The Space Chambers at the Arnold Engineering Development Center (AEDC) are continually exploring new
technologies to improve their characterization, calibration, and mission simulation testing capabilities for imaging
sensors. Part of this task is to develop and integrate methods to simulate high-temperature sources (on the order of 3,000
K) while maintaining the integrity of the low radiometric background within the cryovacuum chambers. The High
Temperature Source Simulator project at AEDC is exploring the use of laser diodes, LEDs, and resistive sources of
varying IR wavelengths to simulate these high-temperature sources within AEDC's Space Chambers. A brief summary
of previous work will be presented with a more detailed discussion of the recent cryospectral shift of the tested sources.
We found that the IR LEDs spectrally shift up to about 20% from their ambient center wavelength while the resistive
sources do not shift at all (as expected). Several different resistive sources as well as LEDs of varying wavelengths have
been procured and will continue to be tested.
OPTRA has developed a two-band midwave infrared (MWIR) scene projector based on digital micromirror device
(DMD) technology; the projector is intended for training various IR tracking systems that exploit the relative intensities
of two separate MWIR spectral bands. Next generation tracking systems have increasing dynamic range requirements
which current DMD-based projector test equipment is not capable of meeting. While sufficient grayscale digitization
can be achieved with current drive electronics, commensurate contrast is not currently available. It is towards this
opportunity that OPTRA has initiated a dynamic range design improvement effort.
In this paper we present our work towards the measurement and analysis of contrast limiting factors including substrate
scattering, diffraction, and flat state emissivity. We summarize the results of an analytical model which indicates the
largest contributions to background energy in the off state. We present the methodology and results from a series of
breadboard tests designed to characterize these contributions. Finally, we suggest solutions to counter these
Aimed to pursue the development of infrared scene projection technology beyond the current state-of-the-art, we
consider advantages of all-silicon bulk pixelless photonic projectors by light down conversion in comparison with
thermal emitter micromachining devices available in the market. There are several reasons for this. First, there are firm
evidences that the technology and performance of thermal emitters have already plateaued and future advances in the
field do not seem assured. Second, we show that photonic devices by light down conversion evolved from scientific
curiosity into technology poised to offer new capabilities to broadband projector applications. Finally, we demonstrate
that silicon becomes enabling material for emitting structures operating in the short, mid, and long wave IR spectral
We report a significant increase in electroluminescence from GaSb based Long-wave infrared
(LWIR) inter band cascade (IC) LED device by substrate thinning and isolating pixel from each
other. We use bottom emitting LWIR LED array for isolating each pixel by chemical etching. We
observed 300% increase in light emission power of etched device. We fabricated an IC LED device
with thirty cascade active/injection layers with InAs/Ga1-xInxSb/InAs quantum well (QW) active
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 object simulation images with polarization content into an imaging sensor. In this paper, we discuss a polarization scene generator that is applicable to testing polarimetric sensor systems. The system was originally designed for operation in cryogenic-vacuum environments to test sensors subject to cold operation. However, it is also applicable to testing warm sensors that are sensitive to polarimetric signatures. This polarization scene generator is currently designed for mid-wave infrared (MWIR) operation. It includes two table-top sparse emitter arrays with individually addressable pixels, polarizers, a beam combiner, and filters to provide flexibility in spectral content. The emitter arrays are combined to generate an output with independent linearly polarized content. The current system generates S1 polarization states, S2 polarization states, or a linear combination of the two. The concept is robust because it is relatively unconstrained by the infrared (IR) scene generators used or the sensors tested.
This paper describes recent results from the Extremely High Temperature Photonic Crystal
System Technology (XTEMPS) technology program. The XTEMPS program has developed a
Photonic Crystal (PhC) based high efficiency IR emitter array for use in the emerging generation
of wide field of view high performance scene projectors. Cyan's approach provides high
dynamic range, multispectral emission from SWIR to LWIR and is uniquely capable of
accurately simulating very realistic system spectral signatures. The PhC array is fabricated from
refractory materials to provide high radiance and long service lifetime. Cyan is teamed with
Sandia National Laboratories for design and fabrication of the emitter and with Nova sensors to
utilize their advanced Read In Integrated Circuit (RIIC). PhC based emitters show improved inband
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 non-Lambertian emission pattern puts a large fraction of the emitted energy
into a straight ahead beam. Both effects significantly boost effective radiance output. Cyan has
demonstrated pixel designs compatible with Nova's medium format RIIC, which ensures high
apparent output temperatures with modest drive currents and low operating voltages of less than
five volts. Unit cell pixel structures for high radiative efficiency have been demonstrated and
arrays using PhC optimized for up to four spectral bands have been successfully patterned and
fabricated into high yield wafers.
Liquid Crystal on Silicon micro-displays are the enabling components on a variety of commercial consumer products
including high-definition projection televisions, office projectors, camera view-finders, head-mounted displays and picoprojectors.
The use and potential application of LCOS technology in calibrated scene projectors is just beginning to be
explored. Calibrated LCOS displays and projectors have been built and demonstrated not only in the visible regime, but
also in the SWIR, MWIR and LWIR. However, LCOS devices are not only capable of modulating the intensity of a
broadband illumination source, but can also manipulate the polarization and/or phase of a laser source. This opens the
possibility of both calibrated polarization displays and holographic projection displays.
