Retroreflective optical prism

BK7

Corner Cube Prism is also called Retroreflector or Trihedral Prism. In the Corner Cube Prism, three reflecting surfaces are perpendicular to each other, like the side wall of the cube. The input surface is perpendicular to the cube diagonal. Disregarding the angle of incidence, the output beam is parallel to the input one, but it is of opposite direction. Inset of the several corner prisms, for better matching, their entrance-exit surface is often hexagonal. In case of this prism the phenomenon of full internal reflection occurs so it is not necessary, (however it is possible) to put mirror coating on the reflecting faces. Normally the reflection surfaces are Al reflection coating, and then covered with Cu and Black Painting.