OPTRA is developing a two-band midwave infrared (MWIR) scene projector based on digital micromirror device (DMD) technology; this projector is intended for training various IR tracking systems that exploit the relative intensities of two separate MWIR spectral bands. Our approach employs two DMDs, one for each spectral band, and an efficient optical design which overlays the scenes reflected by each through a common telecentric projector lens. Other key components are miniature thermal sources and a series of spectral filters. Through the use of pulse width modulation, we are able to control the relative intensities of objects simulated by the two channels thereby enabling realistic scene simulations of various targets and projectiles approaching the tracking system. Performance projections support radiant intensity levels, resolution, bandwidth, and scene durations that meet the requirements for a host of IR tracking test scenarios. In this paper we summarize the design and build and detail the system characterization of a prototype two-band projector. System characterization results include maximum radiant intensity, radiant intensity resolution, and angular resolution. We also present a series of projected images.

The characterization, calibration, and mission simulation testing of imaging sensors require continual involvement in the development and evaluation of radiometric projection technologies. Arnold Engineering Development Center (AEDC) uses these technologies to perform hardware-in-the-loop (HWIL) testing with high-fidelity complex scene projection technologies that involve sophisticated radiometric source calibration systems to validate sensor mission performance. Testing with the National Institute of Standards and Technology (NIST) Ballistic Missile Defense Organization (BMDO) transfer radiometer (BXR) and Missile Defense Agency (MDA) transfer radiometer (MDXR) offers improved radiometric and temporal fidelity in this cold-background environment. The development of hardware and test methodologies to accommodate wide field of view (WFOV), polarimetric, and multi/hyperspectral imaging systems is being pursued to support a variety of program needs such as space situational awareness (SSA). Test techniques for the acquisition of data needed for scene generation models (solar/lunar exclusion, radiation effects, etc.) are also needed and are being sought. The extension of HWIL testing to the 7V Chamber requires the upgrade of the current satellite emulation scene generation system. This paper provides an overview of pertinent technologies being investigated and implemented at AEDC.

Recent advancements in gallium antimonide light emitting diode (LED) arrays have opened the way for the development of LED-based infrared scene projectors. Infrared LED array technology offers the opportunity for high frame rates, broad dynamic range, and high apparent temperatures. Since LEDs are narrow-band devices, relative to blackbody emitters, performance of an LED-based infrared scene projector is highly dependent on how effective and apparent temperatures are calculated in a detector system being tested. Because of this dependence, methods used to compute effective and apparent temperatures are reviewed and applied to published radiometric data from a gallium antimonide LED array. These calculations are used to investigate the effects of detector spectral response, emitter array fill factor, emitter radiant flux distribution, and detector aperture size on the apparent temperature of the LED array. This investigation leads into an analysis of the potential performance advantages and technical challenges of an LED-based infrared scene projector system.

The demand for more complex and multifunctional microsystems with enhanced performance characteristics for military applications is driving the electronics industry toward the use of best-of-breed materials and device technologies. Threedimensional (3-D) integration provides a way to build complex microsystems through bonding and interconnection of individually optimized device layers without compromising system performance and fabrication yield. Bonding of device layers can be achieved through polymer bonding or metal-metal interconnect bonding with a number of metalmetal systems. RTI has been investigating and characterizing Cu-Cu and Cu/Sn-Cu processes for high density area array imaging applications, demonstrating high yield bonding between sub-15 μm pads on large area array configurations. This paper will review recent advances in the development of high yield, large area array metal-metal interconnects which enable 3-D integration of heterogeneous materials (e.g. HgCdTe with silicon) and heterogeneous fabrication processes (e.g. infrared emitters or microbolometers with ICs) for imaging and scene projector applications.

Performing a good non-uniformity correction is a key part of achieving optimal performance from an infrared scene projector. Ideally, NUC will be performed in the same band in which the scene projector will be used. Cooled, large format MWIR cameras are readily available and have been successfully used to perform NUC, however, cooled large format LWIR cameras are not as common and are prohibitively expensive. Large format uncooled cameras are far more available and affordable, but present a range of challenges in practical use for performing NUC on an IRSP. Santa Barbara Infrared, Inc. reports progress on a continuing development program to use a microbolometer camera to perform LWIR NUC on an IRSP. Camera instability and temporal response and thermal resolution are the main difficulties. A discussion of processes developed to mitigate these issues follows.

