This PDF file contains the front matter associated with SPIE Proceedings Volume 6942, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and the Conference Committee listing.

As seekers increase in accuracy and agility, motion simulators must advance in dynamic performance. Certain specifications have major effects in the configuration of a motion simulator. These critical specifications include bandwidth, acceleration, accuracy, axis travel, and payload size. These specifications intertwine and produce a simulator drive system (hydraulic or electric) with a specific simulator weight and facility power requirements. This paper discusses the specification characteristics, their effects on simulator configurations, and typical value ranges for a five-axis flight/target motion system. The performance boundaries of electric and hydraulic drive systems have increased due to the newer magnetic materials and the higher-pressure hydraulic systems. The higher power to weight ratios produce increased accelerations. At the same time, newer seekers and target scene projectors are smaller allowing higher simulator performance.

In an effort to comply with the increasing quest for higher dynamics and increased inertia of test units modern HWIL-systems are employing increasingly larger hydraulic actuators. A new 3-axis flight motion simulator with increased performance is reviewed. Also future trends of the HWIL-systems are discussed both for hydraulic and electric actuators. Some drawbacks of hydraulic systems, including increased acoustic noise levels and extensive service and maintenance requirements from the hydraulic power unit, limited stroke of the actuators for large systems and poor small signal performance are discussed and compared to the performance of electric actuators. Can the electric actuators advantages make up for the power density performance gap?

In the area of Ballistic Missile Defense (BMD), target engagements can traverse numerous intercept envelopes with each incorporating interceptor systems that utilize different hardware, software, and algorithmic implementations. In the area of BMD Hardware-in-the-Loop (HWIL) simulation, historical implementations have focused on the development of simulators which recreate a single "one-on-one" missile engagement, tied to a specific BMD operational envelope, with other, "many-on-many" digital simulation assets developed independently to explore various battle management and engagement coordination concepts. In developing the student-utilized Auburn University BMD HWIL simulation, a key requirement is to construct a single six-degree-of-freedom (6-DOF) simulation software application which allows student investigation, development, and modeling of guidance, control, and mission planning concepts over the entire progression of BMD intercept envelopes. In addition, the application must also support real-time data path and control provisions required by the HWIL simulation. This paper first provides an approach for implementing a "many-on-many" BMD simulation, allowing concurrent, independent simulation of boost, midcourse, and terminal phase engagements which comprise an aggregate threat scenario. This approach incorporates an object oriented design philosophy, as well as specific features of the C++ programming language. Secondly the software architecture is expanded to achieve the time-critical performance necessary to operate the real-time HWIL simulator, as well to allow external communications with distributed HWIL simulation components.

The Strategic Defense Center of the U.S. Army Aviation and Missile Research, Development and Engineering Center (AMRDEC), System Simulation and Development Directorate (SS&DD) provides modeling and simulation (M&S) tools, providing medium and hi-fi sensor stimulation, and test control frameworks to evaluate performance of integrated defense systems. These systems include hardware and software representations provided by and operated by Service Program Offices or their representatives. The representations are geographically distributed, but linked together to provide a dynamic, real-time, interactive test environment that is centrally controlled and synchronized through Global Positioning System (GPS) sources. The distributed nodes and the central control facility communicate through the Single Stimulation Framework (SSF). Operation of the SSF provides characterization and assessment of the integrated defense systems. This paper will summarize the concept, features, and functions of the SSF. The complex communications will be discussed, as well as the philosophy of stimulating the participating system components externally with consistent scenarios and truth state data that will bypass the simulation of these events by the individual participants.

A sensor system for the characterization of infrared laser radar scene projectors has been developed. Available sensor systems do not provide sufficient range resolution to evaluate the high precision LADAR projector systems developed by the U.S. Army Research, Development and Engineering Command (RDECOM) Aviation and Missile Research, Development and Engineering Center (AMRDEC). With timing precision capability to a fraction of a nanosecond, it can confirm the accuracy of simulated return pulses from a nominal range of up to 6.5 km to a resolution of 4cm. Increased range can be achieved through firmware reconfiguration. Two independent amplitude triggers measure both rise and fall time providing a judgment of pulse shape and allowing estimation of the contained energy. Each return channel can measure up to 32 returns per trigger characterizing each return pulse independently. Currently efforts include extending the capability to 8 channels. This paper outlines the development, testing, capabilities and limitations of this new sensor system.

