The concept of multi-band infrared color vision is discussed in terms of combining two or more bands of infrared imagery into a single composite color image. This work is motivated by emerging new technologies in which two or more infrared bands are simultaneously imaged for improved discrimination of objects from backgrounds. One of the current objectives of this work is to quantify the improvement obtained over single band infrared imagery to detect dim targets in clutter. Methods are discussed for mapping raw image data into an appropriate color space and then processing it to achieve an intuitively meaningful color display for a human viewer. In this regard, the final imagery should provide good color contrast between objects and backgrounds and consistent colors regardless of environmental conditions such as solar illumination and variations in surface temperature. Initial performance measures show that infrared color can improve discrimination significantly over single band imaging.

In August 1997 an infrared spectral imaging radiometer (ISIR) based on uncooled microbolometer array technology was flown on space shuttle mission STS-85. In this paper the design of the instrument and experimental goals are presented, and initial results from the flight mission are described. The ISIR instrument provided 1/4 km resolution imagery at four wavelengths that were selected for cloud remote sensing. A major goal of the work is development of compact and less costly cloud imagers for small satellite missions. A large data set of earth imagery and test operations was obtained from the mission. In most regards the ISIR functioned within its design parameters.

Raytheon Sensors and Communications Systems has developed a prototype infrared imaging rifle-sight using an uncooled, microbolometer FPA. The Longwavelength Staring Sensor (LWSS) has been characterized by NVESD, where it demonstrated NETD and MRT values that are unsurpassed for uncooled FPA technology. The NVESD-measured NETD values were 24 mK with f/0.7 optics and 42 mK with an f/1/0 aperture. When used with the f/0.7 optics, NVESD measured MRT values less than 60 mK at the nyquist spatial frequency. Similar measurements at f/1.0 produced MRT values less than 110 mK. Further optimization of the microbolometers is expected to produce FPAs with NETD values less than 20 mK for f/1.0 apertures. The high- performance uncooled microbolometer FPA (SBRC-151) used in the LWSS was developed by Raytheon Santa Barbara Research Center. 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 VO_X microbolometer detectors are produced at SBRC using an advanced dry-etch fabrication process. In addition to the LWSS project, SBRC has initiated low-rate production of the microbolometer FPAs. This work is being performed in support of Raytheon-Amber for commercial radiometer cameras. The pixel operability of the production radiometer FPAs (AE-189) are greater than 99.9%.

Low cost, uncooled hybrid infrared focal plane arrays (IRFPA's) are in full-scale production at Raytheon Systems Company (RSC), formerly Texas Instruments Defense Systems and Electronics Group. Detectors consist of reticulated ceramic barium strontium titanate (BST) arrays of 320 X 240 pixels on 48.5 micrometer pitch. The principal performance shortcoming of the hybrid arrays has been low MTF due to thermal crosstalk between pixels. In the past two years, significant improvements have been made to increase MTF making hybrids more competitive in performance with monolithic arrays. The improvements are (1) the reduction of the thickness of the IR absorbing layer electrode that maintains electrical continuity and increases thermal isolation between pixels, (2) reduction of the electrical crosstalk from the ROIC, and (3) development of a process to increase the thermal path-length between pixels called 'elevated optical coat.' This paper describes all three activities and their efficacy. Also discussed is the uncooled IRFPA production capability at RSC.

This paper reviews Boeing's progress, over the last three years, in Vanadium Oxide (VO_x) uncooled microbolometer focal plane (UFPA) technology and product development. Boeing's UFPA product technology is described, including product capabilities and performance. Focal plane NETD equals 31 mK (F/1), at a 30 Hz sensor frame rate, has been demonstrated on the U3000 320 X 240 UFPA product. At a 60 Hz frame rate, the NETD (F/1) achieved on production U3000 UFPAs is typically less than 60 mK, and spatial pattern noise levels are consistently less than 33 mK after sensor level gain and offset compensation. Key improvements in VO_x tin- film technology have been the achievement of a Temperature Coefficient of Resistance (TCR) approximately 3%, and the achievement of microbolometer resistance uniformity of approximately 1/3% ((sigma) /(mu) ) on the UFPA die. Looking into the future, this year Boeing expects to achieve NETD approximately 20 mK (F/1) with very low pattern noise, and within the next three years higher density 640 X 480 focal planes will be demonstrated with essentially equivalent NETD performance. Large high density uncooled LWIR focal planes, combined with low NETD, will make UFPA technology a prime candidate for higher performance FLIR applications.

The success of uncooled IR imaging at Raytheon has awakened a new view of the potential of thermal imaging. Once relegated to only expensive military platforms, occasionally to civilian platforms, and envisioned for individual soldiers, thermal imaging is now affordable for police cars, commercial surveillance, driving aids, and a variety of other industrial and consumer applications. System prices are as low as $8000, and swelling production volume will soon drive prices substantially lower. The impetus for further development is performance. The hybrid barium strontium titanate (BST) detectors currently in production have limited potential for improved sensitivity, and their MTF is suppressed at high frequencies. Microbolometer arrays in development at Raytheon have demonstrated performance superior to hybrid detectors. However, microbolometer technology lacks a mature, low-cost system technology and an abundance of deployable system implementations. Thin-film ferroelectric (TFFE) detectors have all the performance potential of microbolometers, and arguably more. They are also compatible with numerous fielded and planned system implementations. Like a 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. Initial imaging arrays of 240 X 320 pixels have been produced, demonstrating the feasibility of the technology.

Thermal imaging equipment utilizing microbolometer detectors operating at room temperature has found widespread acceptance in both military and commercial applications. Uncooled camera products are becoming effective solutions to applications currently using traditional, photonic infrared sensors. The reduced power consumption and decreased mechanical complexity offered by uncooled cameras have realized highly reliable, low-cost, hand-held instruments. Initially these instruments displayed only relative temperature differences which limited their usefulness in applications such as Thermography. Radiometrically calibrated microbolometer instruments are now available. The ExplorIR Thermography camera leverages the technology developed for Raytheon Systems Company's first production microbolometer imaging camera, the Sentinel. The ExplorIR camera has a demonstrated temperature measurement accuracy of 4 degrees Celsius or 4% of the measured value (whichever is greater) over scene temperatures ranges of minus 20 degrees Celsius to 300 degrees Celsius (minus 20 degrees Celsius to 900 degrees Celsius for extended range models) and camera environmental temperatures of minus 10 degrees Celsius to 40 degrees Celsius. Direct temperature measurement with high resolution video imaging creates some unique challenges when using uncooled detectors. A temperature controlled, field-of-view limiting aperture (cold shield) is not typically included in the small volume dewars used for uncooled detector packages. The lack of a field-of-view shield allows a significant amount of extraneous radiation from the dewar walls and lens body to affect the sensor operation. In addition, the transmission of the Germanium lens elements is a function of ambient temperature. The ExplorIR camera design compensates for these environmental effects while maintaining the accuracy and dynamic range required by today's predictive maintenance and condition monitoring markets.

