A review of the work of students and faculty in the area of infrared technology is given. The main points are discussed with appropriate recognition of those who accomplished the work.

Design approches to a space-based celestial telescope, called the Advanced Visible Telescope developed at the University of Arizona Optical Sciences Center, are reviewed with particular attention given to stray light reduction. The major design considerations intended to provide a stiff mounting structure for the optics and adjustments that simplify system alignment, and the introduction of baffles to provide stray-light rejection for off-axis sources are discussed. Two stray light rejection modeling methods are compared which were developed under SOAR (a program for rapid calculation of stray light on the IBM PC) and APART (a first order deterministic stray radiation analysis program). It is concluded that below the critical shading angle both programs show similar results but above critical shading angles there were discrepancies in results.

The need for a light weight, compact optical system with a large field of view (FOV), high resolution over a large spectral bandwidth, and flat image plane has prompted the design of a three mirror anastigmat (TMA) with the following properties: it is off axis in aperture and field, is unobscured, and is entirely reflective. Precursor designs based on the Schmidt and Schwarzschild principles of correction are discussed and several variations of the TMA design are introduced.

As part of a team headed by the McDonnell Douglas Helicopter Company and including the Honeywell Systems and Research Division, we have investigated several advanced real-time viewing systems. The study was predicated upon human factors drivers that lead to specifications for several different types of systems. These include systems with 0.6 mr resolution and 170 degree(s) X 50 degree(s), 100 degree(s) X 50 degree(s), and 50 degree(s) X 50 degree(s) fields of view.

The effect of coupling/shunting network for non-uniformity correction is examined on a sequence of two-dimensional images. The results indicate that a network incorporating a resistive grid and lateral inhibition performs well if only small responsivity variations are to be remedied. In the case of hot or dead pixels (zero information artifacts), network connections must exhibit some form of adaptive capability. Parallels with known features of the human visual system are presented and discussed, specifically wash-out of images stationary relative to the retina and the related filling-in of obscurations.

Correction of photoresponse nonuniformity in IR staring sensors is investigated. Spatial noise expressions for uncorrected, one-point corrected, and two-point corrected imaging are developed. These theoretical results take into account the properties of the infrared source, sensor constants, and spatial variations in the infrared imaging device. To demonstrate the application of these results, theoretical spatial noise curves for a platinum silicide IR sensor are presented.

The size of electronic device continues to shrink as efforts to increase device speed push structural dimensions of components into the nanometer range. The ultimate endpoint of this evolution is an information processing technology based on molecular electronic devices. The past decade has seen much conceptual design work on proposed molecular electronic devices, and an increase in the ability of chemists of synthesize complicated organic molecules. We report on progress toward construction of a two-tip scanning tunneling microscope designed to test experimentally the electronic behavior of individual molecular electronic devices.

Throughout the 1980's the Infrared Group of the Optical Sciences Center at the University of Arizona has participated in the national and international efforts to realize self-calibration of photodetectors in the infrared. The results have not been encouraging.

Often the need arises for calibration of infrared systems in the environment of intended use, or field environment. The development of a field calibration platform for performance testing of infrared (IR) imaging and spectral analysis instrumentation is discussed. The calibration hardware is required to provide precise and traceable standards over a range of tests including minimum resolvable temperature difference (MRTD), noise equivalent temperature difference (NETD), minimum detectable temperature difference (MDTD), and modulation transfer function (MTF) for imaging systems, and known spectral content output for Fourier transform infrared radiometers (FTIR) and other spectral analysis instruments. The equipment package must consist of non-development components, and be portable, reliable, and repeatable under field conditions.

The requirements of several target and background situations for a specific target projector system are examined to determine how to present the proper output to the system under test. Consideration is given to both a uniform cold (high altitude) background and a warmer (low altitude) varying background. Target requirements took into account high and low altitude, single or multiple angles, exhaust plumes, and possible countermeasures. It is recommended that a separate, special purpose simulator based on a single mirror for uniform cold backgrounds should be built for limited but important situations. A surface that provides radiation only by reflection using a very cold radiator is proposed for radiative transfer. The very cold radiator contributes only a designed amount of radiation controlled by baffling.

