Abstract

The nowaday most widely used security sensors for perimeter protection are IR light barrier, buried magnetic sensor, and leaky coaxial cable sensor. Requiring alignment, clean optics and clear path which may be degraded by heavy rain or blowing dust, light barriers are not suitable for many out-of-doors applications. Incapable to turn around corners is another disadvantage. On the other hand, magnetic and leaky cable sensors are not suitable for use in extremely hostile EMI environments. Thus there is a need for a better line sensor for areas of severe EMI.

© 1986 Optical Society of America