Abstract: A novel illumination device is provided which is small, inexpensive, and conveniently plugs into a standard power outlet, thereby allowing easy installation and deinstallation by nontechnical consumers, and thereby allowing the security light to be easily moved to any wall outlet as security needs change. This illumination device includes a motion detector so that the illumination is provided only in the presence of one or more persons who would find the illumination beneficial. A photoelectric device is provided such that the security light is illuminated in response to motion only when there is an insufficient amount of ambient light available from other sources. In one embodiment, a vision restrictor is provided such that motion is detected only from a desired detection area. In one embodiment, a vision extender is utilized in order to optimize the field of view for the motion detector, making the device more useful in narrow hallways and other unique installations.

Abstract: The arrangement (201) comprises an optical narrow detection beam (203) focussing system for a passive infrared radiation in accordance with a reference plane (U). A filter selects the spectral analysis band and at least one passive infrared radiation detector is provided in the focal plane. According to the invention, the arrangement comprises a first analog processing chain and a second digital processing chain by means of which it is possible to recover in accordance with a characteristic curve at least the undercarriage of vehicles. On this curve, each turning element of the undercarriage assumes the shape of an identifiable pulse. The arrangement is used in the identification of moving vehicles in a predetermined plane.

Abstract: Since known methods for investigating latch-up propagation have only a comparatively slight chronological resolution, a method and apparatus are proposed in which latch-up is periodically triggered and the intensity of the infrared radiation emanating from an integrated circuit is sensed at a plurality of measuring points that cover the circuit in a grid-like manner in order to respectively determine, at the measuring points, within what time span the intensity of the infrared radiation reaches a threshold, and to respectively register a measured value representing the time interval in a location-dependent manner.

Abstract: A system is disclosed for determining the position of at least one target by triangulation, comprising two passive sighting devices which measure the intensity of radiation received along a sighting line which scans a vertical sighting plane. They are disposed at a distance from each other along the same vertical axis and are driven in rotation about this common axis so that their sighting planes merge. A circuit extracts the angular coordinates of the target, relative to each of the sighting devices, and computes the distance of the target by triangulation in the vertical sighting plane.

Abstract: A radiation detector comprising a first pair of flat reflective surfces parallel to one another and connected by a second pair of flat rectangular reflective surfaces converging toward one another so as to form a reflective chamber having a relatively wide opening for the entrance of radiation and a relatively narrow opening defining a region for receiving radiaiton, there being a radiation sensor positioned in the receiving region for detecting fluctuations in levels of radiation received from a plurality of detection zones.

Abstract: A message spreading apparatus is disclosed to generate an audio message output in response to the presence of a heat radiation generated by body heat. A housing has a front wall provided with an opening therein and a rear wall including a first portion opposed to the opening of the front wall, with the front wall and the rear wall being spaced a predetermined distance from each other. A radiation reflecting member is mounted to the first portion of the rear wall and is configured and arranged so as to reflect a portion of a heat radiation ray entered through the opening of the front wall to a path which is between the front wall and the rear wall and is in a direction substantially parallel to the respective planes of the front and rear walls. A pyroelectric sensor is provided in the path to sense the reflected heat radiation ray and generate an activating signal in response to the reflected heat radiation ray.

Abstract: A method of inspecting solder joints of a circuit card assembly with a laser inspection system having a laser adapted to be operated at a high power in watts to produce a laser beam for a selectable time duration for application to solder joints of a circuit card assembly and a detector system for detecting infra red emission from the heated solder joints to determine the solder joints integrity. For a given type of circuit card assembly and for a given type of solder joint, a laser beam time duration is selected and the laser is operated at a given high power level which is effective to result in the detection of a peak number of defective solder joints of the same type. The time duration of the laser beam employed in the process is that corresponding to the second peak of defective solder joints determined from prior testing.

Abstract: An infrared detection system having a detector which includes elements of different sizes which are electrically selectable to change the operational range of the system without any change in the associated optical assembly. The detector elements can be of two or more element sizes, and various detector configurations can be employed such as single or dual detector configurations. To provide a constant signal amplitude for the different selected ranges, the gain of the detector circuitry can be adjusted accordingly to provide uniform signal amplitude irrespective of range setting.

