The Optical Systems Test Facility was established at MIT Lincoln Laboratory to support a broad scope of program areas, encompassing tactical ground-based sensors through strategic space-based sensors. The Optical Systems Test Facility comprises several separate ranges developed as a coordinated set of test sites at MIT Lincoln Laboratory. There are currently four separate ranges in the facility, an active range (Laser Radar Test Facility), a passive range (Seeker Experimental System), an aerosol range (Standoff Aerosol Active Signature Testbed) and an optical material measurements range. The active range has optical and target facilities for evaluating elements of laser radar sensors as well as complete ladar systems. It has facilities for simulating long range wavefronts and for dynamic target motions. The passive range concentrates on evaluating passive infrared sensors, with capabilities for static and dynamic scene generation in both cryogenic and room temperature environments. The aerosol range is currently configured for the measurement of both particulate and bio-agent aerosol dispersion characteristics. The optical materials measurements range started with measurement capabilities for laser radar target materials and is currently being expanded to measure both emissivity and reflectance of materials from the visible through the infrared.

The Air Force Electronic Warfare Evaluation Simulator (AFEWES) infrared countermeasures (IRCM) test facility currently has the ability to simulate a complete IRCM test environment, including IR missiles in flight, aircraft in flight, and various IR countermeasures including maneuvers, point-source flares, and lamp- and LASER-based jammer systems. The simulations of IR missiles in flight include missile seeker hardware mounted on a six degree-of-freedom flight simulation table. This paper will focus on recent developments and upgrades to the AFEWES IR capability. In particular, current developments in IR scene generation/projection and efforts to optically combine the IR image produced by a resistive array with existing foreground lamp sources.

As seekers increase in resolution and accuracy, test facilities must satisfy more stringent accuracy specifications. Besides imparting high-fidelity motion, the 5-axis flight motion table (FMS) must also report higher position accuracies to represent the true axis position. Various errors combine to form the composite position accuracy. The various errors such as axis wobble, axis orthogonality, and axis position readout are individually measured to ensure the simulator conforms to the accuracy specifications. However, it is difficult to experimentally determine the table orientation errors over the simulator motion space. The vector line from the seeker to the target - called the "pointing vector" - includes all the individual system errors. Some errors are deterministic and some are random. The generally accepted means to analyze this problem is to assume each error is independent and random. The RSS (root-sumsquared) Method of calculating the pointing error is one accepted protocol of combining random errors. This paper discusses the error sources, the error characteristics, and the typical values for a five-axis flight/target motion system.

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). The simulation facility has the capability to simultaneously produce scenes in three spectral bands. This paper describes Near Infrared (NIR) and Imaging Infrared capabilities of the AMSTAR simulation. Additionally, this paper will described briefly the ability to conduct tests in an environmentally conditioned chamber while the unit-under-test is mounted on the Flight Motion Simulator (FMS).

Target Motion Simulators (TMS) are often used in conjunction with Flight Motion Simulators (FMS) to provide a realistic simulation of tracking and target engagement. For near-field applications, the TMS has typically been implemented with two additional gimbals around the FMS. For far-field applications, such as a radar, the TMS has traditionally been implemented with curvilinear X-Y Frames. A curvilinear frame placed at the proper distance from the FMS has the benefit of always pointing the Target back to the FMS intersection of axes. In most cases the curvilinear TMS provides good results. However, the curvilinear TMS lacks the possibility to change the distance between Target and Seeker, which is needed for operation with different radar wavelengths. Acutronic has developed a new approach using a flat frame (X-Y) TMS coupled with a gimballed payload mount that has the possibility of being used at various distances without losing the functionality of continuous pointing back to the seeker. This paper describes the electro-mechanical design and gives an overview of the Computer and Controllers used. It further addresses the problem of coordination transformation that is needed to obtain the correct pointing.

Using Object Oriented Design (OOD) concepts in AMRDEC's Hardware-in-the Loop (HWIL) real-time simulations allows the user to interchange parts of the simulation to meet test requirements. A large-scale three-spectral band simulator connected via a high speed reflective memory ring for time-critical data transfers to PC controllers connected by non real-time Ethernet protocols is used to separate software objects from logical entities close to their respective controlled hardware. Each standalone object does its own dynamic initialization, real-time processing, and end of run processing; therefore it can be easily maintained and updated. A Resource Allocation Program (RAP) is also utilized along with a device table to allocate, organize, and document the communication protocol between the software and hardware components. A GUI display program lists all allocations and deallocations of HWIL memory and hardware resources. This interactive program is also used to clean up defunct allocations of dead processes. Three examples are presented using the OOD and RAP concepts. The first is the control of an ACUTRONICS built three-axis flight table using the same control for calibration and real-time functions. The second is the transportability of a six-degree-of-freedom (6-DOF) simulation from an Onyx residence to a Linux-PC. The third is the replacement of the 6-DOF simulation with a replay program to drive the facility with archived run data for demonstration or analysis purposes.

