Abstract: An infrared radiation detector comprises a pyroelectric detector element in a hermetically sealed housing. The housing comprises a base and a cover. The cover has an aperture surrounded by an inwardly directed flange. A self-locating window capable of transmitting infrared radiation is fastened to the flange with adhesive to close the aperture. The window comprises a first portion which is adapted to fit within and which is located within the aperture. A second wider portion forms a peripheral shoulder which bears against the cover's flange. The second portion of the window is present outside the cover, giving a wide field of view.

Abstract: External noise in an infrared sensor for a ceiling type human detector is suppressed by increasing the conductivity between a conductive window and the can and improving the temperature compensation by offsetting any difference in the electromotive force per unit area of the inside and/or outside electrode of the sensitive element consisting of coaxial electrodes with different areas. In a pair of electrodes for ceiling mounting the electromotive force is larger than in a pair of lower electrodes for floor mounting. The sensor improves a total sensitivity for use in the infrared sensor for a wall installation type human detector, on account of improving performance and reliability of the pyroelectric infrared sensor for use as a human detector.

Abstract: An arrangement for detecting the passage of living beings into and out of a surveillance region includes optics which concentrate thermal radiation energy from the surveillance region into a detection zone where an active area of a pyroelectric detector is situated and converts the thermal radiation energy received thereby into an electrical signal. An evaluating device evaluates the electrical signal of the detector to provide an indication of either the entry of a living being from the outside into, or the exit of a person from, the surveillance region from a change in the total thermal radiation energy received by the active area from the surveillance region. The optics may incorporate a mask which prevents thermal radiation from the outside of the surveillance region from reaching the active area of the detector.

Abstract: An infrared detector is arranged so that a detection-input processing circuit part including an infrared sensor mounted on a circuit board is housed as isolated from ambient air in a chamber inhibiting any ambient air inflow, for sensing infrared rays emitted from a human body or the like object as condensed by a condenser irrespective of the ambient air conditions, the sensing ability of the infrared sensor the accuracy of which is likely to be easily deteriorated even with a very small change in the ambient temperature can be thereby stabilized, and a highly accurate infrared detection can be constantly achieved.

Abstract: A photoelectric sensor comprises a light collecting block having a reflective mirror formed on an inner surface of a light transmitting window and a concave mirror including a light passing portion, whereby the reflective mirror is opposed to the concave mirror. Further, the photoelectric sensor comprises an electronic circuit block having a photoelectric element, a plurality of electronic components and a wiring substrate, wherein the photoelectric element is positioned on a light collecting point of the light collecting block.

Abstract: Pitch and roll attitude information of an orbiting body is provided by sensing the discontinuity of optical radiation in a scan field of view between the reference body and outer space using a scanner which simultaneously scans two concentric conical paths through the field of view about the same axis of rotation of the orbiting body. The scanner comprises a scanning mirror split into two halves which are tilted through an angle with respect to each other and are also displaced in phase with respect to each other about the axis of rotation. The scanner may also be a prism having angled faces on opposite sides of the optical axis of the scanner which are also displaced in phase. Either scanner results in having a detector view two instantaneous fields of view simultaneously. An infrared detector receiving the radiation from these two fields of view produces signals which can be used to determine pitch and roll attidue as well as altitude on each scan which identifies four points around the horizon.

Abstract: A radiation detector is scanned over two fan fields of view by first and second cylindrical lenses spaced about the axis of rotation of a common optical element positioned on the axis of rotation. The optical element is rotated about the optical axis by a motor or the rotation of the orbiting body on which the scanner is mounted. In one form the common optical element is a chisel mirror having the first and second cylindrical lenses positioned on opposite sides thereof and tilted at an angle of 45.degree. with respect to the axis of rotation producing two fan fields which are 180.degree. apart in phase. As an alternative the common optical element may comprise a cylinder having the second cylindrical lens positioned along with a bevelled reflective upper surface for producing a vertical fan field.

Abstract: A ceiling mounted passive infrared detector has an enclosure arranged for mounting to ceiling, a downwardly pointing infrared detecting element within the enclosure, a first multifaceted pyramidal mirror having an apex pointing upwardly toward the detecting element and a plurality of focusing lenses, one for each facet of the mirror and mounted between the base of the pyramidal mirror and the periphery of the enclosure to focus infrared radiation onto the detecting element directly and via reflection in the pyramidal mirror. A further embodiment includes the enclosure wherein the lenses are disposed on the plane immediately above the apex of the mirror so that radiation will be reflected off the mirror and refracted by the lenses onto the detecting element.

