Photon intrusion detector
AssigneeLockheed Martin Corporation
InventorRobert James Howard
Life of this patent
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Abstract
An intrusion detector and method of operation which include a light source having a certain correlation length, and first and second light paths, wherein at least the first path extends through a secured area. A modulator, which is advantageously either a phase rotation modulator or path length modulator, is provided in the second path. At least one optical detector is placed to detect light traveling along the two paths. A comparator is electrically coupled to the detector to compare the detected signal with a signal applied to the modulator.
Claims17
An intrusion detector comprising:
- a light source having a certain correlation length;
- first and second light paths, at least the first path extending through a secured area;
- a modulator disposed in said second light path, wherein said modulator is selected from phase rotation and path length modulators;
- at least one optical detector positioned to detect light from said first and second light paths and operable to generate a first signal in response thereto;
- and
- a comparator electrically coupled to said optical detector to compare said first signal with a second signal applied to said modulator.
A method for detecting an intruder comprising:
- splitting a light beam having a known correlation length into a first beam traveling along a first optical path and a second beam traveling along a second optical path, wherein at least said first optical path extends through a secured area;
- modulating said second beam with a first signal;
- combining said first beam and said second beam;
- detecting light from the combined beams and generating a second signal in response thereto;
- and
- comparing said second signal with said first signal.
Dependencies are inferred from the claim text.