The detection of long range air targets in a Naval scenario using passive Imaging IR sensor is a task of primary importance for current and next generation Naval equipment. The authors have investigated Dynamic Programming based target detection systems utilizing the output of an image filter as the input to a likelihood classifier based on intensity alone. Variations of this technique have been proven to offer high sensitivity to dim targets though environmental characteristics in the Naval scenario can give rise to clutter induced false alarms. The work presented herein investigates augmentation of the intensity classifier with textural analysis techniques on IR imagery in the 3-5 micron waveband to assist in false alarm discrimination. It is shown that augmentation with a textural classifier can improve rejection of false alarms due to clutter. This work is apt of an ongoing program of IRST and Surveillance Sensor processing development.

The US Navy (USN) has long placed a strong emphasis on the production and use of electro-optical (EO) sensors for a wide variety of mission on naval aircraft. Numerous EO fire control and surveillance sensor systems have been developed for USN surface ship applications, but production and deployment has been limited. This apparent dichotomy is due to the vastly different missions and environments of aircraft and ships, and to the need for shipboard system that will support operations dictated by our global interest. EO technology has now evolved to the point where surveillance and fire control sensor systems can be built that have excellent performance under the preponderance of environmental conditions, and where atmospheric refraction, rather than transmission, is the primary design driver. In addition, the consensus of USN decision-makers is that EO sensor system that are designed to complement not supplant, radar systems can provide dramatic improvements in combat system performance at acceptable costs. The two sensor classes that have achieved this level of maturity are Horizon IR Surveillance Systems and the Thermal Imaging Sensors. This paper describes the technologies that have made these sensors possible as well as some of the phenomenological drivers to their designs.

Rockwell is developing the world's largest HgCdTe IR focal plane array (FPA) for astronomy and low background applications. The format of the device is a hybrid 2048 X 2048 with a unit cell size of 18 micrometers X 18 micrometers . SWIR detectors with a spectral response of 0.85 micrometers to 2.5 micrometers have been processed on liquid phase epitaxy (LPE) HgCdTe on sapphire substrates. The MWIR detectors with a spectral response of 0.4 micrometers to 5 micrometers will be processed on molecular beam epitaxy HgCdTe on CdZnTe substrates. The multiplexer has been designed and fabricated at Conexant. Room temperature probing shows that the device is functional with excellent yield. Novel hybrid fabrication techniques will be used to demonstrate the FPA. This HAWAII-2 device is based on the highly successful HAWAII 1024 X 1024 device and the performance will be similar. The ultimate performance expected from the array is: dark currents of < 0.01 3-/s, quantum efficiency of > 75 percent across the spectral band, and noise levels of < 3 e- for the SWIR and < 10 e- for the MWIR band using Fowler sampling. We expected to achieve these performance levels at 77K for the SWIR and > 40K for the MWIR band. The status of the 2048 X 2048 detector arrays and FPAs are discussed.

The use of IR search and track (IRST) sensor is now generally accepted as essential on board ships but their angular 2D target reports are sometimes insufficient when electromagnetic control plans are in use in naval operations. The principle of an on-board 'Quite Silent Search Function' (QSSF) consists in fusing reports from an IRST sensor and a MultiFunction Radar (MFR) with controlled emission to obtain an acceptable covertness level, while having very accurate 3D target indication to the combat system. The main idea pushed ahead consists in tolerating a reduced level of radar emission in order to counteract the ARm tracking capability and to reduce adverse ESM detection. The paper addresses this situation and shows the main contribution of a QSSF compared to standard Search Function using an IRST placed in no false alarm conditions and then in severe false alarms conditions. Statistic performances of the QSSF are provided; they have been obtained through Monte-Carlo analysis using a hybrid simulator. Thus, the IR clutter is compared of true IRST signal recordings while radar clutter and target contact reports are synthetic.

This paper describes algorithm development work undertaken out for the long-range detection and tracking of air targets in an air to air scenario. Algorithm developments to operate in the search, detect and track modes of an IR search and track equipment are described. In particular, recent work in a variation of the technique known as track before detect has demonstrated good performance in this role. The result of some of this work, derived from demonstration of the algorithms against imagery from airborne trials of flying IRST equipment are presented here.

The on-going maturation of electro-optic technology in which the advent of third generation focal plane array is being combined with the capabilities of increasingly powerful signal processing algorithm now points to a new direction in design of electro-optic sensor system for both military and non-military applications. Taking advantage of those advances. Distributed Aperture IR Sensor systems (DAIRS) are currently in development within the Defense Department for installation in a variety of platforms for utilization in a wide variety of tactical scenarios. DAIRS employs multiple fixed identical sensor to obtain the functionality that was previously obtained using specialized sensors for each function. In its role in tactical scenarios. DAIRS employs multiple fixed identical sensor to obtain the functionality that was previously obtained using specialized sensor for each function. In its role in tactical aircraft, DAIRS uses an array of six strategically located sensors which provide 4(pi) steradian sensor coverage, i.e., full sphere situational awareness (SA), to the aircrew. That awareness provides: missile threat warning, IR Search and Track, battle damage assessment, targeting assistance, and pilotage. DAIRS has applicability in providing expanded SA for surface ships, armored land vehicles and unmanned air combat vehicles. A typical sensor design has less than twenty-five percent of the weight, volume, and electrical power demand of current federated airborne IR sensor system and can become operational with a significant reduction in lifetime system cost. DAIRS, when combined with autocueing, may have a significant role in technological advancement of aircraft proximity warning system for in-flight collision avoidance. DAIRS is currently founded in part by the Office of Naval Research which will result in the IR Distributed Aperture System (MIDAS), which is funded as a Navy Advanced Technology Demonstration, the DAIRS will undergo airborne testing using four sensor in FY-00. MIDAS will include integration of a helmet mounted display for situational awareness imaging.

Dynamic area telethermometry (DAT) is aimed at extracting pertinent information on the mechanism underlying periodic changes in temperature of surfaces, manifested in modulation of their IR emission. Such changes occur on human skin as a result of modulation of perfusion due to cardiogenic hemodynamics or neuronal control of blood flow through the vasculature. Clinical applications of DAT involve identification of areas of skin that how abnormal dynamic behavior. Periodic physiological changes in skin temperature range between 10 and 50 mK. Pathological changes in skin temperature dynamics are of the same order. Consequently, clinical uses of DAT require not only high sensitivity and spatial thermal resolution but also a high degree of temporal stability of both the offset and NEDT values of each detector element of the FPA. DAT also requires high rates of data acquisition to allow sufficient resolution of the frequency spectrum of skin's temperature modulation. Adequate DAT studies involve accumulation of 2048 images at a rate of 100 Hz. We found that QWIP cameras meet DAT's requirements of sensitivity, stability and accumulation rate. A single DAT study using a 256 X 256 array yields 256 MB of IR flux or temperature data for subsequent analysis. Interpretation of such an enormous amount of digital information within a reasonable timeframe poses severe software requirements, which have been met.

Rupture of atherosclerotic plaques - the main cause of heart attach and stokes - is not predictable. Hence even treadmill stress tests fail to detect many persons at risk. Fatal plaques are found at autopsies to be associated with active inflammatory cells. Classically, inflammation is detected by its swelling, red color, pain and heat. We have found that heat accurately locates the dangerous plaques that are significantly warmer then atherosclerotic plaques without the same inflammation. In order to develop a non-surgical method of locating these plaques, an IR fiber optic imaging system has been developed in our laboratory to evalute the causes and effect of heat in atherosclerotic plaques. The fiber optical imagin bundle consists of 900 individual As₂S₃ chalcogenide glass fibers which transmit IR radiation from 0.7 micrometers 7 micrometers with little energy loss. By combining that with a highly sensitive Indium Antimonide IR focal plane array detector, we are able to obtain thermal graphic images in situ. The temperature heterogeneity of atherosclerotic plaques developed in the arteral of the experimental animal models is under study with the new device. The preliminary experimental results from the animal model are encouraging. The potential of using this new technology in diagnostic evaluation of the vulnerable atherosclerotic plaques is considerable.

The high blood flow rate and the considerable metabolic activity render the myocardium a possible candidate for IR imaging. The study was aimed to test cardiothermography in evaluating arterial bypass graft patency and in assessing myocardial protection during open-heart surgery. Ten patients underwent arterial bypass grafting. Thermograms were obtained immediately before and after opening the grafts. As the bypasses were opened in hypothermia the warmer blood coming from the extracorporeal circulation readily delineated graft and coronary anatomy. By the end of the 5 min observation period, the revascularized area exhibited a temperature increase of 5.9 +/- 0.7 degrees C. The affectivity of antegrade cardioplegia was monitored in 38 patients undergoing either valve implantations or aorto- coronary bypass surgery. Thermographic imags were taken after sternotomy, before aortic cross-clamping and after administrating the 4 degrees C cardioplegic solution. Most of the patients displayed adequate myocardial cooling, moreover the bypass-group exhibited a more profound temperature-decrease. In conclusion, cardiothermography can visualize arterial grafts, recipient coronaries and collaterals seconds after opening by bypass, thus it properly evaluated arterial bypass graft patency. The obtained images could easily be analyzed for qualitative flow- and quantitative temperature changes. Myocardial protection could also be safely assessed with thermography.

