James R. Kircher

Innovations in IR projector arrays

In the past year, Honeywell has developed a 512 X 512 snapshot scene projector containing pixels with very high radiance efficiency. The array can operate in both snapshot and raster mode. The array pixels have near black body characteristics, high radiance outputs, broad band performance, and high speed. IR measurements and performance of these pixels will be described. In addition, a vacuum probe station that makes it possible to select the best die for packaging and delivery based on wafer level radiance screening, has been developed and is in operation. This system, as well as other improvements, will be described. Finally, a review of the status of the present projectors and plans for future arrays is included.

Development of IR-emitting infrared fibers at the Naval Research Laboratory

Naval Research Laboratory (NRL) has been developing high brightness mid-wave IR emitting fibers for HWIL testing. These fibers, based upon rare-earth doped chalcogenide glass, emit from 3.5 - 5 m and are capable of simulating very high temperatures in this band. To date, temperatures of 2400 K have been simulated. The fiber sources operate at room temperature, are environmentally tolerant, and can be formed into fiber bundles with high fill factors and low pixel to pixel cross- talk for IR scene generation. In this paper, we will present the spectral output, temporal response, temperature simulation and output uniformity of the mid-wave IR emitting fibers. The potential for long-wave IR emitting fiber sources will also be presented.

Resolution and dynamic range capabilities of dynamic infrared scene projection systems

It is shown that commercial-off-the-shelf (COTS) renderers can be used for covering the simultaneous fine temperature resolution and large dynamic range specifications associated with the demands of medium-wave infrared scene projection applications. Appropriate use of the RGB capabilities of the COTS renderer combined with redistribution of the binary scene data by using a nonlinear transformation enables the dual specifications for 0.1 degree Celsius small signal temperature resolution and > 400 degree Celsius range in simulated temperature difference to be simultaneously met.

Measurement of the wideband infrared scene projector (WISP) radiometric and thermal resolution

The third generation of the Wide-band Infrared Scene Projector (WISP) resistor arrays has been delivered to the Air Force Research Laboratorys Kinetic Kill Vehicle Hardware-in-the-Loop Simulation facility. A critical parameter in determining the extent with which the thermal arrays simulate the real world is the radiometric and thermal resolution. The measurement of the resolution is dependent upon several factors including the input data word resolution, drive electronics resolution, system noise factors, and the measurement sensor. Several measurements were made to quantify the noise components of the WISP array and the measurement sensor to determine the limiting factor for the measurements. Due to the nonlinear transfer function between the command voltage and the projected radiance, measurements were made at several input levels to determine how the resolution varies as a function of command voltage level. Measurements were performed both with and without the spatial non-uniformity correction (NUC) applied to determine the impact of the NUC on the radiometric resolution. Based on the results of these measurements the resolution of the WISP arrays is defined in both radiometric and thermal units.

Characterization of the multiwavelength Scophony infrared scene projector

A Scophony Infrared Scene Projector (IRSP) was developed for use in evaluating thermal- imaging guidance systems. The IRSP is a very high frame rate, laser scanned projection system incorporating Scophony modulation. The Scophony IRSP serves as the image projection system in the Kinetic Kill Vehicle Hardware in the Loop Simulator (KHILS) terminal guidance simulation. It is capable of projecting multiband target engagement scenarios with high fidelity using Auras proprietary software/electronic control system. The Scophony IRSP utilizes acousto-optical (AO) devices to produce the required imagery at separate wavelengths, simultaneously. The separate scenes are combined and projected into the imaging guidance system. The Scophony IRSP has been installed and integrated into the KHILS facility at Eglin Air Force Base, Florida. Some performance characteristics of the IRSP have been measured. The current presentation provides a brief description of the Scophony IRSP and a performance evaluation. The performance characteristics measured are spot size, dynamic range, and field of view. Further characteristics may be reported as they become available.

