Thermal imaging systems are characterized by the minimum resolvable temperature (MRT), signal transfer function (SITF) and noise equivalent temperature difference (NEDT). While the NEDT and SITF can be auto-mated, methods to automate the MRT have had limited success. A semi-automated MRT technique is introduced which is faster and more accurate than the classical method. The new method also identifies an observer's variability, distractions and learning curve.

Imaging spectrometers are expected to play a crucial role in many upcoming unmanned planetary missions. The scientific goal of imaging spectrometry is to obtain compositional data about the target body by measuring the intensity and distribution of characteristic spectral signature features in the visible and infrared radiation reflected and emitted by surface materials. As part of the Planetary Instrument Definition and Development Program (PIDDP) sponsored by the National Aeronautics and Space Administration (NASA), a modular imaging spectrometer design with applicability to a diverse range of future planetery missions is being developed at the Jet Propulsion Laboratory (JPL). Derived from the near-infrared mapping spectrometer (NIMS) developed by JPL for the Galileo mission to Jupiter, the first version of the visual and infrared mapping spectrometer (VIMS) has been tentatively selected for NASA's recently approved Mars Observer mission.

Thermal wave imaging is a non-destructive testing technique which uses optically induced heat fluxes to probe the physical and chemical properties of solid samples. Localised heat sources are generated by the absorption of light from a focussed laser beam, and the propagation of heat from these sources is modified by the local thermal properties of the sample, providing a contrast mechanism. The technique can be applied to transparent, translucent and opaque materials. Information can be obtained about the thickness of coatings, the integrity of coating substrate interfaces, the presence of microscopic defects and inclusions, and the thermal characteristics of the material. Information can be obtained with a resolution of a few microns in both the X-Y plane, and along the Z-axis into the sample.

This paper describes a new method of measuring stress on the surface of a structure subjected to dynamic loading. Although the theoretical relationship between the changes in temperature at a point on the surface and the related change in stress has been known for over 100 years, it has only recently been possible to measure reliably and without contact the small changes in temperature down to 0.001°K involved. The performance characteristics of an instrument for Stress Pattern Analysis by measurement of Thermal Emission (SPATE) and the results of measurements on real structures recently obtained will be described.

The RCA Infrared Imaging Experiment (IRIE) flown January 12-18, 1986, on Shuttle Mission 61C is reported. The infrared camera, which was operated in the 3.5- to 5-μm spectral band, replaced one of the visible CCTV cameras on the Shuttle. The camera employed a 160 x 244 element monolithic platinum-silicide (PtSi) area focal-plane array developed at RCA Laboratories. The array characteristics, camera electronics, optics, and focal plane cooling are summarized. The preplanned scenes for the IRIE are listed. A total of about 2.5 hours of data, including some preplanned scenes and unscheduled operation, were recorded on the first, third, fourth, and fifth days of the mission. Several of the recorded scenes are mentioned specifically in the paper, and a short videotape will be shown at the presenta-tion. Quantitative analysis of the data is in progress.

The signal processing techniques of infrared imaging system are discussed. Performance of FEV for chopping mode in the system and some basic designing principles of the system are described. Main methods for processing signal of infrared imaging system are suggested. Emphasis is laid on the multiple fields accumulation and image difference processing technique. On the basis of describing the main principle of the method, the concrete project is put forward. home test results are also given.

A radiometric model designed to facilitate target to background image modeling has been developed (c.f. Schott & Biegel 1985) . The model was designed to incorporate atmospheric transmission, upwelled and ciownwelled path radiance and variations in these factors as a function of view angle. The radiometric model has been applied to Idnetic temperature image models to simulate long wave infrared image characteristics, including spatial resolution and scale. A limitation of the model as presented to this point has been the lack of empirical data on emissivities of natural objects. This paper includes a description of two devices for measurement of the hemispheric and angular emissivity from large irregular surfaces. Emissivities for selected materials are presented and incorporated into the model. The effect of emissivity on simulated images is discussed. This model is being developed as part of an overall effort to expand long wave infrared image science. The potential for application of the expanded model to sensor performance evaluation and target recognition assessment are discussed.

