Comparison of the relative merits of the midwave and longwave infrared bands for various target types using detected thermal contrast

Seán M. Stewart

Research output: Chapter in Book/Report/Conference proceedingConference contribution


The two most important atmospheric transmission bands in the infrared occur at the midwave band of 3-5 μm and the longwave band of 8-12 μm respectively. For a given infrared detector a common question asked is, of the two, which, if any, gives the better performance? A question not without controversy, in this study an analysis designed to assess the relative merits of infrared detectors operating in either of these spectral bands based on the recently defined thermal figure of merit known as the detected thermal contrast is undertaken. Under ideal limiting conditions, by considering a range of targets whose spectral emissivities vary as a function of both wavelength and temperature, we impugn a number of results previously reported in the literature regarding the performance of a detector made using detected thermal contrast as the thermal figure of merit. For the two broad types of detectors considered it is found the midwave band for both thermal and quantum detectors gives better performance for a range of different target types.

Original languageEnglish
Title of host publicationTarget and Background Signatures
EditorsKarin U. Stein, Ric H. M. A. Schleijpen
ISBN (Electronic)9781628418637
Publication statusPublished - Jan 1 2015
EventTarget and Background Signatures - Toulouse, France
Duration: Sep 23 2015Sep 24 2015

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X


OtherTarget and Background Signatures


  • detectors
  • emissivity
  • infrared
  • polylogarithms
  • spectral band comparison
  • thermal contrast

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering

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