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Proceedings Paper

Minimum resolvable temperature difference measurements on undersampled imagers
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Paper Abstract

Minimum Resolvable Temperature Difference (MRTD) is the primary measurement of performance for infrared imaging systems. Where Modulation Transfer Function (MTF) is a measurement of resolution and three-dimensional noise (or noise equivalent temperature difference) is a measurement of sensitivity, MRTD combines both measurements into a test of observer visual acuity through the imager. MRTD has been incorrectly applied to undersampled thermal imagers as a means for assessing the overall performance of the imager. The incorrect application of the MRTD (or just MRT) test to undersampled imagers includes testing to the half-sample (or Nyquist rate) of the sensor and calling the MRT unresolvable beyond this frequency. This approach is known to give poor predictions in overall system performance. Also, measurements at frequencies below the half-sample rate are strongly dependent on the phase between the sampling geometry and the four-bar target. The result is that very little information in the MRT measurement of an undersampled thermal imager is useful. There are a number of alternatives including Dynamic MRT (DMRT), Minimum Temperature Difference Perceived (MTDP), Triangle Orientation Discrimination (TOD), and objective MRT tests. The NVESD approach is to measure the MTF and system noise and to use these measurements in the MRT calculation to give good sensor performance predictions. This paper describes the problems with MRT for undersampled imagers, describes the alternative measurements, and presents the NVESD approach to MRT measurements.

Paper Details

Date Published: 22 August 2003
PDF: 11 pages
Proc. SPIE 5076, Infrared Imaging Systems: Design, Analysis, Modeling, and Testing XIV, (22 August 2003); doi: 10.1117/12.487065
Show Author Affiliations
Ronald G. Driggers, U.S. Army Research Lab. (United States)
Van A. Hodgkin, U. S. Army Night Vision and Electronic Sensors Directorate (United States)
Richard H. Vollmerhausen, U. S. Army Night Vision and Electronic Sensors Directorate (United States)
Patrick O'Shea, U. S. Army Night Vision and Electronic Sensors Directorate (United States)


Published in SPIE Proceedings Vol. 5076:
Infrared Imaging Systems: Design, Analysis, Modeling, and Testing XIV
Gerald C. Holst, Editor(s)

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