Abstract: The invention uses a strip of infra-red detectors comprising a cold screen of the type that provides a constant viewing angle for all the directors in a direction that is prependicular to the axis of the strip. Two cylindrical mirrors are set at the ends of the strip and placed in the heated part of the cryostat containing the strip and the cold screen. The shape and dimensions of the mirrors as well as their positions are chosen so that the detector placed in the center of the strip detects, through reflection in two mirrors, only cold surfaces while the other detectors detect heated surfaces, through reflection in the two mirrors, in a proportion that increases with distance from the central detector of the strip, so that, along the axis of the strip, every detector has a substantially constant viewing angle. Applications: large-sized strips, for example in space applications.

Abstract: A ceiling mounted passive infrared intrusion detector includes a window which has an exterior surface with ridges formed of intersecting planes, which are arranged to provide internal reflection of radiation received from selected angles with respect to the optical axis of the device and to deflect such radiation into a direction parallel to the optical axis. Focusing means arranged as part of the detector focuses the parallel infrared radiation onto a detecting element within the device.

Abstract: The apparatus comprises a radiation-sensitive detector (17) and optical means for directing radiation from an observed field of view on to the detector. The optical means includes a rotatable support member (10) rotatable about an axis (11) and carrying a number of reflecting members (12) equally-spaced around it. Each reflecting member (12) is located in a plane parallel to the axis (11) of the support member and each is arranged at the same non-perpendicular angle to a radius of the support member. A pivoted reflecting member (14) is located inside the locus of the plurality of reflecting members (12) and is rotatable about an axis (15) located in a plane perpendicular to that axis (15). In operation radiation from the field of view is reflected by the pivoted reflecting member (14) on to successive ones of the rotating reflecting members (12) and thence on to the detector (17).

Abstract: A miniature passive infrared motion detector consists of an optical system, a pyroelectric polymer film and an electronic circuit. The optical system is made of a curved Fresnel lens and an elongated wave guide having a reflective inner surface. The polymer film is also curved with the same radius as the lens and has two interdigitized electrodes on the rear surface and one uniform electrode on the front surface. The front electrode is covered with infrared absorbent material. The electronic circuit contains a differential amplifier and a threshold detector.

Abstract: An apparatus for spectral analysis of chemical fractions is disclosed in which separate samples are frozen on a substrate, and infrared radiation passes through the sample either before or after it is reflected from a surface on the other side of the substrate from the sample. This permits radiation to move toward and away from the sample at the same side of the sample, thus simplifying the sample-cooling and sample-deposition techniques. The optical system is designed to defocus (and thus avoid detection of) unwanted radiation reflected by the sample.

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: A two-dimensional infrared focal plane employing a uniquely configured detector array for reducing the thermal conductance between detectors and between each detector and its environment to enhance signal-to-noise and spacial resolution without requiring cumbersome cooling. An array of radiation concentrators placed between the detector array and the image and spaced from the array, permits widely spaced detectors without incurring any substantial dead space on the detector plane. Detector support configurations provide for connection to nodes of a readout IC substrate while positioning each detector over an air-filled or evacuated chamber to further reduce thermal conductivity.

Abstract: The invention is directed to an infrared motion alarm characterized by an infrared detector and an optical arrangement before the detector in the radiation direction for focussing the infrared radiation onto the detector. The optical arrangement is formed by a mirror arrangement and by a lens arrangement with the mirrors being on different levels so the different beam paths are being detected to prevent an intruder from crawling under the infrared detection beam paths.

Abstract: An apparatus for detecting intruders comprising a housing provided with at least one window, a passive infrared detector (for detecting the radiation emitted by an intruder around a wavelength .lambda..sub.1), and an anti-obscuring device (detecting by infrared radiation having a wavelength .lambda..sub.2 the presence of an obscuring of the appparatus for detecting intruders). The apparatus further includes an electronic circuit intended to operate an alarm when the presence of an intruder or an obscuring element has been detected. The apparatus for detecting intruders has a detector for detecting an obscuring element arranged at small and at large distances. It further includes a self-verification circuit. An obscuring element is detected, inter alia, by a mirror arranged at the end of the zone to be supervised, which returns radiation .lambda..sub.2 emitted by an emitter to a detector, both being situated very close to the detector of radiation having a wavelength .lambda..sub.1.