The space simulation chambers at the Arnold Engineering Development Center (AEDC) have performed space sensor characterization, calibration, and mission simulation testing on space-based, interceptor, and air-borne sensors for more than three decades. A continual effort to implement the latest scene simulation and projection technologies into these ground-based space sensor test chambers is necessary to properly manage the development of space defense systems. This requires the integration of high-fidelity, complex, dynamic scene projection systems that can provide the simulation of the desired target temperatures and ranges. The technologies to accomplish this include multiple-band source subsystems and special spectral tailoring methods, as well as comprehensive analysis and optical properties measurements of the components involved. Implementation of such techniques in the AEDC space sensor test facilities is discussed in this paper.

The Seeker Experimental System (SES) is the passive range within MIT Lincoln Laboratory's Optical System Test Facility (OSTF). The SES laboratory focuses on the characterization of passive infrared sensors. Capable of projecting static and dynamic scenes in both cryogenic and room temperature environments, SES supports sensors that range from tactical ground based systems through strategic space-based architectures. Optical infrared sensors are a major component of military systems, having been used to acquire, track, and discriminate between potential targets and improve our understanding of the physics and phenomenology of objects. This paper delineates the capabilities of the SES laboratory and describes how they are used to characterize infrared sensors and develop new algorithms and hardware in the support of future sensor technology. The SES Cryogenic Scene Projection System vacuum chamber has recently been upgraded to allow dynamic projection of radiometrically accurate two-color infrared imagery. Additional capabilities include the ability to combine imagery from multiple sources, NIST traceable radiometric calibration, and dynamic scene projection in an ambient environment using a combination of high speed mirrors, point source blackbodies, and resistive array based dynamic infrared scene projectors.

The Kinetic Kill Vehicle Hardware-in-the-Loop Vacuum Cold Chamber (KVACC) has been a work in progress since its initial delivery in 1995. Originally delivered as a basic cryogenic test chamber with little real world capability, it has evolved over the years to a valuable test asset incorporating many leading edge test technologies. KVACC is now the centerpiece for the cryogenic complex scene test capability within the Air Force Research Laboratory (AFRL). The purpose of this paper is to describe the capabilities of KVACC as they have evolved since its initial delivery.

The authors have worked in the past year on integration, characterization, and calibration of The Johns Hopkins University Applied Physics Laboratory's (JHU/APL's) Infrared Seeker Space Calibration and Test facility, a cryogenic-vacuum chamber designed to test infrared seekers that detect targets against low-radiance backgrounds. The facility includes target-like infrared sources with well-known and controllable radiometric attributes and well-known and controllable size, position, and motion. This paper summarizes the basic facility design, capabilities, concept of operations, current and projected uses, challenges, and lessons learned. It describes the chamber calibration and characterization activities conducted jointly by JHU/APL and the National Institute of Standards and Technology (NIST). In particular, this includes a description of the calibration and characterization methodology, modeling of the chamber optical path from the chamber target source module to the unit-under-test entrance aperture, ongoing calibration of the target source module at NIST with an absolute cryogenic radiometer, and planned end-to-end calibration of the chamber at JHU/APL using NIST's transfer radiometer and JHU/APL's field spectroradiometer.

In order to increase the fidelity of hardware-in-the-loop ground-truth testing, it is desirable to create a dynamic scene of multiple, independently controlled IR point sources. ATK-Mission Research has developed and supplied the steering mirror systems for the 7V and 10V Space Simulation Test Chambers at the Arnold Engineering Development Center (AEDC), Air Force Materiel Command (AFMC). A portion of the 10V system incorporates multiple target sources beam-combined at the focal point of a 20K cryogenic collimator. Each IR source consists of a precision blackbody with cryogenic aperture and filter wheels mounted on a cryogenic two-axis translation stage. This point source target scene is steered by a high-speed steering mirror to produce further complex motion. The scene changes dynamically in order to simulate an actual operational scene as viewed by the System Under Test (SUT) as it executes various dynamic look-direction changes during its flight to a target. Synchronization and real-time hardware-in-the-loop control is accomplished using reflective memory for each subsystem control and feedback loop. This paper focuses on the steering mirror system and the required tradeoffs of optical performance, precision, repeatability and high-speed motion as well as the complications of encoder feedback calibration and operation at 20K.

