Photoluminescence (PL) measurements on as-grown and hydrogenated In-doped CdTe epitaxial films grown on p-CdTe (211) substrates by molecular beam epitaxy have been performed in order to investigate the optical properties and the hydrogenation effects of In-doped CdTe films. The temperature dependence of the PL intensities for the as-grown In-doped CdTe films show that the peak at 1.590 eV observed at 12 K is related to shallow donor band recombination (D, h). Inhomogeneous broadening of the full width at half maximum for the (D, h) peak might be related to the change from correlated electron and hole distributions in the low-temperature region below 20 K to random electron and hole distribution in the relatively high-temperature region above 40 K. The PL spectrum for the hydrogenated In-doped CdTe films shows that the intensity of the (D, h) peak decreases dramatically and that their longitudinal optical phonons disappear. These results indicate that the PL intensity and the linewidth of the (D, h) peak in as-grown In-doped CdTe films are strongly related to the distribution behavior of the electrons and the holes and that the decrease of the PL intensity of the (D, h) peak for the hydrogenated In-doped CdTe epilayer originates from the passivation effect of the ionized In donor level due to the hydrogenation.

In order to investigate the surface states of electron which can tunnel through the sufficiently thin insulator, the electron tunneling spectroscopy is used to measure the tunneling current in function of the bias voltage, and directly to get the subbands of accumulation layer. The tunneling current through ZnS barrier in the Hg_1-xCd_xTe-ZnS-In junction structure is measured by various applied bias at 77 K and 4.2 K. From the measurement at 77 K, the subband energy levels in the electron accumulation layer at the surface of n-type Hg_1-xCd_xTe are found to be located at -59 meV for the ground state and -13 meV for the first excited state relative to the Fermi level of Hg_1-xCd_xTe. At low temperature when the applied bias is larger than the difference between the work function of In and the electron affinity of ZnS, a negative differential resistance is measured. On the calculation using transfer matrix method it is understood that this negative conductance is attributed to Fowler-Nordheim tunneling which is caused by the variation of ZnS barrier according to the various applied bias.

We calculate the bound-to-continuum transition amplitude in a biased GaAs/AlGaAs multiple quantum well structure. The continuum wave functions above the barrier bound on one side and free on the other extreme were normalized using the Dirac (delta) -function. The normalization renders that the amplitude of sinusoidal functions corresponding to different energies should be same in the far flat region. Calculated transition peak agrees well with the experimental results reported. Possibility of using complex energy representation to find the excited states is also discussed.

The progress and current status of HgCdTe infrared detector in Korea during the last ten years is reviewed and future perspectives of infrared detector research and development are also given. The research and development of HgCdTe infrared detector was started in 1987. In the first five years, we had focused on the material growth, especially liquid phase epitaxy (LPE) by slider method and single element MWIR photovoltaic detector with large active area was realized with this LPE material. After that, the development of the linear array infrared detectors including photoconductive and photovoltaic devices was initiated and will be finished very soon. During this period we developed the travelling heater method (THM) for the use of the linear arrays. On the other hand MBE growth of HgCdTe was started for a specific applications and MOVPE process was employed for the two-color infrared development. Focal plane array program will be initiated very soon.

We report in-situ growth of MWIR P-on-n HgCdTe on GaAs by Metal Organic Vapor Phase Epitaxy. HgCdTe epi layers were grown by interdiffused multilayer process (IMP). Tris- dimethylarminoarsenic (DMAAs) was used as a precursor for arsenic doping (p-type layer) and isoprophyliodide (IPI) was used for iodine doping (n-type layer). Standard bubbler configuration was used for both precursors. Doping concentration could be controlled accurately in the range of 2 X 10¹⁵ to 7 X 10¹⁶ cm^-3. After growth, HgCdTe layers were annealed in Hg-atmosphere at 415 degrees Celsius and 260 degrees Celsius consecutively. This Hg- annealing is for activating dopants and then reducing Hg- vacancy concentration. The layers doped with iodine in low 10¹⁵ cm^-3 concentration showed higher Hall mobility than undoped layers. The Hall mobility of iodine doped layers decreased with increasing doping concentration. Secondary ion mass spectroscopy (SIMS) analyses for the iodine-doped layer showed sharp decrease of iodine concentration after IPI precursor being turned off, indicating negligible memory effect and very slow diffusion of iodine during growth and Hg-annealing. SIMS analyses for the arsenic doped layer showed that arsenic diffused by about 1 micrometer during growth and Hg-annealing. These results show that IPI and DMAAs could be used as stable precursors for in-situ growth of HgCdTe heterojunction. A P-on-n structure was grown. The P-layer has x composition of 0.32 and acceptor concentration of 6 X 10¹⁶ cm^-3. The n-layer has x composition of 0.30 and donor concentration of 2 X 10¹⁵ cm^-3. SIMS depth profile for the structure shows well-defined regions of doping concentration and alloy composition. After Hg-annealed, P-on-n structures were fabricated into MESA structure diodes. Electron beam evaporated CdZnTe was used as a passivation layer. This MWIR diode had R_oA value of about 3 X 10⁴ (Omega) .cm².

As HgCdTe technology has been advanced, HgCdTe photodetectors is realized in many application areas. Carrier mobility is one of the most fundamental parameters affecting current-voltage characteristics of the devices. In the conventional simulations the empirical mobility model is used which lacks generality. Especially, the field dependent mobility is found to be wrong by comparing Monte Carlo results. The semi- empirical electron mobility model for the simulator is proposed in this paper. Low field mobility is calculated using the relaxation time approximation, which provides information on the dominant factors affecting the mobility. The ionized impurity model is modified based on Brooks-Herring model to consider the degeneracy effect and overlap integral. For field dependent mobility, a new formula is proposed to take into account features of the dominant scattering mechanism such as nonparabolic relation between energy and wave function at high field. Final formula is accomplished by introducing fitting parameters extracted from Monte Carlo simulation results. The new model retains more physical meaning than conventional model and fits well with experimental data.

In this paper we introduce a new HgCdTe 2-dimensional numerical simulator, HanYang university SEmiconductor DEvice Simulator (HYSEDES). The modified transport models are included to describe the inherent natures of HgCdTe such as the degeneracy,the nonparabolic conduction band, and the band offset at heterointerface. It also takes into account various generation-recombination mechanisms regarding tunneling phenomena. For the advanced devices employing multiple junction, all the material parameters are described as a function of the position. The simulations are performed for some devices such as photo-voltaic devices and two color detectors to prove the validity of the overall models in the simulator and its capability.

We have made nanoscale fabrication for HgCdTe-based Coulomb blockade type quantum devices. Using e-beam lithography and lift-off technique with ZEP resist, multi-lines with 0.1/0.3 nm width and space were nano-patterned on ZnS/HgCdTe surface. SEM and AFM images for the lines display well-splitted patterning result with a little roughing ZnS surface. Split- gate of 200 nm radius was also fabricated on ZnS/MCT for defining nanosize quantum dot. All the work will provide a fundamental basis for the nanofabrication process of HgCdTe- based narrow-gap quantum devices.

In this paper, we report the capacitance-voltage (C-V) properties of metal-insulator-semiconductor (MIS) devices on CdTe/HgCdTe by the metalorganic chemical vapor deposition (MOCVD) and CdZnTe/HgCdTe by thermal evaporation. In MOCVD, CdTe layers are directly grown on HgCdTe using the metal organic sources of DMCd and DiPTe. HgCdTe layers are converted to n-type and the carrier concentration, N_D is low 10¹⁵ cm^-3 after Hg-vacancy annealing at 260 degrees Celsius. In thermal evaporation, CdZnTe passivation layers were deposited on HgCdTe surfaces after the surfaces were etched with 0.5 - 2.0% bromine in methanol solution. To investigate the electrical properties of the MIS devices, the C-V measurement is conducted at 80 K and 1 MHz. C-V curve of MIS devices on CdTe/HgCdTe by MOCVD has shown nearly flat band condition and large hysteresis, which is inferred to result from many defects in CdTe layer induced during Hg-vacancy annealing process. A negative flat band voltage (V_FB approximately equals -2 V) and a small hysteresis have been observed for MIS devices on CdZnTe/HgCdTe by thermal evaporation. It is inferred that the negative flat band voltage results from residual Te⁴⁺ on the surface after etching with bromine in methanol solution.

A new device concept and implementation procedure of a monolithic two-color IR detector using MOVPE grown p-HgCdTe/N- HgCdTe/CdTe/GaAs is discussed. Newly introduced two-color IR detector consists of simple n-p-N structure, which can be realized using simple p-N double layer HgCdTe material. Formation of potential barrier in the conduction band of p-N heterojunction is a key to the successful operation of monolithic two-color IR detector. It prevents photogenerated minority carriers in small band gap region (p-HgCdTe) from diffusing to N-HgCdTe. The monolithic two-color IR detector was firstly fabricated using MOVPE grown p-Hg_0.69Cd_0.31Te/N-Hg_0.64Cd_0.36Te/CdTe/GaAs for SW/MWIR. SWIR diode shows R_oA value of 752 (Omega) cm², while MWIR diode shows R_oA value of 140 (Omega) cm².

The surface of mercury cadmium telluride (Hg_1-xcd_xTe, x approximately equals 0.2) was etched by electron cyclotron resonance (ECR) plasma utilizing a mixture of CH₄ and H₂. The etch rate was optimized as a function of mix ratio of H₂/CH₄ ECR power, total pressure, and DC bias voltage in order to arrive at smooth surface. The etched surface of HgCdTe was characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), FT-IR and Hall effect measurements. Optimized etching conditions were 25% CH₄, ECR power of 200 watts, total pressure of 5-7 mtorr and bias voltage of -80 V. XPS analysis revealed that atomic concentration of Hg and Te decreased, but that of Cd increased, indicating preferential etching. Also, hall effect measurement indicated increased carrier density, but decreased mobility of HgCdTe.

The capacitance-voltage (C-V) and the Hall effect measurements were used, in order to study electron cyclotron resonance (ECR) plasma damage in HgCdTe (MCT). In this study using ECR treatments of MCT and C-V measurements, we observed that the type conversion of MCT surface largely depended on the ECR etching conditions, when MCT was etched by ECR plasma as a function of the ECR power and dc bias. The n-type conversion was not observed when the p-type MCT was etched under the condition of ECR power 150 W and dc bias -20 V. As dc bias of ECR increased over -40 V at the constant ECR power 150 W, the p-type MCT was converted to n-type. The p-type MCT was also converted to n-type when ECR power increased to 500 W at the constant dc bias -20 V. These results probably were due to the inter-diffusion of a large amount of excess mercury, liberated during the ECR treatment, into MCT, which were similar to the results of ion milling process. Another interesting result, observed in C-V measurements, was the p- type conversion from n-type MCT when the n-type MCT was etched under the condition of ECR power 150 W and dc bias -20 V. As dc bias of ECR increased over -40 V, the C-V curve was the results of n-type MCT characteristics. We considered that a low dc bias of -20 V, the hydrogen passivation and the deficiency of mercury in the etched surface were dominant and resulted in conversion to p-type. As dc bias increased over -40 V, the inter-diffusion of excess mercury into MCT was dominant and associated with keeping the n-type characteristics.