Polarization signature information is becoming more useful as an added classifier in a variety of signature analysis applications. However, there are few infrared (IR) scene projection systems that provide the capability to inject target simulation images with polarization content into a seeker, or other imaging sensor. In a previous paper¹ we discussed experimental results for an infrared (IR) polarized scene generator (PSG) concept demonstrator. The concept demonstrator operated in ambient environmental conditions and displayed polarized scenes of resolved targets. The IR PSG demonstrator that is the goal of this research must be capable of testing sensor systems operating in cryogenic-vacuum (cryo-vac or CV) environments. The IR PSG must also be able to accurately project scenes with unresolved polarized targets. As part of the development process, several potential PSG components are being tested in ambient and liquid nitrogen (LN2) environments to verify functionality and changes in behavior at ambient, vacuum, and cryovac conditions. This paper presents test data for several of the components. Components tested were an IR source, a polarizer, and motion control components. We also present test data for an imaging polarimeter being developed to validate the PSG.

We report the IR electroluminescence in two wavelength bands, 3-4 micron (MWIR) and 8-9 micron (LWIR) regions. The epitaxial structure was grown on an n-type GaSb substrate with the MWIR quantum well (QW) region on top of LWIR QW region and a 0.5 μm contact layer grown in between the two QW regions. We measured the light emission from the top surface of the device with different grating structures. We fabricated square mesas varying from 50 to 200 microns on a side. Both room temperature and cryogenic temperature results show emission in the wavelength regions as designed.

This paper describes results from the Extremely High Temperature Photonic Crystal System Technology (XTEMPS) program. The XTEMPS program is developing projector technology based on photonic crystals capable of high dynamic range, multispectral emission from SWIR to LWIR, and realistic band widths. These Photonics Crystals (PhC) are fabricated from refractory materials to provide high radiance and long device lifetime. Cyan is teamed with Sandia National Laboratories, to develop photonics crystals designed for realistic scene projection systems and Nova sensors to utilize their advanced Read In Integrated Circuit (RIIC). PhC based emitters show improved in-band output power efficiency when compared to broad band "graybody" emitters due to the absence of out-of-band emission. Less electrical power is required to achieve high operating temperature, and the potential for nonequilibrium pumping exists. Both effects boost effective radiance output. Cyan has demonstrated pixel designs compatible with Nova's medium format RIIC, ensuring high apparent output temperatures, modest drive currents, and low operating voltages of less than five volts. Unit cell pixel structures with high radiative efficiency have been demonstrated, and arrays using PhC optimized for up to four spectral bands have been successfully patterned.

Radiometrically accurate simulation of InfraRed (IR) signatures is an essential prerequisite for valid IR sensor testing within the IR Scene Projection (IRSP) community. The Electronic Combat Stimulation (ECSTIM) Branch EO/IR Laboratory at the NAVAIR Air Combat Environment T&E Facility (ACETEF), NAWC-AD, Patuxent River, Maryland has recently begun validation testing of their Large Format Resistive-emitter Array (LFRA) IRSP. This is in preparation for developmental and operational testing of emerging mission-critical IR Countermeasure (IRCM) systems. Validation is guided by the Navy Air Defense Threat Simulator Validation Procedures Manual (NAWCWPNS TM 7489-3) and will support s other emerging high priority development programs such as the Joint Distributed IRCM Ground-test System (JDIGS). This paper discusses the ECSTIM/EO/IR Laboratory LFRA IRSP validation testing process, the resulting data collection, measurements and analysis.

The interband cascade (IC) technology is uniquely suited for fabrication of high-density 2-dimensional arrays of MWIR and LWIR emitters. In this talk, we briefly overview the fabrication and performance of MWIR Interband Cascade LED arrays and discuss the design, fabrication, and performance characteristics of vertically-emitting resonant cavity structures. We will assess the current performance of these structures for meeting the requirements of IR scene projection systems.

