Abstract: An electro-optical system including a scanning mirror for scanning an image across an array of radiation detectors. An analog signal generated by the scanning mechanism is utilized to provide a sweep signal in a first axis. A second sweep signal in another axis is operated independently of the first sweep signal. The outputs of the detector array are electronically multiplexed through a plurality of channels and integrated between successive samplings of each detector. A provision for equalizing the outputs of each detector in the array is included. The output of the electronic multiplexer may be utilized to provide a video display in conjunction with the sweep signals, or may be applied to a conventional optical display.

Abstract: Presence and location of infrared radiation-absorbing or emitting gases in the atmosphere can be ascertained by means of an infrared imaging-analyzing means which views a given scene and receives infrared radiation therefrom. Analytic and reference beams are produced, the latter having reduced sensitivity to the gas of interest, and are converted to electric signals, which are processed in real time to provide a signal corresponding to their ratio. This ratio signal is further processed to generate an image, which can be displayed and viewed. This technique is particularly suitable for surveying large areas for seepage of methane or other hydrocarbon gases from underground gas and/or oil deposits.

Abstract: A radiation sensitive detector employed with a thermal radiation scanning system to receive images that are scanned across said detector at predetermined velocities. The detector is sensitive to these scanned images and generates minority photocarriers that drift along the length of the detector in the opposite direction as a majority carrier flow caused by an applied biasing field. The cross-section of the detector is non-uniform along its length direction so that the density and velocity of the photocarrier packets may be appropriately controlled over the length of the detector.

Abstract: A column of infrared detectors are repetitively optically scanned across an nfrared scene. The outputs of the detectors are fed to a viewing matrix of light emitters consisting of a plurality of columns of detectors, each column having light emitters corresponding to respective detectors. As the detectors are scanned across the scene, successive columns of detectors are energized or enabled such that the light emitted by the individual emitters is directly related to the infrared radiation falling on a corresponding detector. The image may thus be directly viewed by an observer. An alternate system employs a storage matrix having light detectors corresponding to the emitters of the viewing matrix such that the output of the viewing matrix, instead of being directly viewed, is stored and is then read out in a normal television raster to provide a video signal for distant television viewing.

Abstract: A thermal imaging system generating high resolution images at commercial T.V. rates while scanning relatively large apertures comprising a facet mirror mounted for rotation about a rotational axis, a framing mirror mounted on axis for oscillation about an oscillatory axis, and an off axis, magnifying relay lens system for reimaging the pupil at the facet mirror onto the framing mirror so that there is a real pupil at the framing mirror with no image artifacts. The relay lens system is located in the optical path between the facet mirror and the framing mirror. The relay lens system defines an image plane and at least one point blackbody is located substantially at the image plane for purposes of providing a video reference and calibration. A detector receives the focused beam of radiation reflected by the facet mirror for subsequent display on commercial T.V. monitors. The detector shares vacuum with the high-speed scanner.

Abstract: A scanning system wherein a linear array of N detector elements having a form spacing of X cm between their centers is oriented parallel to the line scan dimension of a raster so that each element of the array optically scans the entire field of view at a rate of V cm. per second. The detector elements are sampled every t.sub.s seconds where ##EQU1## k being an integer, and each produces, when sampled, an output signal proportional to the integrated energy exposure thereof between samplings. The output signals of the various detector elements are delayed as a function of each element's position within the array and the line scan rate. The delayed imaging signals add to provide an improved signal to noise ratio. The variability of the waveform of the composite output signal for smallsized distant targets is minimized by introducing a progressively increasing phase shift in the relative timing of the sampling signals and initial contact of the image at successive detector elements.

