Modeling and analyzing ghost images for incoherent optical systems

In a previous paper [Proc. SPIE 7428, 742807 (2009)], a methodology was developed to model and analyze incoherent ghosts that are formed by two reflections in the paraxial regime. In this paper, we extend the previously developed methodology to model and analyze ghost images that are formed by N (even) reflections. Rather than dealing with ghosts as spots of light, we apply the concept that each ghost has a structure in the nonparaxial regime that depends on the optical system parameters. A methodology to determine the fourth-order ghost aberration function is developed. We present new key parameters for ghost image formation, namely the ghost sagittal and tangential image surfaces. An expression for the paraxial ghost image irradiance distribution of the point object at the nominal image plane is derived. Since focused ghosts are the most bothersome ghosts, tools are proposed to identify potential problematic ghosts. Simulation examples are provided and are used to validate the developed methodology.