Cube Prisms are designed to reflect any ray or beam entering
the prism face, regardless of the orientation of the prism,
back onto itself. A mirror will only do that at the normal
angle of incidence. As a result, corner cubes are ideal where
precision alignment is difficult or time-consuming. Retroreflectors
will function even at very large angles of incidence. There
are three total internal reflections within the corner cube.
For its special performance, it is often used to the distance
measurement, optical signal process and laser interferometer.