Non-uniformity correction (NUC) of emitter arrays is an important part of the calibration of an infrared scene
projector (IRSP), necessary to provide precise and artifact-free simulations. Producing an accurate and cost effective
NUC of an IRSP is a challenge due to the complexity of the NUC process and the expense of high performance, large
format infrared cameras. Previous NUC methods have typically fallen into either the sparse grid method or the flood
method. The sparse grid method gives independent measurements of each emitter pixel, however, it is time consuming
and becomes impractical for accurate measurements at low radiance levels, especially with lower performance but less
expensive cameras such as microbolometers. Flood measurements are fast and can be applied at lower radiance, but
do not allow precise measurement of the output of an individual pixel. Santa Barbara Infrared (SBIR) has developed a
hybrid approach that makes use of both methods. Sparse grid methods are used at higher radiance levels to perform an
initial NUC of the array. Then, a combination of flood and sparse grid data is used to extend the NUC to lower
radiance levels and improve the high radiance NUC through iteration. Details of the approach and results from its
application to an emitter array are presented.
The Ultra High Temperature (UHT) development program will develop, package, and deliver high temperature scene
projectors for the U.S. Government. The Infrared Scene Projector (IRSP) systems goals are to be capable of extremely
high temperatures, in excess of 2000K, as well as fast frame rates, 500 Hz, and 2 ms rise times. The current status of the
pixel design will be discussed with an emphasis on the models developed to facilitate these designs and estimate
performance prior to fabrication.
Santa Barbara Infrared (SBIR) produces high performance resistive emitter arrays for its line of IR Scene Projector
(IRSP) products. These arrays operate in modes supporting up to 400 hertz frame rates. The physical properties of the
microelectromechanical emitter pixel structures cause the transition times for temperature slewing to be well over the
2.5 milliseconds required to support 400 hertz operation. This paper expands on a study previously conducted by
SBIR to determine the maximum capability of a technique in which the pixel drive of the first frame of a commanded
transition is modified to improve transition time. This technique is referred to as overdrive and in this study it was
effective in reducing rise and fall times from as much as 6 milliseconds to 2 milliseconds.
Achieving very high apparent temperatures is a persistent goal in infrared scene projector (IRSP) design. Several
programs are currently under way to develop technologies for producing high apparent temperatures. Producing a
useful system capable of reproducing high fidelity scenes across a large range of apparent temperatures requires more
than just a high temperature source. The entire scene projection system must support the extended dynamic range of
the desired scenarios. Supporting this extended range places requirements on the rest of the system. System
resolution and non-uniformity correction (NUC) are two areas of concern in the development of a high dynamic range
IRSP. We report the results of some initial investigations into the resolution required for acceptable system
performance and the effects of moving to a higher dynamic range may put on existing NUC procedures.
Arnold Engineering Development Center (AEDC) is tasked with visible-to-LWIR imaging sensor calibration and
characterization, as well as hardware-in-the-loop (HWIL) testing with high-fidelity complex scene projection to validate
sensor mission performance. They are thus involved in the development of technologies and methodologies that are
used in space simulation chambers for such testing. These activities support a variety of program needs such as space
situational awareness (SSA). This paper provides an overview of pertinent technologies being investigated and
implemented at AEDC.
State-of-the-art hardware-in-the-loop (HWIL) test facilities have been established and in operation at the
U.S. Army's Aviation and Missile Research, Development, and Engineering Center (AMRDEC) in
McMorrow Laboratories, on Redstone Arsenal Alabama for over 37 years. These facilities have been
successfully developed and employed supporting numerous tactical and interceptor missile systems. The
AMRDEC HWIL facilities are constantly in a state state of modification and revision supporting
evolving test requirements related to increasingly complex sensor suites, guidance implementations, and
employment strategies prevalent within both existing and emerging aviation and missile programs. . This
paper surveys the role of the U.S. Army Aviation and Missile Research, Development, and Engineering
Center (AMRDEC) in the development and operation of HWIL test facilities and the implementation of
new, innovative technologies that have been integrated within facility test assets. This technology spans
both the Near IR (NIR- 1.064um) and IR (3 - 12um) and RF (2 - 95 GHz) operating ranges. The
AMRDEC HWIL facilities represent the highest degree of simulation fidelity, integrating all the major
parts of a HWIL simulation including tactical missile and seeker hardware, executive control software,
scene generation, and NIR, IR or RF scene projection systems. Successful incorporation of scene
generation and projection technologies have become a key thrust of the AMRDEC HWIL development
focus, with the intention to adapt and anticipate emerging test element requirements necessitated by future
system sensing technologies.
A new enhanced resistor array projector nonuniformity correction (NUC) process based on the flood method is
presented. It relies on precise characterisation of the projector-camera optical system. The information obtained from
the characterisation procedure is used for the rapid derivation of NUC coefficients in a minimal number of iterations.
The new NUC process benefits from using large format cameras but, in contrast to previous flood methods, it does not
depend critically on 1:1 mapping and can be performed using smaller format cameras. Other benefits are improved
handling of emitter array imperfections and sampling artefacts. The procedure is fast and alleviates camera temporal
effects such as drift. In order to further isolate the correction process from temporal effects, we have implemented a
new multi-point multi-temperature camera calibration procedure that allows the corrections to be applied in real time.
We describe our procedure and discuss other possible NUC improvement strategies.
The desired test performance parameters influence the design of a Flight Motion Simulator (FMS) and
affect its size, weight, power, electro-magnetic interference, noise, and vibration. A common desire is to
specify requirements beyond the immediate need for future test programs. This may directly affect cost and
schedule. Critical parameters that affect the FMS design are larger payload sizes, higher accuracies, and
higher dynamic requirements. This paper provides a checklist of parameters and specification tradeoffs to
be considered for the overall system performance requirements.
An approach to streamline the Hardware-In-the-Loop simulation and test process is under development. This technique
will attempt to provide a more flexible, scalable system. The overall goal of the system will be to reduce cost by
minimizing redundant development, operational labor and equipment expense. This paper will present historical progress
and current test results.