Abstract: Apparatus for nondestructive detection of subsurface defects in a continuously moving workpiece of sheet material by using an infrared thermal imager. The temperature of a portion of the surface of sheet material is altered and the presence of subsurface flaws is indicated by development of discontinuities in the surface temperature distribution above the defects. In order to avoid problems due to changes in the infrared emissivity of the surface of sheet material, such as caused by grease patches or oxidized areas as well as errors caused by reflections of other sources of infrared radiation from the surface, the thermal image of the portion is first transferred by contact to a surface of a thermal transfer device whose surface has a high infrared emissivity and a low infrared reflectivity. Then the thermal image of the portion is obtained from the surface of the thermal transfer device.

Abstract: An infrared sensitive system which maintains an inventory of the number of occupants within a monitored room for controlling certain electronic equipment in response to the presence of occupants within the monitored room. The monitoring system activates the electronic equipment when it senses a person entering the unoccupied room, and it deactivates the electronic equipment when the last person exits the room. Switch members provide for manually resetting and overriding the control portion of the system.

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 IR sensing system wherein the focal area is located outside the casing at holds a detector array and a bundle of optical fibres leads from the focal area to the detector array in the array such that the inner, emitting end of each fibre of the bundle is in proximate relationship with only one single detector.

Abstract: Apparatus and methods for modifying existing forward looking infrared systems and for forming new forward looking infrared systems. Generally, the system comprises a Galilean afocal system in combination with a reimaging afocal system. A reimaging afocal lens system is formed with at least first and second lenses and a plane for forming an image therebetween. A thermal reference source is positioned in the imaging plane of the reimaging system. The method for modifying an existing forward looking infrared imaging system includes positioning the reimaging system along the optical path of the system between the Galilean lens combination and the scanning device. According to a method for forming a forward looking infrared system an imaging lens system is arranged along an optical path in combination with a detector array to focus collimated radiation upon the detector array. The detector array subtends the field of view along a first direction.

Abstract: The disclosure relates to a crime-preventing infrared sensor of a passive type in which the infrared detecting element 6 detects the energy of infrared rays radiated from an object in a predetermined visual field to be monitored and an alarm is given in response to a detection signal outputted from the infrared detecting element. The crime-preventing infrared sensor comprises an infrared detector 7 for detecting a human body or any other object approaching the sensor itself independently of an object-detecting function in a visual field, whereby the obstruction in the visual field of the object-detecting function is prevented.

Abstract: Solar powered outdoor lighting and/or alarm systems are provided and include a light source or alarm, a passive infrared (PIR) sensor in conjunction with a battery recharged via solar cells, and a control circuit coupled to the light source or alarm, the PIR sensor, and the rechargeable battery. The control circuit guarantees that the light source or alarm is turned on by the battery only when the sensor senses the presence of a moving target. The systems may include a light detector which is utilized to prevent the system from activating in daylight. In the case of a lighting system, a timer is utilized to turn off a lamp after a desired period of time (e.g. 3 minutes). By limiting the "on-time" of the light source, a two to five watt bulb may be used. In the case of an alarm, the alarm may be hardwired to the control circuit; or if desired, a transmitter powered by the rechargeable battery may be used to transmit an alarm signal to a remote receiver.

Abstract: A head-activated fluoroscopic control which is characterized in a preferred embodiment by a continuous wave infrared transmitter located in a cartridge adapted for attachment to eyeglasses, a headband or other headpiece worn by a surgeon or attending physician and a detector or receiver tuned to the frequency of the continuous wave infrared transmitter for receiving a partially collimated infrared signal beam and activating a fluoroscope. The infrared transmitter emits the collimated beam and the beam is received by the receiver when the surgeon's head is turned toward the fluoroscope monitor upon which the receiver rests or in which the receiver is mounted, to facilitate selective operation of the fluoroscope during surgery.

Abstract: An optical test bench for testing the technical characteristics of electromagnetic wave sensors and emitters of an air and ground surveillance electro-optical module mounted on a missile firing vehicle, the module capable of acquiring, ranging and tracking a target and of guiding a missile toward the target. This test device is specifically designed for factory and environmental testing, by opposition to laboratory controlled environment testing. The optical test bench of the invention includes: two parabolic off-axis collimating mirrors, for focusing the fields of view of the module to a common focal point; a computer-controlled focal plane system, including four test assemblies selectively shiftable to register with said focal point, and a laser alignment periscope system to exactly adjust each parabolic mirror relative to the other so that their focal points coincide.