Abstract: An apparatus for measuring the temperature in a heating system comprising a cooking pot with cooking material positioned on a hot plate where a radiation receiver is arranged at a distance from the wall of the cooking pot and aligned with it, which receiver produces a temperature measurement signal corresponding to the temperature of the cooking material in the cooking pot. The temperature measurement signal is derived from a detected radiation area on the wall of the cooking pot which corresponds to the radiation measuring field of the radiation receiver. The effect of different distances of the cooking pot from the radiation receiver is automatically compensated for by aligning the center axis of the radiation measurement field at an acute angle to the support surface of the hot plate, so that the distance of the center of the detected radiation area from the bottom of the cooking pot increases with an increasing distance of the wall of the cooking pot from the radiation receiver.

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: A pyroelectric infrared ray detector of the so-called dual structure for detecting an intruder or the like through differential output of two pyroelectric infrared ray detecting elements connected in parallel or series to each other. The infrared ray detector comprises a pair of pyroelectric infrared ray detecting elements having substantially identically directed light receiving surfaces and electrically connected to each other and a shield member arranged in front of the said light receiving surfaces to partially shield the infrared ray detecting elements against incidence of infrared light. The shield member is arranged in a plane extending between the infrared ray detecting elements to separate the same on both sides thereof.

Abstract: An intrusion detector evaluates the infrared radiation emitted by an intruder within a closely defined zone or area by means of a virtual protective curtain. Uniform sensitivity independent of incident angle of the radiation is provided by a cylindrical Fresnel lens of small thickness, which divides the field of reception into sharply defined strips or elongate zones of substantially uniform sensitivity. The longitudinal axis of this Fresnel lens defines an arcuate sector of a circle whose radius is determined by the focal length in perpendicular direction, and an infrared sensor is arranged at the circular center point, i.e., the focal point of the curved Fresnel lens. One particularly advantageous embodiment of the intrusion detector includes a double sensor configuration, equipped with several sensor elements cooperating with one or more cylindrical Fresnel lenses, thus covering a number of separate zones for simultaneous radiation detection.

Abstract: A detector assembly of a spectrometer device which includes a built-in test gas chamber, has a housing defining a chamber with a first end having a first aperture and a second end having a second aperture opposite the first aperture. While light transmissive windows can be mounted in the opposed apertures to enclose the chamber, it is preferred that a focusing lens be mounted in the first aperture and a detector in the second aperture in order to enclose the housing ends and define the chamber. The chamber has a cone-like inner surface tapering from the first aperture to the second aperture. The housing has a test gas inlet in communication with the chamber and disposed proximate the first end thereof. A test gas outlet is in communication with the chamber and disposed proximate the second end. The test gas inlet is so oriented as to introduce test gas into the chamber on a tangent to the first end, first aperture resulting in a tangential flow path direction within the cone-like chamber.

Abstract: A passive infra-red sensor includes a window in a housing which also houses an infra-red detector. The window defines a plurality of infra-red transmitting strips which are separated by Fresnel lens segments or infra-red opaque strips. The infra-red transmitting strips provide short range sensitivity. The Fresnel lens segments where provided give longer range sensitivity.

Abstract: A two-beam spectrophotometer comprising a monochromator and a beam splitter is provided. In addition to being inclined to the optical axis by an angle .alpha./2 lying in the optical plane, the beam splitter is inclined to the direction perpendicular to the optical plane, so that the reference beam is deflected out of the optical plane by an angle .beta.. This improves the spectral intensity distribution.A spectrophotometric method employing this apparatus is also provided.

Abstract: A pyrodetector having a concave mirror containing a sensor element arranged in a focus thereof. The sensor element is on a film and is distinguished by a compact structure. The concave mirror is formed of a body having a rectangular cross-section, of a reflector part, and of sidewalls positioned perpendicularly relative to one another. An opening is provided in a reflector portion through which a retaining part provided with plug pins is inserted. The concave mirror, an evaluation means arranged outside of the concave mirror behind the reflector portion, and a honeycomb lattice and a covering are accommodated as an overall arrangement in a housing.

