Abstract: A passive thermal imaging system includes multiple detector arrays, imaging optics, and processing electronics. Each of the detector arrays include pixels and detect thermal electromagnetic radiation (EMR) within a band around a desired EMR wavelength. The imaging optics receive thermal EMR within the band from an object and image the received thermal EMR from a same region of the object onto pixels of each of the detector arrays. The processing electronics receive a detected signal from each of the pixels of the detector arrays, calculate a correlation value based on a multi-correlation of the received detected signals of corresponding pixels of different detector arrays, and compare the correlation value with a threshold correlation value to determine that a detection event has occurred in response to the correlation value exceeding the threshold correlation value, the threshold correlation value being equal to or between 0.8 and 0.85.

Abstract: A passive thermal imaging system is described. The system includes at least one detector array configured to detect thermal electromagnetic radiation (EMR), imaging optics, and processing electronics. The imaging optics are configured to receive thermal EMR from an object, and to image the received thermal EMR onto pixels of each of the at least one detector array. The processing electronics are configured to receive a detected signal from each of the pixels of the at least one detector array, to calculate a correlation value based on a correlation between the received detected signals from the pixels, and to compare the correlation value with a threshold correlation value to determine whether a detection event has occurred.

Abstract: An optical absorption gas analyzer is provided for determining the concentration of a target gas in a sample, comprising: a chamber for containing the sample in use; an optopair, comprising a light emitting diode (LED) arranged to emit radiation into the chamber and a photovoltaic radiation detector arranged to detect radiation transmitted through the chamber from the LED and to output a corresponding detection signal SS; a temperature sensor arranged in thermal contact with the LED and the photovoltaic radiation detector, and to output a temperature signal T representing the temperature of the optopair; a memory having stored therein data representative of the baseline detection signal ST output by the optopair in the absence of the target gas as a function of the temperature of the optopair across a range of temperatures; and a processor adapted to generate a differential detection signal SA indicative of the concentration of target gas in the sample by retrieving from the memory the baseline detection sign

Abstract: An apparatus and methods are provided for heating and sensing the temperature of a chemical reaction chamber without direct physical contact between a heating device and the reaction chamber, or between a temperature sensor and the reaction chamber. A plurality of chemical reaction chambers can simultaneously or sequentially be heated independently and monitored separately.

Abstract: A mechanism of a monitoring unit of an electric rotating machinery covered in a housing that intercepts photoelectron transmission, the mechanism has: a monitoring window penetrating a part of the housing and configured to allow passage of photoelectrons and not to allow passage of gas; a camera arranged outside the monitoring window and configured to receive radiated photoelectron generated in the housing and passing through the monitoring window and to generate image data from the radiated photoelectron; and a computing unit configured to process the image data. The computing unit has reference image data storage means for storing image data resulting from blackbody radiation occurring in a reference state in the housing, as reference image data, and temperature calculating means for comparing the image data with the reference image data, thereby to calculate the temperature in the housing.

Abstract: An apparatus and methods are provided for heating and sensing the temperature of a chemical reaction chamber without direct physical contact between a heating device and the reaction chamber, or between a temperature sensor and the reaction chamber. A plurality of chemical reaction chambers can simultaneously or sequentially be heated independently and monitored separately.

Abstract: A dialysis system includes a dialysis instrument; a disposable item configured to hold a dialysis fluid and including an at least substantially opaque portion and an at least substantially clear portion; at least one non-invasive temperature sensor mounted to the dialysis instrument so as to be pointed selectively at the at least substantially clear portion and the at least substantially opaque portion; and a processor configured to calculate a temperature of the dialysis fluid within the disposable item using (i) a first temperature measurement from the at least one sensor while pointed at the at least substantially opaque portion, and (ii) a second temperature measurement from the at least one sensor pointed at the at least substantially clear portion.

Abstract: Temperature measurement using a pyrometer in a processing chamber is described. The extraneous light received by the pyrometer is reduced. In one example, a photodetector is used to measure the intensity of light within the processing chamber at a defined wavelength. A temperature circuit is used to convert the measured light intensity to a temperature signal, and a doped optical window between a heat source and a workpiece inside processing chamber is used to absorb light at the defined wavelength directed at the workpiece from the heat source.

