Sofradir infrared detectors manufacturing is based on the use of a Mercury Cadmium Telluride (MCT) technology hybridized with silicon readout circuit covering a bandwidth from 0.8 to 14 μm thanks to the ability of MCT material to be tuned in terms of cut-off wavelength. Most of the time, infrared detectors are used to answer applications operating between 0.8 μm and 15 μm. New emerging applications express a need for detectors covering a larger waveband and in particular detectors with waveband sensitivity from the visible spectrum up to infrared spectrum. Some of these applications are for example hyperspectral applications where a panchromatic channel is generally associated to an infrared channel. For these applications, the availability of a detector covering these two channels can greatly simplify the instrument architecture. Other potential applications can be spectroscopic applications in visible range needing an extension of the sensitivity of the sensor in near infrared spectrum which cannot be answered with high performances by classical silicon sensors because of the loss of sensitivity between 0.8 μm and 1 μm. Physically, MCT material is able to operate in the visible range and has a potential to offer a high quantum efficiency and large field factor thanks to the hybrid structure. In addition, Sofradir N on P ion implantation process as well as Sofradir hybridization process offer specific advantages to develop high performances detectors sensitive both in visible and infrared spectra. This kind of detector can be an interesting alternative to answer applications needing a large waveband detector. In this paper, Sofradir approach to develop a new kind of detectors sensitive from visible to infrared spectra is presented. Potential applications and the interest of these new Sofradir detectors are discussed versus these needs. Finally, the last results and performances of these detectors are presented.

This paper presents the infrared detector performance improvement accomplishments by Raytheon Vision Systems (RVS) and by AVYD Devices Inc (AVYD). The RVS-AVYD collaboration has resulted in the demonstration of very large imaging focal plane arrays with respectable operability and performance which could potentially be useful in a variety of promising new applications to advance performance capability for future near and short wave infrared imaging missions. This detector design concept potentially permits ultra-small pixel large format imaging capabilities for diffraction limited resolution down to 5μm pitch focal planes. In this paper, we report on the work performed at the RVS's advanced prototype engineering facility, to fabricate planar detector array wafers with a combination of RVS's Hg_1-xCd_xTe production material growth and detector fabrication processes and AVYD's p-type ion-implantation process. This paper will review the performance of a 20μm pitch 1,024 x 1,024 format SWIR focal plane array. The detector array was fabricated in Hg_1-xCd_xTe material responsive from near-infrared to 2.5μm cutoff wavelength. Imaging capability was achieved via interconnect bump bond connection of this detector array to an RVS astronomy grade readout chip. These focal plane arrays have exhibited outstanding quantum efficiency uniformity and magnitude over the entire spectral range and in addition, have also exhibited very low leakage current with median values of 0.25 electrons per second. Detector arrays were processed in engineering grade Hg_1-xCd_xTe epitaxial layers grown with a modified liquid phase epitaxy process on CdZnTe substrates followed by a combination of passivation/ion implantation/passivation steps. This paper will review the detector performance data in detail including the test structure current-voltage plots, spectral cutoff curves, FPA quantum efficiency, and leakage current.

This paper presents our research and development effort in realizing and perfecting photon upconversion devices for wavelengths from 1.5 μm region to 0.87 μm. The basic idea is to integrate a 1.5-μm detector with a 0.87-μm light emitting diode (LED), connected in series. The detected photocurrent drives the LED, thereby achieving the upconversion. Various approaches of integration methods and device designs have been tested.

Extended wavelength InGaAs material is ideal for laser beam profiling applications from 1 micron to 2 microns wavelength. We report on a focal plane array and camera designed specifically for this application. The format of the camera is 320 x 256 pixels on a 25 micron pitch, and the operation is snapshot exposure with a 16 ms exposure time. The camera may be triggered for synchronization with laser pulses and has a 60 Hz maximum readout rate. Two challenges are encountered with extended wavelength InGaAs material compared to lattice matched material. The first is lower quantum efficiency at the shorter wavelengths due to transitional buffer layers that absorb at the shorter wavelengths. The second is the larger dark current caused by lattice mismatch between the InP substrate and the absorption layers. Neither challenge is a problem for laser beam profiling, since a large energy or power is available from the source. To accommodate the dark current, a gate modulated (GMOD) readout circuit is used, where the continuously variable capacity is increased to several million electrons. Both CW and pulsed illumination linearity are good, allowing accurate profiling. The temperature of the focal plane array is held near room temperature with a thermoelectric cooler for stability. To provide a corrected image, nonuniformity corrections for offset and gain are stored in the camera.

Large-area APDs operating in the wavelength region of 1- 1.5 micron are useful for many low light level applications. Present commercially available InGaAs based APDs are small, (<500 micron diameter size) and thus limit the field of view. We report here on low dark current density, large-area (1 mm diameter) InGaAs APDs. InGaAs APD device structures with InP and InAlAs multiplication layers were grown by metaloragnic vapor deposition method. The combination of good quality material and a proprietary passivation process yielded 1 mm APD devices with low dark current density and high gain. Devices exhibited gain as high as 30 and dark current density as low as 0.5 microamperes per square centimeter.

Laser based imaging systems are becoming common in a number of applications. Many of these systems rely on scanning the laser and receiver over the scene to construct an image. A single pulse laser gated imaging system employing a two dimensional focal plane array sensor has been developed by SELEX Sensors and Airborne Systems Ltd (SELEX S&AS). The system has been deployed on field trials to gather data in order to assess the suitability of the technology for a number of applications. The test system has been used to characterise and optimise subsystem and system level performance, to assess the effects of atmospheric phenomena on system performance, and to gather field data in various applications and scenarios. Recent system and subsystems enhancements to the Laser Gated Imaging, or Burst Illumination LADAR (BIL), test rig are described. Changes to the laser subsystem, the sensor subsystem and the system level integration aspects of the rig resulting from field trials experience and on going system development are discussed. The recent developments for the system control, data and image processing suites are also addressed. Operational observations, images and results from recent field trials, including operation in an airborne environment, are presented and discussed.

The rapid pace of development in the field of long-range imaging is illustrated by two new detector technologies for passive and active imaging. Active systems, using a near-infrared pulse laser and a fast, gated detector, are now adopted for most long range imaging applications. This concept is often called burst-illumination LIDAR or BIL. The SELEX solid state detector is based on two major components: an array of HgCdTe avalanche photodiodes, and a custom-designed CMOS multiplexer to perform the fast gating and photon signal capture. These hybrid arrays produce sensitivities as low as 10 photons rms, due largely to very high, almost noise-free avalanche gain in the HgCdTe diodes. The sensitivity, dynamic range and image quality is now such that the camera performance is usually limited by coherence and scintillation effects in the scene. With this strong sensor capability, it has been possible to launch the next generation of multiplexers to satisfy systems of the future. For instance, most laser-gated imaging systems use a suite of passive infrared and visible cameras to complement the BIL channel. It is highly advantageous to combine these functions into one electro-optic system, leading to a simpler, smaller, lower power and lower cost system. The key technical steps are to find solutions for the difficult multifunctional detector and the dual-wavelength optic. A detector has been developed to image passively in the medium and short wavebands, and actively in BIL mode. The performance of the detector and optic is described. Another major systems enhancement is to be able to generate 3D images, particularly in complex scenes, to further improve background clutter rejection and provide agile, feedback control of the range gating in a dynamic environment. Here the detector senses the range, as well as the laser pulse intensity, on a pixel-by-pixel basis, providing depth context for each laser pulse. A prototype detector has been successfully demonstrated and shown to provide good quality 2D and 3D data for each laser pulse.

We report on a 640 x 512 pixel, 25 μm pitch, InGaAs focal plane array based camera with the ability to perform range-gated imaging, while also allowing integration times longer than 32 ms for imaging in a staring mode at video rates. The combination of gated and video imaging is achieved through a high bandwidth pixel with a capacitive transimpedance amplifier (CTIA) design. The CTIA pixel may be switched between two feedback capacitor sizes to allow two different sensitivities and capacities, depending on the illumination conditions. Anti-blooming is included in the pixel to prevent charge spreading from oversaturated pixels. All pixels are gated simultaneously for "snapshot" exposure. The all solid-state gated camera is very reliable, in addition to being small and lightweight. The low dark current and high bandwidth of the InGaAs photodetectors enables both high sensitivity imaging at long exposure times and high bandwidth at short exposure times. The spectral response of InGaAs extends from 0.9 μm to 1.7 μm, allowing the use of eye-safe commercially available pulsed lasers with 1.5 μm wavelength, several millijoule pulse energies, and nanosecond scale pulse durations.

Laser active imager are introducing a new paradigm in the domain of surveillance. Because they provide the capacity to image objects based on their reflectivity and not their emissivity, and because they provide a capacity to see through glass. Moreover, because that being based on high-performance gated intensified tubes, they can operate in adverse atmospheric conditions, and are becoming looked at as a very valuable tool to gather precise identification information at long ranges. On the other hand, the laser source making this technology so interesting must offer a safe operational mode of deployment. In this paper, we will show the most recent results that this technology can achieve in ship identification and discuss how to implement safety features to make the laser active imager an eye safe new tool for long range observation whatever its wavelength.

Previously, we demonstrated a large format 1024 x 1024 corrugated quantum well infrared photodetector focal plane array (C-QWIP FPA). The FPA has a cutoff at 8.6 μm and is BLIP at 76 K with f/1.8 optics. The pixel had a shallow trapezoidal geometry that simplified processing but limited the quantum efficiency QE. In this paper, we will present two approaches to achieve a larger QE for the C-QWIPs. The first approach increases the size of the corrugations for more active volume and adopts a nearly triangular pixel geometry for larger light reflecting surfaces. With these improvements, QE is predicted to be about 35% for a pair of inclined sidewalls, which is more than twice the previous value. The second approach is to use Fabry-Perot resonant oscillations inside the corrugated cavities to enhance the vertical electric field strength. With this approach, a larger QE of 50% can be achieved within certain spectral regions without using either very thick active layers or anti-reflection coatings. The former approach has been adopted to produce a series single color FPAs, and the experimental results will be discussed in a companion paper. In this paper, we also describe using voltage tunable detector materials to achieve multi-color capability for these FPAs.

Current generation QWIP detectors, although very cost effective, have relatively narrow spectral range and low quantum efficiencies. Tactical operation is generally limited to a single spectral band. These limitations arise from the design approach and restrict applications to those that can tolerate these performance limitations. Using recent device design improvements, a novel material, and special processing approaches, High Quantum Efficiency Dual Band C-QWIP detectors are currently being developed. These are expected to overcome traditional limitations in the QWIP design approach and deliver extremely high performance. In the first phase of the program, single color LWIR and VLWIR C-QWIP FPAs in large (1024x1024) format will be demonstrated with targeted peak quantum efficiency of 35%, and correspondingly high BLIP operating temperatures. In the next phase of the program, the team will continue to improve QE towards 50% with conversion efficiency of 75%, and demonstrate dual band MW/LW FPAs. The detector gain will be optimized for operation in either low background or high background applications. These goals will be accomplished using highly producible/low cost materials and processes. System considerations include ROIC well capacity, noise performance, as optics configuration and other concerns will be addressed. A robust design for high performance in a variety of applications will be shown. This work is being performed by the Army Research Laboratory (ARL) and L-3 Cincinnati Electronics (CE), with funding provided by the Missile Defense Agency.

Standard GaAs/AlGaAs Quantum Well Infrared Photodetectors (QWIP) are now seriously considered as a technological choice for the 3^rd generation of thermal imagers. Since 2001, the THALES Group has been manufacturing sensitive arrays using QWIP technology based on AsGa techniques through THALES Research and Technology Laboratory. This QWIP technology allows the realisation of large staring arrays for Thermal Imagers (TI) working in the Infrared region of the spectrum. A review of the current QWIP products is presented (LWIR, MWIR and dual color FPAs). The main advantage of this GaAs detector technology is that it is also used for other commercial devices. The duality of this QWIP technology has lead to important improvements over the last ten years and it reaches now an undeniable level of maturity. As a result, the processing of large substrate and a good characteristic uniformity, which are the key parameters for reaching high production yield, are already achieved. Concerning the defective pixels, the main common features are a high operability (above 99.9%) and a low number of clusters including a maximum of 5 dead pixels. Another advantage of this III-V technology is the versatility of the design and processing phases. It allows customizing both the quantum structure and the pixel architecture in order to fulfill the requirements of any specific applications. The spectral response of QWIPs is intrinsically resonant but the quantum structure can be designed for a given detection wavelength window ranging from MWIR, LWIR to VLWIR.

