Ghost reflection simulation, analysis, and correction in a multispectral imaging system

Abstract

Ghost images refer to unwanted secondary images or reflections that appear alongside the primary image, causing interference or reducing image quality. These ghost images are caused by multiple reflections of in-field imaging rays within the optical system. We have developed a methodology for comprehensive modeling and analysis of ghost images produced within a catadioptric multi-spectral imaging systems. Instead of characterising these ghosts as mere points of light, we conducted a detailed qualitative and quantitative examination of the ghost reflections. We identify cross-talk ghost as a significant issue, even with low surface reflection coefficients. By identifying major contributors, the study enables the formulation of robust mitigation strategies. Our methodology includes generating ghost layouts, identifying primary contributors, and precisely quantifying the flux stemming from these ghost reflections. Furthermore, we introduced multiple strategies for reducing ghost reflections, culminating in the design of a Ghost Blocker Plate engineered to effectively counteract ghost reflections. A series of meticulously planned experiments was conducted to validate our developed methodology. As a result, we successfully demonstrated a substantial reduction in ghost reflections within an optical system, reducing them from an initial level of 23% to less than 1%.