Right Angle Prism

The Right Angle Prism (RAP) gets its name from the 90 degree (also known as a right angle) apex angle and has 2 equal sides.  These prisms are a workhorse of the optics world and have many uses.  With a mirror coated (to protect from contamination which would ruin total internal reflection)  hypotenuse, the RAP can be used to fold an optical path by 90 degrees and with mirror coated legs an AR coated hypotenuse, the RAP can be used to retroreflect an optical path with an offset.  An uncoated RAP can be used to disperse light such as turning white light into a rainbow.