Abstract: A mechanism of a monitoring unit of an electric rotating machinery covered in a housing that intercepts photoelectron transmission, the mechanism has: a monitoring window penetrating a part of the housing and configured to allow passage of photoelectrons and not to allow passage of gas; a camera arranged outside the monitoring window and configured to receive radiated photoelectron generated in the housing and passing through the monitoring window and to generate image data from the radiated photoelectron; and a computing unit configured to process the image data. The computing unit has reference image data storage means for storing image data resulting from blackbody radiation occurring in a reference state in the housing, as reference image data, and temperature calculating means for comparing the image data with the reference image data, thereby to calculate the temperature in the housing.

Abstract: Temperature measurement using a pyrometer in a processing chamber is described. The extraneous light received by the pyrometer is reduced. In one example, a photodetector is used to measure the intensity of light within the processing chamber at a defined wavelength. A temperature circuit is used to convert the measured light intensity to a temperature signal, and a doped optical window between a heat source and a workpiece inside processing chamber is used to absorb light at the defined wavelength directed at the workpiece from the heat source.

Abstract: This invention provides an apparatus for nondestructive residential inspection and various methods for using a thermal imaging apparatus coupled to inspect exterior residential components, interior residential components, a pitched roof and basement of a residential building and the electrical system of a residential building.

Abstract: A pyrometer for use in measuring temperatures in a furnace, has a lens-tube for supporting an optical head in a port of the furnace for viewing an interior of the furnace along a line of sight. The optical head converts infrared radiation to electrical signals. A photometer circuit connected to the optical head processes the electrical signals and a scaling circuit connected to the photometer circuit scales the electrical signals. An output circuit connected to the scaling circuit receives the scaled electrical signals and produces output signals for display or control of the furnace. A power supply connected to the scaling circuit powers the photometer, scaling and output circuits. Calibration in the scaling circuit scales the electrical signals to be most sensitive to a wavelength of middle infrared radiation to which at least one gas component in the furnace is semi-transparent, for measuring the temperature of the at least one gas component.

Abstract: The invention relates to a device for measuring the temperature of substrates, notably semiconductor wafers. The device comprises at least one radiation sensor for measuring the radiation emitted by the substrate and an element (19) which restricts the field of vision of the radiation sensor and is positioned between the substrate and the radiation sensor. The substrate temperature can be determined correctly and simply, even if the substrate vibrates or is tilting, owing to the fact that the edges (20) of the element extend in a straight line. The invention also relates to a corresponding method.

Abstract: A pyrometer for use in measuring temperatures in a furnace, has a lens-tube for supporting an optical head in a port of the furnace for viewing an interior of the furnace along a line of sight. The optical head converts infrared radiation to electrical signals. A photometer circuit connected to the optical head processes the electrical signals and a scaling circuit connected to the photometer circuit scales the electrical signals. An output circuit connected to the scaling circuit receives the scaled electrical signals and produces output signals for display or control of the furnace. A power supply connected to the scaling circuit powers the photometer, scaling and output circuits. Calibration in the scaling circuit scales the electrical signals to be most sensitive to a wavelength of middle infrared radiation to which at least one gas component in the furnace is semi-transparent, for measuring the temperature of the at least one gas component.

Abstract: Body temperature measurements are obtained by scanning a thermal radiation sensor across the side of the forehead over the temporal artery. A peak temperature measurement is processed to compute an internal temperature of the body as a function of ambient temperature and the sensed surface temperature. The function includes a weighted difference of surface temperature and ambient temperature, the weighting being varied with target temperature through a minimum in the range of 96° F. and 100° F. The radiation sensor views the target surface through an emissivity compensating cup which is spaced from the skin by a circular lip of low thermal conductivity.

Abstract: A substrate to be processed on which a thin film is formed is supported by a support member. The substrate to be processed is heated by a heating section. The surface temperature is measured by a radiation thermometer, and the heating temperature of the heating section is controlled by a control section, in response to the temperature measured by the radiation thermometer. Further, a blackbody is provided at a position optically symmetrical to the radiation thermometer with respect to the surface of the thin film. The blackbody is set at a constant temperature. The blackbody cuts stray light (noise light) which enters into the radiation thermometer.

