scene. Here, we proposed an extremely compact system
for complex amplitude imaging, leveraging the extreme versatility of a
single-layer metalens to generate spatially-multiplexed and
polarization-phase-shifted point spread functions. Combining the metalens with
a polarization camera, the system can simultaneously record four polarization
shearing interference patterns along both in-plane directions, thus allowing
the deterministic reconstruction of the complex amplitude light field in a
single shot. Using an incoherent light-emitting diode as the illumination, we
experimentally demonstrated speckle-noise-free complex amplitude imaging for
both static and moving objects with tailored magnification ratio and
field-of-view. The miniaturized and robust system may open the door for complex
amplitude imaging in portable devices for point-of-care applications.
