This reflective glass beads used inthe reflectorize traffic and airfield marking paints.
The increased retro-reflective values obtained from use of high index of refraction glass beads are onlyapparent to the observer in cases where the observer’s line of sight is in close proximity to the path of the lightsource used to illuminate the markings. Studies by the USAF and the Federal Aviation Administration haveshown that in cases where the light source is not in close proximity to the viewer’s eye position, the addedbenefit from the use of the higher index of refraction beads is negligible.
