Patent ID: 7286213
Filing Date: 2007-10-23
Classification: F41G,F41H,F41J,G01S

Abstract:
1. A device to detect the entry of a target into a zone, comprising: at least one source, which is not a passive detector, for emitting an illuminating beam in the direction of a target, at least two passive detectors placed in proximity to said zone and whose fields of detection overlap, each detector being synchronized with at least one source by a synchronization link, and for receiving radiation reflected from said target along a different direction than the direction along which radiation is emitted by said device, computation means for receiving signals from said detectors and computing either the travel distances between said source and each said detector via said target, or only one of said distances which is then associated with a target presence criterion supplied by another detector, said computation means for supplying a target detection signal when said distance or distances thus computed, as well as any presence criterion or criteria supplied, enabling a point geometrically located in said zone under surveillance to be defined, wherein said source is placed at a distance from said passive detectors, a rear detector directly receiving the beam emitted by said source.