Hostile fire indication (HFI) systems require high-resolution sensor operation at extremely high speeds to capture hostile
fire events, including rocket-propelled grenades, anti-aircraft artillery, heavy machine guns, anti-tank guided missiles
and small arms. HFI must also be conducted in a waveband with large available signal and low background clutter, in
particular the mid-wavelength infrared (MWIR). The shortcoming of current HFI sensors in the MWIR is the bandwidth
of the sensor is not sufficient to achieve the required frame rate at the high sensor resolution. Furthermore, current HFI
sensors require cryogenic cooling that contributes to size, weight, and power (SWAP) in aircraft-mounted applications
where these factors are at a premium. Based on its uncooled photomechanical infrared imaging technology, Agiltron has
developed a low-SWAP, high-speed MWIR HFI sensor that breaks the bandwidth bottleneck typical of current infrared
sensors. This accomplishment is made possible by using a commercial-off-the-shelf, high-performance visible imager as
the readout integrated circuit and physically separating this visible imager from the MWIR-optimized photomechanical
sensor chip. With this approach, we have achieved high-resolution operation of our MWIR HFI sensor at 1000 fps,
which is unprecedented for an uncooled infrared sensor. We have field tested our MWIR HFI sensor for detecting all
hostile fire events mentioned above at several test ranges under a wide range of environmental conditions. The field
testing results will be presented.
Employing an optical readout architecture expands the capabilities offered by uncooled thermal imagers, such as
extremely fast frame rates, dual-band imaging, and multi-megapixel resolution. It also affords the ability to incorporate
multiple pixel designs on the same infrared sensor chip, which we have taken advantage of to fabricate an optical
readout photomechanical imager with 12 distinct pixel designs in the sensor chip layout. Using this methodology, we
were able to quickly sort the designs in terms of performance and suitability for manufacturing, and thus, in an expedient
and highly cost-effective manner, determine which pixel designs have merited future consideration for full-scale
prototyping. A fast frame rate MWIR photomechanical imager based on one of the best pixel designs was built and
tested for high-speed imaging of small arms fire.
In an optical-readout photomechanical imager, the infrared sensor array is physically separated from the ROIC. The
modularity of the optical readout architecture allows for extra design freedom that is not possible in bolometers, negating
fundamental trade-offs, such as NETD versus thermal time constant. For successful commercialization, the
photomechanical imager must meet application-specific performance and functional targets, and to this end, Agiltron has
advanced the photomechanical imaging platform over several technology generations. Improvements have been made to
both the optical readout system and the photomechanical sensor chip, which enabled reductions in size, weight, and
power (SWAP) and NETD over successive generations. The current-generation photomechanical imager has the size
equivalent to a digital camera and an /1-equivalent NETD and MDTD of less than 100 mK.
Agiltron has produced a 280x240 photomechanical sensor array with an optical readout incorporating visible light
cameras for both MWIR and LWIR imaging at speeds up to 1,000 frames per second. The photomechanical sensor is
essentially a transducer that converts the image-induced temperature change into a mechanical deflection actuated by a
micro-cantilevered beam. This defection is measured by an optical readout and converted into an electronic image. The
photomechanical sensor requires no external drive for operation and therefore creates no bottleneck for readout data rate.
It operates uncooled at widely varying ambient temperature. The use of off-the-shelf high speed visible light sensors
allows for high frame rate imaging with no need for custom electronics or ROIC. Results on detection of rapid
occurrence events, such as gunfire and rocket travel, are reported. The influence of detector sensitivity and time constant
on the experimental imaging is discussed. Analysis of the frequency response of the photomechanical sensor is presented.
Applications of the Voltage ImagingTM technique in testing active arrays used in AMLCDs have been widely discussed. Voltage ImagingTM is well known for its simplicity in interfacing with active array panels, and its superior voltage measurement accuracy and repeatability. It is also known for having broad test applicability for many AMLCD panel design technologies, such as TFT, MIM, diode and panels with integrated drivers. This paper briefly discusses a recent improvement related to the application of Voltage ImagingTM for L-contact panel testing. As the panel manufacturers are trying to reduce the manufacturing cost, the number of panels on one substrate also increases which, in several cases, leaves only enough room to add ESD protection shorting rings on two of the four sides of a panel. Since this is the trend of the industry, a methodology that can be employed to test L-contact panels with Voltage ImagingTM is presented in this paper.
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