Arrangement for detecting glass pane break has retroreflective structure or layer formed at periphery of glass pane that reflects radiation back to detector

摘要

The arrangement has at least one optical radiation source and detector. Radiation from the source is coupled into the pane via its edge. A retroreflective structure at the periphery of the pane reflects radiation back to the detector opposite and parallel to the incoming radiation. The detector produces a signal with a defined relationship to the intensity of the detected radiation. Changes in the signal are detected to monitor the pane. The arrangement has at least one optical radiation source (8) and at least one detector (14). At least some light from the source is coupled into the pane via its edge. A retroreflective structure (7) or layer formed at the periphery of the glass pane (1) reflects the radiation back to the detector with an opposite direction of propagation parallel to the incoming radiation, at least in the plane perpendicular to the glass surface. The detector produces a signal with a defined relationship to the intensity of the radiation detected by the detector and changes in the signal are detected to monitor the pane.