Abstract: A scanning arrangement for an infra-red imaging device in which a column of I.R. detectors, and similarly a column of L.E.D.'s, scans a field broadside to produce a band of parallel line scans, a number of such band scans being provided to cover the field. Each band scan is performed by a respective mirror facet of a rotating polygonal drum, the facets being tilted at slightly different angles to provide the band displacement. Non-uniformity of the column of I.R. detectors or the L.E.D.'s or the interconnecting channels tends to produce the same pattern of non-uniformity within each band. This is overcome according to the invention by periodically tilting the drum by a random fraction of a band-width so that on successive occasions a particular element of the field is processed by different detector/L.E.D. channels.

Abstract: The thermal imaging device comprises an IR-transmitting scanning polygon arranged behind an objective system. The polygon rotates about two mutually perpendicular axes, i.e. about the optical axis of the device and about the axis of rotation of the scanning polygon which is perpendicular thereto. The rays which emerge from the polygon pass through a reversing optic, which also rotates about the optical axis but with half the angular frequency of the scanning polygon around this axis. Behind this a multichannel IR detector array is arranged, to which a multichannel summing amplifier is connected. The amplifier is synchronized with the frequency of the rotation of the scanning polygon about its own axis. This rotation of the scanning polygon at the same time constitutes the radial deflection frequency for displaying the image.

Abstract: An infrared radar system. The system includes an infrared laser and associated controller which are adapted to provide a succession of transmit pulses having a relatively high intensity spike portion followed by a relatively low intensity quasi-CW portion. An optical system directs the transmit pulses to a target scene and collects infrared radiation reflected from the scene. The collected radiation is imaged on a heterodyne detector array together with a locally generated reference infrared beam. A range network is responsive to signals from the detector array to provide signals representative of the range of objects in the target scene. A moving target indicator network is responsive to signals from the detector to provide signals representative of the velocity of objects in the target scene.

Abstract: A signal processing method for eliminating fixed error sources in the video signal of a pyroelectric vidicon comprising the step of adding the signal value at each point of the pyroelectric plate to previous signal values relating to the same point for forming an integrated or mean value for a great number of signal values at each point and then subtracting the fixed error estimate from the signal values in the latest received video signal. This mean value, if differing from zero, is the estimate of the fixed error at the respective point.

Abstract: The invention provides a combined spectral radiometer and infrared viewer r use in the infrared and particularly the far infrared portion of the electromagnetic spectrum. A standard thermal viewer is modified by the addition of a temperature reference, a variable filter, a recording minicomputer and circuitry to intercouple these elements and synchronize their functions without impairing the use of the view in its normal make of operation.

Abstract: An optical system for scanning thermographic pictures comprises a rotating polygonal cylinder for line scanning in one coordinate direction. The polygonal cylinder is subdivided into an inner stationary solid cylindrical portion and a ring surrounding the cylindrical portion. The ring is on its outer side provided with the polygonal faces and rotates around the cylindrical portion. The cylindrical portion has a single curved face extending substantially perpendicular to the optical axis. The inner wall of the ring and the curved face define between them a cylindrical air lens element. The shape of the curved face is computed in accordance with the image distortions of the optical system so that the air lens compensates for the image distortions.

Abstract: The imager comprises an array 4 of detectors, and an array 6 of LEDs each detector being connected to a corresponding LED by a respective signal processing channel 5a. Common to all the channels is a ramp generator 12. Each channel has a comparator 9 which compares the ramp with the signal from its detector to produce a pulse width modulated signal for its LED. Thus the LED is always driven at the same point on its characteristic, variation of brightness being achieved by variation of pulse width. Use of a common ramp generator makes for simple change of ramp shape, temperature window, offset and .gamma. law by simply changing only the ramp generator.

Abstract: The invention contemplates a heat-detection system with optical, scanner and display components for periodic mechanical heat-scanning of a given field and for so correcting the phase of electrical signals developed in the course of scanning as to enable development of a visible display of the field without phase-shift errors which are attributable to mechanical motion of the scanner.

