Imaging hidden objects

An imaging system for identifying information of an object hidden from view, the imaging system comprises:

• a light source that generates a first beam of narrow-band light and a second beam of narrow-band light that has temporal fluctuations correlated with the first beam;
• a frequency modulator positioned along a propagation direction of at least one of the first beam or the second beam that shifts a temporal frequency of at least one of the first beam or the second beam, the first beam is directed towards a first scattering surface and the second beam is directed towards a second scattering surface, wherein both the first scattering surface and the second scattering surface have a surface roughness greater than a wavelength of light, and wherein the first scattering surface scatters the first beam to a scattered light that illuminates a hidden object, the hidden object reflects at least a portion of the scattered light towards the second scattering surface, the at least a portion of the scattered light interferes with the second beam and produces an interference pattern on the second scattering surface;
• and
• a lock-in camera that detects an irradiance of the interference pattern, monitors temporal variations of the irradiance caused by the temporal frequency shift introduced by the frequency modulator, and identifies a complex-valued light field that represents information of the hidden object based on the temporal variations of the irradiance.