Inframetrics has developed an advanced 'uncooled' Infrared Radiometer product based on microbolometer focal plane array technology. This development has been the result of a three year consortium effort, funded in part by the Defense Advanced Research Project Agency (DARPA) through the Technology Reinvestment Project (TRP). This paper will give an overview of the camera architecture, and explain some of the more unique aspects of the design. It will describe the camera system and the attributes of this system that have been optimized to yield maximum sensitivity, measurement accuracy and stability. The detector package will be described, with emphasis on items which have been optimized for radiometric applications. Lastly, system radiometric performance will be reported comparing theoretical and measured data.

This paper discusses the design and performance of a 256 X 256 bolometer-type uncooled infrared detector. First, model calculations are carried out to clarify the relations of the noise equivalent temperature difference (NETD) to the electrical properties of the bolometer material. The properties are mainly resistivity, the temperature coefficient of resistance (TCR) and 1/f noise. To obtain real-time images with NETD values smaller than 0.15 K for F/1 optics, vanadium oxide thin film was developed as the bolometer material, having a sheet resistance range of 5 - 50 k(Omega) /square and a TCR value of -2%/K. This material did not exhibit thermochroism like VO₂(A), because it was identified as VO₂(B). The bolometer-array was statistically evaluated and put into the infrared camera. Finally, a thermal image with a NETD of 0.15 K was obtained.

Infrared detectors are growing in size, complexity, and becoming more specialized as applications demand more efficient and cost-effective designs. This paper reviews activities in the forefront of this important technology and illustrates the design of several advanced multispectral and hyperspectral focal plane assemblies.

The performance of uncooled infrared focal plane detector arrays depends on optimization of critical parameters which are determined by geometrical design and the electrical, optical and thermophysical properties of the detector materials. It is desirable to monitor these parameters during array preparation using test cells which are independent of the main array and which can subsequently be used to provide data for performance analysis. This paper describes the use of test structures which function as process control modules and monitor cells for material parameters, from which array operability and performance can be assessed. The focal plane detector arrays described in the paper were designed by Electro-optic Sensor Design and manufactured by the Defence Science and Technology Organization, Australia, in collaboration with the Defence Research Establishment, Sweden.

Over the past two decades, Raytheon Systems Company (RSC), formerly Texas Instruments Defense Systems & Electronics Group, developed a robust family of products based on a low- cost, hybrid ferroelectric (FE) uncooled focal-plane array (FPA) aimed at meeting the needs for thermal imaging products across both military and commercial markets. Over the years, RSC supplied uncooled infrared (IR) sensors for applications such as in combat vehicles, man-portable weaponry, personnel helmets, and installation security. Also, various commercial IR systems for use in automobiles, boats, law enforcement, hand-held applications, building/site security, and fire fighting have been developed. These products resulted in a high degree of success where cooled IR platforms are too bulky and costly, and other uncooled implementations are less reliable or lack significant cost advantage. Proof of this great success is found in the large price reductions, the unprecedented monthly production rates, and the wide diversity of products and customers realized in recent years. The ever- changing needs of these existing and potential customers continue to fuel the advancement of both the primary technologies and the production capabilities of uncooled IR systems at RSC. This paper will describe a development project intended to further advance the system electronics capabilities of future uncooled IR products.

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 90 mK at f/1, 25 Hz and 300 K background can be obtained with high thermal insulation (1.2 10⁷ K/W).

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. However, the multiple applications in which our uncooled sensors have been used have never 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 sniper location prototype cameras to helmet mounted mine detection sensors; from rifle sights to space sensors. These applications will be discussed along with their unique system level performance parameters. Video will be used to demonstrate the various applications discussed.

Mn_1.56Co_0.96Ni_0.48 is RF magnetron sputtered in a series of oxygen partial pressures, and non-stoichiometric films are produced. Conduction is small polaron hopping for all stoichiometries as evidenced by near temperature independent thermopower, and decreasing conduction activation energy with decreasing temperature. The carrier type transitions from p to n type with a decrease in the ratio of Mn³⁺ to Mn⁴⁺ concentration. The resistivity, and conduction activation energy are decreasing functions of the oxygen partial pressure. The Debye frequency increases with oxygen partial pressure as measured from the resistivity, and this is consistent with the observed shift of both the Raman and IR active lattice vibrations. The material has the spinel crystal structure, and as such is an optical window with the 3 phonon cutoff occurring at 17 micrometer. The material is transparent between 6 micrometer to 17 micrometer.

We report on the first successful mixing of 28 THz radiation performed with thin-film nanometer-scale Ni-NiO-Ni diodes connected to integrated bow-tie infrared antennas. Difference frequencies up to 176 GHz were measured between two CO₂- laser 28 THz emissions in mixing processes up to the fifth order by addition of microwaves generated by a Gunn oscillator. The bow-tie antennas show almost perfect polarization with respect to the incident radiation. The mixing of infrared radiation with point-contact metal-oxide- metal (MOM, MIM) diodes was first reported in 1968. In the meanwhile the range of operation of these devices has been extended to the visible. The operation of these diodes in the point-contact configuration is restricted to laboratory applications because of their irreproducibility and low mechanical stability. They are currently used in absolute frequency measurements for the development of time and frequency standards and in high-resolution spectroscopy as tunable far-infrared (FIR) radiation source. Serious attempts were made to integrate the MOM diodes on a substrate in order to produce more practical devices for field applications. In the early seventies, Small et al. and Wang et al. reported the fabrication of thin-film diodes with rectification capabilities in the 10 micrometer region. Small et al. also reported on third-order frequency mixing performed with a FIR carrier frequency of approximately 1 THz with difference frequencies of about 75 GHz. Our own development of thin-film Ni-NiO-Ni diodes with integrated dipole, bow-tie and spiral antennas as detectors has been described previously. The first experiments on mixing 28 THz radiation with our Ni-NiO-Ni diodes were made at LENS (Florence, Italy). They resulted in the measurement of difference frequencies up to 85 MHz. We now report on the first successful mixing of two 28 THz (10.7 micrometer) CO₂-laser transitions in the 10P branch with difference frequencies up to 176.2 GHz performed by thin-film Ni-NiO-Ni diodes.