Because it is impossible to obtain real-image data that represent all of the scenarios and environmental conditions under which target recognizer models should be tested, we have developed a scene composer to aid in the analysis and evaluation of multiple-sensor electronic vision systems. The scene composer can present real-image data, computer-generated synthetic image data, and/or data composed of both real and synthetic imagery merged together so as to mimic an actual scene. For example, synthetic targets can be merged with real-image background scenes or vice versa. In addition, the composer uses a simple multiple scattering model to simulate image degradations due to fog or dust. Presently, our synthetic generator is a simple infrared scene model based on the assumption that a given absolute temperature in a scene will be detected as a graybody radiance value. The temperature model allows wavelength-dependent functions such as surface emissivity, detector responsivity, and spectral filter characteristics to be included in the integration of the Planck equation. Real-image data have been obtained from the Texas Instruments 8-bit LANTIRN Database and from other sources. The paper includes examples of real, synthetic, and merged infrared images and images degraded by simulated fog and dust.

This paper describes the application of matched filter theory and maximum likelihood estimation to point source target position estimation in a scanning electro-optical system. The estimation is maximum likelihood at every pixel regardless of the noise and responsivity characteristics across the detector array. Algorithms are detailed and hardware is presented which is well matched to the implementation of the algorithms. Software issues are also described. The hardware is composed of a data flow processor and a general purpose signal processor, both manufactured by Signal Processing Systems, Inc.

Plume IR emission of turboshaft engines is investigated experimentally in 1-14.5 micron band by a Barnes Spectroradiometer with CVF and two IR scanners (AGA 782 Thermovision SW and LW) in order to compare it to a computer model and therefore to identify the most important parameters. This experimental set-up is completely adequate to field measurements of infrared signature from a turboshaft engine. It is completely interfaced to a HP 9836 computer to drive the instruments and to reduce on-line both spectral and spatial IR data. The spectral results are available as a function of wavelength (also in polar diagrams) and are connected to the emission wavelengths of the plume components. Spatial results are available in pictures (128x128 elements), displayed on a H.R. Colour Monitor. A sophisticated computer program allows to increase the detail of information. Spatial results are important to understand and to investigate phenomena like turbolence, non assial symmetric emission, etc. In order to estimate the real infrared signature of a turboshaft engine the transmittance of the atmo sphere and the background emission have been measured during the field measurements. Also, absolute calibrations of spectroradiometer and scanners are conducted in our lab. Estimate of errors in terms of precision and accuracy of the measure are as well considered. Plume spatial infrared signatures of engine, for real installation on a rotorcraft, have been measured in order to adequate our computer model. This study is connected to a R&D program in the field of IR signature suppression for rotorcraft application.

A description of a test facility for testing and evaluating visible and infrared (IR) focal plane arrays (FPA's) and associated components and subsystems is given. The facility is comprised of three computer controlled test systems for characterization of hybrid FPA's, detector arrays, and readout electronics under cryogenic conditions. Facility capabilities include FPA assembly and dewar test and assembly.

The Aerospace Corporation has conducted 5 flight series on the Kuiper Airborne Observatory (KAO) utilizing two-dimensional array infrared cameras. The KAO is operated by NASA Ames Research Center. These flights have several objectives with the primary task being the test in an aircraft environment of state-of-the-art two-dimensional arrays of both blocked impurity band and bulk silicon devices provided by Rockwell International and the Aerojet ElectroSystems Company under contract to the U.S. Army. There is extremely low crosstalk due to the SWIFET (switched FET) readout scheme employed on all three arrays flown to date. The - 500-element arrays were operated with a frame time of 307 psec which placed a large burden on the data recording equipment. The flight data were recorded on 8" floppy disks, a 9-track tape recorder, and a high-speed 28-track flight recorder. System sensitivities have been shown to be good enough to detect astronomical sources, both pointlike and extended in nature. Both staring and scanning experiments were performed using several astronomical sources. In the scanning experiments, a star was used as a point source which was scanned across the array at a fixed angle and angular rate using the rocking secondary mirror of the KAO. The data were then processed in a Time Delay and Integrate mode by the Boeing Aircraft Corporation; this TDI simulation achieved close to the theoretically predicted improvement in signal-to-noise ratio.