Since 1997, Sofradir has been working with Thales Research and Technologies (TRT) to develop and implement Quantum Well Infrared Photodetectors (QWIP) as an alternative and complementary offer with Mercury Cadmium Telluride (MCT) Long Wave (LW) detectors, to provide large LW staring arrays. Thanks to the low dark current technology developed by TRT, the QWIP detectors can be worked at FPA temperature above 73K, enabling the development of new compact IR cameras thanks to the use of compact microcoolers, and today, Sofradir is entering production with these highly compact QWIP components. For the Long Wave applications, SOFRADIR offers the European TV/4 format with the VEGA-LW detector (25μm pitch 384×288 IDDCA) and the full TV format with the SIRIUS-LW detector (20μm pitch 640×512 IDDCA). The first one is under production for several hundreds of units, to equip the Catherine-XP thermal imager from Thales. The second one has been initially developed for the Catherine-MP high resolution (SXGA) thermal imager and is ready for production. Both detectors present highly uniform performances and sharp images with NETD in the 50mK range when working around 75K at video frame rate. The TV/4 VEGA detector is also offered as a demonstrator for the Mid Wave applications, with a QWIP array adapted to this waveband. In the same time, a dual band MW-LW similar array is developed with spatial coherence, and is currently under demonstration. The performances of these four QWIP detectors are reviewed in this paper.

The use of arsine in metal-organic vapor phase epitaxy (MOVPE) growth is well established in the compound semiconductor industry but associated with large potential risks due to its high toxicity. Worldwide efforts are therefore being made to replace it with less hazardous source materials. Acreo, a commercial supplier of quantum well infrared photodetector (QWIP) focal plane arrays (FPA), is working towards an MOVPE process where tertiarybutylarsine (tBAs) instead of arsine is used in the growth of AlGaAs/GaAs n-type QWIP epiwafers. In this paper we investigate the performance of QWIP FPA produced from conventional arsine and alternative tBAs arsenic precursors. We also discuss the two growth processes regarding uniformity, crystalline purity and production cost. The performance of our QWIP structures grown using tBAs and arsine is comparable in terms of response and response-to-the dark current ratio.

QmagiQ LLC, has recently completed building and testing high operability two-color Quantum Well Infrared Photodetector (QWIP) focal plane arrays (FPAs). The 320 x 256 format dual-band FPAs feature 40-micron pixels of spatially registered QWIP detectors based on III-V materials. The vertically stacked detectors in this specific midwave/longwave (MW/LW) design are tuned to absorb in the respective 4-5 and 8-9 micron spectral ranges. The ISC0006 Readout Integrated Circuit (ROIC) developed by FLIR Systems Inc. and used in these FPAs features direct injection (DI) input circuitry for high charge storage with each unit cell containing dual integration capacitors, allowing simultaneous scene sampling and readout for the two distinct wavelength bands. Initial FPAs feature pixel operabilities better than 99%. Focal plane array test results and sample images will be presented.

THALES have developed for volume manufacture two high performance low cost thermal imaging cameras based on the THALES Research & Technology (TRT) 3^rd generation gallium arsenide long wave Quantum Well Infrared Photodetector (QWIP) array. Catherine XP provides 768 x 575 CCIR video resolution and Catherine MP provides 1280 x 1024 SXGA video resolution. These compact and rugged cameras provide 24-hour passive observation, detection, recognition, and identification in the 8 to 12μm range, providing resistance to battlefield obscurants and solar dazzle, and are fully self-contained with standard power and communication interfaces. The cameras have expansion capabilities to extend functionality (for example automatic target detection) and have network battlefield capability. Both cameras benefit from the high quantum efficiency and freedom from low frequency noise of the TRT QWIP, allowing operation at 75 K, low integration times and non-interruptive non-uniformity correction. The cameras have successfully reached technology readiness level 6/7 and have commenced environmental qualification testing in order to complete the development programmes. These latest additions to the THALES Catherine family provide high performance thermal imaging at an affordable cost.

We report our recent results about mid-wavelength infrared quantum-dot infrared photodetectors (QDIPs) grown by low-pressure metalorganic chemical vapor deposition. A very high responsivity and a very low dark current were obtained. A high peak detectivity of the order of 3×10¹² Jones was achieved at 77 K. The temperature dependent device performance was also investigated. The improved temperature insensitivity compared to QWIPs was attributed to the properties of quantum dots. The device showed a background limited performance temperature of 220 K with a 45° field of view and 300K background. The current device problems are a low quantum efficiency and a stronger than expected performance degradation as a function of operating temperature. Possible ways to improve the quantum efficiency and operating temperature are discussed.

We have exploited the artificial atomlike properties of epitaxially grown self-assembled quantum dots for the development of high operating temperature long wavelength infrared (LWIR) focal plane arrays. Quantum dots are nanometer-scale islands that form spontaneously on a semiconductor substrate due to lattice mismatch. QDIPs are expected to outperform quantum well infrared detectors (QWIPs) and are expected to offer significant advantages over II-VI material based focal plane arrays. QDIPs are fabricated using robust wide bandgap III-V materials which are well suited to the production of highly uniform LWIR arrays. We have used molecular beam epitaxy (MBE) technology to grow multi-layer LWIR quantum dot structures based on the InAs/InGaAs/GaAs material system. JPL is building on its significant QWIP experience and is basically building a Dot-in-the-Well (DWELL) device design by embedding InAs/InGaAs quantum dots in a QWIP structure. This hybrid quantum dot/quantum well device offers additional control in wavelength tuning via control of dot-size and/or quantum well sizes. In addition the quantum wells can trap electrons and aide in ground state refilling. Recent measurements have shown a 10 times higher photoconductive gain than the typical QWIP device, which indirectly confirms the lower relaxation rate of excited electrons (photon bottleneck) in QDIPs. Subsequent material and device improvements have demonstrated an absorption quantum efficiency (QE) of ~ 3%. Dot-in-the-well (DWELL) QDIPs were also experimentally shown to absorb both 45° and normally incident light. Thus we have employed a reflection grating structure to further enhance the quantum efficiency. JPL has demonstrated wavelength control by progressively growing material and fabricating devices structures that have continuously increased in LWIR response. The most recent devices exhibit peak responsivity out to 8.1 microns. Peak detectivity of the 8.1 µm devices has reached ~ 1 × 10¹⁰ Jones at 77 K. Furthermore, we have fabricated the first long-wavelength 640×512 pixels QDIP focal plane array. This QDIP focal plane array has produced excellent infrared imagery with noise equivalent temperature difference of 40 mK at 60K operating temperature. In addition, we have managed to increase the quantum efficiency of these devices from 0.1% [1-2] to 20% in discrete devices. This is a factor of 200 increase in quantum efficiency. With these excellent results, for the first time QDIP performance has surpassed the QWIP performance. Our goal is to operate these long-wavelength detectors at much higher operating temperature than 77K, which can be passively achieved in space. This will be a huge leap in high performance infrared detectors specifically applicable to space science instruments.

Engineered semiconductor quantum structures that enforce carrier confinement in all three spatial dimensions have recently become of interest for potential applications in the sensing of infrared radiation via intersub-level transitions. These structures, most often called quantum dots, may offer a viable alternative to the mercury cadmium telluride semiconductor and GaAs/(Al,Ga)As quantum-well structures for infrared detection. Their major advantages for detection include (i) operation under normal-incidence illumination, (ii) a predicted high responsivity due to a long electron lifetime in the excited states, and (iii) a potential for high-temperature operation. This paper will review the current-state-of-development of (In,Ga)As/GaAs quantum-dot infrared detectors that are sensitive to light in the middle wavelength infrared (3-5 μm) region of the electromagnetic spectrum. The paper will also discuss some of the leading edge experimental results that suggest that quantum-dot active regions may offer a route to elevated device operating temperatures (> 150 K).

The addition of small amounts of nitrogen to III-V semiconductors leads to a large degree of band-gap bowing, giving rise to band-gaps smaller than in the associated binary materials. The addition of a small percentage of nitrogen to GaSb or InSb is predicted to move their response wavelengths into the long or even very long wavelength IR ranges. We report the growth of GaN_xSb_1-x by MBE, using an r.f. plasma nitrogen source, examining the influence of plasma power, substrate temperature and growth rate. We demonstrate high structural quality, as determined by x-ray diffraction, and show a reduction in band-gap by over 300meV, compared with GaSb, based on FTIR transmission spectroscopy. We also report initial experiments on the growth of InN_xSb_1-x and Ga_1-yIn_yN_xSb_1-x, with a view to extending the response into the long and very long wavelength IR ranges.

Over the past few years SCD has developed a new InAlSb diode technology based on Antimonide Based Compound Semiconductors (ABCS). In addition SCD has lead in the development of a new standard of silicon readout circuits based on digital processing. These are known as the "Sebastian" family of focal plane processors and are available in 384 × 480 and 512 × 640 formats. The combination of ABCS diode technology with digital readout capability highlights an important cornerstone of SCDs 3^rd generation detector program. ABCS diode technology offers lower dark currents or higher operating temperatures in the 100K region while digital readouts provide very low noise and high immunity to external interference, combined with very high functionality. In this paper we present the current status of our ABCS-digital product development, in which the detectors are designed to provide improved performance characteristics for applications such as hand-held thermal imagers, missile seekers, airborne missile warning systems, long-range target identification and reconnaissance, etc. The most important Detector-Dewar-Cooler Assembly (DDCA) parameters are reviewed, according to each specific application. Benefits of these products include lower power consumption, lighter weight, higher signal-to-noise ratio, improved cooler reliability, faster mission readiness, longer mission times and more compact solutions for volume-critical applications. All these advantages are being offered without sacrificing the standard qualities of SCDs InSb Focal Plane Arrays (FPAs), such as excellent radiometric performance, image uniformity, high operability and soft-defect cosmetics.

Infrared sensors utilizing Type II superlattice structures have gained increased attention in the past few years. With the stronger covalent bonds of the III-V materials, greater material uniformity over larger areas is obtained as compared to the weaker ionic bonding of the II-VI materials. Results obtained on GaSb/InAs Type II superlattices have shown performance comparable to HgCdTe detectors, with the promise of higher performance due to reduced Auger recombination and dark current through improvements in device design and material quality. In this paper, we discuss advancements in Type II IR sensors that cover the 3 to >30 μm wavelength range. Specific topics covered will be device design and modeling using the Empirical Tight Binding Method (ETBM), material growth and characterization, device fabrication and testing, as well as focal plane array processing and imaging. We demonstrate high quality material with PL linewidths of ~20 meV, x-ray FWHM of 20-40 arcsec, and AFM rms roughness of 1~.2 Å over a 20 μm×20μm area. Negative luminescence at 10 μm range is demonstrated for the first time. Device external quantum efficiency of >30%, responsivity of ~2A/W, and detectivity of 10¹¹ Jones at 77K in the 10 μm range are routinely obtained. Imaging has been demonstrated at room temperature for the first time with a 5 μm cutoff wavelength 256×256 focal plane array.

Optimization of various growth parameters for Type-II GaSb (10MLs)/InAs(10MLs) nanoscale superlattices (SL) and GaSb layers, grown by solid molecular beam epitaxy, has been undertaken. We present optical and structural characterization for these heterostructures, using high resolution X-ray diffraction (HRXRD), photoluminescence (PL) and atomic force microscopy (AFM). Optimized parameters were then used for growth of InAs/GaSb SLs photovoltaic detectors (λ_cut-off ~5 μm) operating at room temperature. By controlling the nature of interfaces, the in-plane mismatch between GaSb-buffer layer and SLs can be reduced enabling the growth of active regions up to 3μm. Normal incidence single pixel photodiodes were fabricated using standard lithography with apertures ranging from 25-300 μm in diameter. The spectral response from the SLs detector was observed at room temperature. This suggests the potential of the SLs technology for realizing high operating temperature (HOT) sensors. Responsivity measurements were also undertaken using a calibrated black body source, 400Hz optical chopper, SR 770 FFT Network signal analyzer and Keithley 428 preamplifier. We obtained current responsivity equal 2.16 A/W at V = -0.3V(300K). The Johnson noise limited D* at 300K was estimated to be 4.6x10⁹ cm·Hz^1/2/W at V = -0.3V

We report on the status of GaSb/InAs type-II superlattice diodes grown and fabricated at the Jet Propulsion Laboratory designed for infrared absorption in the 8-12μm range. Recent devices have produced detectivities as high as 8x10¹⁰ Jones with a differential resistance-area product greater than 6 Ohmcm² at 80K with a long wavelength cutoff of approximately 12μm. The measured quantum efficiency of these front-side illuminated devices is close to 30% in the 10-11μm range without antireflection coatings.

In recent years, infrared and multi-spectrum optical payload technology was making rapid progress in China, and was widely applied in meteorological satellite , oceansat and airborne remote sensing system, etc . Several such typical earth observation systems and corresponding infrared sensors are introduced in this paper. 1.Multi-channel Radiometer loaded on FY-2 geo-stationary meteorological satellite, has 5 bands multi-spectrum scanning radiometer consisted of one visual panchromatic band, two middle-infrared bands and two thermal infrared bands, which was launched in 2004. The ground resolution of visual band is 1.25km, and 5km for infrared; 2. 10 bands Ocean Color and Temperature Scanner (OCTS) loaded on HY-1 sun-synchronous orbit oceansat is a typical ocean observation purpose payload consisted of 8 VIS-NIR bands and 2 IR bands launched in 2002. The ground resolution is 1.1Km; 3. Airborne 128 bands operational modular image spectrometer (OMIS) is applied in 2000 consisted 64 VIS-NIR bands, 48 SIR bands, 8 MIR bands and 8 TIR bands. The FOV (Field of View) of system is 70 degree, and the IFOV (Instant Field of View) is 3 micro-radian.