The Arnold Engineering Development Center (AEDC) has performed characterization and calibration of space-based, airborne, and interceptor sensor systems for over 35 years. The 7V and 10V Chambers provide a suite of IR and visible target systems that operate in a simulated space background (< 20K) and allow complete evaluation of sensor performance within a single test installation. Test facility upgrades are continuously pursued to keep pace with evolving sensor technologies. This paper describes the methodology used to perform calibration and characterization of sensor systems in the AEDC 7V and 10V test chambers. Complex target systems that provide the ability to evaluate system performance against representative mission scenarios are included in both test chambers. Representative results associated with the calibration and mission simulation capabilities are shown. The overall status of the 7V and 10V Chamber facilities is described, and plans to implement improved calibration capabilities are discussed. Results from analysis performed on data collected during checkout testing of source systems included in both sensor test chambers are presented. The results illustrate the ability of the 7V and 10V Chambers to facilitate complete characterization of sensor performance with a high degree of accuracy in a representative mission operating environment.

The QUick Image Display (QUID) model accurately computes and displays radiance images of aircraft and other objects, generically called targets, at animation rates while the target undergoes unrestricted flight. Animation rates are obtained without sacrificing radiometric accuracy by using two important innovations. First, QUID has been implemented using the Open Scene Graph (OSG) library, an open-source, cross-platform 3-D graphics toolkit for the development of high performance graphics applications in the fields of visual simulation, virtual reality, scientific visualization and modeling. Written entirely in standard C++ and fully encapsulating OpenGL and its extensions, OSG exploits modern graphics hardware to perform the computationally intensive calculations such as hidden surface removal, 3-D transformations, and shadow casting. Second, a novel formulation for reflective/emissive terms enables rapid and accurate calculation of per-vertex radiance. The bi-directional reflectance distribution function (BRDF) is a decomposed into separable spectral and angular functions. The spectral terms can be pre-calculated for a user specified band pass and for a set of target-observer ranges. The only BRDF calculations which must be performed during target motion involves the observer-target-source angular functions. QUID supports a variety of target geometry files and is capable of rendering scenes containing high level-of-detail targets with thousands of facets. QUID generates accurate visible to LWIR radiance maps, in-band and spectral signatures. The newest features of QUID are illustrated with radiance and apparent temperature images of threat missiles as viewed by an aircraft missile warning system.

The development and evaluation of precision strike weaponry requires high fidelity image simulation, as data collections involving moving platforms are difficult to schedule and costly to perform. Furthermore, live data collections where the weapon is being guided by an autonomous target acquisition (ATA) system cannot be performed in dense urban environments. The only solution is to develop high fidelity image and navigation simulations of realistic operating environments. We are currently developing a system that automatically generates a detailed urban scene requiring minimal user input. Given a set of parameters such as population, terrain, and city style, the system generates a two-dimensional city plan containing features such as road networks, buildings, vehicles, vegetation, and miscellaneous additional urban objects. The two-dimensional city representation is then processed by an interactive scene modeling and simulation environment that generates a textured, high-resolution, three-dimensional representation of the scene in a format compatible with well-known LADAR and IR sensor simulation suites such as IRMA. At each step in the process, the user has the ability to interact with the scene, whether to change specific scene parame-ters or to manually insert, remove, or modify targets and objects of interest.

A continuing question asked of MMW target signature and model providers is the applicability of data from one frequency band to another. Recent monopulse Ka-band ground target signature measurements made by US Army programs provide an opportunity to do an in-depth comparison of signatures of several ground vehicles. The vehicles measured correspond to those measured at W-band by another Army program. This paper provides a comparison of vehicle signatures produced by models derived by AMRDEC from the measurements. The results have implications for missile programs that do not have an extensive measurement budget but require target signatures and models for algorithm development.