The addition of a calibration capability in the 8-14 micron thermal infrared region to the current ground-based calibration of orbiting sensors is discussed. Radiance- and reflectance-based methods are compared. An infrared thermometer was selected as the favored instrument for the determination of ground truth. Three methods to determine the effect of sky background on the thermal emittance of the ground are presented, along with use of LOWTRAN 7 to determine atmospheric effects.

The design, initial calibration, and performance evaluations of a portable short wave infrared (SWIR) spectroradiometer are described. The spectroradiometer covers the range from 1.1 to 2.5 microns with a spectral resolution that may be varied from less than 10 nm to more than 100 nm. A single spectrum is acquired in about 2 sec. The SNR is about 230 at a wavelength of 2.2 microns for a Lambertian surface of 90-percent reflectance illuminated by the sun at normal incidence with 14.8-nm resolution, a 25 C background temperature, and no atmospheric attenuation. FOV-defining optics are coupled by a flexible fiber-optics bundle to the spectroradiometer, which consists of a concave holographic diffraction grating with a flat focal field imaged onto a 1024-element platinum silicide linear-array detector.

The reflectance and internal quantum efficiency (QE) of three single-element photodiodes are determined using two different light-trapping devices. The QED-200 light trapping device which is based on inversion layer photodiodes exhibits the best performance within the short wavelengths of the visible spectrum (VIS), while the A-O device based on p-n photodiodes, performs best in the long wave VIS up to 950 nm. The combination of the two light-traps provides nearly 100 percent external QE coverage from 400 to 950 nm. The reflectances and internal QE were determined within this spectral range for three photodiodes: UV100, an inversion layer photodiode; X-UV100, a shallow diffused n-p photodiode; and 10DPI/SB, a blue-enhanced p-n photodiode.

Window heating effects are an important consideration in the design and development of airborne missile seeker systems. This paper describes how sharply rising window temperatures can adversely affect detector performance during the seeker homing phase. Initially in the design approach, equations are formulated to calculate target and window radiance on the detector elements for given parameters relevant to target signature, flight aerodynamics, and seeker optics. Using these derived equations, the radiance profiles are plotted as a function of seeker flight time for a typical set of the aforementioned parameters. Then possible design trade-offs and seeker system modifications are discussed that reduce and/or negate window heating effects.

A land-based, passive IR system for the detection of airborne targets has been developed at Saab Missiles. The system operates in the 8 - 12 micrometers region. It scans 360 degree(s) in azimuth and up to 45 degree(s) in elevation and detects targets automatically. The paper describes the system in general, and in more detail the principles of the signal processing, that enable automatic detection of targets in the thermal clutter of sky and terrain background. A unique concept for rejection of false alarms from small objects at short distance (birds) is also described.

A project work within the field of thermal imaging technology was carried out at Nobel Tech Electronics (NTE) by students at the Royal Institute of Technology in Stockholm. This paper describes the purpose and realization of this work.

A thermal imager system including several optimization features is described. The imager is designed to give good image quality even under severe scene conditions. The system includes several types of image processing functions. One is the Ground Scene Optimization, supervising the imager's gain and offset values, and presenting proper scene dynamics on the monitor screen. Another function is the Local Dynamic Control system, which optimizes the information content from the scene presented to the operator on the monitor screen.

A system for identification of aircraft is described. This system is intended to extend the use of a thermal imager. The system uses a hot spot detector for locating possible targets in the image and then performs the identification process within a small window centered around these detections. The identification system uses look-up tables for coordinate rotations and then applies a special transform, the Discrete Contour Transform, to make position- independent feature sets. These sets are then each fed to neural network classifiers. If the target is recognized by one of the neural networks a report is made, which includes the identification and its hit probability.

The need for upgrading of existing systems to IR capacity can be solved by add-on IR-sights with unity magnification. This type of sights allows upgrading with a minimum of modification. The principles for unity magnification sights are explained and comparisons are made with other techniques. Critical design principles are emphasized and are exemplified with the upgrading of two Bofors missile sights.