Abstract: A thermopile radiation detector (10) has an optical filter layer (16) that supports a thermopile detector (22) and, in addition, filters undesired wavelengths. The filtering is accomplished by selectively absorbing electromagnetic radiation at predetermined wavelengths. The use of the thermopile radiation detector simplifies the overall construction of a system that incorporates the detector by eliminating one focal point in the optical system. By altering the filter material, the number of layers of filter material, etc., a plurality of detectors can be constructed, each responsive to a different wavelength. In forming the detector, the filter can be deposited on a thin backing material such as aluminum. Examples of suitable filter materials include alternating layers of zinc selenide/magnesium fluoride or germanium/magnesium fluoride. After the filter is deposited, the backing is etched away and suitable thermocouples, such as bismuth/antimony, are deposited on one side of the filter.

Abstract: A method and device for detecting an incorrect position of a semiconductor wafer during a high-temperature treatment of the semiconductor water in a quartz chamber which is heated by IR radiators, has the semiconductor wafer lying on a rotating support and being held at a specific temperature with the aid of a control system. Thermal radiation which is emitted by the semiconductor wafer and the IR radiators is recorded using a pyrometer. The radiation temperature of the recorded thermal radiation is determined. The semiconductor wafer is assumed to be in an incorrect position if the temperature of the recorded thermal radiation fluctuates to such an extent over the course of time that the fluctuation width lies outside a fluctuation range &Dgr;T which is regarded as permissible.

Abstract: A method of remotely measuring the temperature of a body, such as a semiconductor wafer, whose transparency varies with both wavelength and temperature and is characterized by an optical absorption edge. The body is illuminated at wavelengths on either side of the optical absorption edge. Based on the measured reflectivity at wavelengths shorter than the optical absorption edge, the direct reflectivity at wavelengths longer than the optical absorption edge is predicted and used to estimate the component of total reflectivity, at wavelengths longer than the optical absorption edge, which corresponds to propagation through the body and reflection back through the body. Light reflected from the body, measured in an "active" channel, is distinguished from light emitted passively by the body and measured in a "passive" channel. In the case of an opaque body, this allows the estimation of the emissivity of the body, and a temperature estimate based on Planck's law.

Abstract: Apparatus for processing a silicon workpiece uses reflected UV light to measure and control the workpiece temperature. A linearly polarized beam including UV light is directed onto a silicon surface to produce a reflected beam. The reflected beam is cross-polarized to null out much of the light, and the resulting residual reflectivity spectrum is determined. The temperature is determined from the characteristics of this spectrum. A workpiece heating station uses this measuring technique to accurately control the temperature of a silicon workpiece and temperature-dependent processing over a wide range of processing temperatures, including temperatures below 500.degree. C.

Abstract: A shutter 3 which can be momentarily held open and immediately closed, is disposed adjacent to an aperture stop 4 in an optical system, and a temperature sensor 5 is provided for measuring the temperature of the shutter 3. The blades of the shutter 3 can be utilized as a reference heat source. With the shutter 3 disposed adjacent to the aperture stop 4, the optical equivalence in the case when a reference heat source is inserted and in the other case, is not spoiled. A shutter 202 which can be readily momentarily held open and immediately closed under control of a shutter controller 203, is disposed at the optical pupil position of a combination lens 201. When the shutter 202 is closed, thermal image data is stored in a shading memory 208.

Abstract: A measuring technique and method are provided to simultaneously determine the molecular density of several molecular species and the temperature within a closed process room in a melting or combustion process. In such processes in the industry, e.g. in metallurgic process industry, it is important to determine the temperature and the contents within the gas or flame without physically connect to or disturb the process. This has shown to raise large problems especially at high temperatures. The radio signal over a frequency band is measured on the outside of the process room through a window in the mantel covering as a function of frequency and registered on a computer as a radio spectrum. The system is calibrated by using a known signal transmitted through the process room. The spectral lines are identified by their frequency from a database. The temperature is determined from several lines of the same molecular specie and the molecular densities are determined from the intensities of the lines.

Abstract: A system (10) for simultaneously measuring temperature and CO, CO.sub.2 and HC gas content of vehicle (11) exhaust detects and analyzes a beam of infrared electromagnetic radiation (21) projected through a plume (13) of vehicle exhaust to assess the concentration of CO, CO.sub.2, and HC in the vehicle exhaust and detects and analyzes infrared electromagnetic radiation (15) emitted by the plume (13) to assess the temperature of the plume (13) and, consequently, whether the vehicle's (11) catalytic converter is operating in the cold or hot mode. Essentially simultaneous measurement is taken by intermittently interrupting the beam (21) of projected infrared electromagnetic radiation and detecting and analyzing the emitted infrared radiation (15) during the intervals of interruption when the beam (21) is not projected through the plume (13). Intermittent projection of the beam (21) is accomplished by insertion of a chopper wheel (22) between an infrared beam projector (20) and the plume (13).