Abstract: An accessory for use with spectrophotometers for conducting IR emission spectra analyses of samples comprising a heated highly-reflecting surface for receiving the sample, an apertured reflecting mask located over the sample, and a curved reflector for collecting emissions from the sample via the aperture over a large solid angle to increase the signal-to-noise ratio.

Abstract: An optical receiving system for thermal radiation is useable, with slight modification, for the simultaneous, low-loss reception of laser radiation and is nevertheless still composed of standard, common modules. To this end, a geometrical out-coupling of the laser radiation out of the shared receiving channel following a scanner and the geometrical separation of the thermal and laser radiations is provided, whereby the out-coupled laser radiation, separated from the thermal radiation, is directed via a simple optical assembly onto a preferably shared sensor. For the utilization of the common reception channel and, thus, of the reception optics as well for the emission of the laser radiation, the transmission radiation can be coupled into the separated laser reception channel via a polarization separating filter. By so doing, the transmission optics is eliminated, whereby good optical conditions for the transmission radiation are established without deterioration of the common reception channel.

Abstract: An optical system to permit two detectors to see the same field of view includes an angle converting cone, for mixing radiation from a field of view so that it can be applied to two detectors, and a lens for focusing the radiation onto the cone.

Abstract: Information regarding an object, especially brightness information, is obned by scanning the object with an optical scanner, especially an infrared scanner to provide a respective analog signal. The analog signal is produced by passing the received radiation past a chopper disk onto a detector through a secondary optical assembly. The output signal of the detector is digitized and supplied to a fast Fourier transformation processor which also receives a counting signal derived from the oscillation of the chopper disk. The system may be used, for example, for obtaining deviation and/or presence signals regarding the orientation of an earth satellite relative to the center of the earth.

Abstract: In an infrared intrusion detector which evaluates the body radiation of an intruder by means of a dual radiation sensor having two sensor elements arranged in a differential circuit for emitting an alarm signal, a functional supervision and detection of an attempt at sabotage, e.g., by covering or spraying the entrance window, are achieved by asymmetric irradiation of the two sensor elements through the entrance window by a radiation source. The asymmetry can be achieved by disposing the radiation source outside the plane of symmetry of the sensor elements or by an asymmetrically disposed auxiliary reflector.

Abstract: To monitor that infra-red radiation element 22 within housing 10 has not been disarmed, for instance by rendering opaque an infra-red transparent element 16 masking a window 12, in the housing 10, through which radiation may enter and be focussed by optical system 18 onto the element 22, an infra-red radiation generator 32 comprising a low-temperature lamp 34 is mounted externally of the housing 10 so that element 22 receives radiation therefrom and provides a signal to a processor 30. The latter will provide an alarm in the event of absence of radiation from the generator 32 and/or change in the radiation reaching the element 22 commensurate with approach of a person.

Abstract: The disclosed steerable mirror assembly and cooperative housing for a ceiling mountable passive infrared intrusion detection system of the present invention includes first and second relatively rotatable field forming mirrors cooperative with a focusing mirror to provide first and second substantially curtain-like fields of view at any selected pointing directions through 360.degree. of azimuth. The field forming mirrors have a preselected non-constant radius of curvature selected to provide uniform detection sensitivity at any range within the fields of view of the several curtains. A modular housing is disclosed having cooperative, releasably assemblable components that allows ready in-the-field installation, and subsequent maintenance and troubleshooting. The housing includes a tamper switch that is operative upon an unauthorized tampering with the housing after installation to provide a signal indication of a possible system deactivization attempt.

Abstract: An infrared intrusion detector having a predetermined number of rows of radiation reception zones comprises a primary reflector and a secondary reflector for each row of radiation reception zones. The primary reflectors and their associated secondary reflectors form a folded radiation path. The folded radiation path allows for compact construction and simple manufacturing of the infrared intrusion detector. One reflector of each radiation reception zone forms together with the infrared sensor a compact structural unit. The other reflectors of each radiation reception zone are combined to form a further structural unit which is arranged in a predetermined spaced relationship to the first compact structural unit. In order to achieve uniform detection sensitivity in radiation reception zones having different angles of inclination to the horizontal plane, a larger focal length is chosen for radiation reception zones with smaller angles of inclination and longer range.