We have developed two types of infrared scene projectors for hardware-in-the-loop testing of thermal imaging cameras such as those used by fire-fighters. In one, direct projection, images are projected directly into the camera. In the other, indirect projection, images are projected onto a diffuse screen, which is then viewed by the camera. Both projectors use a digital micromirror array as the spatial light modulator, in the form of a Micromirror Array Projection System (MAPS) engine having resolution of 800 x 600 with mirrors on a 17 micrometer pitch, aluminum-coated mirrors, and a ZnSe protective window. Fire-fighter cameras are often based upon uncooled microbolometer arrays and typically have resolutions of 320 x 240 or lower. For direct projection, we use an argon-arc source, which provides spectral radiance equivalent to a 10,000 Kelvin blackbody over the 7 micrometer to 14 micrometer wavelength range, to illuminate the micromirror array. For indirect projection, an expanded 4 watt CO₂ laser beam at a wavelength of 10.6 micrometers illuminates the micromirror array and the scene formed by the first-order diffracted light from the array is projected onto a diffuse aluminum screen. In both projectors, a well-calibrated reference camera is used to provide non-uniformity correction and brightness calibration of the projected scenes, and the fire-fighter cameras alternately view the same scenes. In this paper, we compare the two methods for this application and report on our quantitative results. Indirect projection has an advantage of being able to more easily fill the wide field of view of the fire-fighter cameras, which typically is about 50 degrees. Direct projection more efficiently utilizes the available light, which will become important in emerging multispectral and hyperspectral applications.

OPTRA is developing a two-band midwave infrared scene simulator based on digital micromirror devices (DMD). The simulator is intended for testing a number of different infrared tracking technologies. Our approach allows for the relative intensities of the two spectral bands to be varied for realistic simulations of an approaching target. The system employs a broadband IR (thermal) source whose energy is spectrally filtered via a series of bandpass filters acting as dichroic beamsplitters prior to being imaged onto two DMDs - one for each spectral band. The "on" reflected images from the two DMDs are then fused, expanded by a telescope, and transmitted towards the unit under test. The relative intensities of each spatial element of the two bands are controlled through the duty cycle of "on" versus "off" of the related micromirror. In this paper we present a breadboard design, build, and test which establishes the feasibility of our approach. A description of the opto-mechanical system is given along with radiometric performance projections. Results from breadboard testing, including maximum radiant intensity and radiant intensity resolution, and a series of simulated images are shown.

The Aviation and Missile Research, Engineering and Development Center (AMRDEC), System Simulation and Development Directorate (SS&DD) is developing a Hardware-in-the-Loop (HWIL) facility known as the Multi-spectral System Simulation (MSS). The simulation facility has the capability to simultaneously produce scenes in three spectral bands. This paper describes the Near Infrared (NIR) and Imaging Infrared capabilities of the MSS simulation.

Cyan Systems is developing a new Extremely High Temperature Projector System Technology (XTEMPS). The XTEMPS is a multispectral emitter array based upon photonic crystals, providing high radiance and tailored spectral emission in infrared (IR) bands of interest. Cyan has teamed with a state of the art MEMS fabrication facility, Sandia National Laboratories, to develop metallic photonics crystals designed for scene projection systems. Photonic crystals have improved output power efficiency when compared to broad band "graybody" emitters due to limiting the emission to narrow bands. Photonic crystal based emitter pixels have potential for higher effective radiance output, while filtering out energy in the forbidden bandgap. Cyan has developed pixel designs using a medium format RIIC from Nova Sensors that ensures high apparent output temperatures with modest drive currents, and low voltage requirement goals of < 5 V. Cyan has developed a pixel structure for high radiative efficiency of the photonic lattice, while suppressing undesired IR sidelobes. Cyan will provide XTEMPS system performance metrics and illustrate with test structures.

