Abstract:
An intruder alarm includes a circuit with a photoresistive cell located in a housing with a piezoelectric crystal sound generator and battery to power the circuit and sound generator. A telescope concentrates light from a distance in a limited field of view upon the photoresistive cell to trigger the piezoelectric crystal sound generator when light intensity on the cell changes sufficiently from an ambient light intensity level.
Abstract:
An infrared detector is described for monitoring a corridor like room having a plurality of focusing means for the collection of infrared radiation emitted by an intruder. The field of view of each focusing means is oriented so as to form a continuous field of coverage in the space to be monitored, without gaps or areas of limited sensitivity. Furthermore, the solid angle subtended by each focusing means is chosen so that the sum of the energy received from the intruder in the monitored area and focused onto the infrared sensor by the multiple focusing means is insensitive to and independent of the range of the intruder from the monitoring device.
Abstract:
An optical wide angle sensor head for directionally sensing optical radiation is made of a plurality of individual sensor optical elements. Each sensor optical element is arranged at an input end of its own fiber optical conductor and has its own light entrance, its own field of view and its own individual optical axis. Neighboring fields of view may overlap each other. The fiber optical conductors lead to a transducer for converting the individual light signals into respective electrical signals. The individual sensor optical elements are arranged on a common mounting member in a housing so that the individual optical axes pass through a common intersection in front of said light entrances. The mounting member is a flat plate or a concave plate having a concave curvature facing in the viewing direction, whereby a spherical mounting is avoided.
Abstract:
In the present invention, an infrared intrusion detection system is disclosed. The infrared intruder detector is typically mounted at a vertical height from a ground plane. The detector has a fresnel lens which has a plurality of lines of focus for focusing infrared radiation received by the detection system through the fresnel lens. A detector in the detection system is located at the focal point for receiving infrared radiation through the fresnel lens. A curvilinearly-shaped mirror is placed apart from the detector in the direction away from the detection plane for receiving infrared radiation from the detection plane and the reflecting and focusing the detected infrared radiation onto the detector.
Abstract:
A passive infrared intrusion detector is arranged for mounting to the ceiling of a room to be protected. Infrared radiation from points within the room is focused onto an infrared sensing element by a multi-segment dome-shaped lens. The multi-segment lens in a preferred embodiment has central, downwardly facing beams of infrared sensitivity and other beams of infrared sensitivity at multiple azimuth angles at selected elevation angles.
Abstract:
Disclosed herein is a dual technology intruder detection system which features a modular optical system by which the field of protection of one subsystem can be changed relative to the field of view of the other by merely altering the orientation of one optical module relative to another. Such modular optical system includes a multifaceted reflector having two sets of planar reflective facets. Depending on the orientation of such multifaceted reflector relative to a separate spherical reflector, two different fields of view are provided, whereby false alarm-producing can be avoided.
Abstract:
Array of Fresnel lenses moulded in a single sheet of plastic 29 are used in conjunction with a thermal radiation detector 1 to provide intruder alarm apparatus. Each lens defines one detection direction in a fan of such directions 26,27,28. Such arrays have been moulded as a curved surface 22 centered on the detector. To reduce moulding costs while maintaining the optical efficiencies of all lenses in the array, a flat array of lenses is provided in which each lens is moulded as an angled facet 30,31,32. The poles 36,37,38 of the lenses lie in a plane.
Abstract:
A folded modular optical system adapted for use, for example, in a passive infrared intruder detection device for directing radiation from a plurality of discrete fields of view onto a radiation-sensitive detector comprises an elongated rectangularly-shaped spherical reflector and a multifaceted reflective element. The latter comprises a plurality of elongated, generally parallel, planar reflectors which serve to direct radiation onto different portions of the spherical reflector. To minimize the effects of spherical aberration, the planar reflectors are arranged so that the portions of the spherical reflector which they irradiate are substantially perpendicular to the longer dimension of the rectangularly-shaped spherical reflector. Preferably, each of the planar reflectors is canted relative to the others so that its field of view is substantially co-planar with those of the other planar reflectors. It is also preferred that the planar reflectors vary in size and, hence, light-gathering power as a function of the intended range of protection they provide.
Abstract:
An alarm system for the surveillance of space, with at least one sensor of electromagnetic, in particular infrared radiation, located on the closed inner frontal surface of a rectangular tube having mirror surfaces on its internal surfaces, the use of focusing means, such as lenses, concave mirrors, objectives, and the like, is avoided by that the sensor is essentially adjacent at least in one direction to the opposing mirror surfaces. This yields an alarm system that is highly compact, has small dimensions, and may be produced cost effectively. The sensor preferably consists of two spaced apart sensor elements operated in a push-pull mode.
Abstract:
A motion detector of the space surveillance type wherein an elongate box has parallel walls and an aperture opening toward sensors, and a pair of upwardly divergent reflectors is provided for at least one of the two sensing field planes, the reflectors making an angle of 20.degree. or less with each other.