Although the pyroelectric vidicon infrared sensitive television camera has been available for over a decade, development of the tubes and cameras did not cease with the demonstration of the first imagery. This paper describes firstly the progress which has been made in the UK towards a higher performance vidicon tube, and secondly the improvements to cameras which were necessary in order to obtain the optimum performance from the tubes. Operation of the cameras in a number of situations will be described.

The Plessey Company, in conjunction with the U.K. Ministry of Defence, has developed a range of pyroelectric infrared detectors which in linear and two dimensional array formats may be used at room temperature. Sensor research based upon these devices is carried out at the Royal Signals and Radar Establishment (RSRE) Malvern, and Plessey (Roke Manor). This paper describes sensors employing linear arrays of detectors, and gives examples of imagery that has been obtained. The sensors built to date employ germanium lenses, a chopper to modulate the incoming radiation, and sixty four element linear arrays of detectors. The Plessey system reads the peak value of signal from the detector with the chopper "open" and displays this in the form of a grey-scale picture, whilst the RSRE system takes the difference between the signal with the chopper open and closed and displays this as a grey-scale picture. For the systems discussed, the instantaneous field of view is about 3.5mR and the NETD (Noise Equivalent Temperature Difference) better than 0.2K. The sensors may be used in a panned mode to give large-area surveillance, in a staring mode to provide image information by virtue of the motion of the target or mounted in an aircraft in a linescan mode. Examples of imagery obtained in these modes are presented.

This paper describes two different focal plane arrays, both using direct injection inputs. We compare a device using a charge coupled device multiplexer with a more novel multiplexed electronically scanned array (MESA), which can give better performance in the 8-10 4m band. The basic limitations of the direct injection technique are discussed, including sensitivity to gate bias voltage and to I•Rproduct of the infrared diode. I•product is proposed as a figure of merit. Charge storage capacity and dynamic range are also discussed, especially in relation to the performance required of the uniformity correction electronics.

An earlier paper by Bradley and Dennis outlined he sampling effects limit the high frequency spatial performance of close-packed two-dimensional focal plane arrays, and described conceptually how these might be overcome. These concepts have since been put into practice and results are presented which show: a) manifestations of the basic effects. b) their reduction through microscanning in a real-time imaging environment. The results were obtained from an imaging system developed by MCCS for RSRE, capable of driving the complete range of 2D detectors currently produced in the UK.

This paper describes a Dual Waveband Imaging Radiometer (DUWIR) which GEC Avionics have developed for RSRE Malvern and which has now been put into production. This calibrated imager basically provides synchronous, simultaneous imagery in both infrared wavebands, that is pixel by pixel overlay, from a single optical channel. It combines current generation modular FLIR performance with the necessary internal calibrated references to enable it to function as a radiometer, measuring apparent temperatures in both bands. It also has all the necessary radiometric and system status information displayed in graphic form, overlaid on video to permit ease of subsequent analysis of the imagery. It is based on the Class II, UK Thermal Imaging Common Module (TICM) modules (Figure 1), which comprise the six processing cards and power supply module, the scanner module, the detector lens module, the head amplifier module and the motor drive module which form the basis of the UK high performance, indirect view, modular thermal imager. Selected systems contractors can configure a complete imaging system from these modules by adding a suitable housing, telescope, display, controls and cryogen supply. Note that as the Class II system is intrinsically TV compatible, scanning one TR line for every TV line (including interlaced fields) it does not require any additional scan convertor or interpolator.