Long wavelength infrared (LWIR) photoconductive (PC) detectors of single element Hg_0.79Cd_0.21Te (MCT) on sapphire substrate were fabricated, using three kinds of MCT etching processes, such as wet only, wet & dry mixed, and dry only process. The ohmic contact metals, which were used to the first contact layer in the IR detector fabrication, were Au, Ni, and Ti. The performance test of the fabricated IR detectors showed the good results in the wet etched MCT IR detectors with the detectivities (D*) of (1-3) X 10¹⁰ cmHz^1/2W^-1 and the responsivities of (2-3) X 10⁴ VW^-1 at field of view (FOV) of 180 degrees.

Hg_0.78Cd_0.22Te n on p photovoltaic diodes were fabricated with the wafers grown by liquid-phase epitaxy on CdTe substrate which have a cutoff wavelength of 10.5 micrometer. The wafer was doped with Hg vacancies and the acceptor concentration was 5 X 10¹⁵ - 2 X 10¹⁶/cm³. We applied the planar ion-implantation technique for the junction formation. Post-implantation annealing was performed to improve reverse bias characteristics and RoA value. Using this method, we obtained RoA values of 2 - 8 (Omega) cm² at 77 K. However, the increase of RoA by post-implantation annealing saturated as the annealing time increased further. This limit is thought to come from the low minority carrier lifetime in the Hg vacancy doped wafer. To improve the device performance further, we adapted the hydrogenation technique. The RoA of the hydrogenated diode was found to be 70 approximately 120 (Omega) cm², which is one order of magnitude higher than that of the post-implantation annealed diode. From the model fitting analysis, the hydrogenation effect was attributed to the increase of the minority carrier lifetime.

HgCdTe is the most important material for LWIR detectors, and n on p type with a planar structure using ion-implantation technique is still the state-of-the-art for fabricating infrared focal plane arrays (IRFPAs). Nevertheless, the implantation introduces lattice damage and increases the dark current, which are expected to be reduced by an annealing process. In this paper, HgCdTe diodes ((lambda) _coutoff,77k equals 11.0 micrometers) were fabricated on Hg-vacancy doped p type HgCdTe wafers grown on CdTe substrates by LPE, and junction was formed with boron ion-implantation. The annealing process was implemented after the ion-implantation at various temperatures, from 120 degrees Celsius to 200 degrees Celsius, under N₂ gas atmosphere. The performance of the annealed diodes was investigated in detail by model fitting analysis. This current model includes four dark current components, i.e. diffusion current, generation-recombination current, trap- assisted tunneling current and band to band tunneling current. Measurements and analyses of 1/f noise characteristics were performed at several bias voltages for samples annealed at 150 degrees Celsius. Among them, both devices annealed for 30, and 60 minutes showed equivalent RoA values, but the latter had lower level 1/f noise current at small reverse bias voltage. From the model fitting analysis, the sample annealed at 150 degrees Celsius for 60 minutes was found to be generation- recombination limited at the small reverse bias while that for 30 minutes was to be trap-assisted tunneling limited. This reduction of 1/f noise was attributed to the decreased trap density in the vicinity of pn junction.

We investigated the passivation properties of CdTe films that were deposited on p-type Hg_0.77Cd_0.23Te using the helicon sputtering method. Crystallinity and morphological microstructure of the CdTe films were determined by transmission electron microcopy and atomic force microscopy, respectively. We found that the CdTe films are polycrystalline and provide good morphological properties: they have no granular-type defects and no pin-holes. Electrical measurements of metal-insulator semiconductor devices showed that the properties of the CdTe/HgCdTe interface mainly depend on deposition pressure and the conditions of post-deposition annealings. It was observed that CdTe deposition at higher pressure reduces the surface deposition damage that is responsible for increasing the positive fixed charges, the slow traps and other degradations of the HgCdTe surface. Moreover, post-deposition annealing at a temperature above 100 degrees Celsius improves the thermal stability of the electrical properties of the interface. A gate-controlled diode that was produced with post-deposition annealing showed that CdTe films deposited by helicon sputtering were essentially suitable for passivation of HgCdTe photodiode arrays.

The relationships between the figure of merit R₀A representing the junction property and deep levels representing electric properties of semiconductors have been investigated. R₀A can be estimated by current-voltage (I- V) measurements. Deep levels can be estimated using spectral analysis of deep level transient spectroscopy (SADLTS). It has been confirmed that values of activation energies concentrate around 30 meV with the increase of R₀A. This suggests that the influence from the inherent deep levels in the HgCdTe device becomes strong due to the increase of R₀A, resulting in the improvement of the diode characteristics.

Based on the application of the direct injection for per detector (DI) input technique, a new readout structure for the infrared (IR) focal-plane-array (FPA), called the variable gain direct inject per detector (VGDI) is proposed and analyzed. The readout circuit of VGDI of a unit cell of photo- voltaic sensor under investigation, is composed of a direct inject per detector circuit, high gain amplifier, and the reset switch. The VGDI readout chip has been designed in 0.5 micrometer double-poly-double-metal (DPDM) n-well CMOS technology in various formats from 8 X 8 to 128 X 128. The simulation 8 X 8 VGDI of the readout chip have successfully verified both the readout function and performance. The high gain, low power, high sensitivity readout performances are achieved in a 50 X 50 micrometer² pixel size.

A novel silicide phase Ir₃Si₄ suitable for medium wave infrared (MWIR, (lambda) equals 3 micrometer - 5 micrometer) detection was prepared and characterized. Iridium is deposited on p-Si(100) substrates at various temperatures in the range from 420 degrees Celsius to 485 degrees Celsius under ultrahigh vacuum conditions. The metallic phase is formed by interdiffusion and reaction of Ir and Si. The phase is identified to Ir₃Si₄ by Rutherford backscattering spectrometry. Ir₃Si₄ films thinner than 10 nm show Schottky barrier heights as low as (Phi) _Ph equals 165 meV for photoemission into the Si valence band. Dark current densities are measured to j_R less than 1 (DOT) 10^-9 A cm^-2 (at reverse bias 5 V and detector operation temperature 50 K). The infrared test detectors exhibit responsivities (lambda equals 4 micrometer) of up to 20 mA W^-1 at 5 V. The temperature resolution of the test detectors -- front illuminated and without antireflection coating and optical resonator -- is improved to a noise equivalent temperature difference NETD_300K approximately equals 53 mK (at 50 Hz) compared to 75 mK of equivalent test detectors fabricated by common HV-PtSi deposition.

Sofradir/Lir HgCdTe homojunction IR detector technology has already demonstrated its high maturity level by delivering more than 1000 second and third generation detector dewar assemblies adapted to LWIR and MWIR waveband applications. More recently, Sofradir and Lir started to work on HgCdTe detectors for SWIR applications. One of the main advantage of HgCdTe material is its ability to operate at high temperatures with high performance, and therefore to reduce the cooling constraints (size, cost...) by using small cryocoolers or by using thermoelectric coolers. As a matter of fact, high performance HgCdTe IRFPAs operate at temperatures up to 100 Kelvin for LWIR, up to 130 Kelvin for MWIR and up to more than 200 Kelvin for SWIR. However tradeoffs between performance and operating temperature are possible for many applications and therefore MWIR IRFPA can be proposed at 150 Kelvin or 200 Kelvin for example. This paper presents the advantages of the use of the Sofradir/Lir HgCdTe technology for high operating temperatures, based on the high performance demonstrated, and the several tradeoffs which are possible for various applications. Performance measured on HgCdTe photodiodes are presented, for several combinations of cut-off wavelengths and operating temperatures. The results are compared to potential applications and examples of IRFPA results are given.

Low-noise pixel-based amplification via sub-micron CMOS is enabling advanced focal plane arrays offering ultra-low read noise for infrared astronomy, wave-front sensing, IR spectroscopy, spaceborne sensors and other discriminating uses. Specifically, we report the achievement of less than 30 e- read noise at video frame rates using capacitive transimpedance amplification and less than 1 e- using an enhanced form of gate modulation. We also compare several low- noise IR FPAs at various cutoff wavelengths from 1.1 micrometer to nearly 17 micrometer.

Images employing focal plane array detectors suffer from aliasing and fixed pattern noise generated by nonuniformities in the response of the detector elements. Aliasing which is caused by undersampling may be removed by microscan which extends the spatial bandwidth of the images by a factor of two. The presence of fixed pattern noise which is caused by nonuniformities in the detector responses is more difficult to eliminate. It severely reduces the performance of imagery and its removal is essential. This paper compares the performance of representative methods for reducing the effect of fixed pattern noise through simulated results. Preliminary results are presented for an alternative method currently under development.

In this paper, we propose a method of constructing a multi- wavelength IR imager and investigate some of its applications. The optical cavity structure has been used to improve the sensitivity of the IR imager for a long time. However, it can also be used as an on-chip interference filter. We developed two kinds of multi-wavelength IR imagers based on the 410 k pixel PtSi IRCCD, which has been previously reported by us. The type A multi-wavelength IR imager is composed of three kinds of pixels. In the device, three kinds of pixels with different spectral responsivities are arranged in the form of a stripe in the vertical direction of the CCD. The type A device is used within the wavelength range of 3 - 5.5 micrometer. The type B device is a multi-wavelength IR imager in which four kinds of pixels with different spectral responsivities are arranged in the vertical direction in the form of a stripe. The type B device is used within the wavelength range of 1.5 - 2.5 micrometer. We report the structure, the characteristics and some applications of the multi-wavelength IR imagers.

'TADIR' is a new high-end thermal imager, developed in El-Op under contract with the Israeli MOD during the last three years. This new second generation thermal imager is based on 480 X 4 TDI MCT detector operated in the 8 - 12 micrometer spectral range. Although the prototype configuration of TADIR was design for the highly demanded light weight low volume and low power air applications, TADIR can be considered as a generic modular technology of which the future El-Op's FLIR applications such as ground fire control system and surveillance systems will be derived from. Besides the detector, what puts the system in the high-end category are the state of the art features implemented in each system's components. This paper describes the system concept and design considerations as well as the anticipated performances. TADIRs fist prototype was demonstrated at the beginning of 1998 and is currently under evaluation.

