Passive infrared detector
First Claim
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1. An infrared detector, comprising:
- a pyroelectric detector equipped with a window and having first and second sensing elements disposed on a first side of said window;
an aperture stop disposed on a second side of said window, wherein said aperture stop has first and second opposing sides which diffusely reflect infrared electromagnetic radiation; and
a Fresnel lens array disposed on said second side of said window, wherein said Fresnel lens array has a focal length of less than about 50 mm.
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Abstract
An infrared detector (301) is provided which comprises a pyroelectric detector (303) having first and second sensing elements (345), an aperture stop (311), and a Fresnel lens array (305). The detector may be used as a passive infrared sensor unit for detecting intrusion into large openings.
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Citations
26 Claims
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1. An infrared detector, comprising:
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a pyroelectric detector equipped with a window and having first and second sensing elements disposed on a first side of said window; an aperture stop disposed on a second side of said window, wherein said aperture stop has first and second opposing sides which diffusely reflect infrared electromagnetic radiation; and a Fresnel lens array disposed on said second side of said window, wherein said Fresnel lens array has a focal length of less than about 50 mm. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. An infrared detector, comprising:
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a window having first and second major surfaces; first and second sensing elements disposed on a first side of said window; an aperture stop disposed on a second side of said window, wherein said aperture stop has first and second opposing sides which diffusely reflect infrared electromagnetic radiation; and a Fresnel lens array disposed on said second side of said window; wherein said Fresnel lens array has a finite focal length, wherein said Fresnel lens has a focal length of less than about 50 mm. - View Dependent Claims (21, 22, 23, 24)
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25. An infrared detector, comprising:
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a pyroelectric detector equipped with a window and having first and second sensing elements disposed on a first side of said window; an aperture stop disposed on a second side of said window, wherein said aperture stop has first and second opposing sides which diffusely reflect infrared electromagnetic radiation; and a Fresnel lens array disposed on said second side of said window, wherein said Fresnel lens array has first and second optical centers; wherein said sensing elements have interior edges which are closest to each other, and exterior edges which are farthest from each other, wherein said first optical center is over the exterior edge of said first sensing element, and wherein said second optical center which is over the exterior edge of said second sensing element. - View Dependent Claims (26)
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Specification