The purpose of this paper is to present the latest developments in Defir (LETI / Sofradir joint laboratory) in the field of bi-color and dual band infrared focal plane arrays (FPA) made with HgCdTe. The npn structure is achieved using the Molecular Beam Epitaxy (MBE) technique, planar ion implantation, and both dry and wet etching steps. This back to back diode architecture that allows a perfect spatial coherence with a high field factor and large quantum efficiencies needs only one indium bump connection per pixel. This makes it possible to achieve small pitches (below 25μm) and opens the way to the fabrication of large FPAs (TV/4 to TV) with reasonable wafer sizes. In this paper we present electro optical characterizations of 256x256 prototypes fabricated in Defir operating in two MWIR bands (3.1 and 5μm) with a pitch of 25μm that exhibit background limited performances together with a very high operability (above 99.9%) and NEDT below 22mK for integration time of only 0.5ms. In parallel an industrial product soon available from Sofradir has been developed with a 320x256 format and with a 30μm pitch operating in the same bands. This product exhibits the same operability and NETD as low as 15mK for an integration time as short as 1 ms. Finally, last results regarding 256x256 prototypes operating in MWIR/LWIR bands are presented, together with preliminary APD operating mode for the MWIR photodiodes of this last dual band detector.

Hitherto, two families of multielement infrared (IR) detectors are used for principal military and civilian infrared applications; one is used for scanning systems (first generation) and the other is used for staring systems (second generation). Third generation systems are being developed nowadays. In the common understanding, third generation IR systems provide enhanced capabilities like larger number of pixels, higher frame rates, better thermal resolution as well as multicolor functionality and other on-chip functions. In the paper, issues associated with the development and exploitation of materials used in fabrication of third generation infrared photon detectors are discussed. In this class of detectors two main competitors, HgCdTe photodiodes and quantum well photoconductors are considered. The performance figures of merit of state-of-the-art HgCdTe and QWIP focal plane arrays (FPAs) are similar because the main limitations come from the readout circuits. The metallurgical issues of the epitaxial layers such as uniformity and number of defected elements are the serious problems in the case of long wavelength infrared (LWIR) and very LWIR (VLWIR) HgCdTe FPAs. It is predicted that superlattice based InAs/GaInSb system grown on GaSb substrate seems to be an attractive to HgCdTe with good spatial uniformity and an ability to span cutoff wavelength from 3 to 25 μm. In this context the material properties of type II superlattices are considered more in detail.

The present generation of uncooled infrared photon detectors relies on complex heterostructures grown by low temperature epitaxial techniques. We report recent results on MOCVD grown Hg_1-xCd_xTe photodetectors and their applications. Special modifications to the interdiffused multilayer process (IMP) has been applied for the in-situ control of stoichiometry, improved morphology and minimized consumption of precursors. As a result we are able to grow fully-doped multiple layer heterostructures without any post-growth thermal anneal. The heterostructures have been used for fabrication of IR photodetectors optimized for any wavelength within the 1 to 15 μm range and operating at temperatures 200-300 K. Variable bandgap absorbers have been used for detectors with tuned spectral response and multicolor devices. The uncooled photodetectors have been applied in sub-ppb gas analyzers, laser warning devices, free space optical communications, Fourier Transform IR Spectroscopy, and many other IR systems.

The InfraRed staring arrays offered by SOFRADIR are more and more compact and offer system solutions in the different IR wavebands. The HgCdTe (Mercury Cadmium Telluride / MCT) material and process, as well as the hybridization technology, have been taken to an even more advanced level of sophistication to achieve these new staring arrays high performances. Latest developments have also been focused on the readout silicon circuit. A frame rate increase, new types of customized functions and digital converter are an important progress in this field. In order to match each system requirements, different flexible architectures of Analog To Digital Converter (ADC) have been developed. These developments implement specific requests in terms of frame rate, power consumption and resolution. Beyond the performance aspects, digital focal plan arrays can be considered as the first step towards a new low cost dewar family, since they allow for a more simple electrical interface on dewar designs. New results concerning these new readout circuit architectures are presented in this paper.

With the recent introduction of infrared cameras that have the ability to produce variable acuity imagery, it has become necessary to develop methods for bad pixel replacement and non-uniformity correction within superpixels. Since a superpixel is formed by averaging a group of smaller pixels on chip prior to readout, producing a single value, we cannot apply gains and offsets to the individual pixels that contribute to the superpixel value, nor can we replace bad pixels within a superpixel before they corrupt the aggregate intensity of the superpixel. Without new superpixel correction methods, the imagery produced by this exciting technology is less appealing to human observers and corrupted superpixel intensities lead to problems with the algorithms that process the imagery to perform useful automated tasks, such as "hot-spot" tracking. This paper will introduce a method for performing the non-uniformity and bad pixel corrections in superpixels and demonstrate the performance.

Raytheon Vision Systems (RVS) has developed and demonstrated the first-ever 1280 x 720 pixel dual-band MW/LWIR focal plane arrays (FPA) to support 3rd-Generation tactical IR systems under the U.S. Army's Dual-Band FPA Manufacturing (DBFM) program. The MW/LWIR detector arrays are fabricated from MBE-grown HgCdTe triple-layer heterojunction (TLHJ) wafers. The RVS dual-band FPA architecture provides highly simultaneous temporal detection in the MWIR and LWIR bands using time-division multiplexed integration (TDMI) incorporated into the readout integrated circuit (ROIC). The TDMI ROIC incorporates a high degree of integration and output flexibility, and supports both dual-band and single-band full-frame operating modes, as well as high-speed LWIR "window" operation at 480 Hz frame rate. The ROIC is hybridized to a two-color detector array using a single indium interconnect per pixel, which makes it highly producible for 20 μm unit cells and exploits mature fabrication processes currently used to produce single-color FPAs. High-quality 1280 x 720 MW/LWIR FPAs have been fabricated and excellent dual-band imagery produced at 60 Hz frame rate. The 1280 x 720 detector arrays for these FPAs have LWIR cutoff wavelengths ≥10.5 μm at 78K. These FPAs have demonstrated high-sensitivity at 78K with MW NETD values < 20 mK and LW NETD values <30 mK with f/3.5 apertures. Pixel operability greater than 99.9% has been achieved in the MW band and greater than 98% in the LW band.

Optical sensors aboard space vehicles designated to perform seeker functions need to generate multispectral images in the mid-wave infrared (MWIR) and long-wave infrared (LWIR) spectral regions in order to investigate and classify man-made space objects, and to distinguish them relative to the interfering scene clutter. The spectral imager part of the sensor collects spectral signatures of the observed objects in order to extract information on surface emissivity and target temperature, both important parameters for object-discrimination algorithms. The Adaptive Spectral Imager described in this paper fulfills two functions simultaneously: one output produces instantaneous two-dimensional polychromatic imagery for object acquisition and tracking, while the other output produces multispectral images for object discrimination and classification. The spectral and temporal resolution of the data produced by the spectral imager are adjustable in real time, making it possible to achieve optimum tradeoff between different sensing functions to match dynamic monitoring requirements during a mission. The system has high optical collection efficiency, with output data rates limited only by the readout speed of the detector array. The instrument has no macro-scale moving parts, and can be built in a robust, small-volume and lightweight package, suitable for integration with space vehicles. The technology is also applicable to multispectral imaging applications in diverse areas such as surveillance, agriculture, process control, and biomedical imaging, and can be adapted for use in any spectral domain from the ultraviolet (UV) to the LWIR region.

We report on bispectral imaging systems based on quantum-well infrared photodetectors (QWIPs) and InAs/GaSb type-II superlattices (SLs) for the mid-wavelength infrared spectral range between 3-5 μm (MW) and the longwavelength infrared regime at 8-12 μm (LW). A dual-band MW/LW QWIP imager and a dual-color MW/MW InAs/GaSb SL camera are demonstrated. The two systems offer a spatial resolution of 288×384 pixels and a simultaneous detection of both channels on each pixel. Both technologies achieve an excellent noise equivalent temperature difference below 30 mK in each channel with F#/2.0 optics.

A wide variety of imaging applications exist for 1K x 1K midwave infrared (MWIR) imagers and Nova's Variable Acuity Superpixel Imager (VAS^TM) technology^1,2 has now progressed to this image format. This paper will demonstrate a variety of imagery from MWIR cameras using this large format "LVASI" device; the in-pixel processing used by the LVASI cameras represents the state-of-the-art for image size, total field of view, high frame rates, low data bandwidths and real-time spatial reprogrammability of focal plane arrays (FPAs). Using these devices, imaging systems may now be implemented that permit the operator to "zoom in" to regions of interest with very high spatial resolution, while covering the remainder of the total field of view (TFOV) at conventional resolutions. The bandwidth compression attainable using these sensors helps to make possible systems that can transmit their high resolution imagery through wireless interconnected networks. We present recent infrared image data that highlight numerous applications including missile detection/tracking, search/rescue and remote surveillance applications.

This paper describes the fabrication and performance of MW and LW infrared focal plane arrays (IRFPAs) made from HgCdTe (MCT) grown by Metal Organic Vapour Phase Epitaxy (MOVPE) bump bonded to silicon read-out integrated circuits (ROICs). MOVPE of HgCdTe is possible on CdTe, CdTe:Si, GaAs or GaAs:Si substrates. When choosing the substrate an important factor is the difference in thermal expansion coefficient between the array and the ROIC; if it is large the hybrid will delaminate when cooled to its operating temperature. GaAs:Si substrates provide a simple solution to the thermal stress problem so these were used initially and several hundred MW 640x512 arrays were made. The NETDs were in the range 10 to 14 mK and the defect levels could be as low as 0.1%. However, HgCdTe grown on GaAs:Si suffers to varying degrees from short-range non-uniformity in cut-off wavelength and the ability of these devices to withstand storage at elevated temperatures is also variable. Recently, the thermal stress problem for arrays on GaAs substrates has been solved and small quantities of MW and LW arrays have been made; they have excellent uniformity and bake stability. For MW 384x288 arrays with a cut-off wavelength of 4.95 μm the NETD is in the range 15 to 18 mK and the defect level can be as low as 0.05%. For LW 320x256 arrays with a cut-off wavelength of 10.0 μm the NETD is in the range 20 to 25 mK and the defect level can be as low as 1.3%. These devices will withstand temperature excursions up to 70°C and higher while in storage. The ability of the devices to withstand temperature cycling is being assessed. A 384x288 array has survived 1800 cycles between room temperature and 80 K with no change in performance. Thus GaAs is the preferred low cost substrate for MOVPE growth of HgCdTe.

At the Army Research Laboratory (ARL), a new ternary semiconductor system CdSe_xTe_1-x/Si(211) is being investigated as an alternative substrate to bulk-grown CdZnTe substrates for HgCdTe growth by molecular beam epitaxy. Under optimized conditions, best layers show surface defect density less than 400 cm^-2 and full width at half maximum of X-ray double crystal rocking curve as low as 100 arc-sec with excellent uniformity over 3 inch area. LW-HgCdTe layers on these compliant substrates exhibit comparable electrical properties to those grown on bulk CZT substrates. Photovoltaic devices fabricated on these LWIR material shows diffusion limited performance at 78K indicating high quality material. Measured R_oA at 78K on λ_co = 10 μm material is on the order of 340 Ω-cm₂. In addition to single devices, we have fabricated 256x256 2-D arrays with 40 μm pixel pitch on LW-HgCdTe grown on Si compliant substrates. Data shows excellent QE operability of 99% at 78K under a tactical background flux of 6.7x10¹⁵ ph/cm²sec. Most probable dark current at the peak distribution is 5.5 x 10⁹ e-/sec and is very much consistent with the measured R_oA values from single devices. Initial results indicate NETD of 33 mK for a cut-off wavelength of 10 μm with 40 micron pixels size. This work demonstrates CdSe_xTe_1-x/Si(211) substrates provides a potential road map to more affordable, robust 3^rd generation FPAs.

The drive towards improved target recognition has led to an increasing interest in detection in more than one infrared band. Many groups have demonstrated two-color detection, typically by employing two back-to-back junctions, one for each color. In this paper we describe a method for introducing a third color via an absorber of intermediate wavelength placed between the two junctions. Electronic barriers are used to isolate this intermediate region. The design and location of the barriers in the structure are such that the barrier height is readily controlled by the applied bias, enabling the intermediate color to be turned on by applied bias. To provide the positional and doping control needed in the materials structure, MOVPE growth of MCT is used. Both FPA's hybridised to a read-out chips with switchable inputs, and test diodes for direct assessment, have been produced. This paper concentrates on the test diode assessment, as this provides the greater insight into the operation of the device. It is envisaged that such a device will be used with sequential framing of the different colors to provide quasi-temporal imaging. The successful demonstration of the 3-color concept is described.

We report on the capabilities and efficiencies made possible by placing image processing functions near or on the Focal Plane Array (FPA). Recent work in advanced near FPA signal processing has shown that it is possible to migrate many of the heretofore off focal plane image processing tasks onto the Readout Integrated Circuit (ROIC). The goals of this work are to describe and demonstrate the feasibility of "Activity Sensing" and the associated computational efficiency with this type of on FPA processing. Bottleneck reduction, intelligent information processing, and adaptive bandwidth compression are also key challenges of the next generation FPA architectures with on FPA processing. We report on the development and performance benefits expected from an Activity Sensing algorithm using recorded infrared (IR) Data from a large format 1024 × 1024 variable acuity Indium-Antimonide¹ FPA sensor.

