| 摘要 |
The system comprises sources of radiation transmitting a beam of light into the monitored area, and detectors responding to it. The beam of light observed from at least one direction is linear, and the detector has limited field of vision (46) which intersects the beam in a certain area. The light sources (26, 27) are typically lasers, modulated by a unit (32) controlled by the modulation signal recognition filter (38), which is connected with the output amplifier (40). In one embodiment of the invention a parabolic reflector is used. |
