Corner Cube Retroreflector Prisms
are designed on the principle of total internal reflection
(TIR), 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.
Retroflectors will function even at every large angles
of incidence. There are three total internal reflections
within the corner cube.
It is usually possible to choose a retroreflector orientation
such that acceptance angle limitations are, for all practical
purpose, nonexistent. It is always possible to guarantee,
by appropriate orientation of neighboring reflectors in
a retroreflector array, that part of the array will be
functional even at very large angles of incidence.
For application in which either the acceptance angle
for TIR is exceeded, or the reflecting surfaces cannot
be kept sufficiently clean for TIR, a metal or dielectric
coating can be applied to the reflecting surfaces.