The standard process for manufacturing mercury cadmium telluride (MCT) infrared focal plane arrays (FPAs) involves hybridising detectors onto a readout integrated circuit (ROIC). Wafer scale processing is used to fabricate both the detector arrays and the ROICs. The detectors are usually made by growing epitaxial MCT on to a suitable substrate, which is then diced and hybridised on to the ROIC. It is this hybridisation process that prevents true wafer scale production; if the MCT could be grown directly onto the ROIC, then wafer scale production of infrared FPAs could be achieved. In order to achieve this, a ROIC compatible with the growth process needs to be designed and fabricated and the growth and processing procedures modified to ensure survival of the ROIC. Medium waveband IR detector test structures have been fabricated with resistance area product of around 3x10⁴ Ω cm² at 77K. This is background limited in f/2 and demonstrates that wafer scale production is achievable.

High Performance Radiation Hardened LWIR and Multicolor Focal Plane Arrays are critical for many space applications. Reliable focal plane arrays are needed for these applications that can operate in space environment without any degradation. In this paper, we will present various LWIR and Multicolor Focal Plane architectures currently being evaluated for LWIR and Multicolor applications that include focal plane materials such as HgCdTe, PbSnTe, QWIP and other Superlattice device structures. We also present AR Coating models and experimental results on several promising multi-layer AR coatings that includes CdTe, Si₃N₄ and diamond like Carbon, that have the necessary spectral response in the 2-25 microns and are hard materials with excellent bond strength. A combination of these materials offers the potential of developing anti-reflection coatings with high optical quality with controlled physical properties.

A digital readout for a 128X128 MWIR imaging spectrometer was developed and demonstrated in a camera system. InSb detectors were hybridized to the readout and mounted in a ceramic pin grid array package. A second order MOSAD, Multiplexed OverSample A/D, is placed at each pixel on a 40 um pitch. Double metal CMOS with 0.5 um geometry was used in the readout design. The sensor is designed to operate at up to 300 ksps. At this rate, depending on decimation, achievable dynamics ranges are, 14 bits at 4 kfps, 20 bits at 1 kps and 32 bits at 30 fps. Effective well capacity reaches 10E10 electrons at 30 fps decimation. On focal plane power consumption is under 90 milliwatts. A single 3.3 volt power supply and clock source drive the sensor. All timing and controls are derived on the sensor. The sensor hybrid was demonstrated in a pour fill dewar with f 2.3 optics. A next generation design can be built on a 10 um pixel pitch with 0.13 um CMOS to support other detector materials with the same or better performance This technology was developed under a SBIR program sponsored by US Air Force, Arnold Air Force Base.

BAE Systems continues to advance the technology and performance of microbolometer-based thermal imaging modules and systems. 640x480 digital uncooled infrared focal plane arrays are in full production, illustrated by recent production line test data for two thousand focal plane arrays. This paper presents a snapshot of microbolometer technology at BAE Systems and an overview of two of the most important thermal imaging sensor programs currently in production: a family of thermal weapons sights for the United States Army and a thermal imager for the remote weapons station on the Stryker vehicle.

This paper reviews characteristics and performance of the first 640 x 480 made from amorphous silicon microbolometers with a pixel-pitch of 25 μm. The full TV format IRFPA product is then described in terms of ROIC architecture, packaging, operability and electro-optical performances. The pixel architecture profits from the low thermal time constant which characterizes the amorphous silicon technology, to design a high performance 640 x 480 array. A new read out integrated circuit structure has been specially developed for this array. High level functions like gain, windowing and image flip could be operated through a serial link to minimize the number of electrical interconnections. At a 60Hz frame rate, focal planes with NETD less than 50mK (f/1) are now achieved with low spatial fixed pattern noise after sensor gain and offset compensation. Thanks to a new pixel design and by pushing the design rules even further, a high fill factor has been kept, without the use of complex, as well as expensive, two-level structure. This new detector has been qualified for production since September 2005.

We have developed an uncooled IRFPA with a chip scale vacuum package and succeeded in obtaining excellent IR images of less than 60 mK in NETD. This package consists of a device chip and a silicon lid. The chip in this study is a 160 x 120 SOI diode IRFPA with a 25 μm pixel pitch. The size of the package is 14.5(L) x 13.5(W) x 1.2(H) mm. The gap between the device chip and the lid is controlled by the thickness of the vacuum sealing material. The lid is prepared by a wafer process and diced just before vacuum sealing. We use DLC (diamond like carbon) as the AR coat because of its high IR transmittance and high endurance in the wafer process. DLC films are deposited on both sides of the silicon lid wafer, and then a ring-shaped metal pattern for solder bonding is formed on one side of the lid wafer. Solder is mounted on the metal pattern by a molten solder ejection method. The patterned thin-film getter is formed on the lid wafer. Because of the use of patterned thin-film getter, there is no need to form a cavity on the lid to allow installation of getter or to insert a spacer between the device chip and the lid. Then the lid wafer is diced into individual lids. The device wafer and the lids are set in a vacuum chamber, which has a heater to melt the solder, so as to pair each die and lid. After pumping the chamber, the patterned thin-film getters are activated and then the lids are bonded simultaneously to the device wafer. Finally the device wafer is diced into individual chips. The measured pressure of the package is less than 0.5 Pa which is sufficient for obtaining high thermal isolation. In this technique, only the good dies in a wafer are packaged in chip scale simultaneously. Thus, a reduction in the size and cost of the package has been achieved.

RVS has made a significant breakthrough in the development of a 640 × 512 array with a unit cell size of 20μm × 20 μm and performance equivalent to that of the 25μm arrays. The successful development of this array is the first step in achieving mega-pixel formats. This FPA is designed to ultimately achieve performance near the temperature fluctuation limited NETD (<20mK, f/1, 30 Hz). The SB-300 is a highly productized readout and is designed to achieve very good sensitivity (low NETD and low spatial noise) and good dynamic range. The improved performance is through bolometer structure improvements and an innovative ROIC design. It also has a simple and flexible electrical interface which allows external electronics to be small, light, low-cost, and low-power. Almost all adjustments can be made through the serial interface; hence there is no need for external adjustable (DAC) circuitry. The improved power supply rejection helps maintain highly stable detector and strip resistor bias voltages which helps reduce spatial noise and image artifacts. We will show updated performance and imagery on these arrays, which is currently being measured at <30mK, f/1,555 30 Hz. Pixel operability is greater than 99.5% on most FPAs, where the uncorrected responsivity nonuniformity is less than 4% (sigma/mean), and time constant for these arrays was measured at <8msec. We will report detailed FPA performance results including responsivity, noise, uniformity and pixel operability. We also plan to present video imagery from the most recent FPAs. The reduction in pixel size offers several potential benefits for IR systems. For a given system resolution (IFOV) requirement, the 20 μm pixel will allow an optical volume that is 50 % the size of a 25 μm based system! We will also provide an update on the enhanced performance and yield producibility of our NVESD ManTech 640 × 480 25 μm arrays, and also show data on 25 μm arrays that have been designed for faster time constants (5 ms), while maintaining high performance. We will also show the improvement in our uncooled 320 × 240 and 640 × 480 sensor electronics in terms of reduced power and size for helmet and rifle mounted sensors.

Last year SCD presented an un-cooled detector product line based on the high-end VO_x microbolometer technology. The first PFA (BIRD384) launched was a 384x288 software configurable (to 320x240 or other) format with 25μm pitch¹. NETD values for these FPAs are better then 50mK with an F/1 aperture and 60 Hz frame rate. Since then SCD has concentrated in improving both spatial and temporal performance. In order to reduce the Residual Non-Uniformity (RNU) and increase the time span between shutter operations, SCD has incorporated various features within the FPA and supporting algorithms². Improved temporal performance was achieved by optimizing concurrently the membrane structure and ROIC electronics. SCD has demonstrated temporal NETD of ~ 20mK @ F/1 at 30Hz on a 160x120 BIRD compatible array. This figure of merit, accompanied by the superior stability and reduced power consumption, makes SCD's VOx based detectors suitable candidates for a broad range of "high-end" military and commercial applications.

Antenna-coupled microbolometers have shown characteristics that makes them a promising option for fast-frame-rate infrared-imaging applications, however commercial application of these type of devices is only possible if a substantial increase in their responsivity is achieved. Due to the fabrication requirements of these detectors the process of optimizing them becomes extremely expensive and time consuming. In this paper a finite-element-based simulation approach to optimize the design of thermally isolated microbolometers is presented and the particular case of a bowtie-coupled microbolometer on a silicon nitride membrane is analyzed. The thermal impedance simulations performed indicate that a responsivity increase of at least a factor of 6× can be obtained by optimizing the membrane shape and the materials used for the bias lines, this would lead to values of D* close to 1×10⁹ cm√Hz/W if applied to devices reported in the literature, which would close the gap between the responsivity of antenna-coupled detectors and detectors used in commercial infrared imaging systems.

We describe an uncooled IR camera that is based on a Fabry-Perot Interferometer (FPI) IR-to-visible transducer. The FPI-based IR camera converts a thermal-IR image to a video electronic image. IR radiation, emitted by an object in the scene, is imaged onto an IR-absorbing material that is located within an FPI. Spatial variations in temperature of the scene translate into corresponding temperature variations in the IR-absorbing material, forming a temperature image in the FPI. Within the FPI, the temperature variations produce variations in optical thickness for any beam of collimated visible light that is reflected from the FPI. The intensity of visible light reflected by the FPI is a function of optical thickness and thus forms an image, with thickness variations translating into intensity variations. The reflected light traverses visible optics that image the IR-absorbing material onto a visible-detector array, where the reflected light is converted into an electronic image. We will describe in detail the various sources of noise that determine the noise-equivalent temperature difference (NETD) of an FPI-based infrared camera. The dominant sources of noise are (1) shot noise in the visible-detector array and (2) temperature fluctuations (thermal noise) in the transducer. For a typical CCD array, we project a total NETD of approximately 40-50 mK for an FPI-based IR camera that is configured so that shot and thermal noise contribute approximately equally to the noise.

Although the rapid development of 2-D focal plane arrays of thermal infrared (IR) detectors has led to remarkable progress in uncooled IR imaging technology, a major limitation of these sensors is the lack of true on-chip spectral discrimination. Multi-spectral detection capabilities enable rapid, efficient and multi-dimensional scene interpretation that is especially beneficial to advanced IR imaging systems for early threat warning and target recognition applications. We propose a novel design for a monolithic micromachined array of bolometric detectors capable of multi-spectral imaging in the long-wave IR (7-14 μm) region. The central ingredient of this approach is to employ planar multi-mode antenna structures to efficiently couple incident electromagnetic radiation to a microbolometeric sensing element that is much smaller than the IR wavelength. The wavelength selectivity of such an antenna-coupled detector can be tuned by optimizing its multiple geometric parameters. We present a planar microbolometer design that can accomplish 3-color LWIR imaging with no moving parts analogous to solid-state color videography in the visible region. The proposed effort targets applications of uncooled color IR imaging where the benefits in space, power, weight and complexity will have a significant impact.

Multi-color narrow-band Salisbury Screen and Jaumann Absorbers using optimized thickness Si₃N₄ layers are designed that produce wavelength selectivity in 7~14μm wavelength band. The Jaumann Absorbers can be used as a vertically stacked pixel structure to save space and enhance resolution compared to frequency selective Salisbury Screens pixels lying in a common plane.

Performance of quantum LWIR/MWIR photo-detectors is limited by dark-thermal current. Common approach is to reduce the thermal current by cooling the devices to cryogenic temperatures, preventing dark-thermal excitation of carriers disturbing the IR detection process. Sirica presents a new approach enabling quantum IR detection at room temperature. Instead of cooling the device, the free carriers are heated. Once their temperature is much higher than that of the device material lattice, heat transfer from the cold lattice to the hot free carriers is not possible due to thermodynamic laws. Heat transfer from hot carriers to the lattice is prevented by selecting a media where free carriers remain hot for long enough time (longer than their expected recombination lifetime). Thus, the device material lattice and hot free carriers are thermodynamically uncoupled and the device appears "cool" at room temperature. The hot carriers are then excited by IR photons to generate electron-hole pairs which are further converted to visible or NIR photons detectable by commercial visible CMOS/CCD sensors, a process known as "energy up-conversion". The energy required for up conversion is provided by an external low power light source. The new media required for effective light conversion is made of all silicon-based materials and offers the following benefits: (a) essentially nonequilibrium free carriers; (b) strong free carrier absorption of IR radiation; and (c) effective visible/near IR luminescence originating from the IR excited carriers. The theoretical model underlying the device and experimental results showing photo-induced free carrier IR absorption and IR-induced photoluminescence are presented.

