A Right-Angle Prism is used as a
mirror to deviate light through 90 degree, and also as a
retroreflector to deflect light throgh 180 degree by total
90 degree deflection occurs at the
hyotenuse face.The image is erected and reversed.
180-degree Deflection 180 degree
deflection uses with hypotenuse as the entrance and exit
face.The mail application of it is used as a retroreflector
provided that the plane of incident beam includes the vertex.