This PDF file contains the front matter associated with SPIE Proceedings Volume 7301, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and the Conference Committee listing.

The new Target Scene Projectors (TSP) mounted to moving gimbals require a high degree of gimbal stability to prevent image blur. Higher accuracy seeker systems require a stable target scene to follow a kinetic impact scenario. A tradeoff exists between stiff, heavy gimbals and travel dynamics. High gimbal dynamics require light, low inertia gimbals and small, simple target projectors. With the lighter and smaller Target Scene Projectors, the tradeoff allows both stiff gimbals and robust dynamics with high lineof- sight accuracies. This paper compares the gimbal-pointing accuracy to the pixel cluster size of current Target Scene Projectors. This allows higher accuracy seekers to remain on target during the highly dynamic terminal phase of a mission scenario.

Flight tables can add unwanted dynamics with increased phase lag and gain attenuation to the Hardware-In-The-Loop (HWIL) simulation. By making flight tables "invisible" we reduce the effects of these unwanted dynamics on the simulation giving the simulation engineer a much clearer picture of the test unit's capabilities. Past methods[1] relied on clever servo techniques to reduce these effects. In this paper we look at the mechanical aspects of the flight table; in particular, we study the effects of using composite materials in the fabrication of the flight table gimbals. The study shows that the use of composite gimbals significantly increases the invisibility of the flight table with the potential added benefit of reduced cost.

The tests which are conducted to observe the behavior of a system in realistic operational conditions have great importance in order to determine its performance prior to the relevant field studies. These studies provide the designers with deciding on the necessary design updates and they also lead to reduce the total development cost in a significant level. In order to execute the mentioned tests, the motion simulators being able to simulate the motion characteristics of the system in a realistic environment are needed. Looking at the available simulators in the world, it is seen that different system configurations have been used in accomplishing the desired test objectives. In these systems, not only the mechanical designs differ from each other, but also the control systems are employed in various structures. In this study, the properties of widely-used motion simulators designed for infrared camera systems are evaluated with regard of the certain design issues. Also, their advantages and disadvantages are emphasized.

The characterization, calibration, and mission simulation testing of space-based, interceptor, and air-borne sensors require a continual involvement in the development and evaluation of radiometric projection technologies. Activities at Arnold Engineering Development Center (AEDC) include Hardware in the Loop (HWIL) testing with high-fidelity complex scene-projection technologies as well as improvements in the radiometric source-calibration systems. These technologies are integrated into a low cryo-vacuum (~20 K) environment. The latest scene simulation and HWIL projection technologies are being investigated that can produce desired target temperatures and target-to-sensor ranges such that sensor mission performance can be evaluated. These technologies include multiple-band source subsystems and special spectral-tailoring methods, as well as comprehensive analysis and optical properties measurements of the components involved. Emphasis areas include the development of methodologies to test wide field of view (WFOV), polarimetric, and multi/hyperspectral radiometric imaging systems.

Due to the rapid acceleration in technology and the drop in costs, the use of commercial off-the-shelf (COTS) PC-based hardware and software components for digital and hardware-in-the-loop (HWIL) simulations has increased. However, the increase in PC-based components creates new challenges for HWIL test facilities such as cost-effective hardware and software selection, system configuration and integration, performance testing, and simulation verification/validation. This paper will discuss how the Digital Video Timing Analyzer (DiViTA) installed in the Aviation and Missile Research, Development and Engineering Center (AMRDEC) provides quantitative characterization data for PC-based real-time scene generation systems. An overview of the DiViTA is provided followed by details on measurement techniques, applications, and real-world examples of system benefits.

An approach to streamline the Hardware-In-the-Loop (HWIL) simulation development process is under evaluation. With increased microprocessor speed, FPGA capacity and increased bus bandwidth over the last decade, a common interface design may be able to support a large number of HWIL interfaces that were previously custom designed interfaces. The Common HWIL approach 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 and operational labor and equipment expenses. This paper will present current results and future plans of the development.

The Aviation and Missile Research, Engineering and Development Center (AMRDEC), System Simulation and Development Directorate (SS&DD) and Redstone Technical Test Center (RTTC) have teamed together to develop a Hardware-in-the-Loop (HWIL) simulation known as the Advanced Multi-spectral Simulation Test Acceptance Resource (AMSTAR) Production Bay Test Facility. The simulation facility has the capability to simultaneously produce scenes in two spectral bands. This paper describes the Near Infrared (NIR) and Imaging Infrared capabilities of the AMSTAR Production Bay Test Facility simulation.