Abstract: An improved optical observation system for a movable body in space which comprises a scanning mirror, imaging optics and a sensor formed by at least one array of photodetectors arranged along a plurality of rows parallel to the apparent displacement of the image points. The electric signals from the photodetectors are driven to be transferred from one photodetector to the following along each row with a velocity equal to the velocity of the apparent displacement of the image points. An advantageous embodiment for the sensor is also disclosed together with suitable means for multiplexing the output signals developed at the ends of the rows onto a unique output line.

Abstract: A rotatable thermal shutter for use with a pyroelectric camera tube is provided with blades having opening and closing edges in the shape of a spiral. The use of a spiral shape allows the rotatable shutter to have a particularly small diameter while still providing satisfactory performance.

Abstract: An automatic responsivity compensator for correcting video output signals om a CCD multiplexer in a cryogenic dewar in IR imaging systems wherein the CCD multiplexer must operate with fixed gain inputs from a plurality of linear detector channels. The automatic responsivity compensator is comprised of a signal reference that is normalized with what the output voltage should be when looking at a fixed temperature source in the field of view of the detectors and which further provides a voltage reference for automatic gain adjustment for each detector channel to normalize and equalize the responsivity of the detectors. The automatic responsivity compensator may be either a feedback system as a direct gain control means of a controllable gain amplifier or may be a feedback system operating on the output from a constant gain amplifier wherein either feedback system equalizes the responsivity of the detectors.

Abstract: A scanning arrangement in which the scanning speed at right angles to line direction is selected so that every line becomes scanned anew by the following element in picture direction. Reproduction is carried out by way of a series arrangement of luminous diodes. The light-emitting diodes (LEDs) are arranged geometrically corresponding to the detector array. For scanning the thermal picture, use is made of a polygon prism permeable for thermal radiation and beams; for reproduction use is made of a polygon prism permeable for visible radiation or beams. Both prisms are located on the same pivot axis and the scanning of the thermal picture, as well as the reproduction of the visible picture in line direction is achieved by turning both polygons and scanning in picture direction is achieved by tilting the pivot axis.

Abstract: An area meter for a thermographic display comprising means for defining a predetermined area within a scan field and means for determining and displaying a numerical representation of the proportional area of said predetermined area relative to the total area of the scan field. This is useful in the medical diagnostic field for determining with increased accuracy areas of the body which contain distinct temperature variances from the general background field.

Abstract: A heat imaging apparatus is used to detect and display heat radiation from target. For this purpose the apparatus has optical components with a diffusion circle of a given dimension and heat detector elements each of which has a size smaller than said given dimension of said diffusion circle, whereby the geometric resolution and hence also the target recognition range are substantially improved.

Abstract: A method and apparatus for generating a raster image, in particular when using thermal or infra-red radiation, using a suitable optical means to guide image strips of the object over a set of detectors consisting of several detectors mounted normally to the direction of motion of the image strips. The method is improved by passing the strips of the object image twice over the set of detectors (7 ) in one cycle of the optical means (3), the first and second image being relative offset in height.

Abstract: Infra-red sensing apparatus for scanning an air space for detecting low-flying airplanes and flying bodies comprising a rotatable modulation screen arranged on a planar circular disc, and optical devices including mirrors and prisms for transmitting images from objectives, each covering a segment of the scanned air space, to the planar disc.

Abstract: In infrared detection and imaging systems circuits are provided for removing the high background thermal component of signal.

Abstract: Two pyroelectric vidicons are adapted to alternately receive infrared ene radiated from an object by means of a rotating half circle mirror and fixed mirror arrangement. The alternations of the infrared energy received between the two vidicons are synchronized by means of a synchronization and drive circuit adapted to receive frame sync pulses from the camera circuitry. By this arrangement, information is received by the camera 100% of the time.

