Abutted IRLED infrared scene projector design and their characterization
Date
2019
Authors
Journal Title
Journal ISSN
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Publisher
University of Delaware
Abstract
Hardware in the Loop (HITL) test and evaluation of advanced infrared aware systems requires the ability to stimulate infrared sensors under test with synthetic IR imagery via real-time IR scene projection. An IRSP must be capable of displaying realistic scenes at required refresh rates with sufficient resolution, dynamic range, pixel response times, and accurate radiant intensity output to properly stimulate the unit under test (UUT). Historically, HITL testing has relied on IRSPs that utilize resistor array emitter technology to project IR imagery to the UUT. However, resistor array based IRSPs are constrained in radiant intensity output and spatial resolution due to material composition and fabrication limitations. These restrictions leave resistor arrays incapable of projecting high resolution high temperature IR imagery needed to adequately test next generation sensors and seekers. Advancements in IR seeker and sensor resolution, sensitivity, and _eld of view are exceeding IR scene projection capabilities. Analogous advancements in IRSP performance are needed for HITL testing of advanced IR sensors and seekers. In particular, a suitable IRSP must provide the capability to project at least 1k by 1k pixel imagery with maximum temperatures up to 3000K at 400Hz or greater with 16 bits of control for the emitted light intensity. Also, IRSPs must operate in a scientifically accurate manner. ☐ Recent developments in alternative IR emitter technology may satisfy requirements to test next generation IR sensors and seekers. In particular, IR LED emitter technology has shown promise in emulating IR scenes that will meet future test requirements. These emitters have demonstrated the capability to present Mid-Wave IR imagery with high temperature emission in a 512 by 512 pixel format using 48m pixel pitch technology. Although the IR LED emitters have demonstrated the ability to emulate high temperature IR scene elements, they have not yet demonstrated the ability to support higher resolutions. ☐ Novel techniques are required to increase spatial resolution of advanced emitter arrays. There are two factors that limit the scaling of emitter array spatial resolution: cost, and wafer size. The current state-of-the-art 512 by 512 system is constructed out of a one inch by one inch CMOS die and a one inch by one inch GaSb wafer that contains the IR LEDs. Die sizes this large lead to a high number of defects during fabrication, increasing the cost to produce a single IRSP emitter array greatly. GaSb wafers are not generally available beyond 4 inches. To solve these two processing limitations and provide a path forward for higher spatial resolution emitter arrays an abutted hybrid solution is proposed for this dissertation. The abutted hybrid solution includes a novel CMOS Read-In-Integrated-Circuit (RIIC) design that supports the post-processing required for abutment, the post-processing steps, and the packaging required to support the new architecture. Higher spatial resolution emitter arrays also require more inputs to maintain frame rates. ☐ To address the need for uniform, accurate, and precise inputs to the emitters novel characterization measurements and instrumentations were designed and implemented. These instrumentations include a novel circuit for measuring settling time of analog signals created by Digital-to-Analog converters and other sources. They also include an experimental setup that repurposed circuitry inside of the RIIC to enable the accurate measurement of IRSP system pixel rise time.
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Keywords
Analog circuit design, IRLED, Metrology, IR sensors, Hardware in the Loop, Read-In-Integrated-Circuit