page_title: Corner reflector
section_title: Principle
hierarchical_section_title: Corner reflector / Principle
context_page_description: A corner reflector is a retroreflector consisting of three mutually perpendicular, intersecting flat surfaces, which reflects waves directly towards the source, but translated. The three intersecting surfaces often have square shapes. Radar corner reflectors made of metal are used to reflect radio waves from radar sets. Optical corner reflectors, called corner cubes, made of three-sided glass prisms, are used in surveying and laser ranging.
context_section_description: The incoming ray is reflected three times, once by each surface, which results in a reversal of direction.   To see this, the three corresponding normal vectors of the corner's perpendicular sides can be considered to form a basis (a rectangular coordinate system) (x, y, z) in which to represent the direction of an arbitrary incoming ray, [a, b, c].  When the ray reflects from the first side, say x, the ray's x component, a,  is reversed to −a while the y and z components are unchanged, resulting in a direction of [−a, b, c].  Similarly, when reflected from side y and finally from side z, the b and c components are reversed. Therefore, the ray direction goes from [a, b, c] to [−a, b, c] to [−a, −b, c] to [−a, −b, −c], and it leaves the corner reflector with all three components of direction exactly reversed. The distance travelled, relative to a plane normal to the direction of the rays, is also equal for any ray entering the reflector, regardless of the location where it first reflects.
caption: Working principle of a corner reflector