The correctability c characterizes the spatial noise of infrared focal plane arrays (FPA). This figure of merit indicates the ratio of the spatial to the temporal detector noise for a single or more frames. The goal of the correction procedure is to reduce the spatial noise to a magnitude below the temporal noise. In this case the correctability c is smaller than unity. In this paper we consider the transient degradation of the correctability after correction and define a novel characteristic number, the long-term stability time constant (tau) _lts. This time indicates operation duration subsequent to a nonuniformity correction after which the spatial noise increases to values higher than the temporal noise, i.e. for which the correctability reaches values larger than unity. Several staring infrared focal plane array detectors differing in array size and in detector material are investigated. The correctability c is determined after various correction procedures and the long-term stability time (tau) _lts is measured for each detector. The degradation of the correctability is caused by individual pixels in the detector array. We found that there are three different types of 'bad pixels,' which lead to a degradation of the correctability. Weak pixels having low or no responsivity as well as flickering and drifting pixels showing 1/f noise are classified.

Sofradir is industrializing a Detector Cooler Assembly aimed at portable, low cost and low maintenance applications. The concept is based on a four stage Thermo Element Cooler (TEC) cooling down to around 200 K a 128 X 128, 50 microns pitch, Cadmium Mercury Telluride Circuit staring array, hybridized onto a Read Out Integrated Circuit (ROIC), especially designed to cope with the important dark current generated at this operating temperature and integrated in a low weight/small dimension packaging. The main feature presented in this paper regards the successful operation of the self calibration and current skimming function developed earlier but which efficiency has since been optimized. The principle results in the enhancement of the effective storage capacity as only the scene current is stored. Integration time higher than 20 ms has been demonstrated. The packaging is built around current technologies adapted to long term vacuum applications. Basic life-time testing has been performed showing promising expectations. In this paper we recall the current skimming concept and its limitations and show the improvement obtained in terms of efficiency of the self calibration. In addition to electrical results, we also present electro-optical characterization obtained with this ROIC and performances in operational conditions. Finally we describe TEC DCA under industrialization in terms of performance and operation.

A novel architecture for both QWIP heterostructure and pixel design is described. This new approach completely eliminates the dark current of a conventional GaAs/GaAlAs multiple quantum well LWIR detector. The concept is first described, then the industrial feasibility is demonstrated on a 4 X 2 array with 50 micrometer pixel pitch. The performance modeling of FPA based on this new design shows that NETD as low as 15 mK is achievable at an operating temperature of 90 K and for arrays with 30 micrometer pitch.

A 9.3 micrometer cutoff 320 X 256 quantum well infrared photodetector (QWIP) based thermal camera has been demonstrated as a laboratory set-up configuration. The development of the QWIP arrays and system integration is described. Performance analysis of systems which are based on QWIP arrays were performed to evaluate the potential of 320 X 256 and 640 X 480 QWIP array to be a candidate for future mid-end and high-end thermal imager.

Inframetrics funded a pilot build of 320 X 256 Quantum Well Infrared Photodetectors (QWIP) designed and fabricated by Lockheed Martin Sanders. QWIP technology is rapidly maturing and approaching commercial viability. Several technology demonstrator cameras will be integrated with QWIP detectors to evaluate their suitability for portable radiometry. This paper will briefly describe the Inframetrics ThermaCAM sensor, provide detector test results, and review the challenges of integrating QWIP detectors.

The Laboratoire Central de Recherches (LCR) of Thomson Csf and the Societe Francaise de Detecteurs Infrarouge (Sofradir) combined their complementary skills to realize a MultiQuantum Well Infrared Photodetector (QWIP) Focal Plane Array (FPA) sensitive in the long wavelength range of the spectrum (LWIR). Sofradir has industrialized a versatile indium bump hybridization technics qualified for operations as low as 50 K and mostly dedicated to connection of Cadmium Mercury Telluride (CMT) PhotoVoltaic (PV) detectors to silicon Read- Out Integrated Circuits (ROIC). On the other hand, the Thomson Csf/Lcr's QWIP technology based on GaAs/AlGaAs heterostructures is now suitable for industrial development. The device described in this paper is a first generation 144 X 192 MQW staring arrays with a 50 microns pitch; it is operated at temperature as high as 80 K. Such a high operating temperature can be achieved thanks to the optimized design of the QWIP active layer and to the use of a multi purpose experimental CMOS ROIC integrating a current skimming function; this structure developed for high temperature operation of CMT detectors allows for in pixel calibration and derivation of photosite current containing no scene information (e.g. dark and background current) and thus offers enhanced effective storage capacity. In this paper, the main features of the hybrid are given showing the adequacy of this hybridization technics to connecting the QWIP structures. A functional description of the ROIC is presented together with its advantages and limitations in terms of conditions at operating temperature of 70 K and 80 K are thoroughly presented and discussed, in particular in reference with the equivalent CMT performances.

We present a model for QWIP-based thermal imagers which allows us to study the effects of the main system parameters on system performance. We use the model to illustrate some of the issues involved in choosing system parameters using a sensitivity analysis. We then present a methodology for choosing the optimal system parameters which takes the constraints presented to the system, such as cost, as an integral part of the model. We propose the use of a benefit- function and a cost-function that allow us to measure the cost-benefit ratio for every system. We use this ratio as the merit figure of the system and optimize for maximal cost- benefit.

Regardless improvements of Stirling and Pulse Tube coolers performances, Joule Thomson coolers are still interested for systems which require very fast cool down, compactness and high reliability. AIR LIQUIDE-DTA- believes that most of the future applications for Joule Thomson coolers would required devices such as single flow or dual flow coolers if manufacturers are able to increase significantly the performances and decrease the cost of such coolers. AIR LIQUIDE-DTA- has developed recently new technologies in order to match this challenge and to widen its range of low cost coolers. Previous developments such as memory shape valve and flat cooler were improved and adapted for cylindrical coolers. Original heat exchanger was also realized for flat cooler applications. Prototypes and results are presented in this paper for coolers with a target price which shall not exceed 200 USD.

Raytheon Mahwah Electro-Optics Center has been developing a Stirling-cycle cryocooler for infrared imaging applications. This new linearly driven cooler has the same weight, fit and function as the current HM7060 series coolers with significant improvement in performance in three areas: cooling capacity, motor efficiency and range of ambient temperature. The cooling capacity has been increased by more than 10 percent by increasing the compressor swept volume. This change will allow faster cooling as well as the more cooling capacity. The design of the magnetic circuit of the linear motor has been further optimized to obtain a 15 percent improvement in motor efficiency. Material selection and clearance seal configuration have been improved to allow smooth operation at high temperature environment with average cooler case temperature at 90 degrees Celsius. As a typical example of the improved performance, the new cooler is capable of providing over 350 mW of cooling at 80 K with a cooler case temperature of 90 degrees Celsius and an ac input power of about 25 W. This paper describes the design, fabrication, and performance test results of this new cooler.

To meet the current and growing demand for low cost and high reliable cryocoolers dedicated to the cryo-electronics, Cryotechnologies and Signaal-Usfa propose a range of suitable answers with Stirling, Pulse Tube and thermoelectric cryocoolers. The paper describes miniature cryocoolers considering Integrated Dewar Cooler Assemblies (I.D.C.A.) for operation in the 60 - 200 K cooling temperature range.

When designing cooled infrared detectors, it is definitely a challenge to get simultaneously high optical efficiency and low radiative heat load of the cold shield. From an optical point of view, cold shield must be as big and absorbing as possible. But the reduction of cooler size, input power and cool down time require precisely an opposite approach. This critical optimization is emphasized by the necessity of conducting long and expensive experiments since radiative exchanges have been extremely complex and can not be accurately estimated by calculation. Recent optical concepts as BRDF (Bidirectional Reflectance Distribution Function) and the increase of computer processor speed have made possible the development of a lighting software for this topic. This software was developed by upgrading an existing non-sequential light propagation one. Upgrades apply particularly to capabilities of modeling complex geometries as IR focal planes, taking into account spectral dependency of radiative properties of surfaces and volumes and introduction of the diffusion behavior of actual surfaces (BRDF). BRDF properties of most current surfaces were measured at both ambient and low temperatures. At least, the software was qualified by comparison of computed and experimental results of exceeding photon fluxes in actual detector. This CAD approach is of high interest in cost driving designs by simplifying cold shield systems and in application where there is very low scene photon fluxes.

Several reverse-Brayton cycle cryocoolers are being developed for long-life, vibration-free applications cooling spaceborne instruments. These coolers employ miniature high speed turbomachines with self-acting gas bearings and low mass shafts to provide the compression and expansion functions without vibration. Advanced, high performance recuperative heat exchangers result in high cycle efficiency at low pressure ratios. Recent advances in this technology permit the construction of smaller machines while preserving important geometric features. As a result, reasonable efficiencies are maintained in these components as sizes are reduced. This is critical for maintaining acceptable overall cycle efficiencies as refrigeration loads and temperatures are decreased. This paper summarizes the present status of developments with respect to turboBrayton crycoolers for a range of conditions between about 75 K and 6 K. The largest of the systems is capable of up to 15 W refrigeration at 70 K; the smallest is designed for less than 100 mW at less than 10 K. Important phsyical characteritics of severla systems and their components will be presented. System performance characteristics will be discussed.

The solid state reliability and convenience of thermoelectric coolers make them an attractive solution to cooling detectors. We present evidence that the temperatures difference of thermoelectric Bi₂Te₃ coolers can be increased by optimizing the device parameters. Computer modeling of multistage coolers was used to analyze the parametric effects on their performance. Experimental coolers were constructed on the basis of modeling results and tradeoffs between performance and size. A heat treatment was applied to the Bi₂Te₃ elements, reducing their resistivity to about 25% of that of untreated elements. The performance of radiation shielded coolers in vacuum was investigated, with the heat sink temperature maintained at 293 K. Without field enhancement, the temperature difference measured for a six- stage cooler was 137 K in presence of a thermal load of 10 mW. To compensate for the increase of the stage dimensions in seven-stage coolers, the thermal resistance of the stage surface was reduced by means of solder coating. For the best seven-stage device, a difference of 166 K could be achieved for a thermal load of 20 mW. For the parameter values used in the experiment, the cooldown time was typically 500 sec regardless of the supplied voltage. The measured ratio of temperatures of adjacent stages varied negligibly, indicating that the coefficient of performance of the studied cooler is close to the optimum value. The good agreement found between experimental and computer modeling data suggests that the developed model may be suited for further performance prediction.