Optical analysis techniques, infrared spectroscopy in the front end, are rapidly achieving new applications in process control. This progress is accelerated by the development of more rugged instrument constructions. This paper describes two analyzer techniques especially developed for use in demanding environments. First, the integrated multichannel detector techniques is suitable for applications where the measurement can be accomplished by using 2 to 4 wavelengths. This technique has been used to construct several compact, portable and battery-operated IR analyzers, and process analyzers which measure exactly simultaneously at each wavelength resulting in very high tolerance against rapid changes and flow of the process stream. Secondly, a miniaturized Fourier transform infrared (FTIR) spectrometer is being developed for use as an OEM module in specific process and laboratory instruments. Special attention has been paid to increase the resistance of FTIR technique to ambient vibrations. The module contains an integrated digital signal processing electronics for intelligent control of the spectrometer and for fast real time spectral data treatment. Application studies include on line measurement of the concentrations of diluted and colloidal organic detrimental substances, especially pitch components, in the circulating waters in paper machine wet end.

Reticle systems are considered to be the classical approach in estimating the position of a target in a considered field of view and are widely used in infrared seekers and trackers. This type of seeker is most suitable for tracking airborne targets such as aircrafts and missiles. For simulation of reticle systems a number of different methods can be used. The relationship between the detector signal u(t), the scene radiance in the reticle plane s(x,t) and the reticle transmission r(x,t) can be expressed as: u(t) equals (integral) _Ar(x,t) (DOT) s(x,t)dx. By using an image processing system where the reticle pattern as well as the received radiation are described as digitized images of rather high resolution, simulations can easily be performed. The method can be used for simulation of systems with spinning reticles as well as for systems utilizing fixed reticles with off-axis rotation lens or mirror. Any arbitrary reticle pattern can be studied and the pattern can easily be altered. The simulations have been performed by using a TERAGON^TM 4200 image processing system. This paper will describe the simulation method and present a number of examples.

NVG (Night Vision Goggle) resolution performance data is usually given as measured against high contrast, black and white, targets. When NVGs are used as night vision aids for visual night flight, the scene viewed by the pilot is in most cases dominated by low contrast. Therefore, NVG performance at low contrast levels is more relevant to the piloting task than NVG resolution at high contrast levels. A set of resolution targets with different contrast levels was designed and ground tests performed at various light levels outdoors at night. The results showed a marked loss of resolution at lower contrast levels. The presentation will describe the test method, give the results and discuss how the results may be explained. A method for using the test results as the basis for correlating piloting performance to light levels will be presented.

We report on the fabrication and characterization of optical detectors made from 100 A thick high Tc superconducting films. A microbridge detector showed response to 50 ps optical pulses with 1 ns rise time. A nonbolometric vortex depairing mechanism at the Kosterlitz-Thouless transition temperature was observed. A detector pattern utilizing a 1.6 micron wide Meander-line showed approximately equal response amplitude at a lower bias current. The response mechanism was mainly bolometric but for 5 ns pulses vortex depairing was observed.

In_0.53Ga_0.47As/InP infrared detectors with peak absorption at a wavelength of 8.5 micrometers have been fabricated and tested. It is shown that very high current responsivities and high gain are obtained. It is found that gain increases drastically when approaching detector voltages close to -8.5 V, which is explained by carrier impact excitation of electrons from the QW ground state to the excited extended state. The detectivity D^* is about 1.2(DOT)10¹⁰ cm Hz^1/2 W^-1 at 80 K for a 45 degree(s) polished edge detector assuming unpolarized radiation. Grating coupling is studied by etching crossed gratings into the upper part of the mesas. The increase in responsivity as compared to a polished edge detector is by a factor of 2.5 to 3, irrespective to mesa sizes 500 X 500 or 150 X 150 micrometers ². This gives a corresponding detectivity of (3 - 3.5)(DOT)10¹⁰ cm Hz^1/2 W^-1 at 80 K for unpolarized radiation.