The feasibility of microcantilever-based optical detection is demonstrated. Specifically, we report here on an evaluation of laboratory prototypes that are based on commercially available microcantilevers. In this work, optical transduction techniques were used to measure microcantilever response to photons and study the electronic stress in silicon microcantilevers, and their temporal and photometric response. The photo-generation of free charge carriers (electrons, holes) in a semiconductor gives rise to photo-induced (electronic) mechanical strain. The excess charge carriers responsible for the photo-induced stress, were produced via photon irradiation from a diode laser with wavelength (lambda) equals 780 nm. We found that for silicon, the photo-induced stress results in a contraction of the crystal lattice due to the presence of excess electron-hole-pairs. In addition, the photo-induced stress is of opposite direction and about four times larger than the stress resulting from direct thermal excitation. When charge carriers are generated in a short time, a very rapid deflection of the microcantilever is observed (response time approximately microseconds).

We present measurements on the spatial-response profiles of nanometer-scale thin-film Ni-NiO-Ni diodes integrated with infrared dipole and bow-tie antennas. Antennas are usually tested for their angular response using collimated radiation. However, in this study, focused radiation with a wavelength of 10.6 micrometer is scanned across the receiving area of the detector. This permits determination of the effective collection area of an individual infrared antenna. The width of the collection area parallel to the antenna axis is shown to scale with the physical length of the antenna. The determination of the effective collection area permits a characterization of the fringe fields surrounding the antenna and can be used to investigate the cross talk between adjacent antennas. It allows calculation on the power collected by an infrared antenna for a given irradiance of the illuminating beam. The spatial response also gives insight into the current-wave modes propagating on the antenna. Fast infrared detectors have dimensions considerably smaller than the wavelength of the incident radiation. Their performance is enhanced with the aid of wire or planar antennas having dimensions comparable with the wavelength. The efficiency of infrared lithographic antennas for detection at wavelengths near 10 micrometer was demonstrated with various types of detectors, including thin film metal-oxide-metal diodes (MOM or MIM) and Nb microbolometers. To investigate the mechanism of infrared antennas, we determine the spatial response of various dipole and bow-tie antennas at 10.6 micrometer wavelength. For this purpose, we scan tightly focused radiation at normal incidence across the receiving area of the detector in two orthogonal directions. The effective receiving area is a relevant parameter for infrared antennas. It first permits a radiometric characterization of the detector based on received power for a given incident irradiance. It also defines the spacing of individual detectors required for construction of an area receiver, and in a two-dimensional array allows calculation of cross-talk level between adjacent devices. The spatial response of infrared antennas on a substrate also contributes to the understanding of the resonant modes propagating on the structure.

Linear thermopile infrared detector arrays have been produced with D* values as high as 2.2 X 10⁹ cmHz^1/2W for 83 ms response times. Typical responsivity is 1000 V/W. This result has been achieved with Bi-Te and Bi-Sb-Te thermoelectric materials on micromachined silicon nitride membranes. Results for several device geometries are described and compared to literature values for Schwartz type thermocouple detectors and for thin film thermopile detectors and arrays. Measurements of responsivity as a function of modulation frequency and wavelength are presented.

We report results for 64 X 64 simultaneous MW/LW dual-band HgCdTe Focal Plane Arrays (FPAs). The MW and LW average cutoff wavelengths at 78 K are in the 4.27 - 4.35 micrometer and 10.1 - 10.5 micrometer ranges respectively. The unit cell size is 75 X 75 micrometer². These staring dual-band FPAs exhibit high average quantum efficiencies (MW: 79%; LW:67%), high median detectivities (MW: 4.8 X 10¹¹ cm- (root)Hz/W; LW: 7.1 X 10¹⁰ cm-(root)Hz/W), low median NE(Delta) Ts (MW: 20 mK; LW: 7.5 mK for T_SCENE equals 295 K and f/2.9), large dynamic ranges (MW: 77 dB; LW: 75 dB), and 87% stare efficiencies for both the MW and LW spectral bands. The dual-band HgCdTe detector array is fabricated from a four- layer P-n-N-P film grown in situ by MOVPE. The dual-band silicon CMOS input circuit utilizes a unique floating-direct- injection approach to achieve separate and simultaneous integration of both bands within each unit cell. There are two Compact Signal Averager circuits in each unit cell, to average subframes within every frame for each spectral band, allowing full stare efficiency in both spectral bands, as well as variable band-independent transimpedance gains. These data confirm that all key features of our P-n-N-P dual-band HgCdTe detector and our dual-band input circuit function as designed.

A high sensitivity triple-coupled quantum well infrared photodetector (TC-QWIP) based on high strain InGaAs/AlGaAs/InGaAs material system has been demonstrated. It consists of a high strain Si-doped In_0.25Ga_0.75As quantum well and two undoped thin Al_0.11Ga_0.89As/In_0.12Ga_0.88As quantum wells (QWs) separated by a thick Al_0.11Ga_0.89As barrier layer. We also investigate the performance dependence of this QWIP with two different numbers of quantum well periods (5- and 10-period). Two response peaks at 9.5 micrometer and 7 micrometer were observed under different negative bias conditions, which are attributed to the transitions from the ground state to the second excited states and the continuum states, respectively. Spectral responsivities of 2.77 A/W and 1.55 A/W and the BLIP detectivities of 2.24 X 10¹⁰ cm-Hz^1/2/W and 1.68 X 10¹⁰ cm-Hz^1/2/W were obtained at V_b equals -3 V and (lambda) _p equals 9.6 micrometer with 45 degree facet illumination and normal incidence illumination, respectively, for the 5-period device. As to the 10-period device, spectral responsivities of 2.7 A/W and 1.05 A/W and the BLIP detectivities of 2.21 X 10¹⁰ cm-Hz^1/2/W and 1.38 X 10¹⁰ cm-Hz^1/2/W were obtained at V_b equals -5 V and (lambda) _p equals 9.6 micrometer with 45 degree facet illumination and normal incidence illumination, respectively, for this device. This represents the highest normal incidence response ever reported for a QWIP operating at 9.6 micrometer peak wavelength. Based on the responsivity and detectivity data the minimum detectable photon flux for this new device is found to be 1.08 X 10¹¹ and 1.09 X 10¹¹ cm^-2s^-1 for the 5-period and 10- period devices, respectively, at (lambda) _p equals 9.6 micrometer, bandwidth equals 1 micrometer, and FOV equals 180 degrees. Thus, the HS-TC-QWIP reported here is capable for lower background IR imaging array applications.