The problem of assessing a product's reliability under limited data and knowledge is a common one. This article presents a reliability assessment algorithm, with application to cryocoolers, designed to handle such problems.

The paper reviews the development of IR detectors for the 8 - 12 micrometer wavelength range based on GaAs/AlGaAs quantum well structures and InAs/(GaIn)Sb short-period superlattices (SPSLs) at the Fraunhofer-Institute IAF. Photoconductive GaAs/AlGaAs quantum well infrared photodetectors (QWIPs) are used for the fabrication of starring IR cameras for thermal imaging in the third atmospheric window. The long wavelength infrared (LWIR) camera, devleoped in cooperation with AEG Infrarot-Module (AIM), consists of a two-dimensional focal plane array (FPA) with 256 X 256 detector elements, flip- chip bonded to a read-out integrated circuit (ROIC). The technology for the fabrication of FPAs, electrical and optical properties of single detector elements in the two-dimensional arrangement and the properties of the LWIR camera system are reported. A noise equivalent temperature difference (NETD) below 10 mK has been measured at an operation temperature of T equals 65 K with an integration time of 20 ms. More than 99.8% of all pixels are working and no cluster defects are observed. InAs/(GaIn)Sb SPSLs with a broken gap type-II band alignment are well suited for the fabrication of IR detectors covering the 3 - 12 micrometer spectral range. Due to the lattice mismatch of the InAs/(GaIn)Sb SPSL with respect to GaSb, tight control of thickness and composition of the layers and a controlled formation of the chemical bonds across the interface in the SPSLs are used for strain compensation. Photodiodes with a cut-off wavelength (lambda) _c equals 8 micrometer and a current responsivity R_(lambda ) equals 2 A/W exhibit a dynamic impedance of R₀A equals 1k(Omega) cm² at T equals 77 K. This leads to a Johnson- noise limited detectivity in excess of D* equals 1 X 10¹² cm(Hz)^1/2/W for these type of detectors.

The family of two dimensional detection modules at AEG Infrared-Modules GmbH (AIM) based on platinum silicide (PtSi) or mercury cadmium telluride (MCT) focal plane arrays for applications in either the 3..5 micrometer (MWIR) or 8..10 micrometer (LWIR) range was recently extended. Two new MCT devices have been realized in the configurations 384 X 288 elements in a 24 micrometer pitch for mid wave applications and 256 X 256 elements in a 40 micrometer pitch for long wave applications. Further a quantum well infrared photodetector (QWIP) device with 256 X 256 elements for long wave applications was introduced. The QWIP material was developed by the Fraunhofer Institute for Applied Physics (IAF) in Freiburg, Germany. Details of the QWIP chip will be presented in a separate paper. The MCT devices provide extremely fast frame rates like 200 Hz and reach even for very short snapshot integration below 350 microsecond noise equivalent temperature differences (NETD's) below 20 mK for the LWIR modules. The QWIP devices provide an NETD even below 10 mK with excellent homogeneity for a rolling frame integration with 20 ms integration time and 50 Hz frame rate. Besides the thermal resolution given by the NETD, the correctability of the devices is discussed as a second important characteristic for the system design. Miniaturized driving and readout electronics and image processing boards for non uniformity correction were developed for different applications. The electronics provide a standardized exclusively digital interface with 14 bit deep resolution for high resolution excellent correctability and simplified exchangeability of modules. The design concepts of the AIM detector family and the main features of some new selected modules are summarized together with measured performance data in this paper.

The last 10 years of engineering and production at AEG INFRAROT-MODULE GmbH (AIM) resulted in continued improvements in performance, yield and reliability of IR modules and cryocoolers. For the optimizing of engineering, production and testing over the complete scope, from semiconductor material growth, FPA fabrication, cryo packaging data processing and software, cooling, etc. up to the camera level, AIM has all critical technologies under one roof. This paper demonstrates how such results were achieved, which criteria are to be met for performance, yield and cost improvements and how contemporary IR modules from AIM reflect these achievements.

The low pressure deposition of polycrystalline diamond and the preparation of diamond windows at the Fraunhofer-IAF is reported. Using microwave plasma CVD, large area (2-6' diameter) diamond wafers with thicknesses of up to 2 mm have been grown. The deposition is carried out in a novel microwave plasma system which uses an ellipsoid cavity to generate very intense, spatially extended plasmas. Several of these plasma reactors with 6 to 60 kW microwave power are presnetly used at the IAF. The diamond wafers are ground and polished and laser- cut to the desired dimensions. To assess the optical and thermal properties, the residual absorption in the 10 micrometer range is determined by CO₂ laser calorimetry, and temperature dependent and spatially resolved measurements of the thermal conductivity are performed. In addition, thermal expansion and refractive index measurements as a function of temperature are reported. Using high-purity process gases and optimized CVD conditions, diamond windows with a residual absorption at 10.6 micrometer below 0.1 cm^-1 and a thermal conductivity over 20 W/cmK have been realized. In addition, low dielectric losses of tan(delta) equals 0.6 X 10^-4 at 140 GHz have been measured.

The design goal of this project was to develop a thermal imaging system with ultimate geometrical resolution without sacrificing thermal sensitivity. It was necessary to fulfil the criteria for a future advanced video standard. This video standard is the so-called HDTV standard (HDTV High Definition TeleVision). The thermal imaging system is a parallel scanning system working in the 7...11 micrometer spectral region. The detector for that system has to have 576 X n (n number of TDI stages) detector elements taking into account a twofold interlace. It must be carefully optimized in terms of range performance and size of optics entrance pupil as well as producibility and yield. This was done in strong interaction with the detector manufacturer. The 16:9 aspect ratio of the HDTV standard together with the high number of 1920 pixels/line impose high demands on the scanner design in terms of scan efficiency and linearity. As an advanced second generation thermal imager the system has an internal thermal reference. The electronics is fully digitized and comprises circuits for Non Uniformity Correction (NUC), scan conversion, electronic zoom, auto gain and level, edge enhancement, up/down and left/right reversion etc. It can be completely remote-controlled via a serial interface.

Results of an investigation into the concept of a multi- spectral (Vis/MWIR) electro-optical long-range oblique-looking digital camera are presented. Choice of the medium-wave band for the IR channel is discussed. An advanced EO camera would take advantage of available multi-element two-dimensional focal-plane-array sensors. Such detectors being of the staring type with integration times in the order of milliseconds imply provisions to be made to keep the sensor foot print fixed on ground during exposure. So precisely controlled forward-motion compensation as well as passive vibration isolation along with excellent active three-axis stabilization is of paramount importance. In order to provide large ground coverage together with good geometrical resolution, the ground is paved with slightly overlapping sensor foot prints by means of step-wise sweeping the line of sight. Space constraints due to existing- pod geometry as opposed to desired sensitivity performance particularly govern the optics design. An off-axis catoptric system has been chosen for the front objective as a most promising method to cope with the two far-away wavebands as well as to have the different sizes of respective detectors coincide with the instantaneous images of identical foot prints of the two channels.

TRM3 is a device and range performance model for modern thermal imagers with their numerous possible design features. The TRM3 computer program contains two different device models: The Conventional Approach model and the TRM3 Approach model. In the Conventional Approach model, the assumptions are similar to FLIR92. The TRM3 Approach model uses different assumptions in case of fixed pattern noise and of undersampled systems. If the imager is undersampled, an MTDP (Minimum Temperature Difference Perceived) is calculated, rather than an MRTD. This MTDP is used to predict the range performance of undersampled imagers. With the new approach, significantly higher ranges are predicted than those expected with FLIR92. The problem in assessing undersampled thermal imagers with the standard 4-bar test pattern is shortly described. The new approaches in the TRM3 Approach model are outlined and discussed. Examples of measured and predicted MTDP data as well as range data are given. Finally, a short introduction to the TRM3 computer program is given.

The paper reports on current advances in the development of the Dornier Obstacle Warning System (OWS) for helicopters, with particular emphasis on the Obstacle Warning Ladar (OWL). Here both segments, development and application of the 1.5 micrometer imaging laser radar (LADAR) will be represented. It will be shown how advances in the eyesafe LADAR technology resulted in Obstacle Warning Ladar optimized for wire detection leading to a system family platform covering the range from the commercial needs up to the military requirements.

The multifunctional properties of modern Laser sources for future military sensor applications will be studied. The goal of this study is the design of a modular laser source which covers various functions like: Laser rangefinding. Target designation (1.06 micrometer), Eyesafe target designation (1.5 micrometer), Laser radar for Automatic target recognition, Identification friend or foe using Laser interrogation with D- band response as well as allowance for Covert communication and Missile jamming with a laser in the 3 to 5 micrometer range. It is obvious that these applications require a wide range of power levels, wavelength agility and pulse repetition rates. The concept for a compact Laser source to cover these requirements will be presented. In addition a concept for the integrated sensor to provide the above mentioned functions will also be presented.

During the last ten years, the impact of infrared and laser devices on surveillance and weapon systems has rapidly increased. Compared to the technology used in the first generation of devices and systems, today's technology has reached a higher level of maturity, allowing such advanced infrared and laser devices to be integrated in a variety of military applications. In Germany, the definition of infrared and laser sensors has changed in the last 10 years, and is almost used synonymously with the complete integration of sensor hardware and sophisticated signal and image processing instead of just considering 'pure' device technologies. This new understanding shows the challenge for future applications and defines the basic methodology for planning the research efforts to improve the use of infrared and laser devices in military systems. This determines the basic elements for future research and development support by the German government: (1) Next generation of infrared detectors (quantum well and superlattices), (2) Thermal imagers, (3) Windows for IR and radar sensors, (4) Multifunction laser sensors, (5) Image processing and pattern recognition, (6) Demonstrators for sensors.

For coding of image sequences taken by an airborne IR sensor, an object-based coding method using MPEG-4 coding tools is investigated. In order to encode the landscape, current frame- based MPEG-4 coding is extended by global motion compensation, as proposed for MPEG-4 version 2, and by a sprite coding technique. This VOP0 encoder saves the bit-rate of the motion vectors due to global motion compensation and provides an additional bit-saving by not transmitting sprite prediction errors. Only extensions of the sprite are encoded. Object- based MPEG-4 coding by the VOP1 encoder is used for encoding moving objects, if the size of a moving object exceeds the size of a 16*16 pel macroblock. Thus, the data rate of the VOP0 and VOP1 coding depends on the size of the sprite extension area and the size of moving objects in the scene. Compared to frame-based MPEG-4 coding which reduces the bit rate by a factor of about 25 without visible distortions an additional compression factor of 2 can be achieved. To facilitate an implementation of the MPEG-4 coding tools a high computation power in combination with frequent access on varying positions of the entire image is required. Therefore, a flexible, parallel, high performance video signal processor architecture called PRISMA has been designed that employs a novel controlling scheme, called associative controlling.