Abstract: Selective thermal examination of a target is provided by scanning the field of view of an infrared detector over predetermined areas of a target. The selection is made by a plurality of infrared fibers having first and second ends with the first ends being stationarily mounted in a fixed array suitable for being scanned by the detector or a detector coupled to each first end which are electrically scanned, while the second ends of the infrared fibers are directed by the user to selected areas of the target which are desired to be thermally examined. The infrared detector or detectors are then scanned over the first ends of the infrared fibers in the fixed array for sequentially thermally examining the selected areas of the target. The selected areas may be changed simply by rearranging and redirecting the second ends of the infrared fibers with respect to the target areas desired to be examined.

Abstract: The disclosed ceiling mountable passive infrared intrusion detection system includes a field forming mirror assembly and a focusing mirror assembly cooperative to provide a field of view having plural first vertical curtains, a generally disc-shaped horizontal second curtain, and a generally conical downwardly directed third curtain. In one embodiment, first and second conical field forming mirrors are cooperative with different and spaced-apart spherical focusing mirrors to provide the horizontal curtain and the downwardly directed conical curtain. An unbalanced detector is disclosed that cooperates with the energy pattern received from the conical field forming mirrors to signal intruder presence. In another embodiment, first and second pluralities of planar field forming mirrors are cooperative with the different and spaced-apart spherical focusing mirrors to respectively provide a first plurality of substantially horizontal finger beams and a second plurality of plural downwardly directed finger beams.

Abstract: A multi-component non-dispersive gas analyzer of a type typically used to measure the concentrations of gases present in automotive emissions and in breath analyzers has no moving parts and employs electrically operated means for effectively inserting and removing a reference cell from the optical path and for selecting a particular filter to determine momentarily the wavelengths of radiation being examined. The means for accomplishing these ends include a substrate on which a layer of vanadium dioxide is deposited. The layer is a good reflector at temperatures greater than 67.degree. C. and reflects only slightly at lower temperatures. The layer is alternately heated by an electrical current and is then allowed to cool to provide the desired optical switching action. This electrically-controlled selectively reflective layer is then used in conjunction with the reference cell and with an array of filters to implement the necessary switching and selection of the components.

Abstract: An infrared radiation detector comprises a pyroelectric detector element in a hermetically sealed housing. The housing comprises a base and cover with an aperture. A Fresnel lens, for example made of polyethylene transmissive in the 8-14 .mu.m wavelength range, is fastened over the aperture on the inside of the cover for condensing the radiation to be detected onto the detector element. In one example the Fresnel lens is held against a flange surrounding the aperture by a press-fit ring. Alternatively, the Fresnel lens is glued to a silicon window which in turn is fastened to the flange surrounding the aperture. The Fresnel lens thus forms an integral part of the detector housing avoiding the need for external mirrors or lenses.

Abstract: A multiple pass optical system comprising a reflecting objective placed across the path of a radiant flux emitted by an illuminator; the objective being mounted pivotally around its own axis. Further, the radiant flux its incident upon a compound collective comprised of two different-curvature mirrors arranged at right angles to each other.From the lens of the radiant flux, the flux is directed again to the reflecting lens to be reflected therefrom and upon passing the final cycle in the system, it emerges.

Abstract: The invention relates to a matrix device for the detection of light radiation with individual cold screens integrated into a substrate and to its production process. This device comprises detectors arranged in matrix-like manner and defined in a detection material, a substrate which is transparent to the radiation to be detected and on which is epitaxied the detection material and provided in its upper part with blind holes distributed in matrix-like manner, each hole being positioned facing a detector, a layer of anti-reflecting transparent material covering the bottom of the holes and a layer of a material absorbing the radiation covering the upper face of the substrate and the walls of the holes.The invention more particularly applies to an infrared imaging system.

Abstract: A passive infrared detector including an optical collector releasably attached to a base with a sensor on which incident infrared radiation directed through the optical collector is focused. The sensor is held by a joint member which is pivotally supported on the base and to which said optical collector is releasably attached, whereby the optical collector is rotatable together with the joint member relative to the base for adjustment of its angular position and the optical collector can be alone replaced as necessary without having to replace the base, the sensor and its associated electric circuitry.

