English: Diagram showing how a corner reflector works. A corner reflector consists of three flat reflecting surfaces at right angles attached at the edges. It has the property of reflecting light rays or radio waves from any direction back toward the source. The diagram shows a corner reflector reflecting two rays from different directions (black and red lines). Each ray is reflected three times, once from each surface.
Metal corner reflectors are used as radar reflectors on boats and bridges to give them a stronger return on marine radar screens. Glass prism corner reflectors are used in surveying.