Abstract: A security system has a wall mounted assembly for installation adjacent an entry door and includes a motion detector for sensing intruders, an alarm for sounding a warning, an alarm circuit, a radio receiver responsive to two codes, and an electric door striker. A portable miniature transmitter has two transmission codes to activate the receiver, one for toggling the alarm circuit between armed and disarmed condition and for releasing the door upon disarming the alarm circuit. When the circuit is armed the motion detector is able to activate the alarm. The second transmission code activates the alarm if the circuit is armed. Remote self contained motion detector and transmitter units for use in other rooms use the second code to activate the alarm when motion is detected by those units.

Abstract: An apparatus (12) for providing information about the power and position of a high laser beam includes a heat absorbing body (46) having a target area within which the laser beam is directed. Position information is provided by a plurality of thermocouples (46) connected in series in a circular array and located radially outward of the target area. In the preferred embodiment, the thermocouple array is divided into four quadrants (60-66), each quadrant generating a voltage proportional to the heat flow in the body at that location. A comparison of the voltages generated by each of the quadrants will provide information about the position of the laser beam with respect to the quadrants. In addition, by summing the output of the quadrants, information about the total power of the beam can be derived.

Abstract: A multi-aperture, non-imaging sensing system is disclosed, for guiding a moving projectile toward a source of infrared energy. The detectors are arranged peripherally about a forward portion of the projectile, with their individual fields of view overlapping one another to selectively separate a composite field of view into a plurality of separate sectors, with a central sector including all individual fields of view. Infrared sensing elements and electrical circuitry are operatively associated with the detectors, for generating a binary one or zero, depending upon whether an infrared energy source is sensed by the associated detector. The combined results are generated as a digital word, utilized to indicate the location of the source within the composite field of view, and to generate a control signal. The control signal adjusts the projectile orientation to locate and maintain the source within the central sector of the composite field of view.

Abstract: A dual channel intrusion detection system comprising first and second radiation sensors. Each sensor has a pair of elements viewing adjacent zones of the protected area, the zones being slightly offset from each other in the direction of expected intruder movement. Sequence detection is provided for producing an intruder-present signal in response to simultaneous actuation of one element of each sensor when preceded by actuation of the other element of one of the sensors. Additional immunity from false triggering is obtainable if this sequence must be followed by actuation of the other element of the second sensor.

Abstract: The present invention is concerned with displaying moving objects (targets) wherein two time-shifted object signatures are imaged on a detector. Target scanning is with a prismatic rotating wheel, the periphery of which has a plurality of adjacent, recessed, and oppositely reflecting triplet mirror surfaces which alternately reflect the two signatures onto the detector. The position coordinates of the objects are defined by taking the difference of the detector output signals of the two object signatures. The display is characterized in that the first signature scan is delayed by an intermediate storage so that it shall be simultaneously available with the second signature scan. After taking the difference of the signals of these signature scans, the uncanceled individual signals remaining in the storage are defined as the coordinates of the moving objects and appear as electronic outputs.

Abstract: The invention is an apparatus for using infrared radiation to distinguish between live and dead poultry eggs. The apparatus comprises a plurality of infrared sensors, means for moving a fixed array of eggs to a predetermined aligned position with respect to the infrared sensors. The apparatus records the infrared radiation emitted by each egg in the array, and calculates a threshold temperature from the individual temperatures for which 70 percent of the eggs measured in the fixed array are cooler. The apparatus includes means for removing dead eggs from the fixed array which are identified as having temperatures more than one degree Fahrenheit cooler than the threshold temperature.

Abstract: Method for observation of vibration mode in which a substance inclusive of structures and materials to be observed in vibration mode is vibrated, heat generated by giving vibration is held at the vibrating parts, infrared emission energy emitted from the substance is optically detected to visually display the distribution of temperature change at each vibrating part as thermal imagery.

Abstract: An infra-red imaging system is operable selectively in wide and narrow field of view modes. Radiation from the object is imaged onto an infra-red CCD staring focal plane array (SFPA) which provides an output representing the image. In the narrow field of view mode, operative on detection of a particular target by target detection electronics, the image is not scanned but is made to follow any movement of the target, and the SFPA stares at the target to build up an image. In the wide field of view mode, the same SFPA is used to provide the image, but the image is scanned along a swath. Smearing of the image is minimized by driving the IRCCD array such that the image-bearing charge is passed down the array from element to element at a speed equal to the scanning speed, so that the output signal from the end element represents the intensity of radiation from a given portion of the object time-integrated by all the elements of the array in succession.

