Optical arrangement for a passive infrared motion detector
First Claim
1. An optical arrangement for a passive infrared motion detector for monitoring a space, said infrared motion detector including detector means for forming a signal from a characteristic change of the detected infrared radiation, said arrangement including mirror means for directing radiation from at least one field of vision onto the detector means, each field of vision forming an optically effective curtain to define at least a boundary of a space to be monitored, said mirror means including at least one planar directional mirror, a body with the shape of a conical frustum, and one concave mirror, said concave mirror being disposed to centrically surround the detector means in the same direction of view, said body being arranged opposite the detector means on the optical axis thereof with a planar mirror surface facing the detector means and extending in a plane perpendicular to the axis of said detector means, said body having a conical reflecting surface extending from said planar mirror surface and facing said concave mirror, each of the planar directional mirrors facing the conical reflecting surface of said body, and being capable of being rotated about an edge facing away from the direction of view with respect to the optical axis of the concave mirror to change the position of the field of view.
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Abstract
An optical arrangement for use with an infrared detector characterized by a concave mirror surrounding the infrared detector, a body having a plane reflecting surface extending perpendicular to the axis of the detector, which surface faces the detector and the conical concave mirror, and having a conical reflecting surface extending from the plane surface, and at least one planar directional mirror pivotably mounted for reflecting infrared radiation at the conical reflecting surface. The arrangement can be used to monitor a space and if used with a second arrangement, whose directional mirrors are arranged to provide new sensing curtains adjacent the curtains of the first detector, the arrangement can determine the direction of movement of the object passing through the space.
37 Citations
6 Claims
- 1. An optical arrangement for a passive infrared motion detector for monitoring a space, said infrared motion detector including detector means for forming a signal from a characteristic change of the detected infrared radiation, said arrangement including mirror means for directing radiation from at least one field of vision onto the detector means, each field of vision forming an optically effective curtain to define at least a boundary of a space to be monitored, said mirror means including at least one planar directional mirror, a body with the shape of a conical frustum, and one concave mirror, said concave mirror being disposed to centrically surround the detector means in the same direction of view, said body being arranged opposite the detector means on the optical axis thereof with a planar mirror surface facing the detector means and extending in a plane perpendicular to the axis of said detector means, said body having a conical reflecting surface extending from said planar mirror surface and facing said concave mirror, each of the planar directional mirrors facing the conical reflecting surface of said body, and being capable of being rotated about an edge facing away from the direction of view with respect to the optical axis of the concave mirror to change the position of the field of view.
Specification