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
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.
Proc. SPIE 7663, Effective and apparent temperature calculations and performance analysis of mid-wave infrared light emitting diodes for use in infrared scene projection, 766304 (24 April 2010); https://doi.org/10.1117/12.849754
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 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.