The design and operation of an advanced bimorph microcantilever based infrared imaging detector are presented. This technology has the potential to achieve very high sensitivities due to its inherent high responsivity and low noise sensor and detection electronics. The sensor array is composed of bimaterial, thermally sensitive microcantilever structures that are the moving elements of variable plate capacitors. The heat sensing microcantilever structures are integrated with CMOS control and amplification electronics to produce a low cost imager that is compatible with standard silicon IC foundry processing and materials. The bimorph sensor structure is fabricated using low thermal expansion, high thermal isolation silicon oxide and oxynitride materials, and a high thermal expansion aluminum alloy bimetal. The microcantilever paddle is designed to move away from the substrate at elevated imaging temperatures, leading to large modeled sensor dynamic ranges (~16 bits). A temperature coefficient of capacitance, ▵C/C, (equivalent to TCR for microbolometers) above 30% has been modeled and measured for these structures, leading to modeled NEDT < 20 mK and thermal time constants in the 5-10 msec range giving a figure-of-merit [1] NEDT.Tau = 100-200 mK.msec. The development efforts to date have focused on the fabrication of 160x120 pixel arrays with 50 micron pitch pixels. Results from detailed thermo-electro-opto-mechanical modeling of the operation of these sensors are compared with experimental measurements from various test and integrated sensor structures and arrays.

We report on the fabrication and characterization of microcantilever based uncooled focal plane array (FPA) for infrared imaging. By combining a streamlined design of microcantilever thermal transducers with a highly efficient optical readout, we minimized the fabrication complexity while achieving a competitive level of imaging performance. The microcantilever FPAs were fabricated using a straightforward fabrication process that involved only three photolithographic steps (i.e. three masks). A designed and constructed prototype of an IR imager employed a simple optical readout based on a noncoherent low-power light source. The main figures of merit of the IR imager were found to be comparable to those of uncooled MEMS infrared detectors with substantially higher degree of fabrication complexity. In particular, the NETD and the response time of the implemented MEMS IR detector were measured to be as low as 0.5K and 6 ms, respectively. The potential of the implemented designs can also be concluded from the fact that the constructed prototype enabled IR imaging of close to room temperature objects without the use of any advanced data processing. The most unique and practically valuable feature of the implemented FPAs, however, is their scalability to high resolution formats, such as 2000x2000, without progressively growing device complexity and cost.

This paper reports modeling, simulation, design and fabrication results for an uncooled MEMS capacitive thermal detector for IR focal plane array (FPA) imaging. Finite element analysis (FEA) was used to simulate the thermal and thermal-structural behaviors of the device. Sensitivity and thermal response time were simulated, as well as noise equivalent temperature difference (NETD). The detector structure consists of a suspended IR absorption/capacitive plate (100μm×100μm) made of Si₃N₄/Pt. The first section of each supporting arm has a bilayer structure, which consists of a SiO₂ layer and a thick Al layer. The arm and the plate exhibit an out of plane movement due to a bilayer effect caused by temperature rise under IR radiation. This results in a capacitive sensing signal. The second section of each arm has a SiO₂ layer and a very thin Al layer to serve as thermal isolation, as well as an electrical connection for capacitive sensing signal. A FEA parametric model was created and several key dimensions of the structure were simulated for better performance. Especially, the thicknesses of Al thermal isolation layer and bilayer were evaluated regarding sensitivity and thermal time constant. For a 0.8μm bilayer Al thickness and a 30nm isolation layer Al thickness, a simulated displacement sensitivity of 0.83nm/(pW⋅μm^-2) was achieved. Subsequent NETD calculations predicted a temperature fluctuation NETD of 3.4mK, a background fluctuation NETD of 1.0mK, a thermal-mechanical NETD of 9.2mK, a capacitive readout NETD of 7.4mK, and a total NETD of 12.3mK, with a 18.6ms thermal time constant. Following the design for the photomasks, fabrication processes were developed and the detectors were fabricated successfully.

In a previous paper presented to this SPIE forum a new technology was described which specifically addresses the high volume IR security sensor market. In the present paper, results are presented of recent research on silicon MOEMS-based resistance microbolometer technology directed towards high volume sensor manufacture. The dissertation includes the results of measurements made with an experimental sensor aimed at confirming performance predictions, including two mosaic-pixel FPA formats designed for multi-role applications. The conclusions support development of a silicon foundry compatible FPA technology using alloys of silicon as the temperature sensitive component, simple FPA packaging, and sensors units employing plastic optics and body components.

A rugged lightweight thermal weapon sight (TWS) prototype was developed at INO in collaboration with DRDC-Valcartier. This TWS model is based on uncooled bolometer technology, ultralight catadioptric optics, ruggedized mechanics and electronics, and extensive onboard processing capabilities. The TWS prototype operates in a single 8-12 μm infrared (IR) band. It is equipped with a unique lightweight athermalized catadioptric objective and a bolometric IR imager with an INO focal plane array (FPA). Microscan technology allows the use of a 160 x 120 pixel FPA with a pitch of 50 μm to achieve a 320 × 240 pixel resolution image thereby avoiding the size (larger optics) and cost (expensive IR optical components) penalties associated with the use of larger format arrays. The TWS is equipped with a miniature shutter for automatic offset calibration. Based on the operation of the FPA at 100 frames per second (fps), real-time imaging with 320 x 240 pixel resolution at 25 fps is available. This TWS is also equipped with a high resolution (857 x 600 pixels) OLED color microdisplay and an integrated wireless digital RF link. The sight has an adjustable and selectable electronic reticule or crosshair (five possible reticules) and a manual focus from 5 m to infinity standoff distance. Processing capabilities are added to introduce specific functionalities such as image inversion (black hot and white hot), image enhancement, and pixel smoothing. This TWS prototype is very lightweight (~ 1100 grams) and compact (volume of 93 cubic inches). It offers human size target detection at 800 m and recognition at 200 m (Johnson criteria). With 6 Li AA batteries, it operates continuously for 5 hours and 20 minutes at room temperature. It can operate over the temperature range of -30^oC to +40^oC and its housing is completely sealed. The TWS is adapted to weaver or Picatinny rail mounting. The overall design of the TWS prototype is based on feedbacks of users to achieve improved user-friendly (e.g. no pull-down menus and no electronic focusing) and ergonomic (e.g. locations of buttons) features.

A dual band thermal/visible weapon sight (TVWS) prototype was developed by INO in collaboration with DRDC Valcartier. The TVWS operates in the 8-12 μm infrared (IR) and 300-900 nm visible wavebands for enhanced vision capabilities in day and night operations. It is equipped with lightweight athermalized coaxial catadioptric objectives, a bolometric IR imager operating in a microscan mode providing an effective resolution of 320 x 240 pixels and a visible image intensifier of 768 x 493 pixels. The TVWS is equipped with a miniature shutter for automatic offset calibration. Real-time imaging at 30 fps is available. Both the visible and IR images can be toggled with a single touch button and displayed on an integrated color micro liquid crystal display (LCD). The TVWS also has a standard video output via a coaxial connector. An integrated wireless analog RF link can be used to send images to a remote command control. The sight has an adjustable electronic crosshair and two manual focuses from 25 m to infinity. On-board processing capabilities were added to introduce specific functionalities such as image polarity inversion (black hot/white hot) and image enhancement. This TVWS model is also very lightweight (~ 1900 grams) and compact (volume of 142 cubic inches). It offers human size target detection at 800 m and recognition at 200 m (Johnson criteria) with the IR waveband while offering the human recognition at up to 800 m with the visible waveband. The TVWS is adapted for weaver or Picatinny rail mounting.

Linear detector array formats are suitable for applications where relative motion between the detector and scene provides an intrinsic scanning mechanism, such as industrial inspection systems and satellite-based earth and planetary observation. The linear array format facilitates the introduction readout features not available in 2-D formats and when combined with low cost packaging approaches reduces sensor cost. We present two linear uncooled detector arrays based on VO_x microbolometer technology and integrated CMOS readout electronics. The IRL256B is a linear array of 256 detectors on a 52 μm pitch. It includes a parallel array of 256 reference detectors to provide coarse offset correction and substrate temperature drift compensation. The IRL512A consists of 3 parallel lines of 512 pixels on a 39 μm pitch. It is particularly well suited to multi-spectral pushbroom imaging applications. Each pixel includes active and reference detectors to reduce pixel offset, eliminate common mode power supply noise and increase immunity to chip temperature drift. All pixels are integrated in parallel and the data are output in 14-bit digital format on three parallel output buses. The microbolometer detector design can be customized for selected wavelength ranges from NIR to VLWIR. The IRL256B has been integrated in industrial thermal line-scan imagers and spectrometers and may also be employed in uncooled airborne imaging and scanned surveillance or inspection systems. The IRL512A has been selected as the baseline detector for a number of future earth observation satellite missions.

We aimed at developing a hands free type practical wearable thermography which will not hinder walking or working of the person wearing the equipment. We installed a small format camera core module, which was recently developed, into the fire fighter's helmet and incorporated image transmission function over radio to the equipment. We combined this thermography with a see-through type head mount display, and called it "Infrared Goggles". A prototype was developed for verification test of lifesaving support system in fire fighting activities.

Thermal IR imagers (bolometer arrays with resistive, ferroelectric or diode detector elements) require sophisticated circuitry to extract the signal out of the noisy background. Suitable models for circuit optimization with simulation tools like SPICE or SPECTRE are therefore inevitable. SPICE has the capability to model electrical and thermal circuits in the same model description. The models described here have a common thermal section, but differ in their electrical description. The thermal SPICE model uses a capacitor to model the thermal capacity of the sensing element, resistors for heat conductance due to radiation and along the supporting legs. The incoming radiation injects a current, as does the power dissipated in the sensor layer, resulting in a temperature rise of the sensor. Electrically the bolometer resistor is modeled via a non-linear dependent current source, changing with temperature, and emitting heat during readout. Noise is injected via dependant noise current sources, including white resistive and 1/f excess noise of the detector resistor and band limited thermal conductance noise of the detector. In the diode bolometer a non-linear temperature controlled diode model replaces the resistor. Shot and flicker noise sources are added. The pyroelectric detector is described by a non linear temperature dependant capacitor and a parallel resistor caused by dielectric losses. A chopper modulating the incoming radiation is required for signal detection.

This paper presents a new approach for compensating resistance nonuniformity of uncooled microbolometers by adjusting the bias currents of both detector and reference pixels. Contrary to conventional nonuniformity compensation circuits, this approach eliminates the need for digital-to-analog converters (DACs), which usually occupy a large area, dissipate high power, and require complicated external circuitry with high frequency data transfer to the microbolometer chip. The proposed circuit uses a feedback structure that dynamically changes the bias currents of the reference and detector pixels and does not need complicated external circuitry. A special feature of the circuit is that it provides continuous compensation for the detector and reference resistances due to temperature changes over time. The circuit is implemented in a 0.6μm 5V CMOS process and occupies an area of only 160μm × 630μm. Test results of the prototype circuit show that the circuit reduces the offset current due to resistance nonuniformity about 2.35% of its uncompensated value, i.e., an improvement of about 42.5 times is achieved, independent of the nonuniformity amount. The circuit achieves this compensation in 12μsec. Considering its simplicity and low cost, this approach is suitable for large array commercial infrared imaging systems.

The Electrophysics PV320 is a broadband thermal imaging system with several attractive features including low cost (about USD 25K including optics and software), small size, uncooled operation with a BST sensor array, spectral response from 0.6 to 14 μm, easily interchangeable warm optics, and on board USB 2.0 digital video output. In this paper we describe the technical challenges that were involved in integrating together two copies of the PV320L2Z camera variant to create an experimental dual-band IR data acquisition system for measuring targets, backgrounds, and clutter. The PV320 manufacturer-supplied software includes a user friendly, all-in-one application as well as software development kits providing camera control routines that are callable from C++, Visual Basic, and LabView. While this software works well for operating a single PV320 camera, it does not provide any direct support for simultaneously imaging with multiple cameras. The main technical issues are that the base software driver can connect to only one camera at a time and that multiple instances of the driver cannot be loaded simultaneously. Therefore, to achieve our goal of acquiring dual-band IR signatures, it was necessary to program a custom distributed algorithm capable of running two copies of the driver simultaneously on two separate computers with one PV320L2Z connected to each.

IR MWS systems enjoy full command of the protected own ship surrounding scenery by virtue of its wide field of view staring IR sensors. This paper will explore the operational benefits and technological challenges that are set by ELISRA PAWS wide FOV system infrastructure. Demonstrations will be given for variety of panoramic vision applications that are operated simultaneously with the missile detection system and are used to enhance situation awareness and support platform piloting missions.

In our previous papers, the FPGA-based processing package and the co-processor board have been introduced for numerous commercial and military applications including motion detection, optical flow, background velocimetry, and target tracking. The processing package is being continually upgraded by new point- and area-applied algorithms for a variety of real-time digital video camera systems including foveal sensors based on Nova's Variable Acuity Superpixel Imager (VASI^TM) and Large Format VASI^TM (LVASI^TM) technologies. This paper demonstrates the FPGA-based processor for high frame-rate target detection in a cluttered background using variable acuity sensors. For the 1024 x 1024 pixel LVASI^TM Focal Plane Array (FPA), the proposed target-detection algorithm increases the frame rate from 4 Hz for the full resolution mode up to 450 Hz for the foveal mode while maintaining full field of view and target-detection performances on cluttered backgrounds that are comparable with detection performances at the full resolution mode.