The evolution in the UK of thermal imaging systems for use in submarines is outlined. A system is described in which a high-performance thermal imager is configured in such a way as to fit within a tubular structure while providing dual-field operation with an elevation facility, giving compatibility with a range of periscope designs. The aspects peculiar to submarine applications are discussed for each part of the system, and a technique for providing rapid surveillance using thermal imaging is described.

The development by Rank Pullin Controls of a compact, low cost, high performance thermal imager is described. This imager is based on a novel coaxial scanning technique designed at RSRE.

This paper discusses a signal processing unit developed for 2D Cadmium Mercury Telluride - Silicon hybrid (CMT-Si) photovoltaic detector arrays. It overcomes the severe fixed pattern noise problems associated with these detectors by performing the required nonuniformity removal in the analogue domain without the use of Digital Signal Processing (DSP) or fast, high resolution Analogue to Digital Convertors (ADC's). The reasons for the adoption of this approach stem from the need for a compact, high speed IR imaging system for use in automatic weapon guidance and homing systems particularly in the anti-armour role. A prototype system using this approach has been developed and used to operate a 32 x 32 element Random Access Line Scanned Array (RALSA) at frame rates in excess of 200Hz with measured NETD of less than 0.1°C. This same system, without further modification, will be capable of operating 64 x 64 element detector arrays with frame rates in excess of 400Hz if required.

Linear systems theory combined with Fourier transform techniques provides a powerful means to characterize electro-optical systems. We present the description and analysis of a particular scanning IR system whose characteristic Point Spread Function (PSF) is space-variant. This peculiarity of the PSF arises from the scanning geometry; the IR sensor spins as it drops toward the ground. A system impulse response, or Point Spread Function (PSF), is derived from effects including diffraction, motion blur, chromatic aberration and detector area. Other effects may be taken into account by cascading PSF's. Once the system PSF is determined, the output of the system is the convolution of the input irradiance with the PSF. Alternatively, the output is the familiar inverse Fourier transform of the product of transforms. However, the space-variance of the PSF makes the latter option impossible and the former difficult. The convolution progresses in a spiral manner, with the PSF width changing continuously. The method is tested using Fortran programs and a digital image processor. The digital images produced show expected results, revealing a marked increase in resolution as the sensor nears the ground.

The extended emission in the infrared celestial background maybe divided into three main components: the zodiacal background, the large discrete sources in the galaxy and the interstellar dust. The zodiacal background is due to the thermal re-radiation of sunlight absorbed by the dust in the solar system. An earth orbiting infrared telescope will detect the diffuse emission from this dust in all directions with maximum intensity lying roughly along the ecliptic plane where the density of dust is highest. Structure with scale lengths of 10° have been measured in both the visual and infrared; finer structure has been detected in the infrared by the Infrared Astronomy Satellite (IRAS). H II regions, areas of ionized gas mixed with and surrounded by dust, are the brightest discrete objects in the galaxy in the long wavelength infrared (LWIR, 7-30km). The visible radiation from the hot star(s) embedded in these regions is absorbed by the dust and re-emitted in the infrared with a range of temperatures characteristic of the thermal equilibrium for the surroundings of the dust. These regions are relatively large and, if close to the sun, can subtend a significant angular area of sky. The emission from the interstellar dust produces a filimentary structured background, the infrared "cirrus". The observed far infrared color temperature of ~20-35K for the cirrus is consistent with emission from graphite and silicate grains which absorb the interstellar radiantion field. The much larger LWIR color temperature is likely due to a greater abundance of submicron particles in the interstellar medium and, perhaps, from band emission due to polycyclic aromatic hydrocarbons. These galactic sources combine along the line of sight to produce an intense band of emission centered on the galactic plane which has full width at half maxima of about 2°.