Endothelin-1 (ET-1) is the strongest vasoconstrictor peptide isolated so far, which has a known arrhythmogenic property, as well. Intracoronary ET-1 infusion may cause ventricular premature beats (VES), ventricular tachycardia (VT) and ventricular fibrillation (VF). The aim of our study was to compare the thermographic and electrophysiologic changes during left anterior describing coronary artery (LAD) occlusion and ic. ET-1 administration. The measurements were performed on 16 sodium-pentobarbital anesthetized, open- chest dogs. The dogs were divided into 2 groups. In group A LAD occlusion was carried out for 30 minutes, followed by a 60 min reperfusion period. In group B ET-1 was administered into LAD at 60 pmol/min dose. Arterial blood pressure, coronary blood flow (CBF), heart rate (HR) and standard ECG were monitored. IR thermography was applied to follow epimyocardial heat emission changes. To determine the electrophysiological changes an endocardial monophasic action potential (MAP) electrode was inserted into the right ventricle and an MAP electrode was placed onto the left ventricle and an MAP electrode was placed onto the left ventricular epicardium. In group A CBF returned to baseline 20 minutes after releasing the occlusion. Ic. ET-1 infusion significantly reduced CBF in group B. Epimyocardial temperature decreased in both groups. In group A ventricular extrasystoles were noticed. In group B ventricular techycardias occurred with satisfactory CBF in 4 cases. In 5 dogs VF was observed. MAP duration 90 (MAPD90) decreased significantly in group A whereas significant increase was observed in group B. The left ventricular epicardial upstroke velocities correlated excellently with the epimyocardial temperature changes. Our result suggests that the decrease of epimyocardial heat emission and upstroke velocity correlates well in both groups, indicating ischemia, whereas the lack of the other ischemic MAP signs and the change of MAPD90 in the opposite direction suggests a different arrhythmia pathomechanisms in the ET group. Cardiothermography proved to be a useful tool in monitoring epimyocardial temperature changes during coronary artery occlusion and ET-1 induced vasoconstriction.

Dynamic area telethermometry (DAT) is a new approach for the use of IR imaging in medicine. DAT allows rapid, non-contact assessment of cutaneous perfusion and study of the dynamics of subcutaneous blood flow. Consequently, DAT can be a useful tool in the management of vascular and plastic surgeries, as well as in the diagnosis of neuronal disorders that affect the vasculature. DAT can also be very useful in the diagnosis and management of non-neuronal disorders, such as cancer, associated with abnormal dynamics of local perfusion. The application of DAT in the diagnosis of breast cancer is described as a model for converting a qualitative subjective imaging technique into a quantitative objective test.

Determination of burn wound depth is at present left to the surgeons visual examination. Many burn wounds are obviously, by visual inspection, superficial 2 degree burns or true 3 degree burns. However, those burn wounds that fall between the obvious depth burns are difficult to assess visually, and therefore wound depth determination often requires waiting 5 to 7 days postburn. Initially, 10 burn patients underwent IR imaging at various times during the evaluation of their burn wounds. These patients were followed to either healing or skin grafting. The IR images were then reviewed to determine their accuracy in determining the depth of the wound. IR imaging of burn wounds with focal plane staring array midrange IR systems appears promising in determination of burn depth one to two days postburn. This will allow clinical decision regarding operative or nonoperative intervention to be made earlier, thus decreasing hospital stays and time to healing.

Uncooled IR sensor technology has accelerated rapidly in the past few years. Higher performance sensor, electronics integration, and enhanced signal processing are generating new applications and increasing production volume. Uncooled sensor are being considered to replace cooled sensor in some applications, but most importantly, the unique characteristics of the uncooled sensor spawn novel uses of the technology. Very small, lightweight and lower power sensor are possible with the uncooled IR. However, moderate levels of performance are expected even from the smallest sensors. This demand for performance stimulates new ideas for thermal detector structures operating at or near the theoretical limit. This paper reviews the exciting new applications of the uncooled technology and investigates the novel technical approaches necessary to bring about a new generation of uncooled IR sensor technology.

Raytheon IRCOE has developed a family of uncooled, microbolometer FPAs. These FPAs have been designed to address commercial and high-performance military applications. The SB-151 is a high-sensitivity 320 X 240 FPA with 50 micrometers pixels. The SB-151 FPA has been fabricated with several microbolometer pixel designs that allow optimization of either sensitivity or response time. Noise equivalent temperature difference (NETD) values as low as 8.6 mK have been measured for the SB-151 FPAs with f/1 optics. NETD values less than 25 mK have been measured for FPAs with thermal time constants of approximately 18 msec.

This paper describes Boeing's next-generation 320 X 320 uncooled IR focal plane product. The basic objectives have ben to at least double focal plane performance, improve focal pane operating stability, and significantly enhance the control interface between the focal pane and the camera. All of these basic objectives have been achieved. Focal plane temporal NETD equals 0.028 degrees C has been demonstrated at a frame rate of 60 Hz on the first lot of UFPAs produced, as well as a worst-case spatial NETD < 0.016 degrees C measured over 10 degrees C temperature calibration range. Operating stability improvement has been successfully demonstrated. The design has validated a 'smart sensor' UFPA/camera control interface that provides externally programmability of on-chip signal gain, on-chip pixel offset compensation, on-chip detector bias regulation, precision on-chip temperature measurement, and a 16 test- point Built In Test function. Based on Lot-1 test results, the next lot, which is now in wafer processing, is expected to achieve NETD < 0.02 degrees C at a 60 Hz frame rate. With an improved microbolometer Thermal Isolation Structure, currently in development at Boeing, NETD < 0.010 degrees C can be demonstrated before the end of this year.

Lockheed Martin is developing the first ever 640 X 480 uncooled microbolometer camera. This camera, designated the LTC650, has a new 28 micrometers pitch 640 X 480 microbolometer focal plane array and electronics which operate at a 30 Hz frame rate. The electronics are based on previous successful 320 X 240 camera electronics which use low power, high performance DSP and FPGA technology. A DSP based software solution provides flexibility to answer the challenge of change and varied customer needs while meeting the low cost, low power, and low real estate requirements of portable, hand held applications. Test data for the first camera are presented.

Lockheed Martin IR Imaging Systems is developing uncooled microbolometer-based imaging products for a wide range of military, industrial and commercial applications. All of these products employ image processing electronics to provide enhanced imagery and flexible control for different applications. Here we report on the second generation video signal processor architecture and the electronics of the SIM200 module. The first generation electronics utilized custom hardware for real-time image processing and a microcontroller for auxiliary processing and control. The SIM200 Module introduces a revolutionary second generation architecture based upon industry-standard DIgital Signal PRocessors and dramatically reduced interface electronics. This enables real time image processing to be performance in software resulting in a dramatic reduction in size, power, weight, and cost for the electronics, so critical to leading edge portable applications. The performance and produce advantages of the SIM200 and its video signal processors architecture will be discussed along with system level performance parameters.

It is well known that the work function of metals decrease when they are placed in a nonpolar liquid. A similar decrease occurs when the metal is placed into contact with a semiconductor forming a Schottky barrier. We report on a new method for detecting photon is using the stress caused by photon-electronics emitted forma metal film surface in contact with a semiconductor microstructure. The photoelectrons diffuse into the microstructure and produced an electronic stress. The photon detection results from the measurement of the photo-induced bending of the microstructure. Internal photo-emission has been sued in the past to detect photons, however, in those cases the detection was accomplished by measuring the current due to photoelectrons and not due to electronic stress. Small changes in position of microstructures are routinely measured in atomic force microscopy where atomic imaging of surface relies on the measurement of small changes in the bending of microcantilevers. In the present work we studied the photon response of Si microcantilevers with a thin film of Pt. The Si microcantilevers. In the present work we studied the photon response of Si microcantilevers with a thin film of Pt. The Si microcantilevers were 500 nm thick and had a 30 nm layer of Pt. Photons with high enough energies produce electrons from the platinum-silicon interface which diffuse into the Si and produce an electronic stress. Since the excess charge carriers cause the Si microcantilever to contact in length but not the Pt layer, the bimaterial microcantilever bends. In our present studies we used the optical detection technique to measure the photometric response of Pt-Si microcantilevers as a function of photon energy. The charge carriers responsible for the photo-induced stress in Si, were produced via internal photo-emission using a diode laser with wavelength (lambda) equals 1550 nm.

A new class of uncooled IR systems has been developed based on advances in both amorphous silicon detectors and signal/system processing techniques. Not only are these devices uncooled but they operate over a wide system ambient temperature range without the use of TEC's or choppers. The devices are DC biased and provide radiometric information from each pixel without the use of a calibrated source. The current imaging system are medium to low resolution. They were designed with a very disciplined 'concept-to-cost' technique in which cost, power, sizes, weight and performance were traded off in the stated order. The result has been a new generation of 'ambient temperature' thermal imaging system and radiometers.

AlliedSignal Driver's Viewer Enhancement (DVE) system is a thermal imager using a 320 X 240 uncooled microbolometer array. This high performance system was initially developed for military combat and tactical wheeled vehicles. It features a very small sensor head remotely mounted from the display, control and processing module. The sensor head has a modular design and is being adapted to various commercial applications such as truck and car-driving aid, using specifically designed low cost optics. Tradeoffs in the system design, system features and test results are discussed in this paper. A short video shows footage of the DVE system while driving at night.

