Corner Cube Retroreflectors

Corner Cube Retro-Reflectors have three mutually perpendicular surfaces and a hypotenuse face. It operates on the principle of total internal reflection (TIR). A beam entering the effective aperture is reflected by the three roof surfaces and emerges from the entrance/exit surface parallel to itself. This property is independent of the orientation of the retro-reflector, within acceptance angle limitations. For applications in which either the acceptance angle for TIR is exceeded, or the reflecting surfaces can not be kept sufficiently clean for TIR, a metal or dielectric coating can be applied to the reflecting surfaces.

Retro-reflectors are used in the following example applications:

•    In surveying with a total station or robot, the instrument man or robot aims a laser beam at a corner cube retro-reflector held by the rodman. The instrument measures the propagation time of the light and converts it to a distance.
•    Aerodrome lighting can be replaced by appropriately colored retroreflectors, the most important of which are the white retro-reflectors that delineate the runway edges, and must be seen by aircraft equipped with landing lights up to 2 nautical miles away.
•    In common (non-SLR) digital cameras, the sensor system is often retro-reflective. Researchers have used this property to demonstrate a system to prevent unauthorized photographs by detecting digital cameras and beaming a highly focused beam of light into the lens.
•    In movie screens to allow for high brilliance under dark conditions.
•    Digital compositing programs and Chroma key environments use retro reflection to replace traditional lit backdrops in composite work as they provide a more solid color without requiring that the backdrop be lit separately.
•    In Long path-DOAS systems, retro reflectors are used to reflect the light emitted from a light source back into a telescope. It is then spectrally analyzed to obtain information about the trace gas content of the air between the telescope and the retro reflector.
•    Barcode labels can be printed on retro-reflective material to increase the range of scanning up to 50 feet.
•    In a form of 3D display; where a retro-reflective sheeting and a set of projectors is used to project stereoscopic images back to the user's eye. The use of mobile projectors & positional tracking mounted on the user's spectacles frame allows the illusion of a hologram to be created for computer-generated imagery.
•    In non-reflective paint used for road markings, retro-reflective glass beads are added to the paint to reflect the headlights of a vehicle for increased visibility of road markings at night.