摘要 |
An alarm system for the surveillance of space, with at least one sensor of electromagnetic, in particular infrared radiation, located on the closed inner frontal surface of a rectangular tube having mirror surfaces on its internal surfaces, the use of focusing means, such as lenses, concave mirrors, objectives, and the like, is avoided by that the sensor is essentially adjacent at least in one direction to the opposing mirror surfaces. This yields an alarm system that is highly compact, has small dimensions, and may be produced cost effectively. The sensor preferably consists of two spaced apart sensor elements operated in a push-pull mode.
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