In the present paper we report a high-fill factor uncooled IR micro-bolometer array; and, more particularly, a three- level IR bolometer including an almost 92 percent fill factor absorber and a separately-designed bridge structure for the electro-thermal isolation of thermal sensor; and a method for the silicon-based fabrication. The present 256 X 256 bolometer array comprises a CMOS readout circuitry, a bridge level, a pari of posts, and an absorption level. The fabrication of the presented bolometer feature that it uses double sacrificial layers so as to separate the absorber level from the bridge structure, electrical and thermal path between the absorber and substrate. Also, we chose a titanium thin-film as a bolometer material which is patterned to make a connection between the substrate contact and the post. The absorber level is compared of titanium metal film sandwiched between PECVD deposited silicon dioxide layers to preserve thermal isolation of a bolometer absorber and release the inertial stresses. Additional contact is formed to connect the metal thin-film to the serpentine resistive pattern on the absorbing membrane defined on the top of the second sacrificial layer. From the structural design, we can obtain a good thermal isolation without reducing IR absorbing area.

We have investigated the performance of VO₂ microbolometers biased on the semiconducting-metal phase transition with negative electrothermal feedback. We deposited crystalline thin films of phase-pure VO₂, patterned these films into useful test structures, and evaluated the electrical and optical properties relevant to improved uncooled bolometric sensors. A novel ac-biasing method allows for biasing of the devices on the hysteretic semiconducting-metallic phase transition near 70 degrees C. Two important advantages result from biasing in the phase transition: high sensitivity, and negative electrothermal feedback. Under these conditions improvements in speed and noise equivalent power are expected. Modest improvements in noise performance and responsivity consistent with simulations were experimentally verified. Our result suggest a large potential performance advantage over current uncooled vanadium oxide sensor which can be realized as either increased bandwidth or higher sensitivity.

The Air Force Research Laboratory laser applications group, also known as 'Scorp Works' has been developing user specific, active illumination systems for the past 8 years. A survey of some of these programs will be presented. Programs to be included are the covet adjustable laser illuminator, the Coast Guard search and rescue laser systems, a camera automated tracking system, and a 1.5 μm covert camera and illuminator.

This paper discusses the development history of real-time imaging active gated TV sensors from 1970 to present at Ball Aerospace and Technologies Corp. A number of AGTV systems are covered including: Video Imaging Detection and Ranging which was developed for hydrofoils in Southeast Asia, AC- 130U gunship, Airborne Laser-Based Enhanced Detection and Observation System search and rescue system for the Canadian Government, and several long-range surveillance systems. Technology developments related to sensor and illuminator over the past 3 decades are also discussed.

Night vision capability has become an indispensable tool for military and civilian surveillance operations. Low-light- level television (LLLTV) and Forward-Looking-IR (FLIR) devices have long been used for these applications. Nevertheless, both have their shortcomings when the identification of the target is essential for the success of the mission. LLLTV cannot provide god image resolution in ultra low-light level conditions and is very sensitivity to parasitic light. FLIR system have poor resolution when the temperature difference contrast conditions are not met.

Search and rescue and general surveillance mission pose a serious challenge to conventional imaging systems used by actual aircraft crews. These systems must often work in low- light and low-visibility conditions to find the identify targets. A new airborne imaging technology has been developed to overcome several deficiencies encountered with common CCD cameras, image intensified system and thermal imaging sensors. The recent developments in laser diode arrays, laser diode beam collimation and gatable micro- channel plate intensifier have made possible the construction of a compact active imagin system, called the Airborne Laser-Based Enhanced Detection and Observation Systems (ALBEDOS). This system proved particularly efficient at night and in degraded weather conditions. In addition, it was demonstrated that range gating, besides eliminating most of the light backscattered by aerosols, provided to some extent immunity to blooming effects specific to highly sensitive cameras. The system was installed on a helicopter and tested in various scenarios in October 1995 to demonstrate its potential. To enhance the surveillance capability over large areas of coverage, to optimize detection of humans and small objects and to improve the effectiveness of the search aircraft, a second-generation payload is presently developed and combines the benefits of two complementary imaging sensors. The Enhanced Low-Light level Visible and IR Surveillance System (ELVISS) consists of an improved range-gated active imager and a high-quality thermal imager, installed in two separate airborne platforms slaved together and controlled by a single user interface. It is expected that such a sensor systems will have a direct impact on improving the response time in finding those in need of assistance or simply in increasing the performance, reliability and efficiency of crews involved in general surveillance operations. This paper explains the concept of range gating, details a preliminary performance model and describes the two generations of Canadian active imagers: ALBEDOS and ELVISS.

The AFRL laser applications group is developing a 1.5 micrometers active TV system for use in military and law enforcement surveillance applications. AFRL supports novel semiconductor laser diode development, recently achieving high power 1.5 micrometers devices capable of providing sufficient illumination for an active TV system. This paper present the components of the 1.5 micrometers system and compares its performance to that of a near-IR active TV system operating at 0.81 micrometers . A qualitative approach is taken to study the reflective phenomenology of the two system to determine if operation at 1.5 micrometers is viable and advantageous.

A series of helicopter flight tests were conducted to test the feasibility and assess the performance of a gimbaled active television system and co-located IR system. The laser light was provided to the gimbal via a fiber optic cable from a remote semiconductor laser. A high power, divergent beam was used to illuminate a scene providing enhanced performance in poor weather, the recording of registry and augmentation to existing night vision devices. The flight tests were conducted in clear-weather conditions over land and water. Additionally, a series of ground test were conducted.

This paper presents background and measured performance data on a novel, low cost, high performance readout integrated circuit (ROIC) for microbolometer uncooled detector applications. The array is designed to offer better than 80mK NEdT performance using f/1.8 optics. The design incorporates advanced on-ROIC signal processing electronics that allow bolometer element non-uniformity control over a wide range of ROIC substrate temperatures. The small format array is ideally suited for high volume low-cost production applications.

This paper aims to update the progress of the FOA and DSTO collaboration on uncooled microbolometer focal plane arrays and digital readout CMOS electronics, and reports on problems and solutions found in the electronics area. Image result are presented showing the feasibility of the FOA/DSTO concept. This concept utilizes monolithic silicon microbolometers and unique 16-bit on-chip analog-to-digital conversion. The focal plane arrays described in the paper were designed by Electro-optic Sensor Design and post- processed at DSTO on to CMOS readout wafers supplied by FOA. All electronics including the 16-bit ADCs have been proven to function up to the sensors format 320 X 240, using 320 parallel channels of electronics. No significant performance degradation has been observed compared to smaller 16 X 16 arrays. Given detector performance obtainable today and low noise preamplification, the dynamic range supplied by this ADC is sufficient to give an NETD better than 0.1K using 40 micrometers X 40 micrometers pixels and f/1 optics while covering a +/- 5 percent detector mismatch. This is sufficient for most applications but analog offset correction prior to A/D conversion will be necessary to achieve a readout noise lower than the detector Johnson noise.

LETI LIR has been involved in Amorphous Silicon uncooled microbolometer development for a few years. This paper reports recent progress that have been carried out both in technological and product field. Due to the very particular features of LETI LIR technology, large fill factor, high thermal insulation, associated with small thermal time constant, can be achieved, resulting in a large detector responsivity. In addition, pulsed bias has been introduced showing performance improvement in terms of power consumption, reliability, faster thermal response. A model has been developed which accounts for these improvements. Electro-thermal results obtained from an IRCMOS 256 X 64, 47 micrometers detector sizes, laboratory prototype show that NETD less than 50 mK at f/1 can be obtained even at a high video scanning rate, that is compatible with micro scanning techniques.

CEA.S/DAPNIA/DSM and LETI/CEA.S are developing since 1996 a new technology for the realizing of far IR bolometer arrays sensitive in submillimeter wavelength range. The operating temperature is 0.3 Kelvin. Microtechnologies on silicon and flip/chip techniques are used for the detector fabrication and CMOS technology is used for the multiplexer and the readout integrated circuit. We present the concept that we have defined for the focal pane architecture and the readout principle design for 16 X 16 or 32 X 32 array. The first experimental result obtained on optical, electrical and thermal parameters are presented.

SAGEM has developed two new third generation IR handheld goggles, MATIS and LUTIS, based on two different cooled and uncooled FPA detectors.

Lockheed Martin IR Imaging Systems is developing low cost, high performance, uncooled IR 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 third 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 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 C is less than 0.5 percent. Our sensor typically have temporal NETDs of less than 70 mK as well as spatial NETDs of less than 50 mK, with an instantaneous dynamic range of 84 dB, and a total dynamic range of 120 dB. MRTD performance is less than 0.4 degrees C at spatial frequencies more than 20 percent 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 sensor have been used have been described in reports 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 camera to driving aids; from long range surveillance cameras to miniature cameras; from rifle sights to helmet mounted camera. These applications will be discussed along with their unique system level performance parameters. Video will be used to demonstrate the various applications discussed.

There is a widespread requirement for low cost lightweight thermal imaging sensors for both military and civilian applications. In Europe, these requires are now being met by systems using large uncooled ferroelectric detector arrays offering performance levels which, until recently, could only be achieved by expensive cryogenically cooled systems. The uncooled technologies a result of collaboration between the UK Defence Evaluation and Research Agency (DERA) and Marconi Electronic Systems (MES) under a 'Dual Use Technology Program (DUTP). The successes from this program have resulted in developments for civil applications, including both hand held and helmet mounted fire-fighter's thermal imaging cameras. Military applications include personal surveillance sensors, vehicle driving aids, airborne flying aids and thermal weapon sighting systems. The products available to date have been based on hybrid ferroelectric detector technology in which the IR sensing material is manufactured separately from the silicon readout circuit to which it is subsequently bonded. Meanwhile, the ongoing DUTP program is developing a high performance 'integrated' detector technology in which the ferroelectric ceramic material is deposited as a microbridge structure directly onto the silicon readout circuit. The improved performance available from this approach will realize major enhancement and cost reductions to be achieved in future thermal imaging sensor developments.