Abstract: The assembly (10, 10') is a real time imaging device for detecting radiation from an object field (12) which is periodic in time. A video camera (14) detects emitted and reflected radiation from the object field (12) and produces a video signal of the image and a timing signal. A processor (16) synchronously averages successive video signals and stores same in an image buffer (26) to obtain an image from which has been eliminated unsynchronous noise. Alternatively, the elimination of unsynchronous or ambient noise may be performed partially or wholly within the camera (14) prior to processing.

Abstract: Method and apparatus for measuring the radiation originating from one side of a wafer of semiconductor material using a pyrometer, wherein non-blackbody compensation radiation is projected onto that side to compensate for the reflectivity of the wafer of material and wherein the intensity of the non-blackbody compensation radiation is controlled subject to the amount of radiation measured by the pyrometer.

Abstract: A method for sensitive and precise determination of the temperature of a thin layer or wafer of bandgap material, without requiring contact to the layer or to the wafer, is based on selection of optical wavelength or wavelengths and the measurements of transmittance through the sample at such wavelength(s). The relationship between the temperature variations of the absorption coefficient, whether determined by band-to-band absorption or a totally different mechanism, and the measured transmittance, provide an indication of the sample temperature, without regard to the ambient temperature. The method prescribes how to select the wavelength(s) based both on the intrinsic properties of the material and on the practical considerations of the measurement situation.

Abstract: A narrow-band pyrometric system measures the temperature of an object (1), such as a semiconductor wafer (1), that is coated with a film (2) having an absorption band. The thermal radiation emitted by the coated object (1) passes through a lens (3) and aperture (4), and then a filter (5). The passband of this filter (5) falls within the absorption band of the film (2). The transmitted radiation is then collected by the radiation detector (6), which measures the intensity. The detected radiation is at a wavelength where the heated object (1) is substantially opaque, and the effect of uncertainties in the emissivity on the temperature measurement is minimized. Thus, a method is provided to coat the object (1) with a film (2) of material having an absorption band encompassing the filter (5) passband, and a thickness sufficiently great that the object (1) appears opaque when viewed through the filter (5).

Abstract: A method of accurately determining the temperature of a thin layer of bandgap material without requiring contact to the layer involves the use of optical radiation through the layer and the detection of optical absorption by the layer. The relationship between the temperature varying bandgap energy and the resulting optical absorption characteristics provides an indication of temperature independent of ambient temperature. Apparatus for performing high quality temperature detection and control is also provided.

Abstract: A method is disclosed for an optical remote measurement of the air temperature at a distance by laser excitation, in which, by means of a laser generator and by excitation of energy band transitions in the Schumann-Runge band of molecular oxygen, fluorescence of the oxygen is caused, the intensities of the fluorescence induced in two different bands are measured, the ratio of these intensities is determined and the temperature is derived therefrom wherein, on a section of appreciable depth, two absorption spectral lines are excited which at least overlap and which belong respectively to two different Schumann-Runge oxygen bands and the emission spectral line of the laser generator has a very small width with respect to that of the absorption spectral lines and its central frequency is adjusted to be substantially close to the maxima of the two absorption spectral lines.

Abstract: A method for remotely measuring an unknown temperature Ts of a transparent medium by comparison with the known temperature Tr of a transparent reference material consisting of the steps ofcombining the outputs of a continuous-wave (CW) laser and a high intensity pulsed laser to form a combined laser output beam, wherein the high intensity pulse component of the output beam exceeds the intensity required to produce stimulated Brillouin scattering (SBS) in the transparent medium;splitting the combined laser output beam into first and second sub-beams;amplifying the CW components of the first sub-beam to an intensity exceeding the intensity required to produce stimulated Brillouin scattering (SBS) in the reference material while simultaneously suppressing the pulse components in the first sub-beam;directing the first sub-beam with the amplified CW component into the reference material and thereby generating a CW phase-conjugate beam;directing the second sub-beam into the transparent medium and generating a pulse

Abstract: A method of accurately determining the temperature of a thin layer of bandgap material without requiring contact to the layer involves the use of optical radiation reflected off the bandgap material and the detection of the reflected energy. The relationship between the temperature varying bandgap energy and the resulting reflection characteristics provides an indication of temperature, independent of ambient temperature.