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: Diffuse reflectance spectra may be obtained that are free from the distortions caused by specular reflections by using an apparatus and method for physically blocking out specularly reflected energy. The apparatus consists of a blocker that is positioned substantially in contact with the surface of the sample at the region wherein an input beam of energy is focused on the sample. Specularly reflected energy that would otherwise be reflected to a detector is physically blocked by the blocker. That part of the input energy beam that penetrates into the sample is diffusely reflected. Part of the diffusely reflected energy passes under the blocker where it is collected and focused on the detector. The blocker is found to have particular application in the field of infrared spectroscopy of inorganic compounds, particularly compounds having a powdered structure.

Abstract: The device for collecting the radiation of a light source (20) within a concave mirror comprises a cylindrical or rotationally symmetrical parabolic or elliptical reflector (10'), which is covered with a curved or planar retroreflector (40) having an opening (42). The retroreflector (40) returns part of the light into the vicinity of the source (20) and brings about, due to the partial transparency of this area, that an intense, quasi-parallel light beam can be coupled out through opening (42). After passing through a monochromator element (31), this light can e.g. be supplied to a gas measuring cell (68). The optical efficiency of the device is increased by the concave mirror (57) in a shape supplementing reflector (10', 10"). The measuring signal can be determined by means of a light detector or a microphone (69). In the latter case, an acoustically decoupling gas exchange device is required, which can e.g. be realized by means of capillaries filled with the liquid (75, 75').

Abstract: A selective infra-red detector is used to determine the amount of a selected gas present in a gas sample. A beam of infra-red energy is passed through a gas sample and into the selective infra-red detector. An outer annular portion of the beam is reflected from a paraboloidal mirror onto a first focal point, while an inner annular portion of the beam passes through a chamber containing a fluid which will absorb the spectral wavelengths of the selected gas and is reflected by a spherical mirror onto a second focal point. Separate infra-red energy detectors are positioned near the first and second focal points to measure the infra-red energy. The difference or ratio between the infra-red energy measured by each infra-red energy detector is a measure of the amount of selected gas present in the gas sample.

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.

Abstract: A compact passive infrared detector is provided with a plane mirror which reflects infrared radiation focused by a lens onto a detector arranged between the lens and the reflector.

Abstract: A method and apparatus is shown for receiving optical rays with a maximum angle of sensitivity so that a single detector can monitor a wide, spherical angle. This method is used with infrared detectors which would be mounted on a wall to switch the lamps of a room on and off as soon as a person enters the room.

Abstract: An optically immersed infra-red detector assembly comprises a planar sapphire substrate bearing a detector with radially disposed lens contact pads. The detector and contact pads are produced by etching a single portion of cadmium mercury telluride and have mutually coplanar surfaces. A hemispherical silicon optical immersion lens is bonded to the pads by applying dilute adhesive to lens-pad interfaces. Capillary attraction draws the adhesive between the lens and the pads to form very thin layers of adhesive after solvent evaporation. The adhesive layers ensure that an air gap is produced between the lens and detector, the gap being much smaller than the infra-red wavelength of interest as required to ensure optical immersion of the detector by the lens.

Abstract: The ceiling mountable passive infrared intrusion detection system of the present invention includes a focusing mirror having an optical axis, and a composite field-forming mirror cooperative with the focusing mirror for providing both a plurality of vertical curtains and a plurality of uniform detection sensitivity finger beams defining fields of view in selected azimuthally spaced relation through which an intruder must pass when in motion about the floor of a protected facility. The composite field-forming mirror includes first and second pluralities of selectively-twisted cylindrical facets defining longitudinal axes that individually intersect the optical axis of the focusing mirror at preselected different non-zero acute angles and provide corresponding ones of the selectively azimuthally spaced fields of view of the vertical curtains.

Abstract: The invention comprises a passive infrared intrusion detector including a lamp for locating the zones being protected by the detector. The detector includes a heat sensor, a lens system for receiving and focusing the body heat of an intruder on the heat sensor, and electrical circuitry responsive to the heat sensor for actuating an alarm or detection signal when the body heat of an intruder is detected.The zone locator lamp is positioned near the heat sensor and its light passes through a lens in the general direction of a zone to be protected. The light parallels a portion of radiation which is focused on the heat sensor by another lens. If the light can be observed from a given position in front of the detector, that position is in a zone being observed by the detector and body heat radiated from that zone will be focused on the heat sensor. Thus, zones protected by the intrusion detector can be established by adjusting the position of the detector until light from the zone locator lamp is observed.