Recent advances in the ability to perform comprehensive ground based Infrared Countermeasure (IRCM) testing have the capability to fill the Test and Evaluation (T&E) gaps for existing and future weapons system acquisition. IRCM testing has historically been dominated and in a manner limited by expensive live fire testing requirements. While live fire testing is a vital part of IRCM T&E, next generation technological developments now enable closed-loop, ground-based IRCM testing to provide valuable complementary test data at a much lower cost. The high cost and limited assets that have prevented live fire and flight testing from providing a thorough hardware based data set required for previous T&E analysis is no longer an issue. In the past, traditional physics based digital system model (DSM) analysis has been utilized to augment the IRCM data sets to make them statistically significant. While DSM is a useful tool in the development of IRCM systems, the newly developed installed system testing utilizing a hardware-in-the-loop construct provides for an enhanced level of fidelity and assurance that the systems will meet the warfighter's needs. The goal of the newly developed test technologies is to develop a statistical significant data set utilizing hardware-in-the-loop at a significantly lower cost than historical methods.

Surface to air missile development programs typically utilize hardware-in-the-loop (HWIL) simulations when available to provide a non-destructive high volume test environment for what are typically very expensive guidance sections. The HWIL, while invaluable, hasn't been able to obviate the need for missile flight tests. Because of the great expense of these missiles the designers are only allowed to perform a fraction of the desired tests. Missile Airframe Simulation Testbed (MAST) is a program conceived by US Army Aviation and Missile Research Development and Engineering Center (AMRDEC) that blends the non-destructive nature of HWIL with the confidence gained from flight tests to expand the knowledge gained while reducing the development schedule of new missile programs.

The Army Tactical Missile System (ATACMS) has been fielded with the US Army for almost 20 years as a deep strike precision weapon, capable of engaging time critical targets at high precision under all weather conditions. This paper will describe the use of the HWIL simulation in the design of the missile, validation of the simulation, the role of the simulation in the production and test process, how the simulation is used to support system shelf life and obsolescence issues and how the simulation is used to answer critical user questions on the performance of the system.

An approach to streamline the Hardware-In-the-Loop (HWIL) simulation development process is under evaluation. This Common HWIL technique will attempt to provide a more flexible, scalable system. The overall goal of the Common HWIL system will be to reduce cost by minimizing redundant development, operational labor and equipment expense. This paper will present current results and future plans of the development.

The requirements for facility designs of flight motion simulators have mechanical, vibration, power, environmental, cooling, and access parameters to ensure a smooth installation. Preparing a facility interface plan during the initial phases of the procurement allows time to develop the installation area of the building. The coordination of the manufacturer, laboratory personnel, and facility personnel is essential to avoid installation problems. This paper provides a checklist of parameters and specification tradeoffs to be considered for the overall system and facility interface design.

Gimbal lock is a phenomenon which occurs in multi-gimbaled systems when two axes are driven into a coplanar orientation, thereby resulting in the loss of one degree of rotational freedom. This paper presents a control scheme which introduces a redundant fourth axis in conjunction with an algorithm that minimizes weighted least-square gimbal rates, ultimately permitting the use of open inner and middle gimbals to achieve a wide field of view. The control algorithm produces a singularity/gimbal lock measure which is derived using the inner three gimbals, and used to adapt the weights and transition the table from three-axis operation to four-axis operation at or near the three-axis gimbal lock orientation. Weight adaptation minimizes the peak gimbal rate required to track a vehicle reference rate profile. The control strategy also minimizes tracking errors between vehicle kinematic motion,which is obtained from the vehicle dynamics simulation, and kinematic motion induced onto the table-mounted payload. The control algorithm accepts Euler angles and body rates, as defined in the body fixed frame of reference, and generates four gimbal command sets. Each gimbal command set consists of gimbal acceleration, rate, and angle. Mathematical analysis, simulation, and 3-D CAD multi-body dynamics visualizations are included, illustrating differences between desired vehicle kinematic motion and that induced by this control strategy onto the table mounted payload, including an examination of effects due to finite gimbal control loop bandwidths.

The Low-Background Infrared (LBIR) facility at NIST has recently completed construction of an infrared transfer radiometer with an integrated cryogenic Fourier transform spectrometer (Cryo-FTS). This mobile system can be deployed to customer sites for broadband and spectral calibrations of space chambers and low-background HWIL testbeds. The Missile Defense Transfer Radiometer (MDXR) has many of the capabilities of a complete IR calibration facility and will replace our existing filter-based transfer radiometer (BXR) as the NIST standard detector deployed to MDA facilities. The MDXR features numerous improvements over the BXR, including: a cryogenic Fourier transform spectrometer, an on-board absolute cryogenic radiometer (ACR), an internal blackbody reference, and an integrated collimator. The Cryo-FTS can be used to measure high resolution spectra from 4 to 20 micrometers, using a Si:As blocked-impurity-band (BIB) detector. The on-board ACR can be used for self-calibration of the MDXR BIB as well as for absolute measurements of infrared sources. A set of filter wheels and a rotating polarizer within the MDXR allow for filter-based and polarization-sensitive measurements. The optical design of the MDXR makes both radiance and irradiance measurements possible and enables calibration of both divergent and collimated sources. Details of the various MDXR components will be presented as well as initial testing data on their performance.