Abstract: Infrared pick-up device comprising an infrared sensitive television pick-up tube and a diaphragm, which is alternately in the open and closed state, the amplitude of the available video signal being proportional to the speed at which the temperature changes, an additional, uniform radiation being superimposed on the scene radiation which can be changed so by a signal processing stage connected to the pick-up tube that the quantity of the average scene radiation plus the superimposed additional radiation is substantially equal to the radiation coming from the diaphragm in the closed state and acting on the target plate of the pick-up tube.

Abstract: A forward-locking far infrared system employing a modulator for infrared iation directed onto one side of a thermal-to-optical transducer. The transducer also has directed onto the same side visible or near infrared radiation. The transducer thus produces a visible or infrared transmission or reflection image of the far infrared scene. This image is detected by an accoupled optical amplifier which provides a signal for a visible display.

Abstract: An optical sighting device consists of a hood with two windows which can transmit radiation within predetermined wavelength ranges to a rotatable reflecting device. The reflecting device receives radiation from one or other of the windows and the hood is rotatable subject to the rotation of the reflecting device. The radiation reflected by the reflecting device is received by two dichroic mirror plates which are suitable for transmitting or reflecting thermal infra-red radiation, visible radiation and near infra-red radiation towards suitable corresponding detectors.

Abstract: A camera system, in particular for the detection of infrared radiation, wherein the detector uses the pyroelectric effect.It permits the viewing of fixed object owing to a time modulation of the radiation coming from such objects. This modulation is achieved by means of a partly transparent grid which moves between the object and the radiation detector.

Abstract: A method of and thermograph for producing and displaying thermographic pictures, according to which a plurality of rasters of different fineness are superimposed relative to each other. The thermograh for practicing this method includes a dual raster arrangement for producing rasters of different fineness.

Abstract: The invention comprises the closer positioning of a conventional telescopic ens, i.e., afocal lens, to a conventional optical scanner in such a combination as to minimize the required scanner mirror size and weight thereby improving scan efficiency, while also reducing physical size and thus the power requirement for driving the scanner mirror. The exit pupil of the telescopic lens is moved to a position close to the center of scanner wheel so that the incoming ray bundle follows the facets of the scanner mirror as it moves through a detector means field-of-view.

Abstract: An imaging system in which radiation from a scene is focussed onto a rotor to sweep the image across a detector whose output is used to drive a display such as a cathode ray tube; the rotor has one or more bundles of radiation transmitting fibres. The system may operate in the visible or infra red part of the electromagnetic spectrum.

Abstract: A portable device providing visual images of infra-red sources by means of I.R. detectors/electric signals/light emitting diodes. Scanning is employed to reduce the numbers of I.R. detector elements and L.E.D.'s, the scanning being effected by a rotating polygon having mirror facets tilted at slightly different angles to scan the object and image fields simultaneously in strips which cover the respective fields in a cycle.One aspect of the invention consists in tilting the I.R. and visual facets oppositely to transfer a low I.R. strip position to a correspondingly high visual strip position and vice versa.A second aspect consists in using a polygon with 45.degree. facets and I.R. detectors and L.E.D.'s on optical paths parallel to the axis of rotation. The scanned strips are then symmetrical about their field center lines.

Abstract: Line-scanning equipment, especially for aerial photography of terrestrial scenes, has an infra red scanner which causes the scanning beam to sweep repeatedly across the scene in the direction at right angles to the direction of travel of the aerial vehicle. As the angle of departure of the scanning beam from the vertical increases the strip of the scene being viewed in any one scanning cycle widens progressively so that the total strip has the shape of a `bow-tie`. A mechanically-actuated shutter is provided to restrict the recorded image to only that part of the recording beam information which is derived from a parallel-sided ground area within the `bow-tie`; and a correcting lens is employed to ensure that the final image is parallel-sided.

Abstract: The invention provides a particular prism arrangement suitable for use between a source of infrared image and a receiving element suitable for receiving infrared radiation. The prism provides for a line scanning of the image and for this purpose is provided with side faces suitably arranged to provide for the scanning of a multiplicity of lines.

