Prisms » Right Angle Prisms

Right Angle Prisms are well suited for beam deviation and retro-reflection. They are often preferable to plane mirrors, because they are easier to mount and align.

High throughput is attained when the hypotenuse is used in total internal reflection (TIR), and the entrance and exit surfaces are anti-reflection coated. An incident beam normal to the entrance surface is reflected at a 90° angle, and mages are inverted.

The hypotenuse may also be used in external reflection, in which case it is coated with a metal or dielectric, high reflectance coating. Right angle prisms may also be used for retro-reflection. A beam entering perpendicular to the hypotenuse is reflected by the legs and emerges parallel to itself. If it is desirable to use either the hypotenuse or the legs in internal reflection mode, but field angle requirements exceed TIR acceptance limits, or if the environment in which the prism is to be used does not allow the hypotenuse to be kept sufficiently clean for TIR, a metal or dielectric coating can be applied to the hypotenuse.