High performance long-wavelength GaAs/Al_xGa_1-xAs quantum well infrared photodetectors for low background applications have been demonstrated. This is the first theoretical analysis of quantum well infrared photodetectors for low background applications and the detectivity D* of 6 X 10¹³ cm(root)Hz/W has been achieved at T equals 40 K with 2 X 10⁹ photons/cm²/sec background. In addition, this paper describes the demonstration of mid- wavelength/long-wavelength dualband quantum well infrared photodetectors and long-wavelength/very long-wavelength dualband quantum well infrared photodetectors in 4 - 26 micrometer wavelength region.

The article deals with infrared detector Si:Ga made by CENG/LETI/LIR. This extrinsic photoconductor is hybridized to a direct voltage silicon NMOS readout circuit (DVR) and works at a temperature closed to 10 K. For some years, ONERA (Office National d'Etudes et Recherches Aerospatiales) has been studying the Si:Ga by testing 32 X 32, 64 X 64 and 128 X 192 focal plane arrays. Several measurements have been done, and permit a good comprehension of the general architecture and behavior of the component, and so the realization of driving and acquisition electronic boards. Other tests have been realized, and the points of interest which will be discussed in this article are the study of the fixed pattern noise and the temporal evolution of the performances of the nonuniformity correction. Indeed, pixel nonuniformity and nonlinearity degrade array performances. Although algorithms (two points correction) have been developed to decrease this fixed pattern noise, the temporal stability of the correction has been analyzed to show if the time since the last calibration reduces its performance. So, all this knowledge about Si:Ga leads to the integration of a 128 X 192 focal plane array (FPA) in CRYSTAL (CRYogenic System for Thermographic analysis of Aerodynamic Layer) camera for ETW (European Transonic Windtunnel).

An analysis of a unit cell of a focal plane array (FPA) read out integrated circuit for very dense low flux applications. In this analysis, the self capacitance of a velocity saturated quantum well detector is operates like a direct injection circuit. The signal processing used is a classical, ramp, and sample process combined with a non-destructive read switched capacitor filter.

Quantum well infrared photodetector (QWIP) technology has developed rapidly in the past decade culminating in the demonstration of large format focal plane arrays. Most of the efforts so far have been on tactical applications in which an increased operating temperature is the major objective. For strategic applications with a cold background and a faint target, low temperature operation is required. Under these conditions, improving the conversion efficiency (quantum efficiency times gain) is very important for QWIPs to collect sufficient signal. Simplified QWIP (S-QWIP) structures with increased optical gains have been demonstrated. In this presentation, experimental results of several S-QWIPs will be given. The properties of simplified QWIPs will be examined at low temperatures with a low background and a faint target. Results of a computer simulation with an unresolved target will be discussed.

We report a two-stack indirect-barrier (IB-) GaAs/Al_0.55Ga_0.45As quantum well infrared photodetector (QWIP) for mid-wavelength infrared (MWIR) and a voltage-tunable In_0.05Ga_0.95As/GaAs/Al_0.19Ga_0.81As triple-coupled (TC-) QWIP for long-wavelength infrared (LWIR) detection. We also investigate the performance dependence of this stacked QWIP with different quantum well periods (20-period and 40- period). The peak responsivity of the 20-period stacked-QWIP at zero bias (PV mode) was found to be 30 mA/W at (lambda) _p equals 4.3 micrometer and T equals 40 K. The maximum peak responsivity (PC mode) was found to be 0.25 A/W at (lambda) _p equals 4.3 micrometer, V_b equals -4 V, and T equals 40 K for the 20-period MWIR IB-QWIP. For the LWIR TC- QWIP, the peak wavelength due to (E₁ yields E₃) transition shifts from 10 micrometer to 9.4 micrometer as bias voltage changes from 5 to 7 V and from 9 to 14 V for 20-period and 40 period devices, respectively. A peak responsivity of 0.16 A/W was obtained at (lambda) _p equals 9.4 micrometer, V_b equals 7 V, and T equals 40 K for the 20-period TC- QWIP. The results show that simultaneous detection of IR radiation at both the MWIR and LWIR bands can be achieved at V_b greater than or equal to 7 V or V_b less than or equal to -5 V for the 20-period stacked QWIP. It is shown that this two-stack QQWIP can be used as a wavelength-tunable IR detector for the MWIR and LWIR bands.

Developing maximum image performance in an infrared imaging system without exceeding physical design parameters, such as size and weight, leads to system requirements for small and closely spaced detector pixels areas on the focal plane array. Small sensitive areas allow high resolution and close spacing that can result in high spatial sampling rates and the ability to discern objects at long distances. The imaging resolution performance of compact two-dimensional Indium Antimonide (InSb) arrays can be limited by the fact that photo generated carriers can diffuse and be collected by junctions removed from the point of generation. Carrier diffusion can limit resolution in compact sensor packages. This paper quantitatively discusses the effect of carrier diffusion on resolution and the advantages of a reticulated pixel design.

Focal plane arrays (FPAs) fabricated from the indium gallium arsenide (InGaAs) ternary alloy system exhibit high performance when operates at room temperature. Material considerations relevant to high device performance are discussed and the status of linear and two dimensional devices summarized. Examples of important imaging applications using InGaAs FPAs are presented.