Polarization signature information is becoming more useful as an added discriminant in a variety of signature analysis applications. However, there are few infrared scene projection systems that provide the capability to inject target simulation images with polarization content into a seeker, or other imaging sensor. In this paper, we discuss a polarization scene generator (PSG) concept that is applicable to testing sensor systems operating in cryogenic-vacuum environments. This polarization scene generator concept demonstrator system was constructed from off-the-shelf technology using commercially available mid-wave infrared (MWIR) scene projectors based on micromirror device display technology, standard infrared polarizers, and standard IR cameras. The demonstrator system used two digital micromirror device (DMD)-based displays, each projecting orthogonal polarization states, which were then combined to generate images with pixels having independent S₁ or S₂ polarization content. This concept is robust because it is relatively unconstrained by the IR scene generators used or by the seekers tested. This paper discusses the test results of the concept demonstrator system with regard to sensitivity to misalignment, radiance mismatch, and display uniformity.

The steady-state and transient behaviors of packaged IR LED arrays have been studied via numerical simulations. The waste heat generated by LEDs must be removed through a cold plate or a cryogenic cold finger attached to the backside of the driver array. Therefore, this heat must travel across the LED array-driver interface and through the driver array. The modeling results demonstrate that the thermal resistance of these components can be significant. The steady-state temperature profiles across several configurations are used to identify the thermal bottlenecks. Transient simulations are used to quantify the rise and fall times of the IR LEDs, and the fall times can be significantly reduced by changes in the LED layout. These proposed guidelines to minimize thermal issues in LED arrays should result in better performing and more reliable IR LED arrays.

In our talk we will report on our progress toward the development of a mid-infrared interband cascade LED array. Our goal is to develop a 256 x 256 array of vertical LED emitters operating at 3.5 microns with each pixel emitting up to approximately 1mW of mid-infrared optical power. The first part of our development plan was to determine the best interband cascade LED structure for efficient generation of light. To this end we first investigated the tradeoff between operating current and voltage that is obtained when the number of cascades within the LED is varied. More cascades leads to a higher LED power versus current slope efficiency; however, this increase in slope efficiency is obtained at the cost of higher operating voltage and dissipated power. We will present the LED performance of interband cascade structures containing 18, 12, 6 and 3 cascades. We will exhibit mid-infrared output power performance versus the number of cascades, input power, the diameter of the LED mesas, and temperature. We will also present the LED output divergence properties. Our results to date indicate a significant drop in the efficiency of the emitted power for LED diameters near 50 microns and a nearly Lambertian power distribution. Our approach toward mitigating these issues will be to fabricate LED structures employing a surface passivation step to inhibit surface recombination on the LED mesa walls and to deep etch the mesa profile to create an index-guided output distribution. We intend to present these new results in our talk.

We designed and fabricated 64x64 supper lattice light emitting diode (SLED) array with peak emission wavelength of 3.8 micron. The light emission is observed from the bottom side of the device through the substrate. The CMOS driver circuit is fabricated in the 130 nm IBM 8HP SiGe process. The unit cells were designed to source up to 100mA to the LED. These unit cells can be individually addressable, and have analog drive and memory that can operate at a 1 kHz array refresh rate. We use supper lattice epitaxial active region LED structures grown on n-type GaSb substrates. After initial mesa etching and contact metal deposition, the LED array is flip chip mounted on the LCC package. The light emission is observed from the LED array by InSb focal plane MWIR camera and the apparent black body temperature is measured.

This paper is a continuation of the merging of two dynamic infrared scene projector technologies to provide a unique and innovative solution for the simulation of high dynamic temperature ranges for testing infrared imaging sensors. This paper will present some of the challenges and performance issues encountered in implementing this unique projector system into a Hardware-in-the-Loop (HWIL) simulation facility. The projection system combines the technologies of a Honeywell BRITE II extended voltage range emissive resistor array device and an optically scanned laser diode array projector (LDAP). The high apparent temperature simulations are produced from the luminescent infrared radiation emitted by the high power laser diodes. The hybrid infrared projector system is being integrated into an existing HWIL simulation facility and is used to provide real-world high radiance imagery to an imaging infrared unit under test. The performance and operation of the projector is presented demonstrating the merit and success of the hybrid approach. The high dynamic range capability simulates a 250 Kelvin apparent background temperature to 850 Kelvin maximum apparent temperature signatures. This is a large increase in radiance projection over current infrared scene projection capabilities.

