(57) An infrared instrusion detector has an otpical system for gathering infrared radiation
from discrete sensitive regions and focusing such received radiation onto an infrared
radiation sensor. The detector includes a monitoring device to sound an alarm when
radiation sensed reaches a predetermined level. The optical system comprises an optical
collector for gathering radiation from a field which includes the sensitive regions
and for converging such radiation onto a plurality of reflectors. Each reflector determines
one of the discrete sensitive regions and, in turn, is oriented to reflect converging
radiation gathered from a sensitive region on the detector. The invention provides
a simple, efficient optic system for a broad field of gathering infrared radiation,
concentrating and focusing it in a manner to provide sufficient levels of received
radiation for purposes of detection.
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