Cat's eye (road)
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A cat's eye or road stud is a retroreflective safety device used in road marking and was the first of a range of raised pavement markers.
Original form cat's eye, UK
Cat's eye glass body and principle of operation; back (left) face is mirror-coated
Double-ended cat's eye is Shaw's original design and marks road centre-line
M9 motorway in Carlow, Ireland, with cat's eyes on the road surface and retroreflectors on barriers
Retroreflector
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A retroreflector is a device or surface that reflects radiation back to its source with minimum scattering. This works at a wide range of angle of incidence, unlike a planar mirror, which does this only if the mirror is exactly perpendicular to the wave front, having a zero angle of incidence. Being directed, the retroflector's reflection is brighter than that of a diffuse reflector. Corner reflectors and cat's eye reflectors are the most used kinds.
A gold corner cube retroreflector
Eyeshine from retroreflectors of the transparent sphere type is clearly visible in this cat's eyes.
Bicycle retroreflectors
"Aura" around the shadow of a hot-air balloon, caused by retroreflection from dewdrops