High resolution millimeter wave RADAR has become a reality in today's sensor world. System development and simulation-based acquisition are increasing the demands for high fidelity environmental models. Therefore, high resolution clutter models are imperative. The RADAR ground clutter signal is most often treated as some random variable with a given probability distribution function with some mean value depending upon the particular RADAR, desired clutter properties, and relative geometry. This paper will show the results of implementing a technique to correlate adjacent clutter scatterers in the clutter model while maintaining the overall clutter statistics. This correlated clutter will be matched to a clutter class map which was derived from visual data of a specific terrain location. Processed images from a high resolution RADAR simulation will be shown and compared to the visual images and clutter maps.

The U.S. Army Research, Development and Engineering Command at Redstone Arsenal, Alabama have developed a dual mode, Ka Band Radar and IIR system for the purpose of data collection and tracker algorithm development. The system is comprised of modified MMW and IIR sensors and is mounted in a stabilized ball on a UH-1 helicopter operated by Redstone Technical Test Center. Several missile programs under development require MMW signatures of multiple target and clutter scenes. Traditionally these target signatures have been successfully collected using static radars and targets mounted on a turntable to produce models from ISAR images; clutter scenes have been homogeneously characterized using information on various classes of clutter. However, current and future radar systems require models of many targets too large for turntables, as well as high resolution 3D scattering characteristics of urban and other non-homogenous clutter scenes. In partnership with industry independent research and development (IRAD) activities the U.S. Army RDEC has developed a technique for generating 3D target and clutter models using SAR imaging in the MMW spectrum. The purpose of this presentation is to provide an overview of funded projects and resulting data products with an emphasis on MMW data reduction and analysis, especially the unique 3D modeling capabilities of the monopulse radar flying SAR profiles. Also, a discussion of lessons learned and planned improvements will be presented.

The Fast Line-of-sight Imagery for Target and Exhaust Signatures (FLITES) is an advanced scene generation program capable of producing high-fidelity synthetic signatures for Infrared (IR) applications. The signature methodology provides physically traceable solutions to compute hardbody and plume radiation. An exact approach to render pixel-accurate scenes is provided to guarantee the pixel intensities are not aliased regardless of scene size, orientation, and range between the viewer and scene object. The FLITES program architecture has been developed to provide an Application Programming Interface (API) suitable to allow direct linking to higher-level simulations. This architecture also supports distributed processing to allow the program to be executed on processor clusters. The program is written in C++ and provisions have been included to allow the important signature routines such as bi-directional reflection and plume radiance transport to be replaced with alternate, application-specific, approaches if required. FLITES principle advancement has been in the area of plume signatures from three-dimensional (3D) plume flowfields. This capability allows complex flowfields to be rendered by FLITES that include helicopter plumes, staging transients, asymmetric turbulent flowfields, and exhaust plumes from airborne objects operating at an angle-of-attack relative to the ambient air stream.

The Aviation and Missile Research, Engineering, and Development Center's (AMRDEC) System Simulation and Development Directorate (SS&DD) has an extensive history of applying all types of modeling and simulation (M&S) to weapon system development and has been a particularly strong advocate of hardware-in-the-loop (HWIL) simulation and test for many years. Key to the successful application of HWIL testing at AMRDEC has been the use of state-of-the-art Scene Projector technologies. This paper describes recent advancements over the past year within the AMRDEC Advanced Simulation Center (ASC) HWIL facilities with a specific emphasis on the state of the various IRSP technologies employed. Areas discussed include application of FMS-compatible IR projectors, advancements in hybrid and multi-spectral projectors, and characterization of existing and emerging technologies.

A Liquid Crystal on Silicon (LCoS) Spatial Light Modulator device was fabricated into an IR Scene Projector Concept Demonstrator for MWIR Hardware-in-the-loop Testing. Presently on-going in-house efforts are establishing performance benchmarks that rival many of the capabilities of the alternative, and presently the high end performance standard device, the suspended-bridge resistor array. New adaptations, like incorporating Ferro-electric Liquid Crystal (FELC) can achieve improved IR performance values breaking through the "slow" settling time limit exhibited by earlier Liquid Crystal based systems. In fact, specific parameters may even exceed some of the resistor array parameter's performance values (such as apparent thermal rise time allowing an overall faster frame rate). In addition, the relatively simple CMOS fabrication for the basic chip and ease of system "customization" allows system fabrication cost to be more on the order of the economical low end performance Digital Mirror Devices for the Infrared waveband; but still keeps the analog controlled thermal gradient in a single switch time to accommodate fast integrating sensors of modern seeker systems. Our research is using a 512x512 array originally intended for visible applications, but tailored for the MWIR operational regime. A new CMOS fabrication run to incorporate additional features and achieve further performance benefits is planned, but the existing product capability is adequate for most HIL simulation requirements. The measured performance of our in-house prototype device using FELC will be discussed.