The U.S. Army Research, Development and Engineering Command (AMRDEC) and Redstone Test Center (RTC) at Redstone Arsenal, Alabama have developed a Ka band, range instrumentation synthetic aperture radar (RISAR) for the purpose of millimeter wave (MMW) target and scene characterization. RISAR was developed as one element of the Advanced Multi-Spectral Sensor and Subsystem Test Capabilities (AMSSTC) program funded and managed by the U.S. Army Program Executive Office for Simulation, Training and Instrumentation (PEO STRI), Project Manager for Instrumentation, Targets and Threat Simulators (PM ITTS). The key objective of RISAR is the collection of MMW SAR data that can be used to develop high resolution target and terrain models for use in digital and real-time hardwarein- the-loop simulations. The purpose of this presentation is to provide an overview of RISAR development and implementation. Example results of funded data collections will be presented with an emphasis on the system's 3D target modeling capabilities for ground targets, and wake characterization capabilities for littoral targets.

Modern millimeter wave (mmW) radar sensor systems employ wideband transmit waveforms and efficient receiver signal processing methods for resolving accurate measurements of targets embedded in complex backgrounds. Fast Fourier Transform processing of pulse return signal samples is used to resolve range and Doppler locations, and amplitudes of scattered RF energy. Angle glint from RF scattering centers can be measured by performing monopulse arithmetic on signals resolved in both delta and sum antenna channels. Environment simulations for these sensors - including all-digital and hardware-in-the-loop (HWIL) scene generators - require fast, efficient methods for computing radar receiver input signals to support accurate simulations with acceptable execution time and computer cost. Although all-digital and HWIL simulations differ in their representations of the radar sensor (which is itself a simulation in the all-digital case), the signal computations for mmW scene modeling are closely related for both types. Engineers at the U.S. Army Aviation and Missile Research, Development and Engineering Center (AMRDEC) have developed various fast methods for computing mmW scene raw signals to support both HWIL scene projection and all-digital receiver model input signal synthesis. These methods range from high level methods of decomposing radar scenes for accurate application of spatially-dependent nonlinear scatterer phase history, to low-level methods of efficiently computing individual scatterer complex signals and single precision transcendental functions. The efficiencies of these computations are intimately tied to math and memory resources provided by computer architectures. The paper concludes with a summary of radar scene computing performance on available computer architectures, and an estimate of future growth potential for this computational performance.

We describe recent improvements in our maritime scene generation program and the extension in capabilities that has been achieved. The motion of multiple boats under independent control can now be simulated, as well as large ship motion. The effects we simulate include ocean surfaces in different sea states, the physically-realistic representation of boat and ship dynamics, wake generation and generation of surface effects including whitecaps, spray, wake trails and foam. We describe our graphical user interface tools, the underlying phenomena that they control and their application in enabling versatile real-time maritime scene simulation.

With the development and widespread availability of computer graphics cards, complex infrared scenes can now be readily generated for application in real-time hardware-in-the-loop simulations. It is important that the best efforts are made to ensure that the scenes are radiometrically valid, to the level where the operation of the imaging infrared unitunder- test can be properly emulated. In this paper we describe the techniques we employ to ensure radiometric validity within our real-time aircraft and boat simulation applications of current interest.

Hardware and software in the loop modeling of maritime environments involves a wide variety of complex physical and optical phenomenology and effects. The scale of significant effects to be modeled range from the order of centimeters for capillary type waves and turbulent wake effects up to many meters for rolling waves. In addition, wakes for boats and ships operating at a wide variety of speeds and conditions provide additional levels of scene complexity. Generating synthetic scenes for such a detailed, multi-scaled and dynamic environment in a physically realistic yet computationally tractable fashion represents a significant challenge for scene generation tools. In this paper, next generation scene generation codes utilizing personal computer (PC) graphics processors with programmable shaders as well as CUDA (Compute Unified Device Architecture) and OpenCL (Open Computing Language) implementations will be presented.