Proliferation and technological progress of Mid Wave Infrared (MWIR) sensors for Missile Warning Systems (MWS)^1,2 and increased sophistication of countermeasures require demanding in-flight testing. The IR sensors are becoming more sensitive for longer range of detection, the spatial resolution is improving for better target detection and identification, spectral discrimination is being introduced for lower False Alarm Rate (FAR), and the imaging frame rate is increasing for faster defensive reaction. As a result, testing a complex MWS/countermeasure system performance before deployment requires more realistic simulation of the threats in their natural backgrounds, and more accurate measurement of the radiometric output, directionality and time response of the countermeasures. Existing stimulator systems for MWS testing during R&D and production cannot reproduce the field conditions faithfully enough, so that it is possible to rely on them for the most sophisticated MWS' testing. CI has developed a unique integrated MWS/countermeasure test system for field use, composed of: i) high intensity dynamic Infrared Threat Stimulator (IRTS), based on large optics and high speed shutter for time dependent scenario construction and projection to several kilometers; ii) sensitive IR Jam Beam Radiometer (JBR) for countermeasure testing. The IRTS/JBR system tests the MWS/countermeasure combination: efficiency range, probability of detection, reaction time, and overall well functioning² can be determined in-flight through projection of threat profiles prepared in advance by the user, and through measurement of the countermeasure IR radiation output as function of time. Design, performance, and example of operation of the IRTS/JBR are described here.

SCD has developed a series of Infra Red (IR) detectors based on the well established technologies of InSb diodes and the most advanced analogue and digital signal processors. These detectors exhibit great advantages for Missile Warning System (MWS). Their special modes of operation combined with a high level of performance enable efficient optimization for MWS applications. These high-end applications require special features including large dynamic range, high frame rate, high sensitivity at low signal and dual-color detection. The first detector that was developed for MWS applications is the "Blue Fairy" detector which has 320x256 elements. After the "Blue Fairy" a new generation of digital detectors was developed, starting with "Sebastian". Sebastian is based on a novel digital Focal Plane Processor (FPP) with formats of 640×512 and 480×384 elements. A detector based on two Sebastian Focal Plane Arrays (FPAs) assembled on a single substrate with a high degree of registration provides a good dual-color solution for MWS systems. In this paper the special features and the performance of all these detectors are presented showing their advantages for MWS applications.

AIM has developed a thermal weapon sight HuntIR based on a cooled MCT 384x288 MWIR detection module combining long range battlefield surveillance and target engagement purposes. Since December 2004 the device is in service for the Germany Future Infantryman (IdZ) basic system. To satisfy the demands of the follow-up program German Future Infantryman extended system (IdZ ES) additional components like a laser range finder, digital magnetic compass and a wireless data link will be included to provide e.g. an improved hit rate by accurate range data. To reduce power consumption and increase operation time of the actual device on the one hand and give the possibility to include new components and functions a new optimized command and control electronics and image processing unit was designed using latest digital signal processors resulting in lower power consumption and higher computing power. This allows also an implementation of additional image enhancement functions. The design concept of the upgraded HuntIR is introduced together which the features of the new electronics. Additionally some new implementations will be presented concerning the existing HuntIR device like fire control for the 40mm Grenade Machine Gun made by Heckler&Koch which where possible due to the reprogrammable architecture of the design. Also an uncooled IR Imaging Module designed for use in small UAVs and short range thermal weapon sights was successfully tested in the German Army small UAV ALADIN made by EMT. After the first flight trials the design was revised to incorporate lessons learned including e.g. an athermal lens design to avoid any need of focussing. The features of the revised design will be presented.

In this paper we discuss methodologies to incorporate the effects of environments and scenarios in the testing of IRST systems. The proposed methodology is based on experience with sea based IRST trials combining the possibilities of performance assessment in required scenarios to the real performance in available coastal scenarios. For this purpose testing procedures depend strongly on accurate infrared target, background and atmosphere models. In particular, background effects can be dominating the performance in clutter conditions and can also dominate contrast values. For this purpose a maritime background model has been developed for use in test procedures. The model generates a scene image sequence containing background structure, including sea, sky, clouds, coastal and sun glint information up to a frame rate of 25 Hz.

This paper presents a study of face recognition performance as a function of light level using intensified near infrared imagery in conjunction with thermal infrared imagery. Intensification technology is the most prevalent in both civilian and military night vision equipment, and provides enough enhancement for human operators to perform standard tasks under extremely low-light conditions. We describe a comprehensive data collection effort undertaken by the authors to image subjects under carefully controlled illumination and quantify the performance of standard face recognition algorithms on visible, intensified and thermal imagery as a function of light level. Performance comparisons for automatic face recognition are reported using the standardized implementations from the CSU Face Identification Evaluation System, as well as Equinox own algorithms. The results contained in this paper should constitute the initial step for analysis and deployment of face recognition systems designed to work in low-light level conditions.

The relationships between optical point spread function, focal plane array geometries and IRST performance in terms of Pd and FAR were investigated in the past. However, specific design algorithms for extreme cases, such as that of small fill-factor arrays, were not presented to date. In this report we present a new optical design algorithm which optimizes Pd and FAR performance in a specific IRST application. Performance predictions are compared to actual hardware tests.

Image fusion of complementary broadband spectral modalities has been extensively studied for providing performance enhancements to various military applications. With the growing availability of COTS and customized video cameras that image in VIS-NIR, SWIR, MWIR and LWIR, there is a corresponding increase in the practical exploitation of different combinations of fusion between any of these respective spectrums. Equinox Corporation has been developing a unique line of products around the concept of a single unified video image fusion device that can centrally interface with a variety of input cameras and output displays, together with a suite of algorithms that support image fusion across the diversity of possible combinations of these imaging modalities. These devices are small in size, lightweight and have power consumption in the vicinity of 1.5 Watts making them easy to integrate into portable systems.

Novel tactics for carrying out military and antiterrorist operations calls for the development of a new generation of portable infrared imagers, the focal plane arrays of which are maintained at a cryogenic temperature. The rotary Stirling cryogenic engines providing for this cooling are usually mounted directly upon the light thin-walled imager frame, which is used for optical alignment, mechanical stability and heat sinking. The known disadvantage of this design approach is that the wideband vibration export produced by the cooler results in structural resonances and therefore in excessive noise radiation from the above imagers. The "noisy" thermal imager may be detected from quite a long distance using acoustic equipment relying upon a high-sensitive unidirectional microphone or aurally spotted when used in a close proximity to the opponent force. As a result, aural stealth along with enhanced imagery, compact design, low power consumption and long life-times become a crucial figure of merit characterising the modern infrared imager. Achieving the desired inaudibility level is a challenging task. As a matter of fact, even the best examples of modern "should-be silent" infrared imagers are quite audible from as far as 50 meters away even when operating in a steady-state mode. The authors report on the successful effort of designing the inaudible at greater then 10 meters cryogenically cooled infrared imager complying with the stringent MIL-STD-1774D (Level II) requirements.

A Naval Infrared Search and Track (IRST) demonstrator has been developed for the UK Ministry of Defence. The system uses two staring infrared cameras and split field of view optics to provide panoramic surveillance of the horizon and has real time processing for detection and tracking. The fusion of IRST and radar sensors offers an improvement in tracking due to their complementary nature. The benefit of integrating an IRST with other sensors has been assessed with simulated and real trials data. The high fidelity simulation begins with infrared scene rendering, followed by addition of targets, atmospheric effects, sensor characteristics and ends with plot extraction. This paper describes the simulation and compares the results with real data gathered with the IRST demonstrator.

This paper is intended to present firstly the current status at AIM on quantum well (QWIP) and antimonide superlattices (SL) detection modules for multi spectral ground and airborne applications in the high performance range i.e. for missile approach warning systems and secondly presents possibilities with long linear arrays i.e. 576x7 MCT to measure spectral selective in the 2 - 11μm wavelength range. QWIP and antimonide based superlattice (SL) modules are developed and produced in a work share between AIM and the Fraunhofer Institute for Applied Solid State Physics (IAF). The sensitive layers are manufactured by the IAF, hybridized and integrated to IDCA or camera level by AIM. In case of MCT based modules, all steps are done by AIM. QWIP dual band or dual color detectors provide good resolution as long as integration times in the order of 5-10ms can be tolerated. This is acceptable for all applications where no fast motions of the platform or the targets are to be expected. For spectral selective detection, a QWIP detector combining 3-5 μm (MWIR) and 8-10 μm (LWIR) detection in each pixel with coincident integration has been developed in a 384x288x2 format with 40 μm pitch. Excellent thermal resolution with NETD < 30 mK @ F/2, 6.8 ms for both peak wavelengths (4.8 μm and 8.0 μm) has been achieved. Thanks to the well established QWIP technology, the pixel outage rates even in these complex structures are well below 0.5% in both bands. The spectral cross talk between the two wavelength bands is equal or less than 1%. The substrate on the sensitive layer of the FPA was completely removed in this case and as a consequence the optical crosstalk in the array usually observed in QWIP arrays resulting in low MTF values was suppressed resulting in sharp image impression. For rapidly changing scenes - like e.g. in case of missile warning applications for airborne platforms - a material system with higher quantum efficiency is required to limit integration times to typically 1ms. AIM and IAF selected antimonide based type II superlattices (SL) for such kind of applications. The type II SL technology provides - similar to QWIPs - an accurate engineering of sensitive layers by MBE with very good homogeneity and potentially good yield and resistivity against high temperature application i.e. under processing or storage. While promising results on single SL pixels have been reported since many years, so far no SL based detection module could be realized with reasonable performances. IAF and AIM last year managed to realize first most promising SL based detectors. Fully integrated IDCAs with a MWIR SL single color device with 256x256 pixels in 40 μm pitch have been integrated and tested. In the next step the pitch was reduced to 24μm in a 384x288 pixel configuration. With this design and further improved technology a very good pixel operabilities with very low cluster sizes (≤ 4 pixel) and performances with quantum efficiencies as high as known from MCT is reached in the meantime. A dual color device based on SL technology on the existing 384x288 read-out circuit (ROIC) as used in the dual band QWIP device is available. It combines spectral selective detection in the 3-4.1 μm wavelength range and 4.1-5 μm wavelength range in each pixel with coincident integration in a 384x288x2 format and 40 μm pitch. Excellent thermal resolution with NETD < 17 mK @ F/2, 2.8 ms for the longer wavelength range (red band) and NETD < 30 mK @ F/2, 2.8 ms for the shorter wavelength range (blue band) has been achieved. The pixel outage rates remains below 1% in both colors. The spectral cross talk of the red band to the blue band is estimated below 1%o which is important to reduce significantly the false alarm rate in missile approach warning systems as the primarily intended use of the dual color detector is. Real time analysis of gases, i.e. the detection of toxic or agent gases, by multi spectral detection in the IR used the characteristic infrared emission or absorption lines of different gas types. Spectroscopic systems consisting of a spectrometer with the need for large linear MCT array with small pixel sizes are used in this case. Possibilities are outlined to use long linear arrays, such as the 576x7 MCT detector, to perform spectral selective measurements in the 2-11μm wavelength range. For these applications a 576x7 MCT FPA is integrated in an open dewar cooler assy without window able to operate directly coupled in an evacuated and cooled spectrometer. The sensitivity of the array is consequently not limited by the transmission of a window for vacuum conservation in the full sensitive wavelength range of MCT up to the cut-off of 10.5 μm.

Quantitative phase imaging generates the refractive and thickness structure of transparent samples in transmission light microscopy. It is a method that utilises the fact that a phase distribution in one plane has visible outcomes on the intensity of the wave as it propagates. This paper shows equivalent shape imaging results appear possible for through-focal stacks in reflection microscope imaging. Comparison is made to the transmission formulation and images to show the appropriateness of the results.

Single and multi-sensor imaging systems are being improved every day through the use of image processing, but there are limits to what software can do alone. The capabilities of image processing software can be improved by careful design of the optical and mechanical components of the imaging system. This paper explores the interaction between opto-mechanical design and real-time image processing for airborne imaging systems. We discuss the design of components for multiple imager systems to support both visual and assisted target recognition applications. Critical concepts include boresight alignment, low distortion optics, and pixel matching across multiple imagers for both image fusion and multi-spectral target detection. Incorporation of these concepts into our latest designs has enhanced both image quality and the effectiveness of our imaging systems. In this paper, we discuss opto-mechanical design considerations for individual cameras and look at the tradeoffs between mechanical and software design for providing effective imagery from multiple cameras.

Emerging applications in Defense and Security require sensors with state-of-the-art sensitivity and capabilities. Among these sensors, the imaging spectrometer is an instrument yielding a large amount of rich information about the measured scene. Standoff detection, identification and quantification of chemicals in the gaseous state are fundamental needs in several fields of applications. Imaging spectrometers have unmatched capabilities to meet the requirements of these applications. Telops has developed the FIRST, a LWIR hyperspectral imager. The FIRST is based on FTIR technology to yield high spectral resolution and to enable high accuracy radiometric calibration. The FIRST, a man portable sensor, provides datacubes of up to 320x256 pixels at 0.35 mrad spatial resolution over the 8-12 μm spectral range at spectral resolutions of up to 0.25 cm^-1. The FIRST has been used in several field measurements, including demonstration of standoff chemical agent detection. One key feature of the FIRST is its ability to give calibrated measurements. The quality of the radiometric and spectral calibration will be presented in this paper. During the field measurements, the FIRST operated under changing environmental conditions while many calibration measurements were taken. In this paper, we will present the stability of the calibration of the FIRST obtained during the field campaigns.