The design and performance of a compact infrared camera system is presented. The 3 - 5 micron MWIR imaging system consists of a Stirling-cooled 640 X 480 staring PtSi infrared focal plane array (IRFPA) with a compact, high-performance 12-bit digital image processor. The low-noise CMOS IRFPA is X-Y addressable, utilizes on-chip-scanning registers and has electronic exposure control. The digital image processor uses 16-frame averaged, 2-point non-uniformity compensation and defective pixel substitution circuitry. There are separate 12- bit digital and analog I/O ports for display control and video output. The versatile camera system can be configured in NTSC, CCIR, and progressive scan readout formats and the exposure control settings are digitally programmable.

A theoretical design of a reconfigurable detector array assembly is presented. This device is capable of changing the angular resolution and thermal sensitivity of the electro- optics array in real time. The apparent layout (i.e., size, spacing, and location) of the focal plane array detector elements is dynamic. This approach allows varying the instantaneous field-of-view as a function of the field angle, and combining adjacent spectral bands when poor atmospheric conditions are presented. This infrared reconfigurable hyperspectral focal plane array (IR-RHFPA) provides a way to get rid of some of the problems related to multi-spectral imagery sensors such as data rate, bow-tie effect, and sensitivity. Curves of spatial resolution versus field angle, and thermal sensitivity versus wavelength are obtained for the proper design and optimization of the IR-RHFPA. The potential operational configurations that best satisfy the system requirements are identified and displayed.

High performance PtSi/p-Si Schottky-barrier detector with quantum efficiency higher than 1% has been achieved. The characteristic of PtSi/p-Si Schottky diode has been measured using both electrical and optical methods. The PtSi/p-Si diode has shown ideal I-V characteristics at different temperatures. The performance of PtSi/p-Si SBD is strongly dependent on the formation conditions of PtSi film. We have observed that the quantum efficiency of PtSi/p-Si detector is higher if the PtSi film is continuous. The formation of continuous PtSi film is crucial on the high performance of PtSi/p-Si detector. However, the formation of continuous PtSi film is strongly related to the detector dimension and formation conditions. The quantum efficiency of PtSi/p-Si SBD can be further improved if the PtSi formation temperature is increased. Transmission electron microscopy results indicate that the PtSi is epitaxially grown on Si if the substrate temperature is 550 degrees Celsius or higher. 256 X 244 PtSi/p-Si arrays monolithically integrated to read-out circuit have been fabricated using standard Si IC processes. From the measurement of uniformity and noise equivalent temperature difference of arrays, the PtSi/p-Si Schottky-barrier detector is shown to be operated under background limited condition.

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. Also a quantum well infrared photodetector (QWIP) device with 256 X 256 elements for long wave applications was introduced. The MCT devices provide extremely fast frame rates like 2200 Hz with snapshot integration times below 350 microseconds and noise equivalent temperature differences (NETD's) less than 20 mK for the LWIR modules while the QWIP device provides a NETD about 10 mK for a rolling frame integration with 20 ms integration time and 50 Hz frame rate. Besides the thermal resolution given by the NETD also a measurement of the correctability of the devices is introduced which is an important characteristic for the system design. The main features of these modules are summarized together with measured performance data of the new MCT devices. The performance data of the QWIP detection module is discussed in reference 1.

Recent improvements in mid-infrared photodetectors fabricated by the liquid phase epitaxial growth of GaInAsSb, InAsSbP, and AlGa(As)Sb on GaSb and InAs substrates are reported. GaInAsSb and InAsSbP p/n detector and AlGaAsSb/GaInAsSb avalanche photodiode (APD) structures have been fabricated. Results from previously reported devices were improved by the addition of high bandgap window layers for GaInAsSb detectors and a new longer-wavelength composition for InAsSbP detectors. Preliminary results indicate that these devices can have higher detectivity with lower cooling requirements than commercially available detectors in the same wavelength range. Infrared p/n junction detectors made from GaInAsSb and InAsSbP showed cut-off wavelengths of 2.3 micrometer and 3.2 micrometer respectively. Room temperature Johnson noise- limited detectivities (D*_JOLI) of 5 X 10¹⁰ cmHz^1/2/W for GaInAsSb detectors and 4 X 10⁹ cmHz^1/2/W for InAsSbP have been measured. Room- temperature avalanche multiplication gain was measured for AlGaAsSb/GaInAsSb avalanche photodiodes.

Long wavelength, infrared focal plane arrays (IRFPAs) fabricated with arsenic doped silicon (Si:As), impurity band conduction (IBC) detectors are being utilized in astronomical applications. In these systems, long integration times and/or the co-addition of consecutive frames are typically used to increase the signal-to-noise ratio. Some of the IBC detectors used in these IRFPAs have exhibited Excess Low Frequency Noise (ELFN) which limits their performance under some operational conditions. Data are presented on two Si:As IRFPAs which exhibit ELFN. These data illustrate the parametric dependence of ELFN on detector bias, photon irradiance, and integration time. Additionally, noise spectra from a single detector with ELFN illustrate the frequency dependence of ELFN at several photon irradiances. Finally, the effectiveness of the co- addition of frames on improving the signal-to-noise ratio when using an IRFPA with ELFN is quantified.

Uncooled IR has been predicted to dominate commercial IR design within five years. The military market is moving in the same direction but with unique requirements. Alliant Techsystems is currently designing and field testing uncooled IR sensors for dual mode seekers, aerial surveillance, fire control systems, and RSTA applications. This paper will review the tradeoffs for several of our airborne program applications. Performance models are given for several microbolometer sensor approaches.

One of the simplest device realizations of the classic particle-in-the-box problem of basic quantum mechanics is the Quantum Well Infrared Photodetector (QWIP). In this paper we discuss the optimization of the detector design, material growth and processing that has culminated in realization of 15 micron cutoff 128 X 128 QWIP focal plane array camera, hand-held and palmsize 256 X 256 long-wavelength QWIP cameras and 648 X 480 long-wavelength camera, holding forth great promise for myriad applications in 6 - 25 micron wavelength range in science, medicine, defense and industry. In addition, we present the recent developments in broadband QWIPs, mid-wavelength/long-wavelength dualband QWIPs, long- wavelength/very long-wavelength dualband QWIPs, and high quantum efficiency QWIPs for low background applications in 4 - 26 micrometer wavelength region for NASA and DOD applications.