In this paper the IR-scene generation method is presented as developed at FGAN-FIM 'Research Institute for Information Processing and Pattern Recognition.' The main task of the generation is the calculation of images approximating the view of a real (or future) IR-imager. The generator is implemented in software and is not intended for creating images in real- time. The modeling of natural backgrounds, vehicles and man- made objects is shown, and short description of the methods used for the scene composition is given. Scene dynamics is introduced by camera and/or target movements under use control. The output of the IR-scene generator is an animated image sequence. The principal advantage of an IR-simulation system is the creation of reproducible and accurate image data. Hence the evaluation and assessment of image analyzing systems (e.g. seekerhead or tracker) can be simplified. Moreover the analyzing system may acquire complete control over the image generation and new images (with well known viewing conditions) can be calculated on request.

Most common approaches to interactive object recognition in multisensor/multispectral imagery are sensor data driven. They address the problem of displaying images of multiple sensor sources in a manner adequate to the characteristics of the sensors. Fusion of sensed data is the topic of those concepts. This paper discusses a supplementing approach from the opposite end: the domain of target objects. Knowledge about the appearance of objects under various spectral conditions guides the image analyst through the interpretation process. Therefore, the basic concept of an >>interactive recognition assistant<< will be proposed. Starting from a set of candidate objects the image analyst is guided through a step-by-step interpretation process by getting indicated the respectively most significant features for efficient reduction of the candidate set. In the context of this approach we discuss the question of modeling and storing the multisensorial appearances of target objects as well as the problem of an adequate dynamic human-machine-interface that takes into account the mental model of human image interpretation.

The threat of hostile surveillance and weapon systems require military aircraft to fly under extreme conditions such as low altitude, high speed, poor visibility and incomplete terrain information. The probability of collision with natural and man-made obstacles during such contour missions is high if detection capability is restricted to conventional vision aids. Forward-looking scanning laser rangefinders which are presently being flight tested and evaluated at German proving grounds, provide a possible solution, having a large field of view, high angular and range resolution, a high pulse repetition rate, and sufficient pulse energy to register returns from wires at over 500 m range (depends on the system) with a high hit-and-detect probability. Despite the efficiency of the sensor, acceptance of current obstacle warning systems by test pilots is not very high, mainly due to the systems' inadequacies in obstacle recognition and visualization. This has motivated the development and the testing of more advanced 3d-scene analysis algorithm at FGAN-FIM to replace the obstacle recognition component of current warning systems. The basic ideas are to increase the recognition probability and to reduce the false alarm rate for hard-to-extract obstacles such as wires, by using more readily recognizable objects such as terrain, poles, pylons, trees, etc. by implementing a hierarchical classification procedure to generate a parametric description of the terrain surface as well as the class, position, orientation, size and shape of all objects in the scene. The algorithms can be used for other applications such as terrain following, autonomous obstacle avoidance, and automatic target recognition.

A field-of-view-multiplexer is presented which images several fields of view with high resolution onto a single focal plane array. The field-of-view-multiplexer consists of a primary objective, a micro-optical image steering device, and a secondary objective. The primary objective images the individual fields of view onto a common intermediate image plane. The image steering device comprises a focusing and a defocusing micro-lens array which are mounted parallel to each other near the intermediate image plane. This micro-optical image steerer selects a particular field of view by laterally displacing the two micro-lens arrays. The selected field of view is relayed onto the focal plane array by the secondary objective. This way, a large field of regard can be sampled quickly without the use of electromechanical gimbals. The paper outlines the IR sensor concept, explains the underlying principles, and delineates the optical systems layout. In addition, performance data of a proof-of-concept imaging system are presented.

A ground-based air surveillance system will be outlined which uses bispectral passive search sensors combined with a high- resolution IR sensor and a laser rangefinder to verify potential alarms and establish target tracks. To achieve highly frequent sampling of the hemispherical field of regard, multiple optical channels are multiplexed with high speed at high-frame rate focal plane arrays. Newly developed micromechanical mirror arrays provide high-speed switching of these optical channels. Image processing algorithms sort out possible target events from clutter in real time. Candidates of potential threat are verified in a second acquisition step using the narrow field of view IR sensor and a laser rangefinder. Thus, high-resolution IR features and three- dimensional range information can be fused with the 2- dimensional search sensor output to distinguish false alarms from real target threats. The paper will focus on the description of the sensor suite. The main system requirements of this new surveillance system will be addressed and the design of an experimental system to demonstrate the performance of its new technology items will be outlined.

In the past, DASA/Dornier has developed various image exploitation systems. A summary of their characteristics will be presented here. The changing reconnaissance tasks in the world, together with cost and manpower restrictions demand new image exploitation solutions which are influenced by different technical approaches. They range from individual image processing steps to powerful fusion and classification techniques. In order to develop, test and integrate improved exploitation techniques, a generic functional architecture for exploitation systems has been designed. In this article we will report on the general development strategy for the realization of DASA/Dornier's image exploitation systems and their technical features. In order to test and validate different exploitation algorithms, image data produced during flight campaigns is fed into the image exploitation systems. Performance of integrated algorithms is evaluated by systematic testing. This is illustrated by some examples.

Anti-ship missiles, especially seaskimmers, are severe threats for the ships of naval forces. Infrared Search and Track (IRST) systems offer the passive detection of such targets at long ranges. The performance requirements for such a warning system are very tough: the false alarm rate (FAR) shall not exceed one false alarm per day. To assess the performance of an IRST system (FAR, detection probability, range) a very large data set must be processed. For this purpose an IRST data acquisition and assessment system has been built. By means of this system a large amount of long IR image sequences can be measured, stored digitally, and processed in near real time. In 1997 two measurement campaigns with this system have been conducted, delivering a huge amount of image data with and without targets. Several sequences of this data have already been analyzed. The essential components of the built IRST data acquisition and assessment system are described. Details about one of the measurement campaigns are reported and samples of measured image data and first results are presented.

Lockheed Martin IR Imaging Systems is developing low cost, high performance, uncooled infrared imaging products for both military and commercial applications. These products are based on microbolometer technology, a silicon micromachined sensor that combines wafer level silicon processing with a device structure capable of yielding excellent imaging performance. Here, in the first of a series of papers, we report on several applications that are utilizing the Lockheed Martin microbolometer sensor. The performance of our basic uncooled sensor has been measured (and reported in multiple papers) to determine sensor capabilities for insertion into both military and commercial products. Non-linearity of the sensor over a scene temperature range of 95 degrees Celsius is less than 0.5%. Our sensors typically have temporal NETDs of less than 70 mK as well as spatial NETDs of less than 50 mK. MRTD performance is less than 0.4 degrees Celsius at spatial frequencies more than 20% beyond Nyquist. Spatial noise variation over time has been measured and found to meet both commercial and military requirements with excellent spatial noise over wide scene and ambient temperature ranges. Some of the multiple applications in which our uncooled sensors have been used have just recently been described in one report demonstrating the varied and unique uses of this product. Our sensor is now used by dozens of partners and customers for applications ranging from hand-held radiometric cameras to driving aids; from driver's aids to miniature cameras from rifle sights to radiometers. These applications will be discussed along with their unique system level performance parameters. Video will be used to demonstrate the various applications discussed.

Uncooled Thermal Imaging (TI) in the UK involves large arrays of ferroelectric bolometer elements, at a pitch of from 100 micrometer down to 40 micrometer. A Hybrid Array Technology, exploiting the pyroelectric property of ferroelectric ceramic materials for the bolometer elements, has produced a range of successful solder bump bonded 2-D arrays. However, in innovative technologies under research, direct deposition of the ferroelectric material as a thin film onto suitable thermal microstructures on the silicon readout IC will provide substantial reductions in costs as well as improved performance. A route has been defined for this Integrated Array Technology, leading to performance enhancements by a factor of three over the Hybrids. In achieving the performance, the optimized ferroelectric signal readout, signal conditioning and processing architectures perfected for the Hybrid Arrays will be retained. Microscan mechanisms, readily incorporated in the IR chopped format used with ferroelectric imaging, have been demonstrated for the Hybrids, and will be even more closely matched to the improved thermal diffusion MTF of the Integrated devices. The ferroelectric capacitative detector filters the high frequencies, limiting noise bandwidths for very large arrays, and with microscan technology added, the ferroelectric arrays retain their potential to provide high quality IR imaging at very large equivalent array sizes.

This paper reports the fabrication of microbolometers using semiconducting YBaCuO as the IR sensing material. The detectors are operable at room temperature and thus are suitable for lost-cost and high performance imaging applications. Semiconducting YBaCuO is promising as a bolometric material as it has a thermal coefficient of resistance near 3% and relatively low noise. Two different bolometer structures will be reported here. First generation YBaCuO microbolometers were built on micromachined SiO₂ bridges using wet etching techniques to undercut the silicon. The second generation structures were processed upon micromachined Si₃N₄ membranes with sputtered MgO films used as sacrificial layers. The membrane structures are the first of its kind to incorporate MgO as a sacrificial layer, and they offer a fabrication technique that is fully CMOS compatible, with all processing at ambient temperatures. Detectivities in the order of 10⁸ cm Hz^1/2/W were measured at 30 Hz chopping frequency in both structures. The thermal conductance of the suspended membranes was on the order of 10^-7 W/K, which is desirable as low thermal conductance yields high responsivities. There are realizable optimizations for both applications to yield detectivities over 10⁹ cm Hz ^1/2/W. All measurements reported here were performed at ambient temperature with no temperature stabilization.

The maturation and commercialization of uncooled focal plane arrays and high density electronics now enables lightweight, low cost, small camera packages that can be integrated with hard hats and military helmets. It is only recently that low weight, staring long wavelength infrared (LWIR) sensors have become available employing uncooled focal planes at array size and sensitivities that provide enough information for useful, man-portable, wearable applications. By placing the IR camera on the head, a hands-free infrared virtual reality is presented to the user. This paper describes applications, the design of a helmet mounted IR sensor and presents images from the helmetcam. The head gear described has a noise equivalent delta temperature (NEDT) of less than 50 milliKelvin, consumes less than 10 watts and weighs less than 3 kilograms.