The computer code FASCOD2 calculates the atmospheric optical depth with high spectral resolution for different meteorological situations. Since the optical depth and the refractive index are related to respectively the imaginary and real part of the susceptibility, which are interconnected by the Kramers-Kronig relations, it is possible to calculate the atmospheric refractive index by a modified FASCOD2. Due to the computational burden and the lack of well-defined distant wings of the molecular line shape, it is only possible to compute the anomalous dispersion in the neighborhood of the molecular resonance frequencies. This presentation describes briefly a theoretical development of the anomalous dispersion from the optical depth which is valid in a spectral interval ranging from radio waves up to the UV. Line by line calculations of the atmospheric anomalous dispersion at high spectral resolution will be demonstrated for different meteorological situations.

The relations between measured aerosol extinction and meteorological parameters have been studied by use of regression analyses. Based on these analyses, a model has been established which uses conventional meteorological parameters and time of day and year for the calculation of aerosol extinction at optional wavelengths. It seems that the model is useful for statistical analysis but of limited value for calculation of aerosol extinction on a singular occasion.

A model for calculating the spectral radiation difference (contrast) between an object and a sea background has been developed at the Norwegian Defence Research Establishment (NDRE). The model calculates both the emitted radiance from the sea surface and the reflected sky radiance. Inclusion of a rough sea surface is also possible. The contrast has been calculated for different meteorological situations ranging from a cold, clear winter atmosphere to an overcast tropical. A comparison between the contrast in the midwave (3 - 5 micrometers ) and the longwave (7 - 14 micrometers ) band has been made.

With the purpose of establishing a model for the IR extinction of atmospheric aerosols in relation to weather parameters, we have performed measurements with a transmissometer and meteorological sensors. A CO2-lidar is used to measure aerosol extinction at 106 microns in slant paths in order to investigate the altitude dependence of the extinction. The beam from a pulsed TEA-laser is emitted into the atmosphere and backscattered radiation is detected. The signal is digitized and used as input in a computer program to solve the lidar equation. The extinction coefficient vs range or altitude is obtained. The principle and characteristic properties of the two instruments are described and examples of obtained results are presented.

A model is presented for analytically predicting the performance of IR staring rays sensitive in the 3-5 and 8-12 micrometer spectral bands. The performance measure will include video SNR, dynamic range, noise equivalent temperature difference, and minimum resolvable temperature difference. The comparative advantages of various arrays such as platinum-silicide, indium-antimonide, and mercury-cadmium-telluride arrays, when viewing terrestrial scenes at various ambient temperatures and through differing atmospheric conditions, are discussed. The analytical approach differs from most others in that signal levels and noise are described in terms of currents which can be readily measured rather than quantized units such as electrons/pixel. Sample calculations are presented, including the effects of optics, cold shields, spectral responsivities, modulation transfer functions, and displays.

A new focal plane array (FPA) figure of merit is derived for use in the design and analysis of staring sensor systems. This new approach maintains historical continuity by building upon the familiar D concept, and includes the three noise sources most often quoted for focal plane arrays.

The use of dither scan to augment gain and offset compensation is an effective method of minimizing the fixed pattern effects occurring in a staring array. Since the process requires multiple samples to effect cancellation, the performance of the process is dependent on the stability of the line of sight over the collection interval. Both additive noise and jitter on the line of sight contribute to errors in the reconstruction of the pattern from dither scan samples. In order to suppress the l/f noise component which occurs due to accumulated noise errors during reconstruction, a complementary filter is employed which provides low spatial frequency data from the original image and high spatial frequency data from the dither scan image. The residual noise produced by line of sight jitter errors is proportional to the input signal level and the jitter modulation level. This paper presents some Monte Carlo simulation results and methods to reduce the effects of jitter.

Westinghouse is developing a detector array whose spectral characteristics can be modified dynamically. The compensation of the detectors for variations in gain, offset, and spectral characteristics provides new challenges for signal processing. In this paper, the compensation process is presented treating the detector as a 'black box'. The method includes dither scanning to provide orthogonalization of the detector with the scene being viewed, plus signal processing algorithms to establish fundamental detector parameters, and the required correction values. The paper includes the description of the detector black box characteristics, the basic application algorithm, and the correction algorithms. It is concluded that the use of a combination of factory calibrations plus dither scan compensation techniques will provide differential spectral amplitude resolution between any object and the background of better than one percent. For absolute spectral discrimination, the addition of focal plane temperature control for long term stability will provide the same capability. Spectral wavelength resolution of a few percent is projected.

