Compared with the fully coherent beam, partially coherent beams viewed as the dynamic random light fields are robust in complex environments. The amplitude and phase of random light fields fluctuate randomly over time.

Significantly, the valuable information is embedded in the statistical properties of random light fields. The optical coherent structure of a random electric field, as a second-order statistical parameter, can determine the beam evolution behavior, far-field intensity distribution and light-matter interaction.

Until now, the random lights with prescribed optical coherent structures have been found applications in coherence tomography, ghost imaging, super-resolution imaging and free-space optical communication. Recently, using the coherent structure of random lights as information carrier for high-security encryption and far-field robust imaging has also been proposed. The rapid development of optical coherence structures related research highly requires the precise measurement of optical coherent structures in return.

To fully recover optical coherent structure, as a complex function, we must precisely measure their real and imaginary parts (or amplitude and phase) simultaneously. The optical coherence structure has traditionally been measured using Young's interference experiment, wherein its magnitude and phase can be predicted based on the visibility and position of the fringes, respectively. However, this experiment only considers two position points.

Full characterization of the optical coherence structure requires that each point be scanned independently across the beam plane, which needs significant time and effort. Improvements to this experiment have been proposed, such as wavefront-folding interferometers, phase-space approach and self-reference holography, Hanbury Brown and Twiss (HBT) effect and generalized HBT effect have been developed to measure optical coherence structures.