  Quantitative phase imaging (QPI) is important in many applications such as
microscopy and crystallography. To quantitatively reveal phase information,
people could either employ interference to map phase distribution into
intensity fringes, or analyze intensity-only diffraction patterns through phase
retrieval algorithms. Traditionally, both of these two ways use pixelated
detectors. In this work, a novel QPI scheme is reported inspired by
single-pixel camera (SPC), which adopts the principle of SPC that retrieves
images through structured illumination and corresponding single-pixel signals.
Particularly for complex-valued imaging, the structured illumination is
performed in the phase domain, and a point detector with restricted sensor size
detects the intensity of zero-frequency area. Based on the illumination
structures and point signals, a complex image is reconstructed by running a
phase retrieval algorithm. This approach is universal for various wavelengths,
and needs no a priori information of the targets. Both simulation and
experiment show that our single-pixel QPI scheme exhibits great performance
even with objects in an extremely rough phase distribution.