A system is described which is capable of capturing full-frame-rate imagery from a variety of PtSi IR systems developed at Rome Laboratory. The system is then used to validate a current model for Minimum Resolvable Temperature Difference (MRTD). Finally, possible extensions to the current MRTD model are discussed.

We have developed a monolithic 1040 X 1040 element PtSi Schottky-barrier infrared image sensor. This device uses the Charge Sweep Device readout architecture with four parallel outputs. The pixel size is 17 X 17 micrometers ², which is 56% of that of our 512 X 512 element PtSi image sensor. In order to keep sufficient sensitivity with such a small pixel, we have developed a 1.5 micrometers Schottky-barrier process technology and improved the fill factor. The fill factor of this device is 53%. As a result of this improvement, a high differential temperature response of 9.6 X 10³ electrons/K and a low noise equivalent temperature difference of 0.1 K have been achieved with f/1.2 optics. We have also improved the saturation characteristics of the device by optimizing the impurity concentrations of the isolation region and guard ring. The saturation level is 1.6 X 10⁶ electrons at a detector reset voltage of 4 V.

An infrared focal plane has been simulated, designed and fabricated which mimics the form and function of the vertebrate retina. The "Neuromorphic" focal plane has the capability of performing real-time local contrast enhancement, much like the response of the human eye, and operates without saturation over an extremely wide dynamic range due to its logarithmic photoresponse. The device makes use of an indium antimonide detector array with a 3 -5pm spectral response, and a switched capacitor network to compute a real-time 2D spatial average. A gaussian subtraction method is used to produce the pixel output which when displayed produces an image with enhanced edges, representing spatial and temporal derivatives in the scene. The spatial and temporal responses of the device are tunable during operation, permitting the operator to "peak up" the response of the array to spatial and temporally-varying signals, Such an array will adapt to ambient illumination conditions without loss of detection performance. The need to post-process infrared images using digital techniques is thus reduced; seekers making use of this technology could be made smaller due to the reduction of off-plane processing hardware. This paper will review the Neuromorphic infrared focal plane from initial operational simulations to detailed design characteristics, and will conclude with a presentation of preliminary operational data for the device.

A few years ago, a microlithographic deposition process on infrared-transmitting substrates was developed in order to produce realistic infrared scenes for FLIR testing. In recent months, the performance of this product, named Thermoscene, has been improved by improving the control over the production process. The two main results are: (1) An increase in the number of simulated grey levels from 15 to 290, without reduction of the total number of pixels. (2) A decrease in imperfections, such as unwanted holes in the mesh deposition, to almost zero. The Thermoscene is useful as a component of infrared simulators, to project realistic infrared scenes through collimating optics to a FLIR, missile seeker, etc., for testing purposes.

The performance of a 640 x 480 PtSi, 3,5 microns (MWIR), Stirling cooled camera system with a minimum resolvable temperature of 0.03 is considered. A preliminary specification of a full-TV resolution PtSi radiometer was developed using the measured performance characteristics of the Stirling cooled camera. The radiometer is capable of imaging rapid thermal transients from 25 to 250 C with better than 1 percent temperature resolution. This performance is achieved using the electronic exposure control capability of the MOS focal plane array (FPA). A liquid nitrogen cooled camera with an eight-position filter wheel has been developed using the 640 x 480 PtSi FPA. Low thermal mass packaging for the FPA was developed for Joule-Thomson applications.

To maintain low cost and efficient cooling as more elements are required for detector arrays used in thermal imaging systems, multiplexing of the array provides an efficient means to reduce the number of leads exiting the package. Lead Selenide (PbSe) and Lead Sulfide (PbS) linear detector arrays are now utilized with a newly designed CMOS multiplexer which provide variable integration rates and ultra-low power consumption. Efficient thermoelectric cooling is possible with a multiplexer dissipating of less than one milliwatt. On chip adaptive detector biasing is used to improve detector response uniformity. A discussion of the design, operation and performance of the multiplexer will be presented along with a video of a thermal imaging system using a Lead Selenide detector array.