Mn and Sb-doped Pb(Zr, Ti)O₃ (PMSZT) and Nb-doped PZT (PNZT) thin film IR detectors have been integrated with Si substrates. A conducting YBCO layer in the IR detector was used as an atomic template for the epitaxial growth of the PMSZT and PNZT thin films, as well as a good IR-reflector. The epitaxial PMSZT and PNZT thin films were self-polarized and exhibited pyroelectric current even without any additional poling. The PMSZT and PNZT detectors were examined as to their pyroelectric current in response to the detector temperature. Doping with Mn and Sb into PZT and doping with Nb into PZT have been shown not only to decrease the Curie temperature T_c, but also increases pyroelectric current significantly in comparison with that of PZT thin films. The PMSZT detectors show high figures of merit, F_v of 1768 cm²/C and F_d of 0.048 (cm³/J)^1/2 at 25 degrees C and F_d of 0.135 (cm³/J)^1/2 at approximately 90 degrees C. The measured normalized detectivity D*, ranging from 2.5 X 10⁸ to 6.0 X 10⁸ cmHz^1/2/W in the 2.5-19.5 micrometers wavelength band, indicated that PMSZT detectors are suitable for broad band IR detector applications. A PMSZT IR detector array with a micro-bridge for thermal isolation has also been fabricated.

The temperature stabilization requirements of unchopped thermistor bolometers and thermopile detectors are analyzed. The detector temperature, on which the bolometer output signal depends, is quite sensitive to changes in instrument temperature but relatively insensitive to changes in scene temperature. In contrast, the difference in temperature between detector and substrate, on which the thermopile signal depends, is equally sensitive to changes in instrument and scene temperature. Expressions for these dependencies are derived based on a simplified instrument model. It is shown that for a typical uncooled thermal imager, the temperature stabilization requirements for a bolometer are tow orders of magnitude more stringent than those for a thermopile detector.

Infrared Solutions, Inc. has developed a family of radiometers which employ silicon microstructure uncooled linear thermoelectric arrays, prepared by Honeywell Technology Center. Included in the family is a handheld imaging radiometer for predictive and preventive maintenance having a frame time of 1.4 sec, a linescanner radiometer for monitoring of industrial web process, an imaging radiometer for monitoring stationary industrial processes such as a die casting, and a linescanner radiometer for monitoring the temperature distribution of railcar wheels on trains moving at speeds up to 80 mph.

The thermionic thermal detector (TTD) sense IR radiation by temperature modulation of thermionic emission current within a silicon Schottky diode. The thermionic emission current is the well known Richardson dark current. The TTD operates in the LWIR band. The physics of TTD operation is distinct from that of silicon Schottky barrier MWIR detectors, such as PtSi/Si which are based on internal photoemission. In fact, the TTD has high detection efficiency. The architecture of a TTD array is very similar to that of microbolometer arrays, expect the detector elements are thermally isolated Schottky diodes, operating under reverse bias. When the TTD array is illuminated by an IR image, the temperature of individual detector elements will vary with the local incident power of the image. Under small signal conditions, the dark current of individual detectors will vary as temperature, resulting in an electronic image of the IR scene. The reverse bias dark current of a Schottky diode varies exponentially with temperature. For the small temperature variations observed on the focal pane of an uncooled sensor, this variation is approximately linear. The rate of temperature variation is determined by the Schottky barrier potential and, to a lesser extent by the applied bias potential. The operating temperature range of the detector can be designed into the device by selecting a metal with the appropriate Schottky barrier height. Experimental Schottky barrier heights were determined using Richardson dark current activation energy analysis. Devices optimized for operating at room ambient temperature have a 6 percent K temperature coefficient. The use of Schottky diode thermionic emission for uncooled IR imaging offers several advantages relative to current technology. TTD manufacture is 100 percent silicon processing compatible. Schottky barrier based thermionic emissions array have the same uniformity characteristics as MWIR Schottky barrier photoemissive arrays. Operating TTDs in reverse bias provides a high impedance 'current source' to the multiplexer, resulting in negligible Johnson noise. This mode of operation also results in negligible detector 1/f-noise and drift. In addition, the TTD thermionic emission detection process has high efficiency, fully comparable with the best current thermal detectors.

We have developed linear micromachined thermopile arrays, and integrated circuit read-out chips for them. Each detector in the array combines a suspended micromachined structure, a thin-film RI absorber, and a thin-film thermopile. The IR absorption in the detectors assures sensitivity over a wavelength range from at least 2.5 micrometers through 50 micrometers . Five array types have been produced, which differ from each other in the thermal conductance values of the detectors. All arrays have 128 detectors on 54 micrometers spacings, with (50 micrometers )² sensitive areas. The CMOS read-out circuit is on a separate chip, and amplifies, digitizes and multiplexes the thermopile signals, yielding a serial digital output on a single line. Measurements of the noise of the read-out chip, with a detector array at its inputs, shows negligible 1/f component to at least as low as 0.1 Hz in frequency. Responsivity, noise D* and time constant have been measured as a function of detector parameters.

Sub-micron CMOS has already enabled the development of IR focal plane array with ultra-low read noise and high sensitivity for many demanding applications. The successful monolithic integration of silicon photo detector with low- noise pixel-based amplifiers in fine pixel pitch via modern CMOS technology now suggests the imminent obsolescence of CCDs and photographic film for consumer uses. Specifically, we report the achievement of < 20 e- read noise at high data rates and video frame rate,s the confirmation of the fundamental superiority of the CMOS imager for visible imaging, and approximately 2X reduction in kTC noise without invoking classical correlated double sampling techniques. These suggest a strong likelihood reduction in kTC noise without invoking classical correlated double sampling techniques. These suggest a strong likelihood that the CCDs long reign is coming to an end.

The family of 2D detection modules at AEG Infrarot-Module GmbH (AIM) based on platinum silicide (PtSi) GaAs/AlGaAs quantum well (QWIP) devices or mercury cadmium telluride (MCT) focal planes for applications in either the 3.5 micrometers (MWIR) or 8.10 micrometers (LWIR) range was recently extended. Two new devices have been realized in the configurations 640 X 512 in a 24 micrometers pitch for mid and long wave applications using either a MCT photovoltaic (PV) array for the MWIR or a QWIP device for the LWIR, respectively. The existing 256 X 256 MCT MWIR was redesigned in a new configuration with increased fill factor of > 80 percent for improved NETD performance. The MCT units provide fast full frame rates up to > 100 Hz for the 640 X 512 units and 200Hz for the 256 X 256 units. The modules achieve with short snapshot integration times of typically 1ms excellent thermal resolution with an average NETD < 25 mK for the 640 X 512 NETD < 9mK for the 256 X 256 modules. The QWIP units are operated in either a rolling frame or snapshot integration mode with typical frame rates of 60Hz and reach a thermal resolution NETD < 25mK for full frame integration times. The FPAs are integrated up to modules using AIM's standard dewar cooler and command/control electronics (CCE) family. The package is basically identical to the existing large FA modules like the PtSi640 X 486 or the QWIP or MCT 256 X 256 in 40 micrometers pitch and is cooled by AIMs 1W split linear cooler. The CCE of the modules provides the common exclusively digital interface, using 14 Bit analog to digital conversion to provide state of the art correctability, access to highly dynamic scenes without any loss of information and simplified interchangeability of the units.

Today, Sofradir has delivered more than 2000 LW new generation IR detectors which gives a very important data base for yield and performance analysis. The target of this paper is on one hand to show a performance statistical analysis both globally and over the year which demonstrates the validity of MCT choice and on the other hand to present the impact of the improvement of the process and the adaptation of tooling on the cost.

The multi-domain smart sensor (MDSS) program combines research efforts of an industry/university consortium and the Army Research Laboratory (ARL). The consortium is headed by Lockheed Martin; other members are DRS, the University of New Mexico, Stanford University, and the Massachusetts Institute of Technology. This paper describes the concept and the current status of research and development of the MDSS program. The goal of this program is to develop technologies that will allow significant improvements in situation awareness and target detection and identification, especially of low observable targets. A notional system concept has been developed that guides the research. Under this concept, improved target detection will be obtained by passive imaging with large-area, dual-color IR focal plane arrays (IRFPA) operating in the mid-wave (MWIR) and the long-wave (LWIR) spectral bands. Once target detection is achieved, target identification - if necessary - can be obtained through active imaging with a noval, scannerless ladar system. To materialize this concept, research and development is performed for dual-color IRFPAs, and an eyesafe laser and a demodulator for the returning radiation - both required to operate up the MHz frequencies. Also, hyperspectral imaging is investigated for detection of camouflaged targets. In support of this effort, field measurements have been performed with boresighted MWIR and LWIR cameras to obtain pixel registered imagery for the development of effective fusion and processing algorithms.

After 20 years of experience in land-based IR systems, THOMSON-CSF is able to offer its customers a new product: SOPHIE. It is the fruit of an assortment of skills mustered at the heart of THOMSON-CSF OPTRONIQUE and of the Integrated Cooler Assembly developed by SOFRADIR and CRYOTECHNOLOGIES. SOPHIE, the world's first handled IR camera/binocular, weighs only 2 kg and offers a reconnaissance range performance well beyond 2 km, comparable to the cameras of the first generation. It can run from its own self-contained power supply or from the mains, giving it further flexibility in use. It is a genuine night-or-day instrument, operating in the 8-12 micrometers wavelength. Its leading edge technologies, together with its light weight, make it a dual-purpose product, functioning either as a camera that can be linked to a monitor, or as a conventional pair of binoculars.