Abstract: To remotely measure the unknown subsurface temperature T.sub.s of a bulk transparent medium such as ocean water, a laser beam having a high power or intensity is split into two parts, a probe beam and a reference beam. The probe beam is directed into a sample of ocean water, and the reference beam into a reference sample of water having a known temperature T.sub.r. The intensities of the two beams, which exceed a predetermined threshold are sufficient to cause stimulated Brillouin scattering (SBS) within the two samples and produce therefrom two phase-conjugate beams. The two phase-conjugate beams are mixed to produce a heterodyne frequency that is proportional to the difference in temperature T.sub.s and T.sub.r. The frequency difference is converted into a temperature value equal to the value of T.sub.s.

Abstract: The invention involves a method for measuring the temperature in a heating system of the type having an electrically heated hot plate with a filled cooking vessel on it and a radiation pick-up located at varying distances from the side of the vessel and pointed at it which emits a signal indicating the temperature of the substance in the vessel based upon radiation from an area on the side of the vessel as detected by the radiation measurement field of the radiation pick-up, the radiation intensity of which decreases as a square of increasing distance. To compensate for the effect on measurements of spurious radiation form the changing position of the vessel on the hot plate, the invention involves adjusting the angle of a non-intersecting radiation measurement field to obtain corresponding reduction in the area of radiation detetion on the vesel for increasing distances between vessel and radiation pick-up.

Abstract: Subsurface waves in an ocean are created by the turbulence in a submarine's wake. These waves can be remotely detected by a search submarine by monitoring subsurface water temperatures using a laser. A pulsed laser beam is directed into the water to at least the depth of the thermocline and an analysis is made of the resultant Brillouin and Rayleigh backscatter components. Wavelength shifted Brillouin scatter is mixed with the unshifted Rayleigh scatter in a self-heterodyne manner for each volume element of illuminated water, and the frequency of the heterodyne signal is measured and converted into equivalent temperature values. This produces the desired temperature-depth profile of the water enabling detection of the first submarine by tracking the internal waves at or near the ocean thermocline.

Abstract: A method of accurately determining the temperature of a thin layer of bandgap material without requiring contact to the layer involves the use of optical radiation through the layer and the detection of optical absorption by the layer. The relationship between the temperature varying bandgap energy and the resulting optical absorption characteristics provides an indication of temperature independent of ambient temperature. Apparatus for performing high quality temperature detection and control is also provided.

Abstract: A temperature measuring apparatus is provided for determining the temperature of a target material to be measured as compared with the temperature of a spaced reference source which has a temperature control for controlling the temperature of the reference source. A differential radiation detector having a first detector exposed to the target material and a second detector which is shielded from the target material and exposed to the reference source provides a differential output or error signal which is used to control the temperature of the reference source. When the reference source temperature is the same as the target, the temperature of the reference source is read out which is the temperature of the target material regardless of the emissivity. The differential radiation detector is positioned in spaced relation to the target material and is focused onto the target and the reference material and the error signal generated is used for controlling the temperature of the reference source.

Abstract: The present invention provides graphs and a method of using the graphs to determine the substrate temperature used during oxygen implantation of SIMOX wafers. The method establishes a relationship between the wavelength of minimum transmittance for infrared energy and the implantation temperature. Such relationships are then expressed, in the form of graphs, for various selected oxygen dose and energy levels.

Abstract: Temperature is measured by launching pulses of light into an elongate optical fibre and determining the temperature at positions along the fibre from the intensity of light scattered at those positions. The input pulses can have either the same or two different wavelengths, and the scattered light can be either Raman or Brillouin scattered and either forward scattered or backscattered. One position along the fibre can be maintained at a known temperature in order to provide a reference for other calculations. In particular embodiments the temperature is derived from the ratio between the intensities at two anti-Stokes wavenumber shifts or between an anti-Stokes scattered and a Rayleigh scattered intensity measurement. Otherwise the intensities of Stokes and anti-Stokes shifted Brillouin back scattered light can be used to derive the temperature.

Abstract: A method of determing the actual temperature of a layer of an infrared material, especially during heat cleaning, which includes measuring the thickness of the layer and the amount of radiation being emitted from it. An apparent temperature corresponding to a desired actual temperature is found from a curve of apparent temperature, which are derived from the radiation amount, versus thickness. The apparent temperature which corresponds to the desired actual temperature compensates for interference effects on the radiation measurement. A computer may be utilized to calculated the apparent temperature which corresponds to the desired actual temperature and to regulate and maintain the infrared material at the apparent temperature.