Increasing seeker frame rate and pixel count, as well as the demand for higher levels of scene fidelity, have driven scene generation software for hardware-in-the-loop (HWIL) and software-in-the-loop (SWIL) testing to higher levels of parallelization. Because modern PC graphics cards provide multiple computational cores (240 shader cores for a current NVIDIA Corporation GeForce and Quadro cards), implementation of phenomenology codes on graphics processing units (GPUs) offers significant potential for simultaneous enhancement of simulation frame rate and fidelity. To take advantage of this potential requires algorithm implementation that is structured to minimize data transfers between the central processing unit (CPU) and the GPU. In this paper, preliminary methodologies developed at the Kinetic Hardware In-The-Loop Simulator (KHILS) will be presented. Included in this paper will be various language tradeoffs between conventional shader programming, Compute Unified Device Architecture (CUDA) and Open Computing Language (OpenCL), including performance trades and possible pathways for future tool development.

The emergence of spectrally multimode smart missiles requires hardware-in-the-loop (HWIL) facilities to simulate multiple spectral signatures simultaneously. While traditional diode-pumped solid-state (DPSS) sources provide a great basic testing source for smart missiles, they typically are bulky and provide substantially more power peak power than what is required for laboratory simulation, have fixed pulse widths, and require some external means to attenuate the output power. HWIL facilities require systems capable of high speed variability of the angular divergence and optical intensity over several orders of magnitude, which is not typically provided by basic DPSS systems. In order to meet the needs of HWIL facilities, we present a low-cost semi-active laser (SAL) simulator source using laser diode sources that emits laser light at the critical wavelengths of 1064 nm and 1550 nm, along with light in the visible for alignment, from a single fiber aperture. Fiber delivery of the multi-spectral output can provide several advantages depending on the testing setup. The SAL simulator source presented is capable of providing attenuation of greater than 70 dB with a response time of a few milliseconds and provides a means to change the angular divergence over an entire dynamic range of 0.02- 6º in less than 400 ms. Further, the SAL simulator is pulse width and pulse repetition rate agile making it capable of producing both current and any future coding format necessary.

AMRDEC sought out an improved framework for real-time hardware-in-the-loop (HWIL) scene generation to provide the flexibility needed to adapt to rapidly changing hardware advancements and provide the ability to more seamlessly integrate external third party codes for Best-of-Breed real-time scene generation. As such, AMRDEC has developed Continuum, a new software architecture foundation to allow for the integration of these codes into a HWIL lab facility while enhancing existing AMRDEC HWIL scene generation codes such as the Joint Signature Image Generator (JSIG). This new real-time framework is a minimalistic modular approach based on the National Institute of Standards (NIST) Neutral Messaging Language (NML) that provides the basis for common HWIL scene generation. High speed interconnects and protocols were examined to support distributed scene generation whereby the scene graph, associated phenomenology, and resulting scene can be designed around the data rather than a framework, and the scene elements can be dynamically distributed across multiple high performance computing assets. Because of this open architecture approach, the framework facilitates scaling from a single GPU "traditional" PC scene generation system to a multi-node distributed system requiring load distribution and scene compositing across multiple high performance computing platforms. This takes advantage of the latest advancements in GPU hardware, such as NVIDIA's Tesla and Fermi architectures, providing an increased benefit in both fidelity and performance of the associated scene's phenomenology. Other features of the Continuum easily extend the use of this framework to include visualization, diagnostic, analysis, configuration, and other HWIL and all digital simulation tools.

A newly fabricated Infrared Scene Projector (IRSP) configured for the Long Wave IR (LWIR) regime has demonstrated simulated apparent temperatures exceeding 1500 oC, more than doubling the maximum temperature capability of prior pixilated scene projector devices. Since the entire array surface is capable of this high temperature output, the same device can be used to generate both the moderate temperature scene background and an unlimited number of high temperature targets in the scene, without having to optically combine a few discrete "hot spot" generators. This performance was enabled by advances in a new large pixel, high voltage, 16-bit backplane Spatial Light Modulator (SLM) coupled with an intense spectral illumination source, and special formulation liquid crystal (LC). The new LC formulation and SLM configuration also achieves an effective usable frame rate of up to 200Hz capability. Performance characterization and resulting data will be discussed in the paper.