Abstract: A system for improving the dynamic range of guidance systems for missiles d bombs by replacing pseudo-logarithmic amplifiers in the processing circuits with transimpedance amplifiers having feed back impedance operating in conjunction with lower bandwidth type logarithmic amplifiers in the log of the ratio circuits.

Abstract: A method and means for detecting the presence of infrared radiation and/or he presence of an optical dielectric transmitting element, such as a lens or window, is provided. By correlating the radiation wavelength with a visible detector wavelength and a specific dielectric element, the element can be identified or the alignment of a beam of radiation passing through the element can be established. In some cases the presence of a quiescent radiation device can be deduced from the identification of the dielectric element.

Abstract: A method and apparatus for covertly viewing a target using transmission of infrared radiation through an atmosphere having given atmospheric conditions. The target is illuminated with only a selected frequency band of infrared radiation having the least effective transmittance properties of all frequencies of infrared radiation in the given atmospheric conditions. This selected frequency band of infrared radiation is reflected from the target and detected. The selected frequency band of infrared radiation may be generated by generating a broad spectrum of infrared radiation and filtering this broad spectrum to output only the selected frequency band of infrared radiation. Alternatively, a laser may be employed to output the selected frequency band of infrared radiation.

Abstract: An alarm system for military objects of a laser-radiating hostile weapon system. A plurality of units for detecting impinging laser radiation are mounted on an airplane, for example. Each detection unit is arranged to detect in one of six directions along three mutually perpendicular axes. The detection units are coupled to output signals representing the direction of incoming laser radiation to processing electronics. Each detection unit has an array of detector elements in a first plane and a diaphragm equal in size to the array in a second plane parallel to the first plane. The diaphragm and array are arranged so that the direction of the laser radiation can be determined from the pattern of detector elements activated in response to laser radiation passing through the diaphragm.

Abstract: An infrared radiation sensor is provided comprising an infrared optical system and a pyroelectric radiation detector for receiving infrared radiation from the optical system and generating an output signal. The optical system has a lens (6) arranged to feed source radiation through an aperture (9) into a reflective radiation cavity (10), the lens and the aperture defining a radiation sensitive angular zone width and direction (2,3,4,5) for the sensor. The pyroelectric radiation detector comprises a film (11) of pyroelectric plastics material within the cavity. The film area can be made large within the cavity without affecting the angular resolution of the sensor which is controlled by the ratio of the optical system focal length to the aperture width.

Abstract: An improved optical assembly which provides a panoramic field of view for infrared motion detection. In one form of the invention the optical assembly comprises a spherical section having an inner surface and an outer spherical surface, the outer spherical surface having a radius of curvature centered in a focal region which is suitable for placement of an infrared detector. The inner surface of the spherical section comprises a plurality of circular convex lenses, each lens having an optical axis passing through the focal region. The combination of the outer spherical surface with each circular convex lens forms a biconvex lens having a focal point in the focal region. Radiation received by each biconvex lens from a zone in the field of view is focused in the focal region for sensing by the infrared detector.

Abstract: A digital infrared detector circuit which converts changes in detector current to time varying pulses and uses feedback to adjust the coincidence of a reference signal with the trigger signal to accommodate to circuit variations caused by changes in infrared detector sensitivity or ambient temperature. To supply a highly accurate feedback reference signal an internal high frequency oscillator is used for feedback control and counted down to furnish the reference signal. The conversion from detector current to time is accomplished by using the detector to discharge an accurately charged capacitor and measuring the time to recharge the capacitor.

Abstract: Overheated railroad journal bearings, wheels, and wheel components on a moving or stationary railroad train are detected by amplifying the current signal from an infrared radiation sensor comprising a pyroelectric cell. A reference temperature is sensed by chopping the incident infrared radiation with an asynchronous shutter that momentarily closes at successive time spacings of shorter duration than the scanning period of the sensor. The amplified signal is converted to a digital signal and processed by a microcontroller and associated hardware and software. The software comprises a free-running loop Main Program which is subject to several interrupts. The output signal may be digital or analog and is transmitted to remote signal processing equipment for further processing.

Abstract: A passive infrared detection system includes a reflective optical system comprising a focusing element (e.g. an elliptical or parabolic reflector) having an apparent focal length dependent upon the displacement of incident rays from the optical axis of such element, and a plurality of planar reflectors arranged at different angles with respect to such optical axis to provide the detection system with a plurality of different zones of detection, each having a different maximum detection range associated with it. According to the invention, the planar reflectors are arranged with respect to the focusing element so that each planar reflector cooperates with a different portion of the focusing element to project onto an IR detector located at the focus of such focusing element a relatively constant size image of a given target located at the maximum detection range associated with that planar reflector.