Northrop Grumman Space Technology (NGST) completed building and testing its Long Wave Hyperspectral Imaging Spectrometer (LWHIS) at the end of 2003. The instrument is a pushbroom sensor that operates in the 8 to 12.5 micron band, providing up to 256 contiguous spectral channels with 35 nm of dispersion per pixel. LWHIS was designed to operate from both ground and airborne platforms and to meet rigorous requirements for instrument performance and calibration. Since its completion, the instrument has undergone laboratory performance validation and has taken part in a number of ground and airborne imaging experiments. These experiments have led to system upgrades which have significantly improved the instrument's performance. This paper will describe the current LWHIS system, including upgrades, data correction and calibration processes, data processing rates, and demonstrate system performance using gas release experiments conducted at ground level.

This paper describes an experimental study of the use of thermal infrared (8 - 12μm) imaging applied to the problem of pedestrian tracking. Generally it was found that infrared images enable better image segmentation, but their tracking performance with current algorithms is poorer. Simple fusion of both types of images has produced some improvement in the segmentation step of the tracking algorithms. In addition to the specific experimental results, this paper also provides a useful set of practical factors that need to be taken into account when using thermal infrared imaging for surveillance applications under real-world conditions.

We present a new real time algorithm for the GPS/INS bias error estimation in aerial platform motion using real time imagery data. The proposed techniques are based on the time-sequential aerial images features matching and digital terrain map information. The main idea of the algorithm is inspired by the optical flow method. The algorithm allows to increase target detection probability and accuracy of the targets tracking.

Panoramic cameras offer true real-time, 360-degree coverage of the surrounding area, valuable for a variety of defense and security applications, including force protection, asset protection, asset control, security including port security, perimeter security, video surveillance, border control, airport security, coastguard operations, search and rescue, intrusion detection, and many others. Automatic detection, location, and tracking of targets outside protected area ensures maximum protection and at the same time reduces the workload on personnel, increases reliability and confidence of target detection, and enables both man-in-the-loop and fully automated system operation. Thermal imaging provides the benefits of all-weather, 24-hour day/night operation with no downtime. In addition, thermal signatures of different target types facilitate better classification, beyond the limits set by camera's spatial resolution. The useful range of catadioptric panoramic cameras is affected by their limited resolution. In many existing systems the resolution is optics-limited. Reflectors customarily used in catadioptric imagers introduce aberrations that may become significant at large camera apertures, such as required in low-light and thermal imaging. Advantages of panoramic imagers with high image resolution include increased area coverage with fewer cameras, instantaneous full horizon detection, location and tracking of multiple targets simultaneously, extended range, and others. The Automatic Panoramic Thermal Integrated Sensor (APTIS), being jointly developed by Applied Science Innovative, Inc. (ASI) and the Armament Research, Development and Engineering Center (ARDEC) combines the strengths of improved, high-resolution panoramic optics with thermal imaging in the 8 - 14 micron spectral range, leveraged by intelligent video processing for automated detection, location, and tracking of moving targets. The work in progress supports the Future Combat Systems (FCS) and the Intelligent Munitions Systems (IMS). The APTIS is anticipated to operate as an intelligent node in a wireless network of multifunctional nodes that work together to serve in a wide range of applications of homeland security, as well as serve the Army in tasks of improved situational awareness (SA) in defense and offensive operations, and as a sensor node in tactical Intelligence Surveillance Reconnaissance (ISR). The novel ViperView^TM high-resolution panoramic thermal imager is the heart of the APTIS system. It features an aberration-corrected omnidirectional imager with small optics designed to match the resolution of a 640x480 pixels IR camera with improved image quality for longer range target detection, classification, and tracking. The same approach is applicable to panoramic cameras working in the visible spectral range. Other components of the ATPIS system include network communications, advanced power management, and wakeup capability. Recent developments include image processing, optical design being expanded into the visible spectral range, and wireless communications design. This paper describes the development status of the APTIS system.

The possibility to grow HgCdTe by Molecular Beam Epitaxy (MBE) on large alternative substrates opens the way of increasing the size and reducing the cost of infrared FPAs operating in the Medium Wave InfraRed (MWIR) bands. Germanium was chosen several years ago at Leti because its 'in situ' and 'ex situ' surface preparations are much easier to control compared to the more conventionally used silicon alternative substrate. Moreover extremely high quality germanium "epiready" substrates are commercially available at a reasonable cost for wafer sizes up to 8 inches. MWIR HgCdTe wafers grown today by Defir (LETI/Sofradir joint laboratory) on germanium (up to 4 inches diameter) using MBE, exhibit electrical and physical properties that enables the fabrication of FPAs with various sizes (320×256, 640×512, 1280×1024) and pitches (from 30μm to 15μm) with electro-optical performances similar to the standard process based on the more conventional epilayers of HgCdTe grown on CdZnTe by Liquid Phase Epitaxy (LPE). Due to the low microscopic and macroscopic defect density that can be obtained on such wafers, operabilities above 99.9% are reached today. A status of this MBE growth technology is presented as well as the FPAs performances, including conventional industrial products manufactured such as 320×256 (pitch 30μm), 640×512 (pitch 15μm) and the largest 1280×1024 (pitch of 15μm) more recently available.

Exposure of p-type HgCdTe material to H2-based plasma is known to result in p-to-n conductivity type conversion. While this phenomenon is generally undesirable when aiming to perform physical etching for device delineation and electrical isolation, it can be utilized in a novel process for formation of n-on-p junctions. The properties of this n-type converted material are dependent on the condition of the plasma to which it is exposed. This paper investigates the effect of varying the plasma process parameters in an inductively coupled plasma reactive ion etching (ICPRIE) tool on the carrier transport properties of the p-to-n type converted material. Quantitative mobility spectrum analysis of variable-field Hall and resistivity data has been used to extract the carrier transport properties. In the parameter space investigated, the n-type converted layer carrier transport properties and depth have been found to be most sensitive to the plasma process pressure and temperature. The levels of both RIE and ICP power have also been found to have a significant influence.

DRS uses LPE-grown SWIR, MWIR and LWIR HgCdTe material to fabricate High-Density Vertically Integrated Photodiode (HDVIP) architecture detectors. 2.5 μm, 5.3 μm and 10.5 μm cutoff detectors have been fabricated into linear arrays as technology demonstrations targeting remote sensing programs. This paper presents 320 x 6 array configuration technology demonstrations' performance of HDVIP HgCdTe detectors and single detector noise data. The single detector data are acquired from within the 320 x 6 array. Within the arrays, the detector size is 40 μm x 50 μm. The MWIR detector array has a mean quantum efficiency of 89.2% with a standard deviation to mean ratio, σ/μ = 1.51%. The integration time for the focal plane array (FPA) measurements is 1.76 ms with a frame rate of 557.7 Hz. Operability values exceeding 99.5% have been obtained. The LWIR arrays measured at 60 K had high operability with only ~ 3% of the detectors having out of family response. Using the best detector select (BDS) feature in the read out integrated circuit (ROIC), a feature that picks out the best detector in every row of six detectors, a 320 x 1 array with 100% operability is obtained. For the 320 x 1 array constituted using the BDS feature, a 100% operable LWIR array with average NEI value of 1.94 x 10¹¹ ph/cm ²/s at a flux of 7.0 x 10¹⁴ ph/cm²/s has been demonstrated. Noise was measured at 60 K and 50 mV reverse bias on a column of 320 diodes from a 320 x 6 LWIR array. Integration time for the measurement was 1.76 ms. Output voltage for the detectors was sampled every 100^th frame. 32,768 frames of time series data were collected for a total record length of 98 minutes. The frame average for a number of detectors was subtracted from each detector to correct for temperature drift and any common-mode noise. The corrected time series data was Fourier transformed to obtain the noise spectral density as a function of frequency. Since the total time for collecting the 32,768 time data series points is 98.0 minutes, the minimum frequency is 170 μHz. A least squares fit of the form (A/f + B) is made to the noise spectral density data to extract coefficients A and B that relate to the 1/f and white noise of the detector respectively. In addition noise measurements were also acquired on columns of SWIR detectors. Measurements were made under illuminated conditions at 4 mV and 50 mV reverse bias and under dark conditions at 50 mV reverse bias. The total collection time for the SWIR detectors was 47.7 minutes. The detectors are white noise limited down to ~10 mHz under dark conditions and down to ~ 100 mHz under illuminated conditions.

At present, infrared photodetectors are being increasingly used in space systems, where they are exposed to the space radiation environment. Consequently, the radiation-hardness-related problem in HgCdTe photodetectors has become a critical issue. In this study, the gamma radiation effects on ZnS- and CdTe-passivated mid-wavelength infrared (MWIR) HgCdTe photodiodes were investigated. Although ZnS has an excellent insulating property, its radiation-tolerant property was revealed very poor in comparison with CdTe. After 1 Mrad of gamma irradiation, the resistance-area product at zero bias (R₀A) value of the ZnS-passivated photodiode was drastically reduced by roughly 5 orders from ~10⁷ Ω cm² to 10² Ω cm², whereas the CdTe-passivated photodiode showed no degradation in R₀A values.

Resonant cavity enhanced HgCdTe structures have been grown by molecular beam epitaxy, and photoconductors have been modelled and fabricated based on these structures. Responsivity has been measured and shows a peak responsivity of 8 x 10⁴ V/W for a 50 X 50 μm² photoconductor at a temperature of 200K. The measured responsivity shows good agreement with the modelled responsivity across the mid-wave infrared window (3-5μm). The measured responsivity is limited by surface recombination, which limits the effective lifetime to ~15ns. The optical cut-off of the detector varies with temperature as modelled from 5.1 um at 80K to 4.4 um at 250K. There is strong agreement between modelled and measured peak responsivity as a function of temperature from 80-300K.

Umicore IR Glass has developed an industrial process to manufacture low cost chalcogenide glasses. These materials called GASIR® are transparent in the 3-5 and 8-12 μm atmospheric windows which allows to use them in all the sensing and thermal imaging applications where Germanium and ZnSe usually stands. During the past 5 years, Umicore has developed and produced with and for its customers various GASIR ® optics in low and medium volume for military and civilian applications. But from the beginning of last year, the company is also very active in the automotive market. For that reason, a huge work of development on optics quality has been done to comply with automotive requests. Umicore's GASIR ® optics are used for instance in the night vision system that BMW launched in September 2005 on its 7-series. This system which will be described in this paper was developed by Umicore's customer, automotive TIER1 producer Autoliv.

This paper presents the design, analysis, and fabrication of a telecentric f/1.3 thermal imaging lens. The 14.8 mm wideangle lens provides a 62° diagonal field-of-view, and was designed to operate over the 8-14 μm infrared spectral band. Focus can be manually adjusted from 0.5 m to infinity, maintaining constant image quality over the entire range. A compact air-spaced doublet design limits the overall length to 34 mm and the maximum diameter to 28 mm. Lens materials were chosen to minimize chromatic aberrations, reduce cost, and fit within the molded chalcogenide glass manufacturing capabilities. Combining a molded aspheric chalcogenide lens with a polished spherical Germanium lens eliminated the need for a diffractive surface to correct chromatic aberrations, and reduced the fabrication cost. Vignetting was purposely introduced at the extreme fields to compensate for the effects of aberrations on the relative illumination variation across the field-of-view. Athermalization of the lens was achieved mechanically over the entire operating temperature range (- 40 to + 80°C).

Optical spectrometers are used in a variety of chemical and biological analytical instruments. Typically these employ a single input slit, a spectrograph, and a CCD or photodiode array for sensing. Only a few wavelengths may be of interest to the operator in many applications, due to absorption or fluorescence occurring within these specific optical regions. In the case of fluorescence, the excitation light intensity can be orders of magnitude greater than the fluorescence signal. In lieu of a detector array, a setup where a microelectromechanical system (MEMS) fabricated mirror array directs only the wavelengths of interest to a few detectors can be advantageous over sequential-readout arrayed detector systems. The MEMS mirrors and detector combination allows the desired wavelengths to be simultaneously and rapidly measured, with specialized detectors or electronics dedicated to each band. Integration time and electronic filtering may be adjusted independently, yielding better sensitivity and dynamic range. This combination is especially relevant in the infrared region, where arrayed detectors can be noisy or expensive, and arrays of dedicated amplifiers and filters are not cost effective. This paper reports on the design, fabrication, testing and control of MEMS-fabricated one-dimensional micromirror arrays for use in visible or infrared spectrometer applications. The micromirrors are fabricated using a surface micromachining process. A multiplexing method is introduced in the design to enable positioning a large number of mirrors from a few electrical inputs, which is necessary for practical applications when integrated control circuitry cannot be created on-chip with the MEMS devices. This approach also enables separate optimization of the actuation and control sections, and significantly reduces the number of drive signals required.