A broad-band infrared detector, sensitive over a 10 - 16 micrometer spectral range, based on GaAs/Al_xGa_1-xAs quantum wells grown by molecular beam epitaxy, has been demonstrated. Wavelength broadening of (Delta) (lambda) /(lambda) _p approximately 42% is observed to be about a 400% increase compared to a typical bound-to- quasibound quantum well infrared photodetector (QWIP). In this device structure, which is different from typical QWIP device structures, two different gain mechanisms associated with photocurrent electrons and dark current electrons were observed and explained. Even with broader response, D* approximately 1 X 10¹⁰ cm(root)Hz/W at T equals 55 K is comparable to regular QWIPs with similar cutoff wavelengths.

Diffractive optical elements (microlenses) for quantum well infrared photodetectors (QWIPs) were fabricated by two techniques: (1) standard lithography of a binary optical structure and (2) PMMA pattern transfer for an analog diffractive optic structure. The binary lenses were fabricated by sequential contact lithography and etching using two binary masks. The analog diffractive lenses were fabricated in PMMA by direct-write e-beam lithography followed by acetone development. The resulting PMMA surface relief profile was transferred into the GaAs by dry etching. Both types of lenses were etching into GaAs using an electron cyclotron resonance (ECR) microwave plasma etching system. Although the lenses were fabricated accurately, the performance of the QWIPs was not improved as much as expected due to the angle-of-incidence sensitivity of the QWIP light-coupling grating. The lenses would have likely improved the performance of detectors capable of absorbing normally incident light.

We have successfully fabricated intersubband GaAs/AlGaAs quantum well infrared photodetectors grown on GaAs-on-Si substrate and evaluated their structural, electrical, and optical characteristics. We have found that the performance is comparable to a similar detector structure grown on a semi- insulating GaAs substrate. The results are promising for applications in the important 8 - 12 micrometer atmospheric window.

A new family of 2 dimensional detection modules based on GaAs quantum well (QWIP) photoconductors was recently developed by AEG Infrarot-Module GmbH (AIM). 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. This paper will concentrate on the features of the QWIP detection module i.e. the integration of this specific focal plane array (FPA) into an integrated detector cooler assembly (IDCA), the driving and readout electronics and the necessary non uniformity correction (NUC) hardware and algorithms for achieving the best performance. The paper shows how the new 256 X 256 QWIP module is integrated in AIM's modular family of detectors. Measured results are shown for the thermal resolution and the correctability of the device. The results are compared with results of recently developed detection modules based on mercury cadmium telluride (MCT) as discussed in a separate paper. The correctability results show, that the full performance of the QWIP module with a thermal resolution as low as NETD less than 10 mK can only be used in systems by highly sophisticated NUC algorithms. AIM has introduced a new self adaptive algorithm (SAICA) which allows a dynamical optimization of the correction coefficients of high performance detection modules. Features of this algorithm will shortly be discussed. AIM contemporarily develops a new 640 X 512 QWIP module in cooperation with IAF. The device is available starting mid 1998. Basic features of the new device will be given as an outlook.

Infrared (IR) sensors are critical to all phases of ballistic missile defense (BMD), including surveillance, threat detection, tracking, identification, discrimination, targeting, and interception. The Discriminating Interceptor Technology Program (DITP) under development by the BMDO Sensors and Interceptors Directorate (BMDO/TOS) supports the requirements of BMDO's National Missile Defense and Theater Missile Defense to counter the emerging threat. Focal plane arrays (FPAs) with high sensitivity, high uniformity, large format, flexible wavelength ranges from mid-wave IR (MWIR) to very long wave IR (VLWIR), and multicolor capabilities are required. The effort is also toward FPAs with high reproducibility, high yield, low cost, and manufacturability. The two most promising near-term IR technologies to meet the BMD requirement are mercury cadmium telluride (MCT) photodiodes and quantum well infrared photodetectors (QWIPs). This paper discusses applications and relative merits of both of these detectors in BMDO applications.

Corrugated quantum well infrared photodetectors (C-QWIPs) use total internal reflection to couple normal incident light into the detectors. In this work, we report the performance of C- QWIPs at different wavelengths. Compared with 45 degrees edge coupling, a C-QWIP increases the background photocurrent to dark current ratio r_I by a factor between 2.4 and 4.4, thereby increasing the background-limited temperature by 3 to 5 K. The detectivity D* is increased by a factor of 2.4. We applied the C-QWIP to two-color detection and obtained precision thermometric measurements. We have also fabricated and characterized a 256 X 256 C-QWIP array with cutoff wavelength at 11.2 micrometer. The uncorrected nonuniformity ((sigma) /mean) in the central 128 X 128 subarray is 2.3%. The NE(Delta) T at 63 K is estimated to be 23 mK. Furthermore, we have shown that r_I can be further increased by fabrication of the C-QWIP into the corrugated hot-electron transistor structure. The enhanced performance of the corrugated structure, combined with its simple processing steps, greatly improves the QWIP technology.

We describe here a study of Mini-Band Transport (MBT) Quantum Well Infrared Photodetector (QWIP) samples in which the binding energy of photoexcited electrons is systematically varied. Each sample has been characterized electrically and radiometrically. Results are reported for variation of absorption spectra, spectral response, IV characteristics, blackbody responsivity, detector noise, and detectivity vs. binding energy for dark current limited mode of operation.

This paper describes the design and evaluation of a 128 X 1 signal processing readout integrated circuit for LWIR HgCdTe scanning infrared focal plane array applications. Smart readout functions, such as charge skimming and on-focal plane gain non-uniformity corrections, are presented along with empirical results measured with LWIR HgCdTe linear arrays.

Development of per pixel analog to digital conversion technology for staring focal plane arrays has resulted in improvements in well capacity, power consumption, linearity and signal to noise performance compared to present analog readout approaches. This new digital approach has also allowed the application of alternative on focal readout approaches. These include passive optical devices for readout as well as current mode switching wired output. Test results and design considerations of a recently completed 128 X 128 staring array are presented. The design was based on MOSAD, Multiplexed OverSample A/D, which places a filtering A/D modulator at each pixel. This readout has been linked on focal plane to passive reflective optical modulators providing high data rate digital outputs as an alternative to wired interconnect. A comparative study of current mode wired switching verses optical mode readout was completed. These results will also be presented. Both the optical readout and focal plane array designs were developed with funding from the U.S. Army Night Vision and Electronic Sensors Directorate.