High performance thermal imagers, such a serial and parallel scanned FLIRs are now readily available. In these sensors an array of photo-conductive HgCdTe detectors is scanned over the infrared scene, using a combination of opto-mechanical components to generate a two dimensional display. The replacement of mechanically scanning with electronically addressed 'staring arrays' is very attractive since the all electronic approach allows the fabrication of small light-weight imagers. The performance of staring imagers is determined more by FPA charge handling capacity and residual nonuniformity after compensation and less by choice of detector material or spectral bands. Our analysis and measurements indicate that a 244 X 320 FPA based upon platinum silicide detectors is well suited to meet the requirements of small high performance thermal imagers.

We applied the PtSi IR CSD to the astronomical instrument fabricated in National Astronomical Observatory Japan. Rapid progress in infrared array detectors enables us imaging observations just like the observations with photographic plates, with higher sensitivity. The PtSi IR CSD is developed and processed by Mitsubishi Electric Co. in Japan. The PtSi Schottky barrier diode array has not high quantum efficiency but an excellent uniformity and stability, a large format size and a low read-out noise. We carried out the wide field infrared observations with PtSi camera. The ultimate goal of our project is to build a large format mosaic array camera for Japan 8 m telescope project 'SUBARU' in Hawaii that was just started in 1991.

An overview is provided of the present state-of-the-art of miniature (less than 3 Watt capacity at 80 K) Stirling cycle cryogenic coolers currently in development at Hughes Aircraft Company. These coolers offer high operating efficiency and significantly improved reliability which are key factors for emerging commercial applications requiring the use of cryogenic cooled sensors. Characteristics of rotary drive compressor designs as well as linear oscillating compressor designs are reviewed. Recent developments in affordable linear cooler designs for commercial applications are summarized. The significant growth in operational reliability of Stirling cycle coolers over the past ten years is discussed, showing a growth in Mean Time to Failure (MTTF) from a few hundred hours in 1980 to 2000 to 5000+ hours today. Over 100,000 hours of reliability testing of Hughes Stirling cycle coolers at varied ambient temperatures are summarized to support the cited growth in cooler reliability. Recent reliability growth in linear drive coolers offers the benefit of easily interfacable designs with extended operating periods requiring maintenance at 4000 to 8000 hours of operation intervals. Performance data on a range of rotary drive and linear drive coolers are summarized to indicate the range of performance currently available for commercial applications. A summary of performance characteristics of a higher capacity linear cooler with structural rigid coldfinger for integration with large area advanced detector arrays is provided. Its combination of high capacity, structural stability, cost effectiveness and inherent reliability make this an attractive cooler for integration with advanced imagers incorporating large focal plane arrays.

A large area infrared focal plane array was designed for use in a variety of military, dual- mode and commercial applications requiring high sensitivity and resolution. A high performance CMOS switched FET readout multiplexer was developed using standard foundry compatible processing. The array can be operated at frame rates up to 240 Hz in either snapshot or rolling readout mode. Independent variable integration control is included for either mode. Array size is logic selectable to either video format compatible 320 X 240, standard 256 X 256, or the entire 320 X 256. Data is read out sequentially through logic selectable 1, 2 or 4 outputs. A line array mode is included, any line selectable, with variable integration time up to 85% of line time. Each 31 micrometers X 31 micrometers cell has > 2.0 E7 electron integration well, coupled to the output via a charge drain sample and hold to maximize performance and to provide a continuous data stream. On chip bias generation, timing generation and level shifters minimize drive requirements. The silicon multiplexer was hybridized to a InSb detector array for a MWIR imaging demonstration.

A NICMOS II array, a NIR (0.80 - 2.6 micron) imaging system, was integrated into the California Institute of Technology Palomar Observatory camera. The Palomar camera system which consists of six discrete subsystems including a focal plane, an electrical interface, data acquisition electronics, a dewar, dewar optics, and the software is described. The performance and calibration data for each subsystem are presented. Emphasis is placed on test data on the focal plane performance.

