Right-Angle Prism
Right Angle Prisms are made with BK7 and UV grade fused silica. Very high prism transmission can be achieved by using the hypotenuse face in total internal reflection (TIR), and by antireflection coating the entrance and exit faces. Antireflection coatings are discussed in the Coatings section of this guide.
A Right-Angle Prism is used as a mirror to deviate light through 90 degrees, and also as a retroreflector to deflect light through 180 degrees by total internal reflection.
90-degree Deflection
90 degree deflection occurs at the hypotenuse face. The image is erected and reversed
180-degree Deflection
180 degree deflection uses the hypotenuse as the entrance and exit face. The main application of it is used as a retroreflector provided that the plane of incident beam includes the vertex.