Development of a two-color projection system for the KHILS Vacuum Cold Chamber (KVACC)

The KHILS Vacuum Cold Chamber (KVACC) was developed to provide the capability of performing hardware-in-the-loop testing of infrared seekers requiring scenes involving cold backgrounds. Being able to project cold backgrounds enables the projector to simulate high-altitude exoatmospheric engagements. Previous tests with the KVACC projection system have used only one resistive-array projection device. In order to realistically stimulate a 2-color seeker, it is necessary to project in two, independently controlled IR bands. Missile interceptors commonly use two or more colors; thus, a 2-color projection capability has been developed for the KVACC system. The 2- color projection capability is being accomplished by optically combining two Phase 3 WISP arrays with a dichroic beam combiner. Both WISP arrays are cooled to user-selected temperatures ranging from ambient temperature to below 150 K. In order to test the projection system, a special-purpose camera has also been developed. The camera is designed to operate inside the vacuum chamber. It has a cooled, all- reflective broadband optical system to enable the measurement of low radiance levels in the 3 - 12 micrometer spectrum. Camera upgrades later this year will allow measurements in two independent wavebands. Both the camera and the projector will be described in this paper.

Radiometric, noise, and spatial characterization of the wideband infrared scene projector

The Wideband Infrared Scene Projector (WISP) has been undergoing development for the AF Research Laboratory Kinetic Kill Vehicle Hardware-in-the-loop Simulator facility (KHILS) at Eglin AFB, FL. Numerous characterization measurements defining array dynamic range, spectral output, temporal response and nonuniformity have been performed and reported on in the past. This paper addresses the measurements and analyses performed to characterize the radiometric, spatial, and temporal noise errors induced by the array on a unit under test (UUT). An Amber camera was used as the UUT. The Amber camera spectral, spatial and radiometric response characteristics were measured. The camera spatial and temporal noises were measured by observing an extended blackbody. Similar measurements were then made on the WISP/UUT system by projecting uniform scenes. The WISP spatial and radiometric responses and the WISP-induced spatial and temporal noise were determined from the measurements. Although the measurements are unique to the UUT adopted, the WISP contribution to the system noise-equivalent temperature difference (NEDT) was determined. The spatial noise measurements provided data for validating a spatial noise model described in a companion paper. The measurements and models are useful for analyzing future measurements and predicting the impact of WISP on various test articles.

Integration and calibration of the steerable laser projector with the wideband infrared scene projector

Kinetic Energy Weapon (KEW) programs under the Ballistic Missile Defense Office (BMDO) need high fidelity infrared (IR) seekers. As imaging sensors have matured to support BMDO, the complexity of functions assigned to the KEW weapon systems has magnified the necessity for robust hardware-in- the-loop (HWIL) simulation facilities to reduce program risk. The IR projector, an integral component of a HWIL simulation, must reproduce the real world with enough fidelity that the unit-under-test algorithms respond to the projected images as though it were viewing the real world. For test scenarios involving unresolved objects, IR projector arrays have limitations which constrain testing accuracy. These arrays have limited dynamic range, spatial resolution, and spatial bandwidth for unresolved targets, decoys, and debris. The Steerable Laser Projector (SLP) will allow the HWIL simulation facility to address these testing issues. The Kinetic Kill Vehicle Hardware-in-the-loop Simulation (KHILS) facility located at Eglin AFB, FL is now in the process of integrating a projector array with the SLP. This new projector combines the capabilities of both projector technologies to provide KHILS with a unique asset that addresses many of the challenges that are required to support testing of state-of-the-art IR guided weapons.

Laser scophony infrared scene project

A scophony infrared scene projector (IRSP) was developed by AURA Systems Inc. for use in evaluating thermal imaging guidance systems. The IRSP is a laser-scanned projector system incorporating scophony modulation with acousto-optical (AO) devices to produce multiband 96 x 96 image frames. A description of the system and preliminary test results with the Seeker Endo/Exo Demonstration Development (SEEDD) breadboard interceptor are addressed.

Radiometric calibration procedures for a wideband infrared scene projector (WISP)

The Wideband Infrared Scene Projector (WISP) has been undergoing development for the Kinetic-Kill Vehicle Hardware-in-the-Loop Simulator facility at Eglin AFB, Florida. In order to perform realistic tests of an infrared seeker, the radiometric output of the WISP system must produce the same response in the seeker as the real scene. In order to ensure this radiometric realism, calibration procedures must be established and followed. This paper describes calibration procedures that have been used in recent tests. The procedures require knowledge of the camera spectral response in the seeker under test. The camera is set up to operate over the desired range of observable radiances. The camera is then nonuniformity corrected (NUCed) and calibrated with an extended blackbody. The camera drift rates are characterized, and as necessary, the camera is reNUCed and recalibrated. The camera is then set up to observe the WISP system, and calibration measurements are made of the camera/WISP system.