Abstract: An apparatus and method are provided for static and dynamic testing of the boresight alignment of an electro-optic system, the system having a line-of-sight sensor responsive to first radiation from a target for sensing the location of the target and setting the direction of a target vector to correspond to the location of the target, and having a line-of-sight illuminator for directing an illumination beam of second radiation at the located target. The apparatus comprises a main optic for receiving the second radiation from the electro-optic system and focusing the second radiation about a focal point in a focal plane substantially perpendicular to a principal radiation path.

Abstract: An infrared detector includes process and circuitry for detecting the direction of movement of a radiation source with a predetermined resolution. Four radiation-sensitive elements defining a square are provided in the detector, each connected to an evaluation circuit which compares the output signals from the elements. A normalized pulse is generated upon the occurrence of the maximum of the output signal from each of the elements. The direction of movement of the radiation source is identified from the chronological sequence and spacing of the normalized pulses.

Abstract: The invention is a method of distinguishing between live and dead poultry eggs. The method comprises monitoring the individual temperatures of the selected group of eggs and then using the monitored individual egg temperatures to determine a comparative egg temperature for the selected group. The difference between each individual egg temperature and the comparative egg temperature of the selected group is determined, and dead eggs are identified on the basis of the difference between their monitored individual temperatures and the comparative egg temperature of the selected group.

Abstract: A personal body detecting device makes it possible to determine the presence and absence of a personal body in a detecting zone by sensing infrared rays in the zone with a plurality of infrared ray detecting elements, detecting at a discriminating means a peak level and output time in connection with respective outputs of the infrared ray detecting elements, and comparing them with each other. The personal body having reached the detecting zone in any direction thereto can be reliably detected, and a highly reliable detecting operation can be realized.

Abstract: A system for locating zones defined by Fresnel lens segments or mirror facets of an optical arrangement in a passive infra-red security sensor uses a prism sheet which deflects light emitted by an LED mounted to the circuit board adjacent the infra-red sensitive detector so that it follows the path of infra-red radiation that would be focused onto the element of the detector without the prism sheet present.

Abstract: An improved passive infrared balanced detector is disclosed that reduces false alarm rates induced from random thermal activity and other causes of splitting of the field(s) of view of the balanced detector into distinct and independent regions. The detector includes balanced elements selectively shaped and arranged to provide common mode rejection within each of the regions into which the field(s) of view are subject to being split. The unbalance susceptibility of the novel detectors may be adapted to the particular requirements of the intended applications environment. The susceptibility for unbalance is materially reduced and therewith the alarm confidence level of the detectors is substantially improved.

Abstract: Appartaus is disclosed for harmonizing onto a common reference axis the optical/optronic axes (4;5;18) of an aiming apparatus consisting of day sight channel (3) and combined thermal image/laser reception channel (1) with a stand alone laser transmitter (2). The laser radiation (9) reflected by the target is incident together with the target and ambient inherent radiation (11) via the scanning mirror (12) on selected elements of the detector row array (30), is optoelectronically converted and represented on the light-emitting diode array (25). Via the back of the mirror the signals are imaged on the retina by means of the deflection mirror (23) swung into the ray path. The visible radiatioin (19) imaged in the plane of the day reticle (21) also passes to the observer's eye when the deflection mirror is swung out. The visible radiation (19) in the day sight channel (3) can be observed when the deflection mirror is swung out via an imaging in the plane of the day reticle (21).

Abstract: A diagnostic instrument (10) for testing the functioning of an infrared radiation emitter (14) contained within a VCR (12) or other electrical equipment is disclosed. The instrument (10) comprises a housing (16) and an electronic circuit received within the housing (16) for detecting the presence of infrared radiation. The electronic circuit comprises a battery (26) or other DC power source electrically connected in series with an infrared sensitive photodetector (22) and a status LED (24) which is illuminated when the photodetector (22) is exposed to infrared radiation produced by the emitter (14). A switch (18) is provided for selectively turning the instrument (10) on and off. A battery condition LED (20) is also provided.