We report here the light emission from IR interband-cascade (IC) Type-II-super lattice LED structures. The light emission is observed from bottom side through the substrate. We employed two different IC epitaxial structures for the LED experiments consisting of 9 or 18 periods of active super lattice gain regions separated by multilayer injection regions. The light output (and the voltage drop) of the LEDs is observed to increase with decrease of device operating temperature from room temperature (300 K) to liquid helium temperature (4 K). At low temperature the light emission as well as voltage drop has peak like structure with device injection currents. We observed a red shift in peak wavelength of LED emission with higher DC injection current where as blue shift due to pulsed injection current.

Microplasma arrays for solar blind ultraviolet scene generation are being investigated in a Phase II SBIR program. An overview of the project and current status is presented. Preliminary work indicates that high flux with either spectral line or broadband radiant emission is possible. Two separate design approaches are being evaluated with array formats up to 100x100 planned for testing. Spectral emission from plasmas formed by multiple gas species have been characterized and several chosen for use in arrays. Design trades between parameters such as: frame rate, # bits of resolution, input power, flux levels, and gas species will be evaluated. The performance of a future system will be estimated.

This paper presents new physical concept and Hardware-in-the-Loop Facility for simulating cold background and/or target in 3-5 μm and 8-12 μm atmospheric transparency windows. The goal for this work is the demonstration of scene projector capable of static and dynamic (>20 kHz frame rate) simulating both point and extended targets across low apparent temperature background (≥210 K in 8-12 μm band) even if a device itself is kept at T≥300 K. We show that these record parameters as well as a possibility to dynamically erase a target (low observable simulation) are easy to achieve by manipulating the below-bandgap local emissivity of initially transparent scene made of Ge or Si and exposed in front of cold screen.

A W-band target glint and background scene generator is developed for compact range hardware-in-the-loop (HWIL) seeker testing and characterization. The device comprises an Electronically Controlled Beamformer (ECB) capable of real time generation of wide variety of wavefronts in the near field of the system under test (SUT). The fine-pixelized ECB aperture with individual control of each pixel allows (in particular) formation of radar returns in a compact range by focusing and steering the (focused) Millimeter Wave (MMW) beam on the SUT aperture. Unlike compact range systems using limited number of radiators and focal plane optics, fine-pixelized ECB allows full glint simulation over SUT's field of view. ECB is compatible with currently used retransmitter and waveform simulator. We present the results of a simulation of the device's operation and compare them with the experiment. Major attention in both the simulations and the measurements was paid to the field distribution in the near-field region of the device. This work has been conducted under US Army Phase II Small Business Innovation Research (SBIR) effort, under the technical management of Mr. James A. Buford Jr., US Army Aviation & Missile Research, Development & Engineering Center (AMRDEC), Redstone Arsenal, Alabama.

We report here a novel photonic infrared scene generator based on integration of IR fiber with MEMS attenuation technologies. We employed an infrared transmission fiber image bundles with one end coupled to an IR light source and the other end for display. A robust electromagnetic actuated MEMS attenuator array is incorporated into each fiber to individually modulate the IR light intensity, forming a 2D and high grayscale scene. The design is versatile, promising to realize the desirable performance specification for IR scene generator. Using an IR lamp as the broadband light source, our scene generator covers the wavelength range from 2~14μm, and provides the sufficient IR power for the high apparent temperature. We reported here a 4×4 format array demonstration unit. This performances achieved to date include: high apparent temperature of 1700°C, high dynamic range over 40dB, high pixel isolation over 40dB, cool ambient background, and the moderate response speed of a few ms as well as continuous gray-scale without flick-ness.

Joule heated resistive emitter arrays are presently limited to pixel temperatures on the order of 1000 K. A phase 2 SBIR program is underway to develop material sets with the goal of increasing the operating temperatures of these arrays by up to a factor of 3. Preliminary work indicates that transition metal oxides and carbides are the most promising materials for 3000 K pixel temperatures. An overview of the project and current status is presented. Thin films will be deposited by numerous vendors using a variety of techniques, and annealed at ultra-high temperatures in vacuum to select the most stable materials. Test emitter pixel arrays will be fabricated and tested.

