Reflection-Reducing Imaging System for Machine Vision Applications

NASA researchers have developed a compact, cost-effective imaging system using a co-linear, high-intensity LED illumination unit to minimize window reflections for background-oriented schlieren (BOS) and machine vision measurements. The imaging system tested in NASA wind tunnels can reduce or eliminate shadows that occur when using many existing BOS and photogrammetric measurement systems; these shadows occur in existing systems for a variety of reasons, including the severe back-reflections from wind tunnel viewing port windows and variations in the refractive index of the imaged volume.