Passive IR intruder detector using rows of mirrors - provides fields of view covering respective detection ranges by using series of differing focal lengths spherical mirrors

摘要

The detector includes a reflection unit with a row of mirrors extending along an optical axis and comprising a number of reflective spherical segments, each with a given focal distance and orientated to provide a respective field of view. A second row of similar mirrors along the same optical axis each have a given focal length and a common focus with the first row of mirrors. They provide further respective fields of view. All the reflective segments provide a uniform optical aperture to allow a uniform overall sensitivity. A detector at the common focus provides signals indicating the presence of an intruder when a movement is detected within the fields of view of the respective segments. A third row of mirrors may be used to provide a third field of view groups, all three groups associated with respective operating ranges.