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Short Wave Infrared (SWIR) Test Capabilities for Imaging Sensors


OBJECTIVE: Develop a compact, rugged infrared image projector to provide high dynamic range target, stellar, and background simulation in the near and shortwave infrared bands. DESCRIPTION: Near Infrared (NIR) and Short Wave Infrared (SWIR) sensors (0.75 - 3.0 microns) are becoming increasing prevalent for military applications; however, the test technology for imaging SWIR sensors is lagging behind the development of the sensor capability. The ability to perform in-band replication of complex target and background phenomenology is essential for development of weapon systems. Laboratory testing allows debugging of interfaces and embedded software, and identification of system limitations in a controlled, repeatable environment prior to flight testing. For longer wavelength phenomenology, where lower temperature emissive sources are predominant, resistive array projection technologies exist that provide continuous dynamic control and continuous output. The same cannot be said for SWIR, although some capabilities do exist; for example, image projectors based on digital mirror arrays are capable of providing high fidelity SWIR scene data under the constraint of tight temporal synchronization and resolution that is inversely related to integration time. Innovative solutions are desired that provide flexibility for test facilities: continuous analog control of pixel output, adaptive source intensity for optimal grayscale range, potential integration into multi-waveband test systems, and simulation of active illumination sources. New high-power SWIR Vertical-Cavity Surface-Emitting laser (VCSEL) sources are now available for projector illumination and VCSEL array technology has advanced considerably during the last decade. Other technologies have also shown promise, e.g., light emitting diode arrays and liquid crystal arrays. Solutions are desired that can achieve formats greater than 1024x1024 and can adaptively apply their dynamic range to resolve both night-time starlit scenarios and daytime scenarios with solar illumination. Solutions should be compatible with lightweight, flight table compatible SWIR projector configurations. The potential for integration of Long Wave IR, Mid Wave IR and semi-active laser designator/pointer targets into the optical path should be taken into consideration. Potential applications include a range of possible field-of-views, from a few degrees for a terminal homing sensor to extreme wide field-of-view multi-aperture sensors intended for optical flow navigation. The target test environment will require non-uniformity correction and absolute calibration at all output levels. Address calibration, non-uniformity correction, wide field of view, and scene generation aspects for the projector system. PHASE I: Design a SWIR image projector concept for weapon and staring stellar inertial sensor testing. Establish the dynamic range requirements, spectral features and other operational consideration for the sources, modulators, and optics to provide a spectrally accurate output to support camouflage, foliage, and man-made target detection. PHASE II: Integrate and demonstrate component technologies, interfaces, and software necessary to demonstrate a prototype projection system. Demonstrate calibration, non-uniformity correction and stability before and after representative test cases involving adaptive source intensity. PHASE III: Develop and transition full up SWIR sensor-seeker and stellar inertial sensor calibration and test systems for use in government and defense industry hardware-in-the-loop applications. REFERENCES: 1. J. Geske, C. Wang, et al.,"High power VCSELs for miniature optical sensors,"Proc. SPIE 7615, 76150E (2010), DOI:10.1117/12.847184. 2. J. R. Lippert, H. Wei, et al.,"Record breaking high-apparent temperature capability of LCoS-based infrared scene projectors,"Proc. SPIE 7663, 76630S (2010), DOI:10.1117/12.850184. 3. R. L. Murrer, R. A. Thompson, and C. F. Coker, Developments at the Kinetic Kill Vehicle Hardware-in-the-Loop Simulator (KHILS) facility Proc. SPIE 3697, 31 (1999), DOI:10.1117/12.352921.
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