| 摘要 |
A security device for monitoring unmanned vehicles within an area, the device comprising at least two oppositely directed light barriers associated with the area. Each light barrier includes a light emitter, a reflector, and a light receiver. The light barriers are disposed such that their light-beams are interrupted by the vehicles entering the area. Reflectors are arranged laterally on authorized vehicles, thereby making them undetectable by the security device. Another embodiment uses the light barriers attacted to the vehicle such that unauthorized objects will cause the vehicle to stop. |