Abstract: A device for measuring the radiation from an object by means of an optical system. The optical system comprises scanning devices for horizontal and vertical scanning with refracting rotating prisms. At least one radiation reference source is arranged in the optical system along the path of radiation from the scanned object so that the radiation source can be scanned by the rotating prisms at intervals which are not coincident with the interval when the object is scanned.

Abstract: A pyroelectric infrared radiation detection system includes a high density solid state pyroelectric detector array for detecting infrared radiation impinging thereon and for producing signals representing the detected radiation, apparatus for readout of the signals from the detector array, and an optical chopper for successively interrupting the radiation impinging on the detector array. In some applications, an integrating device for integrating the signals produced by the detector array would also be included. The optical chopper interrupts or chops the infrared radiation at a relatively high rate to reduce thermal diffusion in the detector array and thereby improve the spatial resolution. In low radiation intensity applications, signals which might otherwise be lost due to the fast chopping are recovered by providing electronic integration or accumulation of the signals produced by the detector array.

Abstract: A series-parallel scan, IR, focal plane array which uses small InSb CID mles. The CID is used to premultiplex photocurrent through a preamplifier before the photosignal is introduced into a Si CCD TDI signal processor.

Abstract: In camera using resistive targets wherein a recording tube of which the target (100) made of a pyroelectric material in the example and read by a beam of electrons, permanently receives a flow of ions formed in the tube by the collision between the electrons of the beam and the atoms of a gaseous mass of which the pressure in the tube is determined by the temperature of a reservoir, the invention provides means for controlling the temperature of the reservoir (filament 03) in dependence upon the average target current which is proportional to the flow of ions in question.

Abstract: A radiation scanning system comprising a focusing lens which forms an image of radiation received from a field of view and a curved reflector is arranged to reflect radiation onto a plane mirror which is mounted for oscillatory motion about a fixed axis to thereby scan the radiation image. A relay lens is interposed between the plane mirror and a radiation detector and in the plane normal to the axis about which the plane mirror oscillates the radius of curvature of the curved reflector approximates to twice the radius of curvature of the scanned image and in this way the scanned image is presented to the detector at a substantially constant angle.

Abstract: A self-stabilizing optical scanner system comprising a multi-faceted mirror formed on or attached to a gyro rotor, which is adapted for being gimbal mounted, such that as each facet is rotated through the optical path of an energy receiving lens system, a detector is optically scanned across a field of view along a first dimension. In accordance with one embodiment, each mirror facet is inclined at a different angle to the rotor spin axis such that as the rotor revolves a two-dimensional pattern is scanned; and in accordance with a second embodiment a driven mirror is disposed in the optical path of the received energy so as to provide scanning along the second dimension.

Abstract: In the present thermographic camera, an object is scanned by a horizontal and vertical scanning mechanisms in order to obtain temperature signals of each point on the object, and the temperature distribution of the object is indicated on a scanning display device, such as a cathode ray tube, on the basis of the signals obtained by the scanning. Temperature information of one or more arbitrary points on the object are sampled from each frame, and temperature variation of a point on the object is measured, while the identity of the point or points is marked on the temperature distribution display.

Abstract: A single three-electrode linear detector replaces the conventional series or parallel linear detector array in a scanned image thermal detection system. The detector comprises an elongated semiconductor/photoconductor strip, typically 0.25 cm long and 50 .mu.m wide, e.g., of cadmium mercury telluride. A bias current in the strip is arranged to give a photocarrier drift velocity in the strip which matches the image scanning velocity thereby giving enhanced image resolution. Modulation in photocarrier current which constitutes the detected image is measured as a bulk resistivity change between two readout electrodes positioned near one end of the strip.