HALOE is an optical remote sensor that measures extinction of solar radiation caused by the Earth's atmosphere in eight channels ranging in wavelength from 2.5 to 10.1 micrometers. These measurements, which occur twice each satellite orbit during solar occultation, are inverted to yield vertical distributions of middle atmosphere ozone (03), water vapor (H20) , nitrogen dioxide (NO2) , nitric oxide (NO) , hydrogen fluoride (HF), hydrogen chloride (HC1), and methane (CH4). A channel located in the 2.7 micrometers region is used to infer the tangent point pressure by measuring carbon dioxide (CO2) absorption. The HALOE instrument consists of a two-axis gimbal system, telescope, spectral discrimination optics and a 12-bit data system. The gimbal system tracks the solar radiometric centroid in the azimuthal plane and tracks the solar limb in the elevation plane placing the instrument's instantaneous field-of-view 4 arcminutes down from the solar top edge. The instrument gathers data for tangent altitudes ranging from 150 km to the Earth's horizon. Prior to an orbital sunset and after an orbital sunrise, the HALOE automatically performs calibration sequences to enhance data interpretation. The instrument is presently being tested at the Langley Research Center in preparation for launch on the Upper Atmosphere Research Satellite near the end of this decade. This paper describes the instrument design, operation, and functional performance.

The calibration of the Halogen Occultation Experiment (HALOE) Sun sensor is described. This system consists of two energy balancing silicon detectors which provide coarse azimuth and elevation control signals, and a silicon photodiode array which provides top and bottom solar edge data for fine elevation control. All three detectors were calibrated on a mountaintop in Tucson, Arizona, using the Langley plot technique. The conventional Langley plot technique was modified to allow calibration of the two coarse detectors which operate wideband. A brief description of the test setup is also given. The HALOE instrument is a gas correlation radiometer that is now being developed for the Upper Atmospheric Research Satellite (UARS).

Novel transmissometry techniques developed for use in support of long path extinction measurements are described along with samples of data from natural and manmade obscurants. Advantages derived from these new techniques include precise control over field of view (FOV), ultra-low drift rates in system baseline response, identical alignment of all multispectral wavelength bands, and negligible humidity and temperature effects on system performance. A multispectral differential field of view technique developed for use with the U.S. Army Atmospheric Sciences Laboratory's SMART system is described along with measurement results. The differential field of view results have implications on sharply peaked forward scatter phase functions in the presence of obscurants from visible to 14-μm wavelengths.

Spectroscopic methods provide an attractive alternative to wet chemical methods due to their fast responses. An instrument using the principle of gas-filter correlation was built in a laboratory and tested to measure methanol concentrations in exhausts from a methanolfueled vehicle. The instrument utilized the infrared spectrum between 8 pm and 11 pm. The sensitivity and discrimination against other interfering gases were adequate enough to obtain a detection limit of 0.5 ppm. The precision of the instrument varied from 5.5% to 1.2% for methanol concentrations ranging 7 ppm to 113 ppm. The study demonstrated a good agreement with the gas chromatograph analyses. The instrument has a strong potential for real-time monitoring of automobile emissions. A small drift in the zero setting was primarily due to the unstable temperature of optical components, especially the liquid-nitrogen cooled detector. An improvement in stability can be achieved by thermally insulating the analyzer to maintain a constant temperature.

Monitorization and regulation of the chip behaviour in the cutting zone present one of the major problems in the reliable operation of flexible manufacturing systems. The chips should be formed so as to eliminate the tool damage and enable their easy disposal from the cutting zone. For solving the problem a convenient regulation strategy should be developed. In the development of the strategy the authors extended the theoretical and experimental works on a special experimental device,which makes the cutting process modelling possible, and carried out a number of studies. The paper presents the philosophy of the problem solution and the results of experimental studies. The experimental system is composed of a device,which allows to observe the cutting zone, and systems for model-ling and dual monitoring operations. The work includes the description of experimental subsystems and analyzes the results of the observed chip states. The authors suggest a formulation for the state control, strategy and base their research on the graphical computer interpretation of the chip states. The system developed makes use of TV and IR cameras which allow to investigate the cutting zone. The advanced recording and computing technologies enable a real time recognition of the chip states and thermal fields both in the tool and the chip.