We present thermal IR microscopy systems suitable for a spatial resolution below 10micrometers . This resolution close to the fundamental limit is achieved using high resolution FPA - IR cameras, a high speed microscopy optic and acquisition of multiple frames which are shuffled by software in real time. Some fundamental consideration to gain insight into the task of thermal microscopy are briefed. The minimum resolvable temperature and the noise equivalent temperature difference both are a function of thermal diffusivity i.e. material properties, integration time and optics. The basic relationships are explained using numerical modeling. Based on our considerations and knowledge we developed different TIM-Systems, each having specific advantages and are therefore more or less suitable for certain applications. A high spatial temperature or thermal resolution is necessary for different materials under investigation. Examples demonstrate the unique capabilities of the innovative systems and give a glance of the various technical applications of TIM systems.

Sensors Unlimited, Inc. has developed focal pane arrays (FPAs) fabricated with indium gallium arsenide (InGaAs) photodiode arrays and silicon CMOS readout integrated circuits. These devices are readily available in a wide variety of formats suitable for commercial and industrial applications. InGaAs FPAs are sensitive to the near IR, operate without cooling, and come in both 2D formats and 1D formats. 1D InGaAs FPAs are used as both spectroscopic detectors and line scan imagers. Key applications include miniature spectrometers used for wavelength control and monitoring of WDM laser sources, octane determination, the sorting o plastics during recycling, and web process control. 2D InGaAs FPAs find use in applications such as laser beam profiling, visualization of 'clear' ice on aircraft and roadways, and industrial thermal imaging.

Temperature dependent low-field mobility models in the commercial device simulation program are studied to check their effects on the drain characteristics. The results show that low-field mobility has not effect on threshold voltage, subthreshold swing, and the saturation voltage, but it is very important in determining the drain saturation current, transconductance, and the channel conductance of the CMOS devices under low temperature operation. Better understanding of the carrier mobility and the usage of it in the simulation program can help us in designing high performance circuits and process development for the low temperature applications.

We introduce the method of Polarimetric-Spectral Intensity Modulation (P-SIM) and discuss how it enables a new robust class of hyperspectral polarimetric imaging sensor. P-SIM was invented by one of us and has been submitted for patent. We are presently building a sensor, dubbed the IR Polarimetric HyperSpectral Imager which implements the P-SIM concept. P-SIM employs a novel and robust optical multiplexing scheme that enables simultaneous measurement of spectral and full elliptical polarimetric image content, employing a single focal plane detector and conventional optics, and eliminating moving parts and difficult alignment issues. The technique is equally viable across the visible through long-wave IR bands. The P-SIM concept constitutes a breakthrough for the inclusion of polarimetry in optical hyperspectral imaging. To date, even single-band polarimeter designs for remote sensing are compromised due to their lack of spatio temporal measurement registration, inapplicability to marginally resolved scene elements, costly optical configurations, or polarimetric ambiguity from too few 'channels'. Polarimetric imaging from a moving platform or against moving targets rules out the standard methods of time-sequential polarimetry via rotation of a polarizer or waveplate. P-SIM eliminates these limitations while additionally extending polarimetry into the spectral imaging domain.

In this paper, we approach the problem of point target detection in IR image sequences by modeling the temporal behavior of clutter and targets on a single pixel basis. These models, which are experimentally verified, are then used to develop a temporal likelihood ratio test and drive the corresponding decision rule. We demonstrate the effectiveness of the technique by applying it to real IR image sequences containing targets of opportunity and evolving cloud clutter. The physical models and resulting hypothesis testing approach could also be applicable to other image sequence processing scenarios. Using acquisition system besides IR imaging, such as detection of small moving objects or structures in a biomedical or biological imaging scenario, or the detection of satellites, meteors or other celestial bodies in night sky imagery acquired using a telescope.

Monocular Passive Ranging (MPR) employs a single multicolor IR sensor to passively range to a boosting theater ballistic missile (TBM). Airborne active ranging sensor, such as radars and ladars, may attract anti-radiation missiles, and are forced to large standoff distances. Thus, they may not be positioned to give adequate early warning of a missile launch, Estimation of launch position, or prediction of impact points. Ground based radars may not 'see' sufficiently over the horizon. In contrast, an MPR sensor can be deployed close to or within denied enemy territory and remain covert to observe a TBM as early as its launch, to discriminate and track the TBM target, and to provide very timely and accurate reports on launch position, predicted flight and impact positions. A passive sensor can be in a small package, have low weight, low power, relatively low cost, and be readily adaptable to airborne and spaceborne platforms. This paper discusses an airborne data collection program to demonstrate useful MPR accuracy to boosting TBMs. Engineering and sensors performance tradeoffs, and range error budgets are discussed.

Imaging spatial heterodyne spectroscopy (ISHS) was invented by Roesler and Harlander and applied to the far UV. It also has advantages for remote sensing applications in the visible and IR bands. We have designed, assembled, and ground-tested a new instrument designed for eventual airborne or spaceborne deployment for imaging spectroscopy at ultraspectral resolution. IRISHS is a true, imaging, Fourier transform spectrometer (FTS) with a fully open square field of view, where the third dimension required to assemble data cubes is acquired by scanning the FOV linearly over the scene. Spatially displayed fringes are difference with a spatial frequency determined by a pair of diffraction gratings, giving easily sampled fringe patterns. The current system operates between 8 and 12.5 microns in six sub-bands and employs a 256 X 256 pixel focal plane array. In comparison to dispersive imaging spectrometers with equivalent resolution, ISHS has: 1) much larger etendue in a small package; 2) full-field imaging for ease in image reconstruction; 3) approximately the same signal-to-noise ratio in equivalent observing scenarios, expect in the case where the entire dispersive spectrometer is cryogenically cooled. In comparison to conventional FTS, ISHS has: 1) no moving parts during data collection; 2) pushbroom imaging, 3) approximately the same S/N for equivalent conditions, 4) much lower data rate.

The RISTA II sensor was integrated into the Altus Unmanned Aerial Vehicle (UAV) and flown over Camp Roberts and Ft. Hunter Ligget, CA in July 1998. The RISTA II demonstration system consisted of a long-wave IR imager, a digital data link, and a ground processing facility (GPF) containing an aided target recognizer, data storage devices, and operator workstations. Imagery was compressed on the UAV and sent on the GPF over a 10.71 Mbit per second digital data link. Selected image frames from the GPF were sent near real-time over a T1 link to observers in Rosslyn, VA. The sensor operated in a variety of scanning and framing modes. Both manual and automatic sensor pointing were demonstrated. Seven flights were performed at altitudes up to 7500m and range sup to 60 km from the GPF. Applicability to numerous military and civilian scenarios was demonstrated.

The effect of IR focal plane array phasing nose on overall IRST system performance is studied in terms of the ROC of a detection system. First, the phase noise is defined and quantified by means of first order statistics of the detected signal. Phase noise statistics are demonstrated for some system configurations. Then, the zero-time-correlation phase noise is studied in depth for five system settings. Based on ROC results - the cost effectiveness of these settings are examined.

This paper deals with the design of two second generation thermal imagers that Alenia Difesa OFFICINE GALILEO has successfully developed for the Navigation FLIR of the NH90 Tactical Transportation Helicopter (NH90 TTH) and for the Electro-Optical Surveillance and Tracking System for the Italian 'Guardia di Finanza' ATR42 Maritime Patrol Aircraft (ATR42 MPA). Small size, lightweight and low power consumption have been the main design goals of the two programs. In particular the NH90 TTH Thermal Imager is a compact camera operating in the 8 divided by 12 micrometers bandwidth with a single wide field of view. The thermal imager developed for the ATR42 MPA features a three remotely switchable fields of view objective equipped with diffractive optics. Performance goals, innovative design aspects and test results of these two thermal imagers are reported.

A linear thermopile array with characteristics of high responsivity, fast response and low cost has been developed for use in searching for and detecting heat-radiating objects. The thermopile is fabricated by means of a silicon surface micromachining, compatible Si CMOS process and a lift-off technique, which result in a precisely patterned Au black absorption layer. The dynamic signal-to-noise ratio is proposed as a new figure of merit for evaluating thermal IR sensors and is used to design the thermopile configuration so as to obtain optimum responsivity and thermal time constant. The newly fabricated thermopile array is composed of a zigzag arrangement of two rows of seven IR sensing elements and achieves responsivity of 230 V/W and a thermal time constant of 0.5 msec. The array, incorporating an optical system with a 30-mm-diameter of 80 m for a target with a background temperature difference of 25 degrees C.

A 320 X 240 uncooled IR focal plane array (IRFPA) with series PN junction diodes fabricated on a silicon-on- insulator (SOI) wafer has been developed. Resistive bolometers, pyroelectric detectors and thermopile detectors have been reported for large scale uncooled IRFPAs, while the detector developed uses the temperature dependence of forward-biased voltage of the diode. The diode has low 1/f noise because it is fabricated on the monocrystalline SOI film which has few defects. The diode is supported by buried silicon dioxide film of the SOI wafer, which becomes a part of a thermal isolated structure by using bulk silicon micromachining technique. The detector contains an absorbing membrane with a high fill factor of 90 percent to achieve high IR absorption, and the readout circuit of the FPA contains a gate modulation integrator to suppress the noise. Low cost IRFPA can be supplied because the whole structure of the FPA is fabricated on commercial SOI wafers using a conventional silicon IC process.