Abstract: A device for visually imaging invisible radiation, having a detector and ht emitting diode circuit interposed between two identical coded rotating discs, wherein the LED provides an output in response to the invisible radiation passed by the first disc and detected by the detector. That portion of LED output passed by the second disc is the output of the system, which output will visually appear as a gray field with a bright spot corresponding in position to the position of the radiation source in the field of view of the system. The appearance of the output results from the patterns of the disc which permits 50% transmissivity at any moment in time when an infrared source is present. The visual appearance resulting from at least one complete rotation of the disc is a field of 25% illumination with bright spots of 50% illumination therein corresponding to bright spots in the field of view.

Abstract: An infrared line scanning instrument is provided which scans a single line in a field of view of the instrument. The scan is performed by a scanning mirror which is transparent in the visible and reflective in the infrared region of the spectrum. The infrared radiation is applied to an infrared detector which feeds a display in the form of a light-emitting diode array to light an element in the array in accordance with the amplitude of the IR irradiance seen by the instantaneous field of view throughout the scan. The display is superimposed from the back side of the scanning mirror upon the visible field of view seen by the observer and/or a camera. The instrument thus generates a record of the thermal profile of a single line of a viewed target which is spatially correlated with its location on the target.

Abstract: A thermal energy receiver is disclosed comprising a cooling means for cooling an infrared detector including a detector array for producing electrical representations of thermal energy radiating from a scene and an array of cold shields providing an individual cold shield aperture for substantially shielding each detector element of the array from energy generated outside the solid angle subtended by the optical elements, and electro-optics for converting the electrical output of the detector array to visual signals for displaying the scene.

Abstract: The invention contemplates improvement in the interpretability of heat-detection data, resulting from scanning a field. One or more heat-detecting devices are caused to scan the field and to create light modulation, superposed on a monitoring display of the field, the monitoring display being the product of observing the field in a band (e.g. visible light) other than that of the scanned heat response. The result is to superpose on the monitoring display brightened light modulations in accordance with heat sources encountered in the course of heat scanning the same field.

Abstract: Infrared radiation over a field of view is scanned in a first direction by an aximuth scan mirror and optically coupled to a spherical reflecting mirror. The scanned infrared radiation is reflected by the spherical mirror to a first surface of a vertical scanning mirror which forms an image on an adjacent detector array. The electrical signal output of the detector array, proportional to the intensity of the detected infrared radiation, is processed and coupled to an array of light emitting elements. The array of light emitting elements produces a visible image, corresponding to the infrared image, which is projected onto the other surface of the vertical scanning mirror, the visible radiation reflected therefrom being optically coupled to the rear surface of the azimuth scan mirror and thereafter to a recording medium or display device to produce a thermal image of the field of view.

Abstract: An infra-red scanning system with raster scan display unit operating in the visible spectrum, in which the image is scanned across a linear array of detector elements to provide a signal multiplexer with electrical signals related to the detected radiation pattern. The operation of the raster scan display unit is synchronised to the operation of the scanning system so that the horizontal time base integrator is gated according to the speed of the scanning system, and the vertical time base is gated to operate in synchronism with the multiplexer in order to minimise optical distortion in the display.

Abstract: A device for the elimination of the effect of background radiation on the image representation in an IR-camera comprises scanning elements and a detector for the conversion of IR-radiation to a video signal and this video signal is supplied to an image representation unit via an a.c. voltage-coupled circuit, an image signal and a background signal appearing periodically and separate from each other in the camera.

Abstract: A thermal imaging system having a scan generator for optically scanning a field of view in a two dimensional interlaced object space scan pattern; and for applying received thermal energy to an array of detector elements having a geometrical configuration relative to said scan pattern, such that each detector element views every point in the field of view during each scanning frame. The detector output signals are applied to a light emitting diode array so that each detector element is electrically coupled to a corresponding light emitting diode whose angular location within the diode array corresponds to the angular location of the associated detector within its array; and the resultant visible light is processed through the scan generator to provide a two dimensional interlaced scan reconstruction pattern which is synchronized with the object space scan pattern.