A prism whose cross-section is a right triangle, used for deflecting rays through 90 degrees (if they enter through one of the faces forming the right angle) or 180 degrees (if they enter through the hypotenuse face).
Origin
Late 19th century; earliest use found in The English Mechanic.
Definition of right-angle prism in US English:
right-angle prism
noun
Optics
A prism whose cross-section is a right triangle, used for deflecting rays through 90 degrees (if they enter through one of the faces forming the right angle) or 180 degrees (if they enter through the hypotenuse face).
Origin
Late 19th century; earliest use found in The English Mechanic.