A new type of simple pixel circuit has been developed in an IR image sensor of dielectric mode (DB). The detector pixel consists of capacitors of ferroelectric BST thin film prepared by laser ablation, whose dielectric constant changes drastically with temperature. Our new circuit is a serially-connected capacitor-capacitor circuit with a source-follower output buffer, where one capacitor is an IR detecting BST thin film capacitor formed on a membrane and the other is the same capacitor as reference but on Si bulk and nonirradiated. In order to avoid crack and deformation on the thermally insulated structure, a stress-balanced structure by multi-layered membrane has been newly developed, where the ferroelectric capacitor is formed on a triple layer of SiO₂/SiN_x/SiO₂ films. A BST film on membrane is found to show positive TCD ranging from 1 to 6 percent K in our experiment. A new monolithic process flow is developed to combine an n-MOSFET process and a Si-bulk micromachining process, and ferroelectric capacitors on the stress-balanced membrane are able to be formed monolithically with MOSFET's for source-follower output buffer. Finally, it is especially noted that the operation in the detector pixel in the DB mode is confirmed on the monolithically integrated device structure.

We investigated the sensitivity enhancement of quantum well IR photodetectors (QWIP) with the pseudo-random optical coupler. We fabricated QWIP focal plane arrays (FPA) containing AlGaAs/GaAs multi-quantum wells (MQW) detecting 7-8 micrometers IR regions. After QWIP-FPA and read-out integrated circuits were hybridized, GaAs substrates attached to the back of the FPA were removed. We compared the sensitivity of a QWIP-FPA without a GaAs substrate with that of a QWIP-FPA with the substrate. When the input IR beams illuminated only some pixels in the QWIP-FPA, the output signal from the FPA without GaAs substrate was about ten times higher than that from the FPA with a substrate. The output signals were almost same for both QWIP-FPAs where all pixels were uniformly illuminated by the IR inputs. These result indicate that the reflected beams from the GaAs back surface illuminate another pixels far away from the pixels which input beams strike first, when the FPA has a sufficiently thick GaAs substrate. We confirmed that the pseudo-random grating coupler for QWIP enhanced IR absorption by confining multi internal total reflections in one pixel, when thick substrates were removed.

We have developed a monolithic 512 X 512 element GeSi/Si heterojunction IR focal plane array (FPA). The operation mechanism of the GeSi/Si heterojunction detector is the same as that of the PtSi/Si Schottky-barrier detector. We have fabricated the GeSi/Si heterojunction using MBE technology, and have confirmed that ideal strained GeSi films are grown on Si substrate. We have evaluated the dependencies of spectral responsivity on the Ge composition, impurity concentration and GeSi thickness, and have optimized them for 8-12 micrometers IR detection. The 512 X 512 element FPA has a pixel size of 34 X 34 micrometers ² and a fill factor of 59 percent. A low noise equivalent temperature difference of 0.08 K was obtained with a 300 K background with a very small responsivity dispersion of 2.2 percent.

Thermal vision system with 2D sensor such as PtSi, InSb, MCT and any others in the commercial market is generally required to correct non-uniformity of response of every pixels in order to display satisfactory IR images. We have studied the non-uniformity correction methods for our thermal vision systems and in a previous study we proposed the most suitable non-uniformity correction method for PtSi SBD sensor. This method was optimized at a certain operating temperature, which was a room temperature. However thermal vision systems could be used at a various operating temperature. It is also obvious that his change of operating temperature causes input IR flux change to a sensor, this affects the accuracy of the measured results. Therefore, it is necessary not only to correct non-uniformity of each pixel but also to compensate this influence by the change of temperature to have a satisfactory IR image. In this paper, this compensation method is described. Besides, the result of this method is presented.

The submillimeter wavelength region is the last undeveloped spectral window in astronomy. The poor transmission of the atmosphere, and the lack of high-performance detectors prevent astronomical observations in this window. We have recently started a development of photoconductors utilizing shallow donor levels in GaAs semiconductors. The GaAs photoconductor promises to be a good candidate of a photo detector for use in future space mission for submillimeter astronomy. We have constructed facilities for liquid-phase epitaxy to obtain ultra-pure GaAs crystals which were absolutely necessary for a fabrication of photoconductors. The first experimental results are reported.

Basic design and current development status of IRC, infrared camera on-board the IRIS is presented. IRC employs state-of- the-art format IR arrays for imaging and low-resolution spectroscopy at wavelength 2-25 micrometers . IRC consists of 3 cameras; NIR, MIR-S, and MIR-L. These 3 channels simultaneously observe different fields of the sky, with diffraction-limited spatial resolution.

The Army after Next will be lighter, faster, and more lethal than today's force. Survival of the force will be highly dependant on accurate and timely information about enemy forces and movements. CECOM NVESD has a number of ongoing efforts that directly support the vision of networked, low cost, low power, multifunction microsensor to enhance the lethality and survivability of the force. The three key technical areas of investigation: microsensor, signal processing, and communications.

Optical material characterization encompasses absorption, refraction and scattering phenomena as a function of frequency and temperature. The level of knowledge of the optical constants for most optical materials is sparse, especially at temperatures outside of room temperature. Critical future applications will require a more complete database. The need for greater precision in the optical constants requires both improved experimental techniques and more detailed modes. Since a comprehensive experimental database is impossible, physically-based models, allowing accurate interpolation and extrapolation, are an essential part of optical characterization. Furthermore, most optical constant characterization is reported in the frequency- domain. However, high-speed optoelectronic materials require time-domain characterization.

IR radiation was discovered less than 200 years ago by Herschel. This century, along with many other technical advances, IR technology has made incredible progress. Where is this technology headed. What will drive the progress and what will limit it. What will not change in the third millennium. And what changes are anticipated in the next ten to twenty years.

We report the result of intersubband absorption measurement on a series of doped quantum-well samples and the determination of both the nonparabolicity parameters and the conduction band/valence band offset ratio of the GaAs/(AlGa)As material system. Absorption spectra were obtained in an FTIR spectrometer for samples with nominal quantum-well widths of 4.0, 4.5, 5.0, 7.5, 10.0, and 15.0 nm and for a series of miniband-transport quantum-well IR photodetectors. X-ray diffraction was used to determine quantum well and barrier thicknesses and the Al mole fraction x of the (Al,Ga)As barrier layers. Absorption measurements were made at temperatures of 295 K and 77 K. An empirical two-band model with an energy-dependent effective mass was used to calculate energy levels, transition energies, and spectral lineshapes for the quantum-well structures. Parameter values for nonparabolicity and band offset ratio were determined by comparison of calculated transition energies to measured spectral data.

Standard GaAs/AlGaAs Quantum Well IR Photodetectors (QWIP) are now well established for long wavelength IR (LWIR) detection. The first advantage of this technology is the duality with the technology of commercia GaAs devices. The realization of large focal plane arrays employing the standard III-V technological processes is already demonstrated. The second advantage widely claimed for QWIPs is the so-called band-gap engineering, allowing the custom design of the quantum structure to fulfill the requirements of specific applications like multispectral detection. In this paper, we present electro-optical results on Middle Wavelength IR (MWIR) detectors. We demonstrate the ability of QWIPs to cover the two spectral ranges. As the operating temperature is crucial for commercial thermal images, we report the temperature dependence of the performances of our MWIR QWIP detector up to 150 K. Performances of QWIPs in the MWIR with the implementation of the new skimming architecture are discussed.

Many commercial and government applications need high performance, large format, long-wavelength IR (LWIR) detector arrays in the range of 6-20 micrometers . NASA and the Ballistic Missile Defense Organization (BMDO) have devoted a significant effort to develop highly sensitive IR detectors and large format focal plane arrays (FPAs) based on novel, 'artificial' low effective band-gap semiconductor material system such as GaAs/AlGaAs. Caltech's JPL under contract form NASA and BMDO has extensively pursued GaAs/AlGaAs based multi-quantum wells for IR radiation detection. Optimization of the detector design, light coupling schemes, large format focal plane array fabrication and packaging have culminated in the realization of portable IR cameras with a mid-format FPA of QWIP detectors and the demonstration of a TV format QWIP camera. QWIP Technologies under an agreement with Caltech is manufacturing the QWIP-Chip, a 320 X 256 element FPA, which will be available in the summer of 1999. In this paper we discuss the advantages of MQW technology and our experience in the commercialization of QWIP FPAs.

As electro-optic sensors increase in size and frame rate, the data transfer and digital processing resource requirements also increase. In many missions, the spatial area of interest is but a small fraction of the available field of view. Choosing the right region of interest, however, is a challenge and still requires an enormous amount of downstream digital processing resources. In order to filter this ever-increasing amount of data, we look at how nature solves the problem. The Advanced Guidance Division of the Munitions Directorate, Air Force Research Laboratory at Elgin AFB, Florida, has been pursuing research in the are of advanced sensor and image processing concepts based on biologically inspired sensory information processing. A summary of two 'neuromorphic' processing efforts will be presented along with a seeker system concept utilizing this innovative technology. The Neuroseek program is developing a 256 X 256 2-color dual band IRFPA coupled to an optimized silicon CMOS read-out and processing integrated circuit that provides simultaneous full-frame imaging in MWIR/LWIR wavebands along with built-in biologically inspired sensor image processing functions. Concepts and requirements for future such efforts will also be discussed.