A cooled Fabry-Perot spectrometer working in the far-infrared the 350 and 450 micrometers wavelength atmospheric windows is presented. It is designed for low temperature operation (1.5 K), in vacuum. The reflecting surfaces (gold inductive grids) are deposited on monocrystalline quartz substrates. Three push-pull motors perform the scanning of the spectrometer.

An airborne IR system for the detection of aerial point sources has been designed. The sensor uses a detector based on a vector of elements. The coverage of the horizontal field of regard is achieved by scanning the complete sensor while vertical coverage is obtained by the detector's IFOV. The system is integrated into an airborne stabilized payload. System design considerations including selection of the spectral band, sensor optics and tradeoffs of SNR vs. horizontal revisit period, were made by using an IR point detection system design code. This code was used to calculate system performance in a clutter-free background.

The VIMS instrument (Visible and Infrared Mapping Spectrometer) will be flown in the late 1990s on the CASSINI mission to Saturn and its moons. VIMS is designed to generate two-dimensional multispectral images of planetary surfaces and their features in the visible and infrared spectra. Compared to earth-based instruments, the stellar occultation experiment will provide unprecedented thickness resolution and chemical composition of planetary atmospheres. It will also gather high SNR optical depth profiles and particle size distribution of the Saturnian rings. The stellar occultation mode ideally requires continuous data acquisition for periods of up to several hours as the instrument stares at a star. This presents a sizeable challenge to the instrument's operational mode: processes that normally occur during mirror retrace must be shifted to data acquisition cycles, thereby creating timing difficulties in the sequencing of these cycles. The presentation focuses on the analysis of the stellar occultation mode and presents solutions to the challenge of an uninterrupted data stream. Several options will be presented that minimize any possible degradation of the experiment's science content.

Testing of scanned linear infrared detector arrays, particularly in a developmental environment, can be facilitated through the use of Common Module FLIR (forward-looking infrared) equipment. The modular nature of these FLIRs allows rapid exchange of detector/Dewar modules, however, the cost of Common Module Dewars can become excessive if many arrays are tested. It is desirable to utilize a reusable Dewar, but the problem of quick and reliable multiple electrical connections to the array must be solved. We have designed and fabricated a reusable Dewar, which maintains the Common Module detector/Dewar envelope with a minor exception, in which the arrays can be quickly mounted and dismounted with little effort and limited expertise. In the described version, 148 electrical connections are automatically completed when the array is fastened in place on the cryogenic thermal sink. Interchangeable radiation shielding and cold filtering is also easily accomplished in the same operation. After evacuation through a valve, the Dewar mounts quickly in the Common Module FLIR for laboratory and field testing with standard Common Module cryogenic coolers. The interconnection is also adaptable to integral cooler Dewars where the detectors are mounted directly on the cryogenic generator.

A new concept of circuit structure of FPA multiplexer is proposed here, which incorporates an additional MOS switch and a charge-storage capacitor into each pixel of the conventional circuit. The MOS switches are actuated with a high frequency pixel clock, thus enabling the photoexcited charges in each detector to be shared and shielded by the individual storage capacitor. The action of the charge sharing has been analyzed in close form and been simulated by SPICE program. It shows that the saturation capacity indeed can be enhanced. The technique therefore can provide a longer integration time and an additional electronic iris function by controlling the pixel-clock behavior.

The photo-carrier concentration of SPRITE devices is calculated and discussed in detail in the present work. The results obtained in this paper show that the influence of some parameters on the photo-carrier concentration is more complicated and interesting, and then some results are different from the photoconductor, they must take into account to design the SPRITE devices.

Principles of the theory of nonstationary processes in extrinsic photoconductors and main deductions, following from it, are expounded. They are confirmed by the experimental data for Si and Ge samples doped by various elements. The theory helps to understand the functioning of the extrinsic detectors and arrays on their base.

Fourier Transform Infrared Spectrometer (FTIR) measurements on flat witness samples are combined with ray trace results of transmission through a 1/8 inch, 12 mill focal length lens to estimate the net transmission of that lens as it is used in the Geostationary Operational Environmental Satellite (GOES I) Sounder optical train. The ray trace code uses a "double random" ray method allowing radiometry to be done with a standard ray propagation algorithm.

