This paper describes a new approach for the control of microbolometer detector array uniformity as a function of substrate temperature change. This approach, called the bias equalization method, uses an electronic means of controlling the microbolometer array uniformity. For this method a three stage non-uniformity correction algorithm is employed. The first stage corrects for substrate temperature non-uniformity effects on the microbolometer detector elements followed by traditional offset and gain non-uniformity correction stages. To correct for substrate temperature non-uniformity effects, bias equalization coefficients are supplied to the readout integrated circuit (ROIC) to allow the control of a unique operating bias or temperature delta for each microbolometer detector element in the array. The bias equalization method circuitry allows microbolometer array non-uniformity control over a wider range of ROIC substrate temperatures while maintaining better than 8OmK NEdT using f/i .8 optics. This approach is expected to allow removal of the thermoelectric cooler from uncooled systems, thus making it ideally suited for high-volume, low-cost, low-power, and low-weight production applications.
The partnership between RVS, Seek Thermal and Freescale Semiconductor continues on the path to bring the latest technology and innovation to both military and commercial customers. The partnership has matured the 17µm pixel for volume production on the Thermal Weapon Sight (TWS) program in efforts to bring advanced production capability to produce a low cost, high performance product. The partnership has developed the 12µm pixel and has demonstrated performance across a family of detector sizes ranging from formats as small as 206 x 156 to full high definition formats. Detector pixel sensitivities have been achieved using the RVS double level advanced pixel structure. Transition of the packaging of microbolometers from a traditional die level package to a wafer level package (WLP) in a high volume commercial environment is complete. Innovations in wafer fabrication techniques have been incorporated into this product line to assist in the high yield required for volume production. The WLP seal yield is currently > 95%. Simulated package vacuum lives >> 20 years have been demonstrated through accelerated life testing where the package has been shown to have no degradation after 2,500 hours at 150°C. Additionally the rugged assembly has shown no degradation after mechanical shock and vibration and thermal shock testing. The transition to production effort was successfully completed in 2014 and the WLP design has been integrated into multiple new production products including the TWS and the innovative Seek Thermal commercial product that interfaces directly to an iPhone or android device.
This paper describes a standardized high performance 640 by 512 readout integrated circuit [ROIC] for p-on-n detectors such as InSb, Heterojunction HgCdTe, QWIP, and InGaAs. The array is intended to support a wide range of systems through flexibility and advanced modes of operation. The 1SC9803 uses a flexible, programmable, multistage pipelined architecture to achieve a state-of-the-art ROIC suitable for applications ranging from hand-held infrared viewers to high-speed industrial imaging systems. A simplified default mode directly supports single output NTSC or PAL operation. Using the programmable mode, the 1SC9803 supports such advanced features as dynamic image transposition, dynamic windowing, multiple high-speed multiple output configurations, and signal 'skimming'. Both default and programmed modes support integrate-while-read and integrate-then-read snapshot operation, and variable gain. This array is part of the Indigo Systems family of standard ROICs that use a common architecture and electrical interface.
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