Abstract: A detector for a gas analyzer includes a thermal detector, an absorptive film on the surface of said thermal detector, and an enclosure containing a reference gas of the gas species of interest such that the thermal detector is in thermal contact with both the absorptive film and the reference gas. During irradiation, the absorptive film absorbs radiation which passes through the reference gas and causes the thermal detector to generate a corresponding output. When the irradiation is terminated, the heat content of the reference gas, which will be dependent upon the amount of the radiation absorbed, will be communicated to the thermal detector to cause the thermal detector to provide a second output representing the amount of radiation absorbed by the reference gas.

Abstract: A two-wavelength I.R. pyrometer for monitoring the rapid heating of materials by C W lasers or electron beams. The I.R. radiated from the material is separated into two closely adjacent wavelengths and signal values representative of those wavelengths are obtained. These signal values are then processed through an electronic circuit where the signal value of one of the signals is held substantially constant by a feedback control while the other signal value is influenced by approximately the same feedback control applied to the first signal value and wherein the resultant signal values are then processed through a circuit determining a ratio of one signal value divided by the other. This is then a measure of the temperature of the material. Also disclosed is a chopper wheel for a two-wavelength I.R. pyrometer. The wheel has a plurality of circumferentially extending I.R. filters of alternating wavelengths (.lambda..sub.1, .lambda..sub.2).

Abstract: The method of determining temperature of gas and particles in a conductive working medium of a magneto hydrodynamic generator comprises the steps of measuring values .phi.1, .phi.2 and .phi.3 of radiation fluxes from a primary radiation source, the working medium of the MHD generator and a working medium subject to radiation from the primary source at least on two wavelengths .lambda..sub.1 and .lambda..sub.2 ; and computing the temperature of gas and particles from relationships obtained by a generalized method of reversing spectral lines. The wavelength .lambda..sub.1 is found at the center of a resonant line of an alkaline metal spectrum. Selection is made during measurements of those groups from a sequence of the obtained groups of values .phi.1, .phi.2 and .phi.3 at a permissible error k.

Abstract: A system for the measurement of temperatures in a reactor such as those operated under high pressure and/or temperature is disclosed. The temperature is measured by the use of a pyrometer which is in optical communication with a measuring duct which can be disposed in the wall of the reactor and is in optical communication with the reactor interior. The measuring duct comprises two concentric tubes the outer one of which extends beyond the inner tube in the direction of the reactor interior and has a conical construction immediately following the termination of the inner tube. The concentric tubes are provided with a common end section such as in the form of a cone in the direction of the reactor exterior. A hermetic housing defining a safety chamber is disposed exterior thereof, the hermetic housing having two opposed pressure type and heat resistant windows in alignment with the inner tube and the pyrometer. The hermetic housing is not normally permanently attached to the measuring duct.

Abstract: The self-generating thermal radiation properties of an optical fiber element are employed to determine the temperature, location and length of a hot spot, or region, of an object.

Abstract: A method and apparatus are provided for indicating the altitude of the tropopause or of an inversion layer wherein clear air turbulence (CAT) may occur, and the likely severity of any such CAT, which includes directing a passive microwave radiometer on the aircraft at different angles with respect to the horizon. The microwave radiation measured at a frequency of about 55 GHz represents the temperature of the air at an "average" range of about 3 kilometers, so that the sine of the angle of the radiometer times 3 kilometers equals the approximate altitude of the air whose temperature is measured. A plot of altitude (with respect to the aircraft) versus temperature of the air at that altitude, can indicate when an inversion layer is present and can indicate the altitude of the tropopause or of such an inversion layer. The plot can also indicate the severity of any CAT in an inversion layer.

Abstract: Apparatus is described for detecting air disturbances created by low level wind shear. The apparatus includes optics for directing infrared radiation towards a continuously rotating chopper wheel having a plurality of infrared filters which have effectively different distance sensitivities and therefrom to a radiation sensor which produces an analog output signal that is demodulated by a synchronous demodulator. The demodulated signal is then routed through a gated integrator to a selective multiplexing circuit which has a plurality of output channels and is controlled by an electronic detector connected with the chopper wheel. Each channel includes a low pass filter and the outputs therefrom are coupled to a signal processor which thus receives periodically updated information to provide a display indicative of sensed air disturbances due to low level wind shear.