Shadow Imaging with Low-Intensity Thermal Light*

The ability of image reconstruction using low photon flux would be desirable for numerous scientific, commercial, and defense imaging applications. We demonstrate this ability with the Shadow imaging (SI) scheme. In this novel imaging technique, the photon noise statistics of the probe beam is manipulated after its interaction with the object. Homodyne-like detection protocol eliminates the detrimental effect of the dark noise of the CCD camera. The SI scheme was originally proposed with the squeezed vacuum probe. Here, we use thermal state probe and provide theoretical as well as experimental validation of its utility in the SI scheme. We evaluate the signal-to-noise (SNR) and identify the regimes where the SI scheme has an advantage over the classical imaging scheme. Finally, to exhibit the full potential of this scheme, we image a biological specimen on a CCD camera using fewer than 500 photons in total from a low-intensity ( ≤1 average photons) thermal probe.