| 摘要 |
A monitoring device for security surveillance application, the device comprising: an electromagnetic wave sensor for sensing electromagnetic wave from an external electromagnetic wave source; a detection window for forming a partition between the external electromagnetic wave source and the electromagnetic wave sensor; and an anti-tampering arrangement comprising an optical arrangement for deploying an optical surveillance beam and control circuitry, wherein i. the optical surveillance beam comprising a first beam portion and a second beam portion, the first beam portion being a beam emitted by the optical arrangement towards the detection window and the second beam portion being due to total internal reflection of the first beam portion by the detection window, and ii. the control circuitry being for detection of a variation of the second beam portion, wherein the variation is indicative of tampering of the detection window.
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