Definition - What does Retroreflector mean?
This is an optical device, also known as the corner-cube prism, which contains mutually perpendicular trihedral surfaces that reflect light incident on its surface at 180°. It is used to coat surfaces that require the return of a beam of light back to its source. It is used in automobile taillights and traffic signs or barriers. It can be used on surfaces where UV rays are undesirable.
Corrosionpedia explains Retroreflector
In mirrors, the reflection depends on the angle of incidence, but in retroreflectors the light is reflected back at 180° regardless of the angle of incidence. Natural retroreflectors are found in animals that have a layer of the tapetum lucidum, which is a highly reflective tissue.
The manufactured type uses micro prisms and glass beads. The three reflective surfaces are aligned perpendicular to each other, such that any ray that falls on one surface is reflected on the surfaces, so that the reinitialized trajectories are parallel to their initial trajectories. They are available as solid or hollow, mounted and unmounted.
Retroreflector arrays were used in Apollo 11, 14 and 15 with laser technology to determine the distance between the moon and the Earth; it can therefore be used in instrumentation to determine the distance between two bodies.