Abstract: A miniature active infrared motion detector contains a self-heating temperature sensitive resistor, an electronic circuit to maintain temperature of that resistor at predetermined constant level which is higher than ambient temperature. The detector actively radiates thermal energy to environment and measures electric power required to generate that energy. This provides information about temperature variations in surrounding objects. The detector is also comprised of a focusing system, image distortion means and a threshold circuit. An optical system can be made of a curved Fresnel lens or curved mirror, such as parabolic, cylindrical, spherical, etc. which distributes thermal radiation over narrow or wide field of view, potentially up to 360.degree.. The method of detecting movements is based on the use of a warm sensor whose temperature is maintained constant and above ambient.

Abstract: A testing and battery exercising method and control for an emergency lighting unit, which is activated by a drop in voltage of a primary power source, provides for frequency testing of the unit by utilizing a control unit in conjunction with an infrared sensor and photocell to control a voltage reduction simulation device. The control device includes a means for sensing a change in a heat pattern over a pre-determined illumination area, a means for sensing ambient light in the illumination area, a means for simulating a reduction in voltage of a primary power line and control a unit which causes a reduction in voltage to be simulated to turn on the emergency lighting unit only when a change in the heat pattern and the illumination area is detected while the ambient light over the illumination area is below a threshold value.

Abstract: An electromagnetic lock which mounts at the top of a door frame and magnetically bonds with an armature employs both an ultrasonic sensor and a passive infrared sensor to detect the approach of an individual at the doorway. Both the ultrasonic sensor and the passive infrared detector have fan-shaped sensing regions which are positioned forwardly from the doorway. Upon detection of an individual approaching the doorway, the lock is capable of automatically releasing to allow egress through the doorway.

Abstract: Movement monitors with segmented collecting optics have dead zones between the individual focusing segments, in which a radiating object can stay without tripping a signal. These dead zones are to be practically avoided with the movement monitor according to the invention. To this end, deflecting optics after the collecting optics in each case deflect a portion of the bundle of rays incident parallel to the principal ray of a segment in such a way that at least two radiation maxima occur. Given a corresponding change in position of a radiating object, these radiation maxima strike sensor elements of the sensor one after another. In this way, dead zones are reduced to such an extent that they are practically eliminated. The movement monitor serves for zonal monitoring inside and outside buildings. By transmitting a signal, it can switch on lighting or trip an alarm.

Abstract: The emissivity of camouflage material is determined from the apparent body emperature measured by a radiometer, calibrated to indicate a temperature of a blackbody would emit corresponding to the radiation received therefrom; and the true temperature of the material and the true temperature at an infrared detector of the radiometer of a radiometer. Computation means is provided for calculating emissivity from the so measured temperatures and for displaying the result.

Abstract: An intrusion detector with a plurality of reflector segments that focus infrared energy from a corresponding plurality of detection zones onto a common sensor. Uniform coverage of a rectangular area with detection zones and detection sensitivity unaffected by distance is achieved by means of a reflector segment arrangement in which the reflector segments are mounted on supporting structures and in which the distance from the sensor and therefore the focal length of the reflector segments is substantially proportional to the detection distance. The reflector segments are staggered horizontally and vertically on the supporting structures such that the centrally positioned reflector segments are set lower and have a different shape than the laterally positioned segments, and whereby the number of reflector segments is reduced with decreasing detection distance such that the density of the detection zones is uniform throughout the retangular protected room.

Abstract: A passive analog equalizer is connected to the output of an infrared detector to provide increasing pyroelectric detector sensitivity with increasing target frequency in order to provide a detection sensitivity which is substantially flat over the target velocity range of interest. An interruptable modulator is connected to the equalized pyroelectric detector signal to shift its frequency upwardly in order to provide negligible drift, fast recovery from transients, and the ability to quickly shut down the modulator when a transient occurs. A transient detector is operative in response to transients in the pyroelectric detector output signal to provide a window during which the modulator is interrupted in order to prevent transient induced false alarms.

Abstract: A switch assembly actuated by passive infrared radiation for operating a light in a space, the switch assembly including an optical system which senses infrared radiation over a 180.degree. range in horizontal plane including two separate vertical fields of view, a generally horizontal "look-out" field and a vertical semi cone-shaped "look-down" sensing field for directing to a common sensing element passive infrared radiation produced by a person moving within the sensing field of the switch assembly, the sensing element connected to a control circuit which responsively turns on the light, maintains the light on while the person remains in the space, and turns the light off automatically when the person leaves the space. The switch assembly includes a one-piece optical shell enclosed within a housing which is adapted for installation in a conventional light switch box in room.