AMRDEC has developed and implemented new techniques for rendering real-time 32-bit floating point energy-conserved dynamic scenes using commercial-off-the-shelf (COTS) Personal Computer (PC) based hardware and high performance nVidia Graphics Processing Units (GPU). The AMRDEC IGStudio rendering framework with the real-time Joint Scientific Image Generator (JSIG) core has been integrated into numerous AMRDEC Hardware-in-the-loop (HWIL) facilities, successfully replacing the lower fidelity legacy SGI hardware and software. JSIG uses high dynamic range unnormalized radiometric 32-bit floating point rendering through the use of GPU frame buffer objects (FBOs). A high performance nested zoom anti-aliasing (NZAA) technique was developed to address performance and geometric errors of past zoom anti-aliasing (ZAA) implementations. The NZAA capability for multi-object and occluded object representations includes: cluster ZAA, object ZAA, sub-object ZAA, and point source generation for unresolved objects. This technique has an optimal 128x128 pixel asymmetrical field-of-view zoom. The current NZAA capability supports up to 8 objects in real-time with a near future capability of increasing to a theoretical 128 objects in real-time. JSIG performs other dynamic entity effects which are applied in vertex and fragment shaders. These effects include floating point dynamic signature application, dynamic model ablation heating models, and per-material thermal emissivity rolloff interpolated on a per-pixel zoomed window basis. JSIG additionally performs full scene per-pixel effects in a post render process. These effects include real-time convolutions, optical scene corrections, per-frame calibrations, and energy distribution blur used to compensate for projector element energy limitations.

Polarization is increasingly being considered as a method of discrimination in passive sensing applications. In this paper the degree of polarization of the thermal emission from the emitter arrays of two new Santa Barbara Infrared (SBIR) micro-bolometer resistor array scene projectors was characterized at ambient temperature and at 77 K. The emitter arrays characterized were from the Large Format Resistive Array (LFRA) and the Optimized Arrays for Space-Background Infrared Simulation (OASIS) scene projectors. This paper reports the results of this testing.

The characterization, calibration, and mission simulation testing of space-based, interceptor, and airborne sensors require a continual involvement in the development and evaluation of radiometric projection technologies. Recent efforts at the Arnold Engineering Development Center (AEDC) include hardware-in-the-loop (HWIL) testing with high-fidelity, complex scene projection technologies integrated into a low-cryovacuum (~20 K) environment as well as improvements in the radiometric source calibration systems. The latest scene simulation and projection technologies are being investigated, technologies that can produce desired target temperatures and target-to-sensor ranges that will make it possible to evaluate sensor mission performance. 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. This paper discusses the implementation of such techniques at AEDC.

Resistor array infrared projector nonuniformity correction (NUC) is currently limited in fidelity. In the flood technique a fundamental limitation has been the inevitable presence of Moire fringes. In this paper, an advanced NUC procedure is described in which the Moire patterns are successfully subtracted, leading to improved levels of residual nonuniformity. It is shown that, irrespective of the projection technology, the Moire fringes exist at the unit-under-test image plane where they appear in general as sampling noise. Their control through choice of mapping ratio is discussed.

The U.S. Army Aviation and Missile Research, Development, and Engineering Center (AMRDEC) recently developed an infrared projector mounted on a flight motion simulator (FMS) that is used for hardware-in-the-loop (HWIL) testing. The initial application of this system within a HWIL environment required variations in the projected background radiance level to be very low. This paper describes the investigation into the causes of the variations in background radiance levels and the steps employed to reduce the background variance to an acceptable level. Test data collected before and after the corrective techniques are provided. The procedures discussed provide insight into the types of practical problems encountered when integrating infrared scene projector technologies into actual test facilities.

Santa Barbara InfraRed (SBIR) is producing high performance 1,024 x 1,024 Large Format Resistive emitter Arrays (LFRA) for use in the next generation of IR Scene Projectors (IRSPs). The demands of testing modern infrared imaging systems require higher temperatures and faster frame rates. New emitter pixel designs, rise time enhancement techniques and a new process for annealing arrays are being applied to continually improve performance. This paper will discuss the advances in pixel design, rise time enhancement techniques and also the process by which arrays are annealed. Test results will be discussed highlighting improvements in rise time, uniformity and reduced numbers of defective pixels.