The MOSAD, Multiplexed Oversampled Analog to Digital conversion approach at Amain Electronics research center, introduces an extremely low power on focal plane analog to digital conversion at each pixel site. The MOSAD technology has been tested and characterized for different focal plane array sizes. This approach has demonstrated superior linearity, well capacity and signal to noise ratio, which exceeds existing A/D capabilities, by eliminating all analog multiplexing and readout electronics off focal plane. This document describes the design, characterization and testing methodology to satisfy the variety of requirements for the readout interface to the MOSAD technology. The necessary readout interface electronics used to validate the MOSAD technology with Dewar assembly is presented. Results from the testing performance considerations such as signal to noise ratio are discussed. Amain Electronics test methodology considerations are described to show that an all digital focal plane array simplifies the future FPA test complexity and methodology.

We have measured the relative spectral response of MCT infrared detector, and based on distribution of spectral response G((lambda) ), we have calculated the waveband responsivity R_(Delta (lambda) ) and waveband detectivity D*_(Delta (lambda) ) of infrared detector. This paper briefly describes the measure process and results of MCT photoconductive (PC) infrared detector (at temperature 105 K) which is intended to be used in certain waveband for space application, and analyses the measure error.

The Arnold Engineering Development Center (AEDC) has been involved in the characterization of infrared detector and focal plane arrays (FPAs) since 1986. Test facilities have been developed to allow all aspects of FPA performance and operation to be evaluated. Basic radiometric characterization can be performed in several low background chambers, and a scene generation system has been developed and implemented to allow complex scenes to be projected and evaluated. The facilities have been continuously upgraded to accommodate testing of increasingly larger and more complex arrays. Special analysis tools have been developed to allow processing of the large quantity of data acquired for the arrays.

A methodology for validating the measured relative spectral response function of infrared detectors is described. Typically, the spectral response of sister detectors, fabricated on the same wafer as the detectors for infrared focal plane arrays (IRFPA's), are characterized in lieu of measuring the spectral response of the actual IRFPA. It is then generally assumed that the spectral characteristics of the IRFPA detectors are equivalent to the spectral characteristics of the sister detectors. To validate this assumption, a measurement methodology has been developed to assess the accuracy the measured relative spectral response curves. This methodology is based on the premise that infrared detector's measured peak responsivity is independent of the spectral content of the irradiance at the detector. The peak wavelength responsivity of the infrared detector is measured as a function of spectral photon irradiance to evaluate the accuracy of the measured detector relative spectral response. If the measured peak responsivity of the infrared detector is independent of spectral irradiance, then the measured spectral response accurately represents the spectral characteristics of the infrared detector. However, if the peak responsivity varies with spectral irradiance, then the measured spectral response is in error. The shape of the peak responsivity versus spectral irradiance curve provides insight into the spectral region where the measured spectral response is in error. Sample relative spectral response data are presented along with analysis of the spectral response curves.

High performance scanning time-delay-and-integration and staring hybrid focal plane devices with very large formats, small pixel sizes, formidable frame and line rates, on-chip digital programmability, and high dynamic ranges, are being developed for a myriad of defense, civil, and commercial applications that span the spectral range from shortwave infrared (SWIR) to longwave infrared (LWIR). An essential part in the development of such new advanced hybrid infrared focal planes is empirical validation of their electro-optical (EO) performance. Many high-reliability, high-performance applications demand stringent and near flawless EO performance over a wide variety of operating conditions and environments. Verification of focal plane performance compliance over this wide range of parametric conditions requires the development and use of accurate, flexible, and statistically complete test methods and associated equipment. In this paper we review typical focal plane requirements, the ensuing measurement requirements (quantity, accuracy, repeatability, etc.), test methodologies, test equipment requirements, electronics and computer-based data acquisition requirements, statistical data analysis and display requirements, and associated issues. We also discuss special test requirements for verifying the performance of panchromatic thermal and multispectral imaging focal planes where characterization of dynamic modulation transfer function (MTF), and point-image response and optical overload is generally required. We briefly overview focal plane radiation testing. We conclude with a discussion of the technical challenges of characterizing future advanced hybrid focal plane testing where it is anticipated that analog-to- digital conversion will be included directly on focal plane devices, thus creating the scenario of 'photons-in-to-bits- out' within the focal plane itself.

Measuring of the photoelectric parameters of the IR arrays is the important stage in manufacturing of the IR thermovision camera photoreceivers. This work is directed toward the novel construction of the optical part (cold camera) of the testing unit (TU) for measuring of the IR arrays input/output photoelectric parameters in the process of the industrial production. This device can measure such parameters as sensitivity, NEI, NETD, saturation voltage, their array's field uniformity, etc. The TU's cold camera consists of the cold head, the cold shield, the new cold diaphragm, the cold filter (if needed) and the gray or black body (BB) with the plane emitting surface. All this parts placed in the small size vacuum cryostat without any windows. In our case it is the vacuum cryostat with the close cryogenic system produced by CTIcryogenics. The distance between FPA's plane and the diaphragm is 15.0 mm, and between the diaphragm and the emitting surface of BB is 10.0 mm. The diameter of the emitting surface is 50 mm. The temperature change needed for the characteristics measurements is 5 - 45 degrees Celsius. The cold diaphragm has the shape of annular slot so that the irradiance in FPA's plane is very uniform (better than 0.5% for (Delta) T(x,y) less than 0.5 degrees Celsius and 1 ring). These factors indicate on the measurement correctness. The outside diameter of the diaphragm is in accordance with the array's place and the BB emitting surface diameter so that only emitting surface points would be viewed from the array's place. Parameters of the diaphragm define the set background illumination value and the irradiance uniformity. The temperatures of the measured IR array and the cold shield (with diaphragm and filter) are set in accordance with their temperature requirements to the array and the background.

