Phase-shifting digital holography with a low-coherence light source for reconstruction of a digital relief object hidden behind a light-scattering medium

Hiding image data with a light-scattering medium is effective as a basic data protection technique. The hidden image data can be observed only by using a lowcoherence interference technique and is thus protected from unauthorized access. Unlike an intensity-distributed object, a digital relief object has no intensity distribution, making it possible to hide its existence by using a dilute light-scattering medium. To reconstruct the digital relief object through the light-scattering medium, we developed phase-shifting digital holography with a low-coherence light source. The experimental performance, including the spatial resolution and phase error of the reconstructed image, is estimated.