We have developed an uncooled thermal imager having 160 X 120, 50 micrometer X 50 micrometer pixels which operates at 30 Hz frame rate. It employs a complementary metal oxide silicon (CMOS) redout integrated circuit (ROIC) beneath a vanadium oxide (VOx) silicon microstructure bolometric array. Imagery output is in RS-170 format. An RS-232 port can be employed to command operation from a remote location. Weight of the 'engine,' consisting of the focal plane array in is package plus three circuit boards, each 3 X 3 inches, is 8 oz. Input power is 2.5 Watts. Also included on the boards is a circuit which avoids the need for a temperature stabilizer in the array package. Operating in the 8 - 14 micrometer spectral interval, the imager has a noise equivalent temperature difference (NETD) with an f/0.8 lens against 295 K targets of less than or equal to 0.1C. The dynamic range of 66 dB will accommodate very hot targets without saturation of an image which also contains 290 K targets.

Progress is reported on the development of uncooled microbolometer IR focal plane detector arrays (IRFPDA) under a research collaboration between the Swedish Defence Research Establishment (FOA), and the Defence Science and Technology Organization (DSTO), Australia. The paper describes current focal plane detector arrays designed by Electro-optic Sensor Design (EOSD) for readout circuits developed by FOA. The readouts are fabricated in 0.8 micrometer CMOS, and have a novel signal conditioning and 16 bit parallel ADC design. The arrays are post-processed at DSTO on wafers supplied by FOA. During the past year array processing has been carried out at a new microengineering facility at DSTO, Salisbury, South Australia. A number of small format 16 X 16 arrays have been delivered to FOA for evaluation, and imaging has been demonstrated with these arrays. A 320 X 240 readout with 320 parallel 16 bit ADCs has been developed and IRFPDAs for this readout have been fabricated and are currently being evaluated.

An uncooled IR camera making use of a 128 X 128 pixel bolometric FPA is presented. The reconfigurable bolometric focal plane array consist of 50 micrometer X 50 micrometer pixels and simple on-chip CMOS readout electronics which can be operated in random access, independent row and column clocking, and self-scanning modes. Depending on the selected pixel format and frame rate, the FPA's NETD varies from 0.52 degrees Celsius down to 0.10 degrees Celsius. The modular IR camera is software configured and provides RS170A analog video and 12-bit TTL format digital outputs.

A medium scale infrared sensor dedicated to applications in agriculture, hydrology, forest fires and environment has been studied within the framework of a European Commission contract. An innovative push broom concept using linear arrays of uncooled microbolometers has been preferred to a traditional scanner concept using cryogenically cooled photoconductor detectors, for its performances and because it does not require any cooling, and is free of micro-vibrations. The instrument offers a resolution of 250 m for a swath width of about 1400 km, and the radiometric resolution is better than 0.5 K in two spectral channels around 11 and 12 micrometer. Focal plane topology and radiometric modeling will be presented in this paper, demonstrating the suitability of microbolometers focal planes for medium resolution radiometric missions on board Low Earth Orbit satellites.

Today, a large number of uncooled infrared detector developments are under progress due to the availability of silicon technology that enables realization of low cost 2D IR arrays. LETI/LIR, which has been involved in this field for a few years, has chosen resistive amorphous silicon as thermometer for its uncooled microbolometer development. After a first phase dedicated to acquisition of the most important detector parameters in order to help the modeling and technological development, an IRCMOS laboratory model (256 X 64 with a pitch of 50 micrometer) was realized and characterized. It was shown that NETD of 70 mK at f/1, 25 Hz and 300 K background can be obtained with high thermal insulation (1.2 10⁷ K/W).

Once relegated to expensive military platforms, occasionally to civilian platforms, and envisioned for individual soldiers, uncooled thermal imaging affords cost-effective solutions for police cars, commercial surveillance, driving aids, and a variety of other industrial and consumer applications. System prices are continuing to drop, and swelling production volume will soon drive prices substantially lower. The impetus for further development is to improve performance. Hybrid barium strontium titanate (BST) detectors currently in production are relatively inexpensive, but have limited potential for improved performance. The MTF at high frequencies is limited by thermal conduction through the optical coating. Microbolometer arrays in development at Raytheon have recently demonstrated performance superior to hybrid detectors. However, microbolometer technology lacks a mature, low-cost system technology and an abundance of upgradable, deployable system implementations. Thin-film ferroelectric (TFFE) detectors have all the performance potential of microbolometers. They are also compatible with numerous fielded and planned system implementations. Like the resistive microbolometer, the TFFE detector is monolithic; i.e., the detector material is deposited directly on the readout IC rather than being bump bonded to it. Imaging arrays of 240 X 320 pixels have been produced, demonstrating the feasibility of the technology.

Thermoelectric infrared sensors has been fabricated by adding to the CMOS process a surface micromachining technique and a highly accurate process for forming an infrared radiation absorbing layer. The sensor, or thermopile, consists of alternating areas of p-type and n-type polysilicon connected in series on a Si₃N₄ layer. An anisotropic etching technique using hydrazine is employed to form a thermally isolated membrane. While a Au-black layer for infrared radiation absorption provides the best absorption efficiency over a broad infrared wavelength region, it has been difficult to pattern the layer precisely. Patterning is accomplished by forming the Au-black layer by a low-pressure vapor deposition technique on amorphous Si and a PSG sacrificial layer and then removing it on PSG by the lift-off technique or wet etching PSG. This technique makes it possible to obtain a Au-black pattern with the same degree of accuracy as with the CMOS process. As a result, sensor performance has been improved and a device array has also been achieved. A simple sensor design method has been established by which simulations are easily conducted using a thermal equivalent circuit based on the CMOS process. Prototype sensors, having external dimensions of 160 micrometer X 160 micrometer, achieved responsivity of 300, 149 and 60 V/W and a time constant of 2.0, 0.46 and 0.27 msec in the air, respectively. These performance figures surpass the performance reported to date for thermoelectric infrared sensors.

Raytheon Systems Company has developed a prototype infrared imaging rifle-sight using an uncooled, microbolometer FPA. The high-sensitivity FPA (SBRC-151) used in the Long-wavelength Staring Sensor (LWSS) was developed by Raytheon Infrared Center of Excellence (IR COE). The NETD (noise equivalent temperature difference) sensitivity of the camera has been measured at 14 mK with f/1 optics and at 74 mK with an f/2.1 aperture stop. Excellent imagery has been demonstrated with the f/2.1 aperture. The 320 X 240 FPA utilizes a high-yield CMOS readout integrated circuit (ROIC) that achieves high sensitivity, low output nonuniformity, and large scene dynamic range. The ROIC provides multi-level, on-chip nonuniformity correction and on-chip temperature compensation. The FPA has 50 micrometer X 50 micrometer pixels and operates at frame rates up to 60 Hz with a single output. The LWSS was characterized by the U.S. Army's NVESD in 1997 using an earlier version of the SBRC-151 FPA. The NVESD measurements validated the Raytheon NETD data. The NVESD evaluation also demonstrated outstanding MRT and spatial noise characteristics. The VO_x microbolometer detectors are produced at the Raytheon IR COE facility in Santa Barbara, CA using an advanced dry-etch fabrication process. In addition to the LWSS project, the IR COE has initiated production of the microbolometer FPAs (AE-189) for commercial applications. Over 600 FPAs have been produced on this project, and data is presented for the first 250 FPAs that have been packaged and tested. The pixel operability of the production radiometer FPAs (AE-189) is typically greater than 99.9%.

The bi-material concept for room-temperature infrared imaging has the potential of reaching an NE(Delta) T approaching the theoretical limit because of its high responsivity and low noise. The approach, which is 100% compatible with silicon IC foundry processing, utilizes a novel combination of surface micromachining and conventional integrated circuits to produce a bimaterial thermally sensitive element that controls the position of a capacitive plate coupled to the input of a low noise MOS amplifier. This approach can achieve the high sensitivity, the low weight, and the low cost necessary for equipment such as helmet-mounted IR viewers and IR rifle sights. The pixel design has the following benefits: (1) an order of magnitude improvement in NE(Delta) T due to extremely high sensitivity and low noise; (2) low cost due to 100% silicon IC compatibility; (3) high image quality and increased yield due to ability to do offset and sensitivity corrections on the imager, pixel-by-pixel; (4) no cryogenic cooler and no high vacuum processing; (5) commercial applications such as law enforcement, home security, and transportation safety.

We have developed a new type of detector pixel circuit operated in an infrared image sensor of dielectric bolometer mode. The detector pixel consists of capacitors of ferroelectric BST (Ba_1-xSr_xTiO₃) thin film, whose dielectric constant changes drastically with temperature. Our proposed circuit is a serially connected capacitor-capacitor, where one capacitor is composed of a BST ferroelectric thin film irradiated by infrared light and the other is nonirradiated one. BST film has been prepared on Si membrane structure by laser ablation. Dielectric constant of the BST film, which is about 450 at 25 degrees Celsius, changes by about 1 to 10%/K in ambient temperature. The maximum change is as large as about 100/K, and more than about 10%/K relative change in the dielectric constant or the corresponding capacitance has been induced. As a result of on-board evaluation of the assembled circuit with a source-follower output, the output level is about 40 mV when a relative capacitance change in the capacitor is about 3%. On the other hand, in PSPICE circuit simulations, the output level is about 25 mV when a relative capacitance change in the capacitor of about 100 pF is 1%. The simulated relationship between the output voltage and capacitance change of the BST film in the assembled circuit agrees well with that in the experimental results. It is considered that the circuit has enough output signal level for input of conventional operational amplifier. Calculated thermal responsivity R_v, and specific detectivity D* are 50 kV/W and 6.5 X 10⁹ cm (DOT) Hz^1/2/W, respectively, which means high-sensitivity compared to the other type of IR sensors. The pixel structure also shows a simple configuration, and then is very effective in reducing their pixel size and then increasing the pixel density.

The performance of microbolometer infrared sensors is typically characterized by its thermal time constant, heat capacitance, and thermal conductance. Therefore, the determination of these parameters accurately and efficiently is of considerable interest for the design and operation of microbolometer infrared sensors. Usually, the thermal time constant is obtained by measuring the frequency response of microbolometers under infrared excitation and the thermal conductance and capacity are extracted using electrical measurement. In this paper, a technique is described to extract all three parameters using a single electrical measurement. In the measurement, we have employed a Wheatstone Bridge consisting of a bolometer and three reference resistors. The resistance of the bolometer changes as a result of self-heating under an external bias which in turn generates an output voltage across the Bridge. The time dependence of the output voltage was used to extract thermal parameters of the bolometer. We believe this technique is useful in determining the thermal parameters of microbolometer based sensors.