We have developed 1024 X 1024 HAWAII (HgCdTe Arrays for Wide-field Astronomical Infrared Imaging) focal plane arrays (FPAs) for use in astronomical applications. These devices have been delivered to various astronomy organizations around the world and have resulted in increased sensitivities and decreased observation times for deep space imaging. The detector material is PACE-I for SWIR and Molecular Beam Epitaxy (MBE) HgCdTe on CdZnTe for MWIR. The 1024 X 1024 multiplexer has a 18.5 micrometer unit cell pitch, source follower per detector (SFD) input, and it was fabricated at or internal commercial CMOS process line with excellent yield. Mean dark currents as low as 0.02 e-/s have been measured at 77 K for 2.5 micrometer devices (1024 X 1024 format, 18.5 micrometer pitch) and 0.39 e-/s for 5.3 micrometer devices at 50 K (256 X 256 format, 40 micrometer pitch). Quantum efficiencies are greater than 50% for both SWIR and MWIR detectors; with AR coatings, these are expected to be above 75%. Noise levels of 3 e- have been measured by multiple sampling techniques for the SWIR and 75 e- for the MWIR. All of these devices are simple to operate and are readily available. We are presently developing 2048 X 2048 FPAs with 18 micrometer unit cell pitch for both SWIR and MWIR applications.

Hg_1-xCd_xTe films with x values varying from 0.2 to 0.23 have been grown and characterized. N-type carrier concentrations in the range of 1 X 10¹⁵ cm^-3 to 3 X 10¹⁵ cm^-3 have been obtained. Hall effect measurements before and after anneals at 250 degrees Celsius have led to the evaluation of the Hg vacancy concentration in the samples. Dislocation density less than 10⁵ cm^-2 and X-ray rocking curve width less than 25 arc- secs measured in some of the films attests to the excellent crystallinity of the material.

A 640 X 480 snapshot IRCMOS array with 25 micron pitch operating in the 3 - 5 microns range was fabricated and an image demonstrated at the Infrared Laboratory (LIR). The readout circuit with 2 pC charge handling capacity was designed and processed with a 1.2 micrometer design rules standard CMOS technology. Photovoltaic (PV) detectors were achieved by ion implantation in liquid phase epitaxy MCT layers and interconnected by indium bumps on the readout circuit. A description of the component is given and the main electro-optical characteristics are presented. The pixel operability is greater than 99.8% and a NEDT of 15 mK was measured at half dynamics. Excellent imagery has been obtained with this component operating at 77 K and f/2 optics.

A 256 X 256 IRCMOS array with a 35 micron pitch operating at 77 K in the MWIR range, has been developed using HgCdTe and CdTe layers grown by Molecular Beam Epitaxy (MBE) on a germanium (Ge) heterosubstrate. The CdTe(211)B layer is first grown on a 2 inch diameter (211) oriented Ge wafer with a smooth surface morphology and good crystalline quality. The HgCdTe(211)B layer is also grown by M.B.E. on this CdTe/Ge heterosubstrate with the same quality. The material characteristics are detailed. The 256 X 256 photodiode array is made using the standard LETI/LIR planar n-on-p ion implanted technology. At 80 K, photodiodes exhibited an RoA figure of merit higher than 10⁶ (Omega) cm² for a cut- off wavelength of 4.8 micrometer. An NEDT of 6 mK at 80 K was also obtained on the IRCMOS. The electro-optical characteristics of the component are presented and we show that the 256 X 256 component performances using HgCdTe grown on Ge heterosubstrate are comparable for MWIR applications to those obtained on 256 X 256 component using HgCdTe grown on CdZnTe homosubstrate.

The technology was developed and 128 X 128 LWIR FPA's based on HgCdTe epitaxial layers MBE-grown on GaAs substrates with cutoff wavelength (lambda) _c equals 8 micrometer and 13 micrometer was fabricated. The photosensing layer HgCdTe was graded-gap layer with the higher content of Cd to boundaries of a layer. The manufactured LWIR FPA's had NETD 32 mK and 17 mK for (lambda) _c equals 8 micrometer and 13 micrometer, correspondingly, at 295 K background and 80 K operation temperatures.

Current-voltage characteristics of narrow-gap HgCdTe p-on-n photodiodes at different temperatures have been investigated. Forward tunneling current is seen in a certain forward bias region. A constant-current mode was also used to identify the trap-assistant tunneling, and the results show this forward tunneling current influences the zero bias resistance. Ideality factors, calculated from current-voltage experimental data, show a peak in the intermediate forward bias region. The height of peak in ideality factor decreases as the temperature increases. This peak is thought due to the multi-step tunneling current.

Doping of the lead telluride and related alloys with the group III impurities results in an appearance of the unique physical features of a material, such as persistent photoresponse, enhanced responsive quantum efficiency (up to 100 photoelectrons/incident photon), radiation hardness and many others. We review the physical principles of operation of the photodetecting devices based on the group III-doped IV-VI including the possibilities of a fast quenching of the persistent photoresponse, construction of the focal-plane array, new readout technique, and others. The advantages of infrared photodetecting systems based on the group III-doped IV-VI in comparison with the modern photodetectors are summarized. Some new ideas concerning the possibilities provided by the doped IV-VI are presented.

Short wavelength (SWIR) devices have been fabricated using boron implantation. The capacitance-voltage measurement has been used to examine the junction doping profiles. The junction doping profile can be n/n^-/p type or n/p type depending on the p-side doping concentration. Only the junctions made on the lightly doped substrates show the n/n^-/p type abrupt junction, with the n^- region in the low 1 X 10¹⁴ cm^-3 range. On the heavily doped substrates, we obtain the n/p type graded junctions. The peak detectivity D*_(lambda p) performance at room temperature of the large area (A_j equals 5.9 mm²) detector was about 2.6 X 10¹¹ cm-Hz^1/2/W at the zero bias. Higher D*_(lambda p) performance about 1.4 X 10¹² cm-Hz^1/2/W was obtained on smaller area detectors at 250 K.

We report results from a field demonstration of a non-scanning high-speed imaging spectrometer capable of simultaneously recording spatial and spectral information about a rapidly changing scene. High-speed spectral imaging was demonstrated by collecting spectral an spatial snapshots of a missile in flight. This instrument is based on computed-tomography concepts and operates in the visible (420 - 740 nm). Raw image data were recorded at video frame rate (30 fps) and an integration time of 2 msec. Reconstructions of the spatial and spectral scene information from the raw image data take considerably longer, on the order of 30 seconds. Comparisons of reconstructed spectra with spectra acquired by a non- imaging reference spectrometer have shown that extended-source spectra were reconstructed accurately. We present representative missile spectral-signature data and missile- tracking linear-classifier results from the missile firing.