Hardware-in-the-Loop (HWIL) simulation is becoming increasingly important for cost-effective testing of imaging infrared systems. DSTO is developing real-time scene generation and image processing capabilities within its HWIL simulation programs, based on the application of COTS desktop PCs equipped with Graphics Processing Unit (GPU) cards, and including limited use of Field Programmable Gate Arrays (FPGAs). GPUs and FPGAs are high-performance parallel computing machines but are fundamentally different types of hardware. To determine which hardware type should be used to implement a real-time solution of a given application, a methodology is required to expose the concurrency within the problem and to structure the problem in a way that can be mapped to the hardware types. In this paper we use parallel programming patterns to compare the architectures of recent generation GPUs and FPGAs. We demonstrate the decomposition of a parallel application and its implementation on GPU and FPGA hardware and present preliminary results.

We describe the extension of our real-time scene generation software VIRSuite to include the dynamic simulation of small boats and their wakes within an ocean environment. Extensive use has been made of the programmabilty available in the current generation of GPUs. We have demonstrated that real-time simulation is feasible, even including such complexities as dynamical calculation of the boat motion, wake generation and calculation of an FFTgenerated sea state.

AMRDEC has developed real-time rendering techniques for generating a real-time dynamic physics-based high altitude wake geometric model for ablating objects re-entering the Earth's atmosphere. Computation was optimized for COTS graphics processing unit (GPU) hardware using minimal preprocessing for operating in AMRDEC's Hardware-in-the- Loop (HWIL) facility. These techniques are built around the Joint Signature Image Generator (JSIG) framework and involve a five stage render process per frame. JSIG's zoom anti-aliasing algorithms were used to preserve depth buffer information required by several of the render stages. New key features of this new modeling technique are dynamic flow field mesh generation based upon an object's arbitrary angle-of-attack and volumetric line-of-site integration. The concepts developed under this effort can be extended to other areas, such as atmospherics and cloud modeling, plume modeling, and marine effects.

U.S. Army Aviation and Missile Research, Development and Engineering Center (AMRDEC) has long been a leader in in-band high fidelity scientific scene generation. Recent efforts to harness and exploit the parallel power of the Graphics Processor Unit (GPU), for both graphics and general purpose processing, have been paramount. The emergence of sophisticated image generation software packages, such as the Common Scene Generator (CSG) and the Joint Signature Image Generator (JSIG), have lead to a sharp increase in the performance of digital simulations and signal injection and projection systems in both tactical and strategic programs. One area of missile simulations that benefits from this technology is real-time modeling of optical effects, such as seeker dome distortion, glint, blurring effects, and correcting for facility misalignment and distortion. This paper discusses the on-going research of applying convolution filters to the GPU multi-pass rendering process to compensate for spatial distortion in the optical projection path for synthetic environments.

Matched filter processing for pulse compression of phase coded waveforms is a classic method for increasing radar range measurement resolution. A generic approach for simulating high resolution range extended radar scenes in a Hardware in the Loop (HWIL) test environment is to pass the phase coded radar transmit pulse through an RF tapped delay line comprised of individually amplitude- and phase-weighted output taps. In the generic approach, the taps are closely spaced relative to time intervals equivalent to the range resolution of the compressed radar pulse. For a range-extended high resolution clutter scene, the increased number of these taps can make an analog implementation of an RF tapped delay system impractical. Engineers at the U.S. Army Aviation and Missile Research, Development and Engineering Center (AMRDEC) have addressed this problem by transferring RF tapped delay line signal operations to the digital domain. New digital tapped delay line (DTDL) systems have been designed and demonstrated which are physically compact compared to analog RF TDLs, leverage low cost FPGA and data converter technology, and may be readily expanded using open slots in a VME card cage. In initial HWIL applications, the new DTDLs have been shown to produce better dynamic range in pulse compressed range profiles than their analog TDL predecessors. This paper describes the signal requirements and system architecture for digital tapped delay lines. Implementation, performance, and HWIL simulation integration issues for AMRDEC's first generation DTDLs are addressed. The paper concludes with future requirements and plans for ongoing DTDL technology development at AMRDEC.

OPTRA is developing a two-band midwave infrared (MWIR) scene simulator based on digital micromirror device (DMD) technology; this simulator is intended for training various IR threat detection 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 include two miniature thermal sources, bandpass filters, and a dichroic beam combiner. 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 threat detection system. Performance projections support radiant intensity levels, resolution, bandwidth, and scene durations that meet the requirements for a host of IR threat detection test scenarios. The feasibility of our concept has been demonstrated through the design, build, and test of a breadboard two-band simulator. In this paper we present the design of a prototype two-band simulator which builds on our experience from the breadboard build. We describe the system level, optical, mechanical, and software/electrical designs in detail as well as system characterization and future test plans.