The stressed liquid-crystal (SLC) electro-optic effect promises fast electro-optic response times even for design wavelengths in the infrared (IR). Here we report characteristics of SLC devices appropriate for use as liquid-crystal-onsilicon (LCOS) spatial light modulators (SLMs) in the near ( λ = 1.8-2.5 μm), mid (3-5.5 μm) and far (8-14 μm) IR bands. For these three bands we fabricated SLC devices with 5, 10, and 20 μm thicknesses; at drive voltages of 25, 50, and 125 V respectively these devices gave half-wave modulation with response speeds in the 1.3-1.6 ms range. Visiblelight measurements on a 20-μm-thick SLC device between crossed polarizers gave a contrast ratio of 360:1 which improved to nearly 18,000:1 with a Babinet-Soleil compensator offsetting residual SLC retardance. Widely available high-voltage options in standard CMOS processes offer sufficient drive for near- and mid-IR SLCOS devices; with modest increase of SLC material birefringence Δn and dielectric anisotropy Δε far-IR devices would be feasible, too. Pixel drivers utilizing these options have pitches less than 24 μm, making 1000 ×1000 SLMs feasible.

This paper describes an electrically-tunable Fabry-Perot interferometer array and a method for scene projection. Processed on either a silicon or a silicon-on-sapphire (SOS) substrate with an integrated circuit, the array is sized with 256x256 pixels (extendable to mega pixels) and made to cover the entire ultraviolet (UV) to long wave infrared (LWIR) spectra region, especially the LWIR region. Each pixel of the array is a micro Fabry-Perot interferometer cavity, sandwiched between two parallel mirrors, whose spacing is changed by moving one of the mirrors relative to the other with a voltage applied across the cavity, tuning it to transmit a waveband with a bandwidth and a central wavelength determined by the mirror reflectivity and the cavity spacing, respectively. Thus, an array of different wavebands is electrically tuned to transmit from the array. When illuminated with a laser source, narrow bands with different intensities will be generated for projection, resulting in a high dynamic range as well as a high fidelity in the scenes generated.

Resistor array infrared projectors offer the unique potential of simultaneously covering both a wide apparent temperature range and providing fine temperature resolution at low output levels. The temperature resolution capability may not be realized, however, if the projector error sources are not controlled; for example, residual nonuniformity after nonuniformity correction (NUC) procedures have been applied, temporal noise in analog drive voltages and quantization at several points in the projection system, all of which may introduce errors larger than the desired resolution. In this paper the temperature resolution limits are assessed in general. In particular, the quantization errors are assessed and the post-NUC residual nonuniformity levels required for achievement of fine temperature resolution are calculated.

In recent hardware-in-the-loop tests conducted in a cryogenic chamber, a dual band sensor observed radiometric anomalies for extended targets. In order to understand the radiometric errors associated with the infrared projection arrays, systematic measurements were performed at both cryogenic and ambient temperatures. Air Force Research Laboratory (AFRL) engineers have previously investigated an artifact observed in these arrays called "busbar robbing," but these observations were of square blocks of emitters and did not characterize radiometric accuracy of extended targets in a dynamic engagement scenario. It was discovered that when numerous emitters in a contiguous pattern are turned on, rather than scattered over the array, the "busbar robbing" effect causes the actual emitter outputs to be different from what you measure if you drive them to the same level with fewer pixels. When the emitters that are driven have some "aspect ratio" or elongated shape, then the effect is dependent on how this pattern is aligned with the emitter axes. The results of these experiments address the radiometric error that can be expected from the resistor array projectors for end game scenarios when a target becomes extended at both ambient and cryogenic temperatures.

Dynamic infrared scene projection is a common technology used to provide end to end testing and characterization of infrared sensor systems. Scene projection technology will play an increasing role in infrared system evaluation and development as the cost and risk of flight testing increases and new display technologies begin to emerge. This paper describes a series of tests performed in the Seeker Experimental System (SES) at MIT Lincoln Laboratory (MIT LL). A small collection of 128×128 element Nuclear Optical Dynamic Display System (NODDS) resistive arrays were tested and compared using FIESTA drive electronics developed by ATK Mission Research. The residual spatial nonuniformity of the NODDS arrays were calculated after applying a sparse grid based nonuniformity correction algorithm developed at MIT LL. The nonuniformity correction algorithm is a slightly modified version of the industry standard sparse grid technique and is outlined in this paper. Additional metrics used to compare the arrays include emitter temporal response, raw nonuniformity, transfer function smoothness, dynamic range, and bad display pixel characteristics.