The infrared radiometer has been used in various fields to measure and visualize the radiation temperature distribution on the surface of a material. Radiation energy measured by the infrared radiometer is summation of an emitted radiation and reflection, which is called a radiosity flux. The present paper shows characteristics of the radiosity of tested materials and represents special keynote parameter such as the variance of radiation temperature, cavity- effect, area effect and so on. Application studies had been undertaken to detect surface and internal flaws of tested materials by an active thermal incidence and to measure the erosion rate of the graphite by ion beam injection. The temperature distribution of a cutter and an elimination of the reflecting energy based upon an irradiation of the material was studied experimentally.

Because temperature is one of the most important factors influencing combustion reactions, a variety of temperature measurement methods have been developed for burnt gas. Infrared radiation pyrometry using water vapor or carbon dioxide, which are present in high density in a burnt gas, has a long history. However, these classical methods can measure only a mean temperature or step-wise temperature distribution of several segments along an optical path. Due to the severe demand for cleaner and more efficient combustion, more detailed temperature information is required. Computed tomography (CT) applied to radiation methods (same as X-Ray CT in medical use) enables measurement of a two-dimensional temperature distribution. The authors have developed several types of infrared CT pyrometers. Because CT methods generally take a long time to obtain projection data, it is thought that they are not applicable for high speed unsteady combustion. In this report, a two-band-emission-CT pyrometer, which was developed by the authors, is further developed to enable time-resolved measurement. An algorithm and optical configuration is introduced for fan-beam scanning. The accuracy is then investigated. The experiment was performed using only one optical unit as a preliminary investigation using a jet flame with good reproducibility.

This paper describes an experimental approach to validation of the radiometric integrity of an end-to-end thermal infrared SIG model. The approach attempts to break down the overall SIG model into a set of submodels with measurable input and output parameters. A scene is then instrumented and imaged in a time lapse fashion over an extended period. This scene is also synthetically produced so that the actual and synthetic scenes can be compared. The experimental approach includes acquisition of meteorological data, object data, atmospheric data, and image data. Error propagation models are used in conjunction with the experimental data to determine the source and relative importance of errors in the modeling process.

A description of the development of a 3 - 5 and 8 - 12 micron IR collimator which combines multiple sources to accurately simulate real world thermal targets to a missile seeker. The primary target (or vehicle), its thermal background and up to three flares, each of which may be independently controlled to provide variable radiance, trajectory, velocity and acceleration, are combined in a collimated output beam. The collimator beam diameter is approximately 8' and, at the exit pupil, provides an 8 degree(s) X 8 degree(s) field-of-view. All components of the system, including most thermal sources, are under computer control. As missile system performance has increased, test system requirements have become more demanding. Testing advanced missile seeker systems in hardware-in-the-loop simulation facilities requires that target presentation systems become correspondingly capable. This paper describes an evolutionary approach being taken in the development of a hardware-in-the-loop facility in the Simulation Laboratory of the Naval Air Warfare Center--Weapons Division (NAWC). The optical baseline for the development of this infrared target projection system is known as Jaws II. This baseline system has been extensively modified, and further system improvements are planned. Guidance, exploitation and countermeasures studies may now be validly conducted in a lab using this system.

This paper first describes the effect of the fixed pattern noise and limits of some important IR Image systems to it. The source of the fixed pattern noise is explored and the output function of the infrared detection element is derived. Finally, the method of correction for the fixed pattern noise according to this function is developed and some photos of corrected result are given. Key words IRCCD, opto—electronic imaging, noise correction

It has been shown in [1—2] that using MIS—avalanche structure as a sensitive head in modern optoelectronic devices could open new vistas in their applications in spectral measurements, medicine, chemistry etc. In this paper are presented results concerning creation of a new type of IR—(up to 3.3 pm) MIS Avalanche Photodetector based on InAs substrate. The coefficient of light pulses(l pm) internal avalanche multiplication for the best samples under LN conditions (77 K) was about M = 10 - 12.