MIRAGE WF is the latest high definition version of the MIRAGE infrared scene projector product line from Santa Barbara Infrared Inc. (SBIR). MIRAGE WF is being developed under the Wide Format Resistive Array (WFRA) program. The WFRA development is one of several efforts within the Infrared Sensor Simulator - Preplanned Product Improvement (IRSS P3I) umbrella funded by the Central Test and Evaluation Investment Program (CTEIP) and led by the US Navy at Patuxent River, MD. Three MIRAGE WF infrared scene projection systems are being delivered as part of the WFRA program. The main differences between the MIRAGE XL (1024x1024) and MIRAGE WF are a 1536x768 emitter array and 100Hz true raster capability. The key emitter requirements that have been measured and will be discussed include: Operability, Maximum Apparent Temperature, Rise Time and Array Uniformity. Key System specifications are: 1536x768 pixels, maximum apparent temperature of 600K, maximum frame rate of 100Hz, raster and snap shot updating, radiance rise and fall time less than 5 ms and windowed mode (1024x768) operation at up to 200 Hz.

Liquid crystal spatial light modulators are emerging as a viable alternative to emitter arrays as the display engine for infrared scene projection. Some benefits of liquid crystal spatial light modulators include low cost, light weight (to enable portable test engines) flickerless scene generation with no dead pixels. Other possible advantages include high efficiency operation, scalable architecture and potential for high apparent temperature simulation. We discuss a recently developed high voltage 512x512 liquid crystal on silicon spatial light modulator. Design considerations and experimental data on device performance are presented.

Electroluminescence in the range of 7-9 μm is observed from an Sb-based type II interband quantum cascade structure. The LED structure has 30 active/injection periods. We have studied both top emitting and flip-chip mount bottom emitting LED devices. For room temperature operation, an increase, saturation and decrease in light output occur at successively higher injection currents. An increase of about ten times in light output occurs when device is operated at 77 K compared to room temperature operation. This increase is attributed to reduced Auger non-radiative recombination at lower temperatures. We varied indium mole fraction between 18-30% in the device active regions. An increase in light output is observed for lower indium mole fraction. These devices can be used for high temperature simulation in an infrared scene generation experiment.

This paper presents recent work on a VLSI-Membrane-Mirror-Light-Modulator (VLSI-MMLM) for scene projection. This prototype spatial light modulator uses a membrane-mirror atop a custom very-large-scale integration (VLSI) chip to modulate an off-chip light source. This modulator offers flickerless frame rates in excess of 100 Hertz and an array size of at least 200 x 200 pixels. The modulator achieves a high-degree of compactness and portability and offers low power operation since it uses external sources of light. Preliminary images have been projected in both the visible and midwave infrared wavebands. This paper focuses primarily on the design, development, testing and performance of the custom VLSI chip required for this application.

It is typically assumed in calibrating emitter array projection systems that the radiated spectrum is Planckian and that intervening optics attenuate the signal but do not change the spectral shape significantly. Calibrating such a system is relatively easy in that blackbody reference sources are available to calibrate the unit under test (UUT), or other sensor with similar spectral responsivity, which can then be used as a transfer standard for array calibration. In this way the projector command value required to produce the same response in the UUT as the modeled object is readily obtained. With a visible projector, this is not the case. The modeled object spectrum is often solar reflective. To calibrate using the same approach as infrared systems would require a 5800 K blackbody. Furthermore, the spectrum of the visible output in a multispectral, common boresight projection system can differ pathologically from the visible projector subsystem alone because of dichroic beam combiner characteristics. This paper describes a process developed to calibrate a visible projector in such a system without even having the UUT or spectrally equivalent surrogate available as a transfer standard.

Santa Barbara Infrared (SBIR) produces high performance resistive emitter arrays for its line of IR Scene Projectors (IRSPs). These arrays operate at frame rates up to 200 hertz. The inherent properties of the pixels can result in transitions between two temperatures that are more than the 5 millisecond frame time. Modifying the pixel drive level on a frame by frame basis can lead to improvements in the measured rise times. This paper describes a new capability developed by SBIR that improves the rise time of the pixels. It discusses the process by which array drive levels are modified to achieve quicker transitions together with test results showing improved rise time. In an example transition cited here, the risetime is reduced by more than a factor of two from 8.3 ms to 3.7 ms.

We assess the issues that need to be addressed to ensure that a resistor array infrared projector is capable of validly simulating the real world. These include control of the additional sources of blurring and aliasing arising from the presence of the projector and its associated scene generation system, nonuniformity correction, busbar robbing, spurious back reflections and narcissus. In particular, we reconfirm that a 2 × 2 projector/unit-under-test pixel mapping ratio offers a good compromise for controlling the additional blurring and aliasing, and furthermore, we demonstrate achievement of projector nonuniformity noise equivalent temperature differences (NETDs) in the 20 mK range.