Third generation FPAs are being designed to incorporate numerous sophisticated 'smart' functions, useful in the preprocessing and filtering of real-time image data. Designers at Nova Research, Inc. have developed ROIC designs which have increased the capabilities of these devices in the are of signal and image processing. These new FPAs are more versatile than their predecessors through the implementation of a variety of programmable modes of operation. This paper will discuss a variety of such processing functions and modes. Design configurations for such FPAs sill be discussed with regard to the incorporation of general and specific signal processing functions. Such functions will include but not be limited to: edge enhancement and edge extraction, accommodating high and low signal flux environments, high speed windowing and foveated pixel arrangements.

Future high performance IR imaging system require high density focal planes containing up to one million or more detectors. Technological advances are needed to handle the resulting readout data rates in excess of Gbauds/sec and to minimize the on-focal-plane heat load caused by the currently used drivers and signal carrying cables connecting the focal plane inside the vacuum dewar with the outside signal processor. Optical interconnects are a practical alternative only for digital data because of the high non- linearity of the electrical to optical conversion process. We propose to solve these problems by A/D converting the detector signals on the focal pane (FPA) and using on-focal- plane quantum well light modulators to transform the electrical to optical signals. The latter are transmitted by a light beam from the FPA to the signal processor or the display electronics. The enabling technologies are the recently demonstrated on-focal-plane MOSAD converter achieving 14 bit dynamic range and the quantum well light modulators being develop by Lucent Technologies for highspeed bistable optical switches called SEED's for use in telecommunication. We will demonstrate one optical readout channel servicing 4 columns of a LWIR detector array mounted in an experimental dewar.

This paper describes a new approach for the control of microbolometer detector array uniformity as a function of substrate temperature change. This approach, called the bias equalization method, uses an electronic means of controlling the microbolometer array uniformity. For this method a three stage non-uniformity correction algorithm is employed. The first stage corrects for substrate temperature non- uniformity effects on the microbolometer detector elements followed by traditional offset and gain non-uniformity correction stages. To correct for substrate temperature non- uniformity effects, bias equalization coefficients are supplied to the readout integrated circuit (ROIC) to allow the control of a unique operating bias or temperature delta for each microbolometer detector element in the array. The bias equalization method circuitry allows microbolometer array non-uniformity control over a wider range of ROIC substrate temperatures while maintaining better than 80 mK NEdT using f/1.8 optics. This approach is expected to allow removal of the thermoelectric cooler from uncooled systems, thus making it ideally suited for high-volume, low-cost, low-power and low-weight production applications.

This paper describes a high performance 320 by 256 readout integrated circuit (ROIC) designed for P-on-N short wave IR (SWIR) detectors including InGaAs and HgCdTe, which also has the ability to operate at low input current levels with N- on-P detectors. The ROIC/FPA will support a wide range of system requirements from very low background applications to daytime high illumination conditions. To accommodate the wide scene dynamic range requirements, two selectable integration capacitors are used to control the input circuit transimpedance gain. A 10fF integration capacitor is used for low noise and low flux levels down to 10^-5 ft Lambert, corresponding to approximately 2 X 10¹⁰ ph/cm²-sec for 0.9 micrometers to 1.7 micrometers spectral band using f/1.5 optics, assuming a 2856 Kelvin blackbody distribution. For higher flux levels, a 0.21pF integration capacitor can be selected, thus providing over a factor of 20 dynamic range. A capacitive feedback transimpendance amplifier provides a low noise detector interface circuit capable of operating at low input currents without frame-to- frame image lag. A sample and hold capacitor is also part of the input unit cell architecture, which allows the FPA to be operated in full frame snapshot mode and provides the maximum integration time available. The integration time is electronically controlled by an external clock pulse, and is adjustable form 0.5microsecond(s) ec to approximately the frame time of 33.3 msec for 30Hz operation. This produces an additional factor of 66,000 to the total nine orders of magnitude in scene dynamic range.

This paper describes a standardized high performance 640 by 512 readout integrated circuit (ROIC) for p-on-n detectors such as InSb, Heterojunction HgCdTe, QWIP, and InGaAs. The array is intended to support a wide range of system through flexibility and advanced modes of operation. The ISC9803 uses a flexible, programmable, multistage pipelined architecture to achieve a state-of-the-art ROIC suitable for applications ranging from hand-held IR viewers to high-speed industrial imaging system. A simplified default mode directly supports single output NTSC or PAL operation. Using the programmable mode, the ISC9803 supports such advanced features as dynamic image transportation, dynamic windowing, multiple high-speed multi tout configurations, and signal 'skimming'. Both default and programmed modes support integrate-while-read and integrate-then-read snapshot operation, and variable gain. This array is part of the Indigo Systems family of standard ROICs that use a common architecture and electrical interface.

This paper reports an improved Current Mirroring Integration (CMI) unit cell and a new readout structure based on it. The new structure combines the benefits of the current mirroring direct injection and switch current integration structures, satisfying the requirements for the high resolution and high performance IR FPA readouts. The improved CMI readout circuit provides very high injection efficiency, almost-zero detector bias, and large dynamic range, while it can be implemented in a small pixel area. the circuit provides a maximum charge storage capacity of 5.25 X 10⁷ electrons and a maximum transimpedence of 6 X 10⁷ (Omega) for a 5V power supply and a 2pF integration capacitance, which is paled outside the unit cell. The unit cell employs only nine MOS transistors and occupies an area of 20micrometers X 25 micrometers in a 0.8 micrometers CMOS process.

To obtain the optimal performance of quantum well IR photodetectors (QWIP) focal plane array, the readout circuit (ROIC) has to be tailored to the detector characteristics. Different concepts will be compared with respect to signal to noise performance, linearity and power consumption. In particular an active direct injection (DI) circuit will be compared with a passive direct injection circuit. The active and passive DI circuits give similar temporal NETD but the passive DI is shown to have superior spatial noise performance. Furthermore, the latter circuit type offers higher flexibility with respect to on-chip signal processing. The intended application is in high-resolution QWIP focal plane arrays.

Several new 2D detection modules have expanded the family of focal plane arrays (FPA) at AEG IR-Modules GmbH (AIM) recently. Large quantum well (QWIP) and mercury cadmium telluride (MCT) devices, e.g. a 512 X 640 QWIP long wave (LWIR) module, were introduce. These devices provide high thermal resolution with typical noise equivalent temperature differences (NETD) below 25mK. In this performance range the residual spatial noise after non-uniformity correction is often the limiting noise source and more sophisticated correction algorithms than a two-point correction are necessary for a temporal noise limited operation. AIM has developed a self-adaptive iterative correction algorithm to fit these requirements. Its scene based approach eliminates the need of a calibration procedure with thermal references. This algorithm is implemented on AIM's standard video image processing unit VIP-ICM80 running with a maximum frame rate of 50 Hz with 256 X 256 pixels image size. Larger image sizes and higher frame rates of the new AIM detection modules leaded to a new designed video image processing board. This board also provides a microscanner interface to improve geometrical resolution of staring IR imaging modules. The implementation of non-uniformity correction in hard- and software for AIM's 2D detection modules is discussed together with measured performance data concerning the correctability of the devices.

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-photovoltaic (PV) multielement arrays were designed, manufactured and tested in T equals 77-300 K temperature temperature region. Into these read-out devices were incorporated the testing switches which attach the sources of direct injection transistors to the common load resistors to imitate the output signal of mercury cadmium telluride photodiodes. The silicon read-out devices for 2 X 64 n⁺-p- or p(superscript +_{n- linear arrays and n(superscript +}-p-2 X 4 X 128 time delay and integration arrays with skimming and partitioning functions were manufactured by n- or p-channel MOS technology with buried channel CCD register. The designed CCD readout devices are driven with four- or two-phase clock pulses.

The uniformity of the output of an integrated, quasi-linear array of bolometer elements is evaluated in terms of substrate temperature gradients, variations in bolometer thermal conductivity and temperature coefficient of resistance, and self-heating during readout. With a suitable offset compensation procedure, the array non-uniformity can be as low as a few parts per million of the DC offset voltage. Uniform substrate temperature changes as large as 10K can be tolerated.

Indigo Systems Corporation has developed a family of standard readout integrated circuits (ROIC) for use in IR focal plane arrays (FPAs) imaging systems. These standard ROICs are designed to provide a compete set of operating features for camera level FPA control, while also providing high performance capability with any of several detector materials. By creating a uniform electrical interface for FPAs, these standard ROICs simplify the task of FPA integration with imaging electronics and physical packages. This paper begins with a brief description of the features of four Indigo standard ROICs and continues with a description of the features, design, and measured performance of indium antimonide, quantum well IR photo- detectors and indium gallium arsenide imaging system built using the described standard ROICs.

All IRFPAs require nonuniformity correction. Although two- point or multi-point correction algorithms may correct the nonuniformity of IRFPAs they can be limited by pixel nonlinearities and instabilities. So adaptive nonuniformity correction techniques are needed. Many researchers develop the methods of real-time correction based the scene being viewed. The nonuniformity correction process is completed in IRFPA sensor named smart FPA. However, the smart IRFPA is developing. The purpose of this paper is to describe a digital signal processing electronics for the nonuniformity correction. It includes ADSP21060 digital signal processor, 8751 chip and display circuit module. The image data from IRFPA are put into the dual RAM. The ADSP21060 DSP completes the nonuniformity correction function while the 8751 chip operates control function. At the same time, the correction results will be displayed on a monitor. The neural networks algorithms and the constant-statistics algorithm are tested in our digital implementations. When the image size is 60*97, processing time per frame is 14.75 millisecond for the neural network algorithm and it is 12.65 millisecond for the constant-statistics algorithm. Measured results show that digital processing system designed by us may achieve demand of real-time nonuniformity correction based the scene for small IRFPAs.

