| 摘要 |
A multi-sided retroreflective body is disclosed having at least two retroreflective substantially planar faces adapted to intercept light that is to be retroreflected. Each face has a predetermined angular relationship with the other and each contains a plurality of light-reflecting units and each unit comprises three mutually perpendicular surfaces. Each of said at least two retroreflective faces is tilted in the same general direction about a lower portion angularly away from a vertical plane and is angularly related in a horizontal plane with respect to another vertical plane disposed substantially at right angles to the direction of said light to define said angular relationship. All four of said angles are so interrelated as to make said at least two retroreflective faces substantially optically equivalent, such that light passing through said another vertical plane is retroreflected by both of said two retroreflective faces in return paths substantially parallel to that of the intercepted light. |
