Zehnder, Alan T. and Guduru, Pradeep R. and Rosakis, Ares J. and Ravichandran, G. (2000) Million frames per second infrared imaging system. Review of Scientific Instruments, 71 (10). pp. 3762-3768. ISSN 0034-6748. http://resolver.caltech.edu/CaltechAUTHORS:ZEHrsi00
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An infrared imaging system has been developed for measuring the temperature increase during the dynamic deformation of materials. The system consists of an 8×8 HgCdTe focal plane array, each with its own preamplifier. Outputs from the 64 detector/preamplifiers are digitized using a row-parallel scheme. In this approach, all 64 signals are simultaneously acquired and held using a bank of track and hold amplifiers. An array of eight 8:1 multiplexers then routes the signals to eight 10 MHz digitizers, acquiring data from each row of detectors in parallel. The maximum rate is one million frames per second. A fully reflective lens system was developed, consisting of two Schwarszchild objectives operating at infinite conjugation ratio. The ratio of the focal lengths of the objectives determines the lens magnification. The system has been used to image the distribution of temperature rise near the tip of a notch in a high strength steel sample (C-300) subjected to impact loading by a drop weight testing machine. The results show temperature rises at the crack tip up to around 70 K. Localization of temperature, and hence, of deformation into "U" shaped zones emanating from the notch tip is clearly seen, as is the onset of crack propagation.
|Additional Information:||©2000 American Institute of Physics. (Received 5 May 2000; accepted 14 June 2000) This work was performed at Caltech with support from the National Science Foundation, through Grant No. CTS-9512517, the Department of Energy, Grant No. DE-FG03-95-ER14560, and the Office of Naval Research, Grant No. N00014-95-1-0453. The design and most of the fabrication of this system were performed while the first author was a sabbatic visitor to Caltech in the 1996–97 academic year. The authors would like to thank Fermionics Inc. for custom building the IR detector array and Gage Applied Sciences for a substantial discount on the digitizing system.|
|Subject Keywords:||infrared imaging; crack detection; analogue-digital conversion; data acquisition; impact testing; stainless steel; focal planes; infrared detectors; mercury compounds; cadmium compounds; II-VI semiconductors|
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|Deposited On:||11 Aug 2006|
|Last Modified:||29 Sep 2016 23:33|
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