A dual-band MWIR/Visible Electro-Optic sensor suite has been developed for use in the CM010 family of Optronics Masts, currently being evolved by Pilkington Optronics for the Royal Navy's new Astute Class submarines. The sensor suite features a medium wave IR thermal imaging camera and a broadcast standard color TV camera, both of which view the scene through a common sapphire pressure window. Three-axis stabilization is provided for both sensors, in which pitch and yaw are controlled by a common line-of-sight prism behind the sensor window, while control of roll about the line of sight is achieved by individual optical derotators within the TI and visible band optics. Precision stabilized control is provided in both the MWIR and visible optical chains. The MWIR sensor consists of a diagonally-microscanned 320 X 240 focal plane, the microscan beam deflection being carried out by the TI piezo mirror. The visible sensor, designed for daylight use, consists of three 1024 X 1024 pixel frame transfer CCD focal planes, which in conjunction with variable neutral density filters yield excellent performance over a 10³ dynamic range of daylight scene illuminance. Both optical systems provide Fields of View of 3, 6 and 24 degrees, and a Field of Regard covering from -15 degrees in depression to +60 degrees in elevation. Field of view switching is carried out by dual-band afocal optics situated in the common optical path. A 'Quick Look Round' mode allows both sensors to capture imagery through a full 360 degree azimuth sweep for subsequent analysis, with minimal mast exposure time.

Multispectral sensors are increasingly being employed in military applications. Just as in satellite imagery of the earth, multispectral data is required in order to extract the maximum amount of information from a scene. The advantages of image fusion have been postulated for navigation, surveillance, fire control, and missile guidance to improve accuracy and contribute to mission success. The fusion process is a critical element of each of these applications. Imagery from various sensors must be calibrated, enhanced and spatially registered in order to achieve the desired 'fusion' of information into a single 'picture' for rapid assessment. In a tactical military environment this fusion of data must be presented to the end user in a timely and ergonomical fashion. The end user (e.g., a combat pilot) may already be operating at maximum sensory input capacity. Does he or she really need another cockpit display?

The Defense Research Establishment, Valcartier has an ongoing project on a multi-sensors system, called CAMUS (Common Aperture MUlti-Sensors). The main objective of this project is to demonstrate the concept of fusing three sensors on a single chassis. The project covers the development of the sensors' head and the processing sub-systems required for fusing the acquired data and information. The three sensors identified for this project are: a visible camera, a 3 - 5 micrometer infrared camera and a 94 GHz millimeter-wave radar. This paper describes the approach used to combine the three sensors along with the various processing schemes to merge the visible and infrared images with the radar information. The CAMUS system will present all the information gathered by the three sensors on a single display to the operator. The main application of this project is to demonstrate an advanced sight for a direct fire control system.

A multi-sensor approach to buried object discrimination has been developed by Coleman Research Corporation (CRC) as a practical successor to currently prevalent metal detectors. The CRC multi-sensor unit integrates with and complements standard metal detectors to enable the detection of low- metallic and non-metallic anti-tank and anti-personnel mines as well as the older metallic-jacketed mines. The added sensors include Ground Penetration Radar (GPR) and Infrared (IR). The GPR consists of a lightweight (less than 1 LB) snap on antenna unit, a belt attached electronics unit (less than 5 LB) and batteries. The IR consists of a lightweight (less than 3 LB) head mounted camera, a heads-up virtual display, and a belt attached processing unit (Figure 1.1). The output from Automatic Target Recognition algorithms provide the detection of metallic and non-metallic mines in real-time on the IR display and as an audio alert from the GPR and MD.

This paper presents a few unique features and capabilities using quantum wells for infrared detection and imaging. We first review the basics and key shortcomings of quantum well infrared photodetectors (QWIPs), and point out the possible directions for improvement. We then present the idea of the integrated QWIP and LED for optically readout imaging device. Discussions of different schemes of fabricating multicolor QWIPs follow. Finally, we present the high frequency capabilities of QWIPs.

Abstract not available.

The use of multilayer heterostructures based on the narrow-gap semiconductor materials InSb/InAlSb and HgCdTe is leading to a range of IR and other devices which can operate without cooling. Work in DERA will be reviewed which has demonstrated uncooled detectors out to 12 micrometer; uncooled infrared LEDs for the 3 - 12 micrometer region, employing either positive or negative luminescence; diode injection lasers with output between 3.9 micrometer and 5.1 micrometer (operating up to 150 k); and uncooled very high speed, very low voltage transistors.

The emitting area of the infrared sources comprising silicon micromachined thermal pixel arrays is often notably smaller than the actual pixel area. This results in the infrared sources being operated at higher temperatures than apparent temperatures which therefore limits radiometric dynamic range. An optomechanical means has been developed that transforms the low-fill factor devices into having a much higher fill factor. The theory, fabrication, and initial tests results are presented.

A 64 X 64 Mercury-Cadmium-Telluride (MCT) focal-plane array detector attached to a Fourier transform infrared (FT-IR) microscope has been used to spectroscopically image a cross section of a laminated polymer film in the fingerprint region of the infrared spectrum (1800 - 900 cm-1). Image contrast is achieved due to the intrinsic chemical nature of the sample at each pixel location in the image. This technique is clearly able to identify the individual layers in this polymer film laminate. Infrared spectra of individual pixels in a 7.5- micrometer-thick adhesive tie layer of this polymer laminate show no interference from adjacent layers.

Infrared imaging of the breasts has been shown to be of value in risk assessment, detection, diagnosis and prognosis of breast cancer. However, infrared imaging has not been widely accepted for a variety of reasons, including the lack of standardization of the subjective visual analysis method. The subjective nature of the standard visual analysis makes it difficult to achieve equivalent results with different equipment and different interpreters of the infrared patterns of the breasts. Therefore, this study was undertaken to develop more objective analysis methods for infrared images of the breasts by creating objective semiquantitative and quantitative analysis of computer assisted image analysis determined mean temperatures of whole breasts and quadrants of the breasts. When using objective quantitative data on whole breasts (comparing differences in means of left and right breasts), semiquantitative data on quadrants of the breast (determining an index by summation of scores for each quadrant), or summation of quantitative data on quadrants of the breasts there was a decrease in the number of abnormal patterns (positives) in patients being screen for breast cancer and an increases in the number of abnormal patterns (true positives) in the breast cancer patients. It is hoped that the decrease in positives in women being screened for breast cancer will translate into a decrease in the false positives but larger numbers of women with longer follow-up will be needed to clarify this. Also a much larger group of breast cancer patients will need to be studied in order to see if there is a true increase in the percentage of breast cancer patients presenting with abnormal infrared images of the breast with these objective image analysis methods.

A novel mid infrared patented (IR) endoscopic imaging system is described with applications as both a medical and industrial diagnostic tool. The endoscopic and borescopic IR imaging systems can be configured to work in the range of 2 to 15 microns, according to the application.

Maintenance of our world's infrastructure presents many unique challenges. Engineering and maintenance personnel must maintain around the clock service to millions of people each year while maintaining millions of cubic meters of concrete distributed throughout facilities. This infrastructure includes runways, taxiways, roadways, walkways, bridges, building walls and roofs. Presently only a limited number of accurate and economical techniques exist to test this myriad of concrete structures for integrity and safety as well as insure that they meet original design specifications. Remote sensing, non-destructive testing techniques, such as Infrared Thermography, Ground Penetrating Radar, Magnetometer and Pachometer, measure physical properties affected by the various materials and conditions found within, and under, concrete infrastructure. These techniques have established reputations for accurate investigations of concrete anomalies. This paper will review the applications of different non- destructive testing techniques on many concrete infrastructure components.

This paper describes the evaluation of the long wave radiant field using the spherical thermography technique we developed in previous studies. Four urban street spaces were chosen for comparison based mainly on differences in the above-ground conditions. Evaluations were conducted during good weather on summer days. The measurement results indicate that the long wave radiant field is directly influenced by the design characteristics of the urban space. The present study confirmed the usefulness of spherical thermography for evaluating the long wave radiant field.

Three types of uncooled IR bolometric detector arrays equipped with 256 X 1 and 256 X 40 VO₂ thermistor pixels and on-chip readout electronics are presented. These reconfigurable arrays consist of 50 micrometer X 50 micrometer pixels and CMOS readout electronics that can be operated either in random access mode or in self-scanning mode. Depending on the operational conditions, the NETD of the arrays can be as low as 20 mK.

The article describes the basic design and essential properties of developed multispectral detectors based on the pyroelectric material lithium tantalate (LiTaO₃). The detector concepts presented here make parallel measurements possible in two to twelve spectral channels in the wavelength range of typically 1 - 25 micrometer. It is shown that these concepts are also useful for other responsive elements (thermopiles, PbS, PbSe). In one case, the detector consists of: (1) an optical unit with a beam splitter and interference filters for the spatial and spectral dispersion of the incident total radiation; and (2) the responsive elements with appropriate low-noise preamplifiers. The detector is a discrete and compact component in a TO 8 transistor casing (0 14 mm X 10 mm) with an aperture of typically 0 2 mm. Essential properties of a four-channel detector for gas analysis (CO; CO₂; HC; REF) are described. The influence of the beam splitter geometry on the overlap of the measuring spots in the spectral channels is discussed. In the other case, the paper describes a hybrid arrangement of a six- channel multispectral detector which only uses interference filters for spatial and spectral dispersion of the input radiation. Its dimensions are about (22 X 22 X 33) mm³. It is shown that the radiation efficiency of this arrangement is higher than the first case.

Amorphous Materials produces for IR applications three chalcogenide glass compositions: As₂S₃, Ge₃₃As₁₂Se₅₅ designated AMTIR 1, and Ge₂₈Sb₁₂Se₆₀ designated AMTIR 3. Methods of production will be discussed. AMTIR 1 and AMTIR 3 were used extensively in FLIR systems. Amorphous Materials produces thousands of small sensor lenses for non contact temperature measuring devices. Drawing of chalcogenide glass fibers at Amorphous Materials will be described. Chemical sensing is the main application. Currently, the fabrication of coherent fiber imaging bundles is under development. Extrusion of glass rods for chemical sensing will be mentioned.

Within the RTP 8.2 one of the main goals of the START programme is to develop a software simulator which incorporates the results of the research activities devoted to evaluate new IRST technologies and technical solutions which can be the basis of new concepts for future generations IRSTs. The software simulator development is based on the use of a commercial framework to speed up its implementation. The main simulator features are: modularity, expandability, capability to simulate the IRST behavior in different situation and under various scenarios. It is based on an analytical and statistical approach and provides an easy user interface with friendly tools for data supplying and results presentation.

