Visualizing Pure Phase Objects Using a Degenerate Self-Imaging Optical Cavity

Abstract

Theoretical analysis demonstrates that pure-phase objects, when positioned on the flat mirror of a self-imaging cavity, can be imaged outside the cavity as ordinary objects. The theory was developed based on the following assumptions: (i) the object is non-polarizing, (ii) it is binary (with phase values of 0 or 1 rad), (iii) it has a single refractive index, (iv) the mirror is non-absorbing, (v) the mirror is dielectric, and (vi) it reflects isotropically. These images are degraded by a bright background, with the signal-to-background ratio (SBR) improving as mirror reflectivity increases. Computational simulations validate these findings and reveal similar behavior for objects with more complex phase structures, depending on mirror reflectivity. This indicates that the method is effective beyond the binary case, as examined using theoretical methods.