The nonuniformity correction (NUC) of a resistor array is typically performed with a high-grade infrared (IR) camera in the approximate waveband of a sensor under test (SUT). The array emitter outputs, and therefore the response nonuniformity, are a complicated function of the spectral band. In this paper, we study the performance obtained when measuring and NUCing the projector in one spectral band, then using the projector for testing in a different band. This is a practical necessity, since a test facility typically cannot own cameras for NUCing a projector in the wavebands of all test articles. We show that some aspects of the NUC can be reliably 'converted' or adjusted from one spectral band to another. But there are several different mechanisms that contribute to the response nonuniformity, and their dependence on the spectral band is different. We present several studies showing the results of measuring the nonuniformity in one band, and operating the projector in a different band.

Testing of two-color imaging sensors often requires precise spatial alignment, including correction of distortion in the optical paths, beyond what can be achieved mechanically. Testing, in many cases, also demands careful radiometric calibration, which may be complicated by overlap in the spectral responses of the two sensor bands. In this paper, we describe calibration procedures used at the Air Force Research Laboratory hardware-in-the-loop (HWIL) facility at Eglin AFB, and present some results of recent two-color testing in a cryo-vacuum test chamber.

SBIR has completed development of the Large Format Resistive Array (LFRA) Infrared Scene Projector (IRSP) and shipped the first production system. Nine more systems are in production and will be shipped to several US Government customers on approximately six week centers. The commercial name of the LFRA IRSP is Mirage XL. System performance meets a broad range of program requirements and SBIR has been extremely successful in producing this ground breaking projector. Tests performed on System #1 reveal broad compliance to the specification and, in particular, outstanding emitter array performance. Key emitter requirements that have been met or exceeded include Operability, Maximum Apparent Temperature, and Array Uniformity. Key System specifications are: Large-format emitter array (1024x1024); High maximum apparent temperature (>700K); 200 Hz full-frame operation; 400 Hz static window mode (1024x512); Non Uniformity (uncorrected) <10%.

This work will present a new approach to large format projection optics suitable for HWIL testing. Aspects of the design's modular approach and its ability to accommodate widely varying spectral ranges, focal lengths, zoom capabilities and the ability to deliver multi-spectral scene data are presented.

SBIR has completed design and development of prototype emitter arrays and is completing custom cryogenic vacuum device packaging and support electronics for the Optimized Arrays for Space-background Infrared Simulation (OASIS) program. The OASIS array is a 512 x 512 device featuring high output dynamic range, a selectable analog/digital scene data interface, and the capability to operate from cryogenic to ambient substrate temperatures - thereby providing an enabling technology for projection of simulated radiance of space-background scenes. Prototype emitter production has been completed at RTI International in support of initial deliveries. The OASIS array package incorporates novel electrical bussing schemes optimized for the OASIS RIIC and a modular architecture to allow user re-configuration of both window and emitter shield. The OASIS package leverages LFRA operation features, and supports both ambient and cryogenic chamber-based operation with a minimum of mechanical and electrical re-configuration. The OASIS close support electronics (CSE) supports both analog and digital input data modes, while providing easy electronic connection between arrays installed in the cryogenic chamber and the external control and scene-generation systems. We present a technical overview of the OASIS array/package and CSE designs, and will report on measured radiometric performance from prototype OASIS arrays.

The zoom anti-aliasing (ZAA) procedure used for rendering computer-generated targets at long range is examined in the light of its lack of conformality with sampling theory. This has led to the development of a GPU-based conformal version, called Schade ZAA. It is shown that Schade ZAA leads to improvement in intensity errors and significantly less scintillation when the target subtends less than a single pixel in screen space. It is shown further that the intensity errors for the normal type of irregularly-shaped target of most user interest are considerably smaller than has been previously reported. This is a significant result in that it gives confidence that the intensity of small and point source targets can be successfully conserved within the ZAA process.

Recent advances in Field-Programmable Gate Arrays (FPGAs) and innovations in firmware design have allowed more complex image processing algorithms to be implemented entirely within the FPGA devices while substantially improving performance and reducing development time. Firmware innovations include a unique memory buffer architecture and the use of floating-point math. The design discussed takes advantage of these advances and innovations to implement a geometric transformation algorithm with bilinear interpolation for applications such as distortion correction. The firmware and hardware developed in this effort support image sizes of up to 1024x1024 pixels at 200 Hz and pixel rates of 216 MHz with versions available that support oversized input images.

