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Proceedings Paper

Comparison of emissivity evaluation methods for infrared sources
Author(s): Stephen D. Scopatz; Jason A. Mazzetta; John E. Sgheiza; Miguel A. Medina
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Paper Abstract

This paper starts with a back to basics review of the definition of blackbody emissivity, how it is measured and how it is specified. Infrared source vendors provide emissivity specifications for their blackbodies and source plates, but there is fine print associated with their declarations. While there is an industry agreement concerning the definition of emissivity, the data sheets for blackbodies and source plates are not consistent in how they base their claims. Generally, there are two types of emissivity specifications published in data sheets; one based on design properties of the source and thermometric calibration, and another based on an equivalent radiometric calibrated emissivity. The paper details how the source properties including geometry, surface treatment, and coatings are characterized and result in an emissivity value by design. The other approach is that the emissivity can be claimed to be essentially 100% when measured directly with a radiometer. An argument is derived to show that as the optical parameters of the unit under test and the radiometer diverge, the less useful an equivalent radiometric emissivity claim is. Also discussed, is under what test conditions the absolute emissivity does not matter. Further suggestions on how to achieve the clearest comparative emissivity specifications are presented.

Paper Details

Date Published: 22 April 2009
PDF: 11 pages
Proc. SPIE 7300, Infrared Imaging Systems: Design, Analysis, Modeling, and Testing XX, 73000Q (22 April 2009); doi: 10.1117/12.818217
Show Author Affiliations
Stephen D. Scopatz, Electro Optical Industries, Inc. (United States)
Jason A. Mazzetta, Electro Optical Industries, Inc. (United States)
John E. Sgheiza, Electro Optical Industries, Inc. (United States)
Miguel A. Medina, Electro Optical Industries, Inc. (United States)


Published in SPIE Proceedings Vol. 7300:
Infrared Imaging Systems: Design, Analysis, Modeling, and Testing XX
Gerald C. Holst, Editor(s)

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