Patent ID: 8507867
Filing Date: 2013-08-13
Classification: G07C

Abstract:
1. Apparatus for detecting a breach in security of an enclosure as indicated by a change in a closed status, the apparatus comprising: a detector enclosure where the enclosure is held at a relatively constant uniform temperature; a window opening in the detector enclosure; a reference black body emitter having an image slit accessible from within the detector enclosure, the reference black body emitter having peak wavelength regions of radiance; an IR radiation detector that is sensitive in the peak wavelength regions of the reference body emitter radiance; a reflective chopper capable of alternating reception by the radiation detector between receiving radiation through the window opening in the detector and receiving radiation from the reference body emitter through the image slit; a circuit capable of providing an indication of radiation levels of the received radiation through the window opening and the received radiation from the reference black body emitter through the image slit or a difference between the received radiation levels, whereby a change in reception through the window opening provides an indication of a change in the closed status of the enclosure.