Commercial-Off-The-Shelf (COTS) personal computer (PC) hardware is increasingly capable of computing high dynamic range (HDR) scenes for military sensor testing at high frame rates. New electro-optical and infrared (EO/IR) scene projectors feature electrical interfaces that can accept the DVI output of these PC systems. However, military Hardware-in-the-loop (HWIL) facilities such as those at the US Army Aviation and Missile Research Development and Engineering Center (AMRDEC) utilize a sizeable inventory of existing projection systems that were designed to use the Silicon Graphics Incorporated (SGI) digital video port (DVP, also known as DVP2 or DD02) interface. To mate the new DVI-based scene generation systems to these legacy projection systems, CG² Inc., a Quantum3D Company (CG2), has developed a DVI-to-DVP converter called Delta DVP. This device takes progressive scan DVI input, converts it to digital parallel data, and combines and routes color components to derive a 16-bit wide luminance channel replicated on a DVP output interface. The HWIL Functional Area of AMRDEC has developed a suite of modular software to perform deterministic real-time, wave band-specific rendering of sensor scenes, leveraging the features of commodity graphics hardware and open source software. Together, these technologies enable sensor simulation and test facilities to integrate scene generation and projection components with diverse pedigrees.

Modern, military scene generators increasingly utilize advanced features of consumer graphics hardware to produce wave band-specific sensor scenes. Unfortunately the advances available in the consumer graphics accelerator market do not translate immediately into product applications for military scene generators required to test next generation sensors. Testing infrared (IR) sensors used in terminal homing missiles and missile warning systems (MWS) require generating frame rates of 200 Hz or more. Modern IR emitter arrays are now able to project dynamic scenes at this higher rate, however personal computer (PC) based scene rendering systems cannot generate high-resolution, real-time frames fast enough. InterSpace has leveraged its high-speed pixel processor technology to produce high-speed rendering based on PC devices. The Hardware-in-the-Loop Functional Area of the US Army Aviation and Missile Research Development and Engineering Center has developed a suite of modular software to perform deterministic real-time, wave band-specific rendering of sensor scenes, leveraging the features of commodity graphics hardware and open source software. Together, these technologies provide the performance and accuracy to drive high-rate, high-dynamic range scene projectors.

We present radiometric calibration methods and data for a HgCdTe longwave IR focal plane array camera that will be used for nonuniformity correction and calibration of an ambient-background IR scene projector at the Johns Hopkins University Applied Physics Laboratory. Reported results include spectral response, responsivity (in terms of radiance), and non-radiometric measurements important in the IRSP NUC process. Uncertainty sources and estimates are discussed as they apply to this problem. We found that a responsivity measurement should be performed each time the camera is powered on, and that drift in the output signal stabilizes within about an hour. Even after waiting an hour, it may be necessary to measure a blackbody source periodically during IRSP calibration to ensure that camera drift does not skew the results.

The Space Systems Test Facility (SSTF) at the Arnold Engineering Development Center (AEDC) has tested interceptor, airborne, and space-based infrared sensors for over 30 years. In that time, the 7V Chamber has been the primary calibration facility at AEDC. It is used to perform sensor characterization, calibration, and mission simulation testing. The 10V Chamber has been developed to perform hardware-in-the-loop sensor testing. A crucial aspect of this testing is the accurate simulation of point-source targets. The sources used must be able to simulate the range and temperature of the simulated target for realistic testing. A detailed characterization and analysis program is conducted to ensure their radiometric fidelity. The 7V Chamber has a total of six blackbody sources. Four are used as point targets, one is a flood source, and one is a standard reference source. For every chamber pumpdown, source calibrations are performed and radiometric data are taken. The data are then used to perform uncertainty analyses. A total of four blackbody sources are used in the 10V Chamber. Two of these blackbodies are used for point targets, one is a standard reference source, and the final blackbody is a spare. All four blackbodies have been tested and compared with NIST-traceable blackbodies at AEDC. The design and testing of these sources is discussed.

Results from sparse grid and flood nonuniformity correction (NUC) obtained using the DSTO Primary Infrared Scene Projection at 1:1 mapping ratio are reported. Residual nonuniformities in the 0.5-1.0% range are currently being achieved, the flood results equating to noise equivalent temperature differences in the 50-100mK range within the low drive thermal imager and FLIR simulation region. The NUC techniques and results are discussed in the light of both their present applicability and scope for further improvement.