The Buchdahl dispersion model provides a rapidly converging polynomial form for describing the dispersion of refractive materials. Via this model, the dispersion of a material over the waveband of concern can be accurately characterized by a simple polynomial form, often out to only the second order. In this paper, the Buchdahl model is applied to hybrid refractive-diffractive achromats for both 3-5μm (MWIR) band and 8-12μm (LWIR) band. For each waveband, Buchdahl dispersion coefficients of IR materials and the diffractive optical element (DOE) are defined by optimally choosing the Buchdahl chromatic coordinate and best-fitting the Buchdahl model to the dispersion of materials and the DOE. The principles for selecting 1 to 2 IR materials combined with a DOE to produce hybrids achromatized at 3 and 4 wavelengths are discussed. A series of thin lens predesign examples are presented.

Imaging and detection systems are susceptible to detector saturation or permanent damage caused by powerful light sources or high power lasers. We propose and demonstrate a passive, solid-state threshold-triggered optical protection filter. At input power below threshold, the filter has high transmission over the whole spectral band. However, when the input power exceeds the threshold power, transmission is decreased dramatically. As opposed to fixed spectral filters, which permanently block only specific wavelengths, the wideband filter is clear at all wavelengths until it is hit by damaging light. When high incident optical power impinges on the wideband filter at a certain spot, this spot becomes permanently opaque. The wideband protection filter is fast enough to block nanosecond laser pulses.

This paper addresses the variety and impact of dispersive model variations for infrared materials and, in particular, the level to which certain optical designs are affected by this potential variation in germanium. This work offers a method for anticipating and/or minimizing the pitfalls such potential model variations may have on a candidate optical design.

Applications for imaging spectrometers are expanding to cover a broader spectral range with higher fidelity, often from the VNIR to the SWIR with one common aperture. These fore-optic systems range from short focal length refractive optics for micro-UAV platforms, to large all-reflective telescopes for surveillance systems. Off-the-shelf lenses and standard prescription telescopes typically do not have the telecentricity and color correction performance to meet foreoptic system requirements for low distortion and broadband operation. This paper evaluates several wide- and narrowfield VIS-SWIR fore-optics designs, describes the effects of fore-optics aberrations on spectrometer performance, and outlines the effects of these constraints on aperture, spectral coverage, and optimal packaging.

Optical interference notch filters shift to shorter wavelengths with increasing angles of incidence. This phenomenon restricts the filter's field of view and limits the practical application of narrow reflection notch filters. The amount of shift is inversely proportional to the effective average index of the composite film. A method of designing narrow notch optical filters with very broad field of view and controllable bandwidth is demonstrated. Because this method produces a filter that is predominantly composed of the high refractive index material, it will shift on angle less than a typical quarter-wave notch filter. Increasing the effective index of the filter also reduces the separation of S and P-polarized light with angle. This paper presents modeled and measured performance for both mid and far-infrared filters developed using this technique. Narrow notch discrete and rugate filter designs are compared.

Optical filters and windows are fundamental components of all modern infrared detectors. Their primary function consists in the transmission of the adequate portion of the electromagnetic spectrum which is to be measured by the sensor and in the rejection of undesired radiation. Therefore, the optical performance of the chosen filter has direct impact on the responsivity and on the signal-to-noise ratio of the detector. Recent developments of infrared filters optimized by JENOPTIK Laser, Optik, Systeme GmbH in accordance with several application requirements are presented. On the other hand the optical filter also represents an integral part of the opto-mechanical system of the detector set-up. Thus, for reasons of cost efficiency and higher integration it is desirable to provide the filters with additional system functionality. At JENOPTIK Laser, Optik, Systeme GmbH processes have been developed for the production of infrared filters with such enhanced functionality. On customer demand the filters may be equipped with solderable edges, structured apertures, stray light suppressing elements or other features, all of very high precision. Depending on the application both highest-efficiency and very costeffective infrared filters and windows may be realized on industrial scale. Solution examples and design options are presented.

Parameter calculations were carried out for two types of filtering devices in one of which the phenomenon of the total internal reflection was used and in the other the multibeam interference was used for the optical radiation filtering. It is expected that these devices may be suitable for imagery of objects in the given narrow spectral bands - spectral imaging (SI).

Today's warfighter requires a lightweight, high performance thermal imager for use in night and reduced visibility conditions. To fill this need, the United States Marine Corps issued requirements for a Thermal Binocular System (TBS) Long Range Thermal Imager (LRTI). The requirements dictated that the system be lightweight, but still have significant range capabilities and extended operating time on a single battery load. Kollsman, Inc. with our partner Electro-Optics Industries, Ltd. (ElOp) responded to this need with the CORAL - a third-generation, Military Off-the-Shelf (MOTS) product that required very little modification to fully meet the LRTI specification. This paper will discuss the LRTI, a successful result of size, weight and power (SWaP) tradeoffs made to ensure a lightweight, but high performance thermal imager.

Advances in infrared (IR) focal plane arrays (FPA) have steadily encroached upon the limits of technology. Larger formats, smaller detectors, and higher operability have improved performance. The next step is an FPA that accepts photons and converts them into a corresponding digital word. This advancement reduces susceptibility to electromagnetic interference (EMI) at the interface and minimizes the complexity of the downstream electronics. Attempts to integrate this function in an FPA involved technical difficulties such as increased power, low resolution, and non-linearity. Santa Barbara Focalplane has successfully developed a number of different types of digital FPAs with improved performance and lower power than equivalent analog FPAs. These FPAs have been integrated into closed-cycle dewar-cooler assemblies (IDCA) and are being shipped in production quantities.

The paper describes the newest layouts and the basic properties of pyroelectric single-element detectors and linear arrays with up to 512 responsive elements which are built on the basis of lithium tantalate. The research aimed to develop detectors with a signal-to-noise ratio that is as high as possible thereby ensuring optimum adjustment of the detectors to their planned application. Typical applications can be found in pyrometry, gas analysis, spectrometry and security technique. It is shown that special technologies (e. g., ion beam etching, absorption layers) are used to manufacture responsive elements for detectors with very high signal-to-noise ratios. For example, a specific detectivity D* (500 K; 10Hz; 1 Hz; τ_W=1) ≥ 1.5 x 10⁹ cmHz^1/2W^-1 has been obtained for single-element detectors with a responsive area of [2x2] mm². The measured peak value of the NEP for a linear array with 256 responsive elements was smaller than 0.5 nW (128 Hz). Moreover, the acceleration responsivity (disturbance variable) of the examined detectors was fundamentally reduced (factor 5) thanks to the application of new chip and detector layouts.

The existing technology for uncooled MWIR photon detectors, based on polycrystalline lead salts, is stigmatized for being a 50-year-old technology, and it has been traditionally relegated to single-element detectors and relatively small linear arrays due to the chemical deposition techniques used on the manufacturing process. Along the last 10 years, it has been developed an innovative technology based on thermal evaporation of polycrystalline PbSe in vacuum at CIDA. In this work a new 32x32 format FPA is presented. These devices, processed on 4" silicon wafers, have a pitch of 200 μm and a filling factor of 80 %. It is a remarkable fact that the manufacturing process has been optimized and adapted to high volume requirements, allowing a considerable unitary cost reduction. Preliminary calculus based on experimental processing yields show that now, as it, is possible to deliver devices with a price per unit around 1000 $. This photonic detector is sensitive to MWIR radiation with a value of detectivity around one order of magnitude higher than that of the best thermal detector, and also much faster. Taking that into account, it can be asserted without any doubt that there is a new player in the domain of very low cost IR devices.

Readout integrated circuits (ROICs) for focal plane arrays (FPAs) have become increasingly complex to meet the needs of modern infrared systems. BAE Systems has pioneered a number of advanced signal processing architectures for FPA ROICs. Demonstrated signal processing capabilities of BAE Systems FPAs include analog-to-digital conversion, offset subtraction, individual pixel automatic gain compensation, transient noise suppression, on-FPA defect deselection, reconfigurable pixels, spatial neural network processing and subframe noise averaging. BAE Systems FPA advanced signal processing is not just for demonstrations, but is used in many of their deliverable FPAs, improving real system performance.

With terrorist threats continuing to be a top concern at critical infrastructure sites, a complete detection, management, and control system is imperative for providing the confidence that the site has put all possible measures in place to prevent unthinkable disasters from occurring. When used together, powerful technologies provide complementary services from image detection through to control room decision making and can be thought of as stepping blocks in creating a highly-effective security system. By integrating the highest standard technologies at each step, the complete system is the most powerful addition to security systems: Thermal imaging is unsurpassed at detecting intruders in the dark of night and in challenging weather conditions at the sensor imaging level; Automated software detection creates an initial alert; Immersive 3D visual assessment is used for situational awareness and to manage the reaction process; Wide area command and control capabilities allow control from a remote location.

Video fields are commonly labeled "odd" and "even", depending on the order of field. Odd fields contain scan lines that correspond to the odd lines of the video frame. Even fields contain scan lines that correspond to the even lines of the video frames. One odd field and one even field are used to create a video frame. Deinterlacing algorithms convert video from the interlaced scan format to the progressive scan format. This paper presents a deinterlace metric which evaluates the performance of a deinterlacing algorithm. The metric is based on a frame processed with a deinterlacing algorithm. The described approach is a no-reference metric, meaning that the quality measure is not dependent on previously deinterlaced frames. In previous literature, the mean squared error (MSE) is frequently used as a performance metric for deinterlacing. MSE does not necessarily correlate with the effectiveness of the deinterlacing. Rather than using MSE, our metric is based on high frequency components of deinterlaced frame. We found that the metric corresponds well with subjective testing and is therefore suitable for quick qualitative characterization of deinterlaced frames.

Thales Cryogenics has presented the LSF 9599 SADA II flexure cooler in 2005. Based on Thales' well-known moving magnet flexure technology, the LSF 9599 complies with the SADA II specification with respect to performance, envelope and mass. Being the first manufacturer offering a full flexure-bearing supported cooler that fits within the SADA II envelope, Thales Cryogenics has been selected in several new (military) programs with their LSF coolers. For many of these new programs, the cooldown time requirements are more stringent than in the past, whereas at the same time size, complexity and thus thermal mass of the infrared sensor tends to increase. In order to respond to the need created by the combination of these trends, Thales Cryogenics started a development program to optimize cryogenic performance of the LSF 9599 cooler. The main goal for the development program is to reduce the cooldown time, while maintaining the SADA II compatible interface, and maintaining the robustness and proven reliability of the cooler. Within these constraints, the regenerator was further optimized using among others the experience with mixed-gauze regenerators obtained from our pulse tube research. Using the mixed gauze approach, the heat storage capacity of the regenerator is adapted as a function of the temperature profile over the regenerator, thus giving the optimum balance between heat storage capacity and pressure drop. A novel way of constructing the regenerator further decreases shuttle heat losses and other thermal losses in the regenerator. This paper describes the first results of the trade-offs and gives an overview of impact on cooldown times and efficiency figures achieved after the regenerator and displacer optimization.

Bias-dependent response of an extrinsic double-injection IR detector under irradiation from extrinsic and intrinsic responsivity spectral ranges was obtained analytically and through numerical modeling. The model includes the transient response and generation-recombination noise as well. It is shown that a great increase in current responsivity (by orders of magnitude) without essential change in detectivity can take place in the range of extrinsic responsivity for detectors on semiconductor materials with long-lifetime minority charge carriers if double-injection photodiodes are made on them instead photoconductive detectors. Field dependence of the lifetimes and mobilities of charge carriers essentially influences detector characteristics especially in the voltage range where the drift length of majority carriers is greater than the distance between the contacts. The model developed is in good agreement with experimental data obtained for n-Si:Cd, p-Ge:Au, and Ge:Hg diodes, as well as for diamond detectors of radiations. A BLIP-detection responsivity of about 2000 A/W (for a wavelength of 10 micrometers) for Ge:Hg diodes has been reached in a frequency range of 500 Hz under a background of 6 x 10¹¹ cm^-2s^-1 at a temperature of 20 K. Possibilities of optimization of detector performance are discussed. Extrinsic double-injection photodiodes and other detectors of radiations with internal gain based on double injection are reasonable to use in the systems liable to strong disturbance action, in particular to vibrations, because high responsivity can ensure higher resistance to interference.

An actively operated standoff infrared detection system was designed from commercial infrared equipment: VECTOR 22 FTIR (Bruker Optics), an external mirror and an external MCT detector. One type of experiment was done for IR detection of high explosives RDX and TNT on reflective surfaces. In the detection on surface, the samples were move to different distances and a beam of infrared light was reflect on surface in angle of ~ 0° (backward collection from surface normal). First the samples: 2 to 30 μg/cm² of high explosives TNT and RDX were characterized after depositing on stainless steel reflective surfaces using Reflection-Absorption Infrared Spectroscopy (RAIS). Then targets were moved to increasing distances: 3 to 12 feet and remote-sensed spectra were collected in active reflectance mode. The limits of detection were determined for all distances measured in both nitroexplosives. Limit of detection of 18 and 20 μg/cm² for TNT and RDX respectively in the longest distances measured.