The paper describes a Real Time InfraRed Scenario Digital Simulator (RTIRS) developed for laboratory test and for performance evaluation of Infrared equipment. The RTIRS is designed for the simulation of complex scenarios consisting of: (1) moving objects (aircraft, vehicles, man made structures and -- for airborne applications -- ownship platforms); (2) background and clutter; (3) atmosphere; (4) optics, scanner and detector of the Infrared equipment. The RTIRS is designed to interface with: (1) an operator via a graphical user interface for setting the scenarios characteristics; (2) a remote computer generating kinematics data; (3) the Infrared equipment under test. The outputs of these simulations consist of a digital data stream representing the simulated response of the Infrared detector to the scenario. These data are sent to the signal and data processor of the equipment under test with the appropriate format and in real time. The equipment is designed to be used either for imaging systems or tracking systems.

The role of the atmosphere in target acquisition modeling is investigated experimentally. Three models are compared to experimental results measured on the Golan Heights, Israel. Concepts considered are atmospheric attenuation versus atmospheric blur, and contrast limited (blur-limited) versus noise limited imaging. Results indicate that the role of the atmosphere in target acquisition is blur rather than attenuation, and that for ranges on the order of a kilometer or more, target acquisition is limited by atmospheric blur rather than by hardware. A significant portion of the atmospheric blur derives from small angle forward scattering by aerosols, which actually increases measured temperature differences for ranges up to a few kilometers.

A MATLAB-based model has been generated for a range of senors used in Missile Approach Warner (MAW) applications. The sensors modelled operate over the ultra-violet, mid and far infrared bands and include indium antimonide, thermal and multi-quantum well technologies. The primary purpose of the model is the evaluation and comparison of different sensor technologies against a range of missile threats. Signatures may be calculated for real or user-specified missile and platform trajectories. Alternatively, real signature data can be imported directly into the model to support trials analysis. Outputs include tabular and graphical data such as trajectories, detection range and signal to noise ratio.

Range of detection and time of performance criteria for missile warning (MWS) and infra read search and track (IRST) systems rely on a vast number of design parameters, as well as design approach (e.g. spectral range, scanning/staring configurations, etc.). The characteristics of the potential targets are as important as the system design. We present a robust performance evaluation techniques that rely upon various statistical models for background, sensor noises and target signature behaviors. The performance evaluation results are well supported by actual field test results.

Test, Verification and Validation (TV&V) are key activities in the development of sensor system model and its subsequent usage. A set of TV&V methodologies is described ranging from widely used approaches to more novel concepts that could find a greater level of applicability to electro-optic sensors. A number of examples of TV&V are given that are based on performance predictions from the Generic Sensor Model (GSM) developed by Pilkington Optronics.

A pyroelectric detector was calibrated against the National Institute of Standards and Technology (NIST) High Accuracy Cryogenic Radiometer (HACR) at 10.6 mm using a CO₂ laser as a source. The purpose of this calibration was to link the NIST infrared (IR) radiometric detector scales to the HACR. Issues addressed in this calibration included the spatial non- uniformity of the pyroelectric detector, the transport and alignment of the IR laser beam, and the measurement of ac signals. The final combined relative standard uncertainty of the calibration is 0.48%, with the largest uncertainty component arising from the spatial non-uniformity of the pyroelectric detector. The apparatus, measurement procedures, and results of the calibration will be discussed.

We present an approach for fusion of video streams produced by multiple imaging sensors such as visible-band and infrared sensors. Our approach is based on a model in which the sensor images are noisy, locally affine functions of the true scene. This model explicitly incorporates reversals in local contrast, sensor-specific features and noise in the sensing process. Given the parameters of the local affine transformations and the sensor images, a Bayesian framework provides a maximum a posterior estimate of the true scene. This estimate constitutes the rule for fusing the sensor images. We also give a maximum likelihood estimate for the parameters of the local affine transformations. Under Gaussian assumptions on the underlying distributions, estimation of the affine parameters is achieved by local principal component analysis. The sensor noise is estimated by analyzing the sequence of images in each video stream. The analysis of the video streams and the synthesis of the fused stream is performed in a multiresolution pyramid domain.

We propose a novel system to produce the short pulse using a halved confocal of the unstable concave-convex resonator on radio frequency discharge excitation slab type carbon dioxide laser. This method is provided a full reflection concave mirror to have a function of variable curvature which can control using a piezo electric device (PZT). Generally, the slab type laser is directly modulated by applying pulse voltage for pulsation of laser. There is a large capacity and fluctuation of plasma at the transition of pulsation. Consequently, the pulse width is longer than 1.0 micro second and repetitive frequency is less than 10 kilo Hertz. On the other hand, the pulse oscillation by our proposed method has the short pulse width which is 300 nano second and maximum repetitive frequency is about 100 kilo Hertz. We can choose the pulse oscillation or the continuous wave (CW) oscillation at the each condition on same resonator. The peak power at the pulse oscillation is about 12 times as high as that at the CW oscillation.

For preliminary selection of the silicon read-out devices designed for applications in hybrid mercury-cadmium-telluride (MCT) IR linear or matrix arrays manufactured according to flip-chip technology, there was designed constructions of the testing circuits imbedded into the read-out devices to test them before hybridization. Also the procedure of their testing at room temperature without attachment to the MCT photo- voltaic multielement arrays was developed. There were designed some types of multielement silicon read-out devices with input direct injection and buffered direct injection circuits and charge coupled devices (CCD) multiplexers to be used with n⁺-p- or p⁺-n-photodiodes with dynamical resistance at reverse bias R greater than or equal to 10⁷ (Omega) . Into these read-out devices there were incorporated the testing switches which attach the sources of direct injection transistors to the common load resistors to imitate the output signal of MCT photodiodes. The silicon read-out devices for 2 X 64 linear arrays and 2 X 4 X 128 (144) TDI arrays with direct and buffered direct charge injection were manufactured by n-channel MOS technology with CCD register with buried channel. By changing the frequency of the control impulses here were investigated the characteristics of the read-out devices for time delay and integration (TDI) arrays in the regime of integration and without it (in TDI channel).

This paper describes some of the work performed in the course of the design and development of a new IR sensor system for early detection of forest fires. The proposed device is a non- imaging sensor that would discriminate angular position by means of a simple IR array, working in the 3 - 5 microns wavelength region, placed at the focal plane of the optical system. In order to accomplish low cost requirements, a system with a sole IR lens has been designed. In this work, a study of the spot shape, size and optical IR power on the detector has been performed. From the analysis of the influence of lens-detector distance and incidence angle, we have derived an optimum pixel size and optical configuration. The use of TE- cooled PbSe detectors is proposed, as well as a simplified cell array.

A two-dimensional thermal conducting model which deals with the thermal diffusion in continuous wave (cw) laser processing of material is presented in this paper. The temperature distribution during the interaction between HgCdTe and cw carbon dioxide laser is calculated using numerical method. Experiment is carried out to measure the damage threshold of HgCdTe with cw CO₂ laser. The apparent damage temperature threshold, 670 - 680 K is obtained which corresponds to the solid-solid phase transition of HgCdTe. All the calculations are in good agreement with the experimental results.

We propose to develop a submillimeter quantum cascade laser in the GaAs/AlGaAs material system. This device relies on intersubband transitions in GaAs quantum wells of the device for lasing. Preliminary calculations show that there is sufficient gain to produce lasing in the wavelength range 80 to 125 micrometer. The active region of the laser structure consists of coupled quantum wells which can be grown by molecular beam epitaxy (MBE). The model uses a 30 nm-wide active quantum well which contains two levels separated by 14.8 meV which corresponds to a wavelength of 83.5 micrometer at a bias of 8850 V/cm with 12.2 nm and 29.8 nm wide quantum well energy filters inserted on either side of the active well. The energy filters are designed to allow only electrons with the energy of the upper state to be injected into the active well and only electrons with the energy of the lower state to be extracted from the active well. The proposed device uses a 10-period injector/active well/collector structure. The collector/injector is a superlattice region, which acts as a reservoir for the electrons. The gain of this system has been calculated to be approximately 2500 cm^-1. Threshold current density has been calculated to be about 622 A/cm² at 77 K.

Application of the infrared (IR) spectroscopy to early medical onco-hematological diagnostics, in particular to leukemia, is described. Leukemia is characterized by the orthophosphates acid (soluble) forms (HPO₄^2-) accumulation in bone apatites. Bone hydroxyapatite contains predominantly basic PO₄^3- nonsoluble orthophosphate. At the same time condensed forms of pyrophosphates (e.g., CaH₂P₃O₇) in bones and especially in dried urine were found by the analysis of IR absorption spectra of persons with leukemia. It was show that the dried urine infrared quantitative absorption spectra investigations of phosphates contents make it possible to trace the dynamics of these elements contents during the leukemia progression and can serve for onco-hematological diagnostics at early stage of leukemia.

Quantum Well Infrared Photodetectors (QWIPs) offer greater flexibility than usual extrinsically doped semiconductor IR detectors because the wavelength of the peak response and cutoff can be continuously tailored by varying layer thickness (well width), barrier composition (barrier height), and carrier density (well doping density). The GaAs/Al_xGa_{1- x}As material system allows the quantum well parameters to be varied over a range wide enough to enable light detection at any wavelength range between 6 - 20 micrometer. The spectral band width of these detectors can be tuned from narrow ((Delta) (lambda) /(lambda) approximately 10%) to wide ((Delta) (lambda) /(lambda) approximately 40%), allowing various applications. Also, QWIP device parameters can be optimized to achieve extremely high performance at lower operating temperatures (approximately 40 K) for low background, long- wavelength, infrared applications in the strategic arena as well as in Astronomy. Furthermore, QWIPs offer low cost per pixel and highly uniform, large format, focal plane arrays (FPAs) mainly due to mature GaAs/AlGaAs growth and processing technologies.

Spectral radiometers and imaging radiometers have been used for decades to provide detailed information about the infrared properties of remote objects. Both of these senors provide complementary information. Even more information can be obtained using a fusion of these two instruments. A spectral imaging radiometer provides data absolutely registered in the spatial, spectral and temporal domain. In this paper we present SARIS, a new spectral imaging radiometer that will operate both from airborne and ground-based platform. SARIS will provide high speed, highly accurate, 16 X 16 spatial radiometric measurements with 1 cm^-1 spectral resolution in the 2 to 5 micrometer spectral band. SARIS will measure up to 150 datacubes (a datacube is a complete spatial/spectral measurement) at a spectral resolution of 8 cm^-1 and covering the spectral range from 3.5 to 5 micrometer. In this paper we present the mission, technical requirements and conceptual design of SARIS.