The rapid development of very-large format infrared detector arrays has challenged the IR scene projector community
to also develop larger-format infrared emitter arrays to support the testing of systems incorporating these detectors.
In addition to larger formats, many scene projector users require much higher simulated temperatures than can be
generated with current technology in order to fully evaluate the performance of their systems and associated processing
algorithms.
Under the Ultra High Temperature (UHT) development program, Santa Barbara Infrared Inc. (SBIR) is developing a
new infrared scene projector architecture capable of producing both very large format (>1024 x 1024) resistive emitter
arrays and improved emitter pixel technology capable of simulating very high apparent temperatures. During earlier
phases of the program, SBIR demonstrated materials with MWIR apparent temperatures in excess of 1400 K. New
emitter materials have subsequently been selected to produce pixels that achieve even higher apparent temperatures.
Test results from pixels fabricated using the new material set will be presented and discussed. A 'scalable' Read In
Integrated Circuit (RIIC) is also being developed under the same UHT program to drive the high temperature pixels.
This RIIC will utilize through-silicon via (TSV) and Quilt Packaging (QP) technologies to allow seamless tiling of
multiple chips to fabricate very large arrays, and thus overcome the yield limitations inherent in large-scale integrated
circuits. Results of design verification testing of the completed RIIC will be presented and discussed.
Santa Barbara Infrared (SBIR) is continually developing improved methods for non-uniformity correction (NUC) of its Infrared Scene Projectors (IRSPs) as part of its comprehensive efforts to achieve the best possible projector performance. The most recent step forward, Advanced Iterative NUC (AI-NUC), improves upon previous NUC approaches in several ways. The key to NUC performance is achieving the most accurate possible input drive-to-radiance output mapping for each emitter pixel. This requires many highly-accurate radiance measurements of emitter output, as well as sophisticated manipulation of the resulting data set. AI-NUC expands the available radiance data set to include all measurements made of emitter output at any point. In addition, it allows the user to efficiently manage that data for use in the construction of a new NUC table that is generated from an improved fit of the emitter response curve. Not only does this improve the overall NUC by offering more statistics for interpolation than previous approaches, it also simplifies the removal of erroneous data from the set so that it does not propagate into the correction tables. AI-NUC is implemented by SBIR’s IRWindows4 automated test software as part its advanced turnkey IRSP product (the Calibration Radiometry System or CRS), which incorporates all necessary measurement, calibration and NUC table generation capabilities. By employing AI-NUC on the CRS, SBIR has demonstrated the best uniformity results on resistive emitter arrays to date.
Infrared scene projectors (IRSPs) are a key part of performing dynamic testing of infrared (IR) imaging systems. Two important properties of an IRSP system are apparent temperature and thermal resolution. Infrared scene projector technology continues to progress, with several systems capable of producing high apparent temperatures currently available or under development. These systems use different emitter pixel technologies, including resistive arrays, digital micro-mirror devices (DMDs), liquid crystals and LEDs to produce dynamic infrared scenes. A common theme amongst these systems is the specification of the bit depth of the read-in integrated circuit (RIIC) or projector engine , as opposed to specifying the desired thermal resolution as a function of radiance (or apparent temperature). For IRSPs, producing an accurate simulation of a realistic scene or scenario may require simulating radiance values that range over multiple orders of magnitude. Under these conditions, the necessary resolution or “step size” at low temperature values may be much smaller than what is acceptable at very high temperature values. A single bit depth value specified at the RIIC, especially when combined with variable transfer functions between commanded input and radiance output, may not offer the best representation of a customer’s desired radiance resolution. In this paper, we discuss some of the various factors that affect thermal resolution of a scene projector system, and propose some specification guidelines regarding thermal resolution to help better define the real needs of an IR scene projector system.
The rapid development of very-large format infrared detector arrays has challenged the IR scene projector community to develop correspondingly larger-format infrared emitter arrays to support the testing needs of systems incorporating these detectors. As with most integrated circuits, fabrication yields for the read-in integrated circuit (RIIC) that drives the emitter pixel array are expected to drop dramatically with increasing size, making monolithic RIICs larger than the current 1024x1024 format impractical and unaffordable. Additionally, many scene projector users require much higher simulated temperatures than current technology can generate to fully evaluate the performance of their systems and associated processing algorithms. Under the Ultra High Temperature (UHT) development program, Santa Barbara Infrared Inc. (SBIR) is developing a new infrared scene projector architecture capable of producing both very large format (>1024x1024) resistive emitter arrays and improved emitter pixel technology capable of simulating very high apparent temperatures. During an earlier phase of the program, SBIR demonstrated materials with MWIR apparent temperatures in excess of 1000K. New emitter materials have subsequently been selected to produce pixels that achieve even higher apparent temperatures. Test results from pixels fabricated using the new material set will be presented and discussed. Also in development under the same UHT program is a 'scalable' RIIC that will be used to drive the high temperature pixels. This RIIC will utilize through-silicon vias (TSVs) and quilt packaging (QP) technologies to allow seamless tiling of multiple chips to fabricate very large arrays, and thus overcome the inherent yield limitations of very-large-scale integrated circuits. Current status of the RIIC development effort will also be presented.
High pixel temperatures for IR scene projector arrays face materials challenges of oxidation, diffusion, and recrystallization. For cost effective development of new high-temperature materials, we have designed and fabricated simplified pixels for testing. These consist of resistive elements, traces, and bond pads sandwiched between dielectric layers on Si wafers. Processing involves a pad exposure etch, a pixel outline etch, and an undercut etch to thermally isolate the resistive element from the substrate. Test pixels were successfully fabricated by electron-beam lithography using a combination of wet and dry etching.
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