Many IR lenses include Diffractive Optical Elements (DOEs) which have been incorporated to reduce the lens complexity and/or the tolerance sensitivity. In many cases the diffractive surface includes an asphere to achieve further aberration correction. For complex lens systems such as IR multi-FOV and IR zoom lenses there is a strong motivation to use multiple diffractive optical elements. This paper reviews the performance impact and productivity advantages of using multiple diffractive optical elements in an IR lens.

We use the point spread function and the modulation transfer function as the most appropriate measures to analyze the performance of the multi-aperture interferometric configurations. We design non-redundant interferometric layouts that provide satisfactory coverage of the spatial frequencies. We compare our designs with the previously proposed configurations.

The optical design for an IR imaging spatial heterodyne spectrometer is described. The evolution of the design from a paraxial layout to a final working system is detailed, showing how the basic ideas outlined by the inventors of the ISHS concept were realized in an instrument operating in the long wave IR. Several design constraints unique to operation in the LWIR posed challenges to the design; the choices made to solve these problems are discussed. The predicted imaging performance of the design is modeled, and improvements to the design of a second generation instrument are proposed.

As the market for uncooled 8-12 micrometers thermal imaging cameras continues to expand and prices decrease the expense of the objective lens is increasingly becoming the major factor for total system cost. Limited mainly to expensive raw materials for lens element substrates and requiring costly optical polishing man-hours for manufacture, the lens costs have been difficult to reduce without sacrificing optical performance. A family of fast objective lenses has been designed for uncooled long wave IR cameras that utilize multiple diamond turned aspheric surfaces to reduce the size and number of lens elements. The cost of the objective is thereby reduced without giving up any of the necessary optical performance while at the same time gaining improvements in overall size and weight. A description is given of this family lenses and its inherent advantages. The effectiveness of this solution is demonstrated with several examples that have been manufactured and fielded.

Pilkington Optronics have a wide experience in designing IR optical system to meet harsh military environments. Success relies on close co-operation between optical and mechanical designers. This paper reviews and discusses some of the considerations and opto-mechanical trade-offs that must be made when designing IR systems for such environments.

We develop a new expression for the thermal contrast of a black-body radiator. The derivative of exitance of a blackbody radiator with respect to temperature, integrated over the wavelength interval, is given in a closed form. The thermal contrast is found within an interval using a series evaluation and a closed-form compensated approximation. The compensated approximation is more accurate than the series expansion for lower values of x, corresponding to high temperatures and/or longer wavelengths.

In the present paper we consider hologram parameters required to obtain highly selective holographic spectral filters operating in near IR range of spectrum. The properties of photopolymer with diffusion amplification as a medium for recording of narrowband spectral filters for near IR, namely the dispersion dependence of refractive index variations in a wide spectral range, and its influence on the resulting parameters of the holographic filter are analyzed. The experimental result on the recording of a filter optimized for operation at 1.06 micrometers and a combined filter for visible and near IR are discussed.

The 1-3 micrometers short wave IR detector has many applications in astronomy, optical radar and optical communications. The devices applied in air will inevitably influenced by all kinds of particle irradiation. So it is very important to study the influence of irradiation to the device performance. In this paper HgCdTe photovoltaic devices with different wavelengths were irradiated by gamma rays under different doses. The changes of their response spectrum, I-V characteristics, photo signal, noise, responsivity and detectivity were studied. It is observed that there is no noticeable change in the peak and cut-off wavelength after 22.7Mrad gamma irradiation, but the responsivity and detectivity decreased within a large extent. The results were analyzed at last.

Spatial heterodyne spectroscopy (SHS) is a Fourier transform spectroscopy technique capable of very high spectral resolution with no moving parts. The original work described non-imaging SHS, and it became a true imaging spectroscopy technique without much fanfare. We describe the imaging technique and relate it to another 'image plane interferometer' described by Horton, called HEIFTS, which does not have heterodyned fringes. One configuration of a basic SHS is a two-beam Michelson interferometer with both mirrors replace by diffraction gratings operated in the Littrow configuration. To convert a parallel light SHS device to imaging, incoming light must be focused on the gratings, so that each grating receives a full image of the scene. To acquire 3D data cubes, the open field of view is scanned across the scene. Although the focal plane array sees both spatial and spectral information, they are not mixed, because information is encoded by optical path difference according to position on the focal plane.

Short wavelength, middle wavelength, mid-long wavelength, long wavelength, and very long wavelength focal plane arrays (FPAs) are required for remote sensing applications. Advances in the Molecular Beam Epitaxy (MBE) growth of Mercury Cadmium Telluride (HgCdTe) and detector architectures utilized, have resulted in high performance detectors being fabricated in the 1 micrometers to 16 micrometers spectral range Custom Read Out Integrated Circuits (ROICs) are designed and fabricated to interface the HgCdTe detector arrays. The hybrid focal pane array is made up of the HgCdTe detector array and the CMOS-based ROIC. Hybrid FPAs performance parameters are presented. The HgCdTe detector material is used are grown by MBE on lattice matched CdZnTe substrates. Custom ROICs are fabricated in a commercial CMOS foundry. FPA D* performance values have been obtained for a multitude of spectral ranges and configurations that include; (i) (lambda) _c equals 1.8 micrometers , 12 X 256 arrays operating at 295 K with median D* approximately 1.4 X 10¹² cm Hz^1/2/W, (ii) (lambda) _c equals 10.5 micrometers , 256 X 256 arrays operating at 85 K with medina D* equals 3.9 X 10¹¹ cm Hz^1/2/W at a background flux (phi) _b equals 7.82 X 10¹⁵ ph/cm²-2 and (iii) (lambda) _c equals 15.8 micrometers at 65K, 128 X 128 array operating at 40K with peak D* of 2.76 X 10¹¹ cm Hz^1/2/W at a background flux (phi) _b equals 8.0 X 10¹⁵ ph/cm²- s. The performance of these FPAs will be presented.

Corrugated quantum well IR photodetector (QWIP) focal plane arrays (FPAs) with cutoff wavelength of 11.2 and 16.2 micrometers were fabricated and tested. Each detector array has 256 X 256 pixel elements, indium bumped to a direct injection readout circuit manufactured by Rockwell Science Center. The rest of the supporting electronics were designed and built in-house to provide biases and clock functions to the FPAs. IR imageries with good aesthetic attributes were obtained from both FPAs. For the 11.2 micrometers FPA, background limited IR performance (BLIP) was obtained at 63 K under F/2 optics, consistent with the test results of a large area detector. This operating temperature is substantially higher than the grating coupled arrays with comparable cutoff wavelengths. On the other hand, the optics of the present camera were not optimized for wavelengths beyond 14 micrometers . As a result, the BLIP temperature for the 16.2 micrometers FPA, observed to be 38 K, was somewhat lower than the expected 42 K from the single detector characterization. Despite the reduced detector volume of a C-QWIP structure, the measured internal quantum efficiency remains to be high, being 20.5 percent and 25.4 percent at 2 V bias for the 11.2 micrometers and the 16.2 micrometers FPA, respectively.

Efforts invested at El-Op during the last four years have led to the development of TADIR - engineering model thermal imager, demonstrated in 1998, and eventually to the final production version of TADIR to be demonstrated in full operation during 1999. Both versions take advantage of the high resolution and high sensitivity obtained by the 480 X 4 TDI MCT detector as well as many more features implemented in the system to obtain a state of the art high- end thermal imager. The production version of TADIR uses a 480 X 6 TDI HgCdTe detector made by the SCD Israeli company. In this paper, we will present the main features of the production version of TADIR.

An optimized long-wavelength two-color quantum well IR photodetector (QWIP) device structure has been designed. This device structure was grown on a three-inch semi- insulating GaAs substrate by molecule beam epitaxy (MBE). This wafer was processed into several 640 X 486 format monolithically integrated 8-9 and 14-15 micrometers two-color QWIP focal plane arrays (FPAs). These FPAs were then hybridized to 640 X 486 silicon CMOS readout multiplexers. A thinned FPA hybrid was integrated into a liquid helium cooled dewar to perform electrical and optical characterization and to demonstrate simultaneous two-color imagery. The 8-9 micrometers detectors in the FPA have shown background limited performance (BLIP) at 70 K operating temperature, at 300 K background with f/2 cold stop. The 14-15 micrometers detectors of the FPA have reached BLIP at 40 K operating temperature at the same background conditions. In this paper we discuss the performance of this long-wavelength dualband QWIP FPA in quantum efficiency, detectivity, noise equivalent temperature difference, uniformity, and operability.

IR spectral remote sensing has demonstrated much in the last few years including the potential for low contrast day/night military target detection. The status, needs, and challenges in the area of physics and phenomenology, sensors, and modeling are discussed. Successful further development of IR spectral remote sensing depends on research and development investment in (1) IR focal plane arrays to lower cost and increase the number of pixels, (2) processing algorithms that utilize the a priori information available from physics and phenomenology studies, and (3) end-to-end performance models encompassing target, scene, atmosphere, sensor, and processing effects.

In-the-loop IR signal adjustment is a technology designated to control the output signal gain. Remotely directed in-the- band IR radiance increases detector noise up and in such a way decreases the signal-to-noise ratio down. This technology could be used to reach signal breaklock level, when a target signal can not be resolved. This technology can be used for Remote IR Automatic Gain Control either.