Spectral Emissivity & Emittance

San Diego CA, USA –Surface Optics’ ET10 measures emissivity values in two most commonly used spectral regions, 3 to 5 and 8 to 12 microns.

Its main application is to produce emissivity values for the infrared cameras.

Advanced IR cameras require the input of an emissivity value for accurate temperature calculations. The emissivity values obtained from tables can be far from real leading to large temperature uncertainties.

The ET10 can be used in the lab or in the field and on small or large objects. With the ET10 one can measure emissivity of any surface in just a few seconds.

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Noninvasive Polymer Reaction Monitoring by Infrared Emission Spectroscopy with Multivariate Statistical Modeling
Randy J. Pell, James B. Callis, and Bruce R. Kowalski
Applied Spectroscopy, Vol. 45, Issue 5, pp. 808-818 (1991)

Abstract

“Infrared absorption and emission spectroscopy have been used to monitor the curing of a commercial paint product. Principal component analysis of the absorption data indicates that three factors are needed to explain the observed spectral/temporal variance. The interpretation of this finding in terms of changes in the physical state of the reaction mixture is discussed. A similar analysis of the emission data proved more difficult due to a nonlinear concentration/response relationship. A linearization step based on an approximate theoretical model is suggested. The absorption, linearized emittance, and raw emittance data are fit to a two-step sequential rate model using multivariate nonlinear optimization and error estimates derived by Monte Carlo calculations. Better agreement of the model parameters between the absorbance and emittance data is found after linearization, but it is found that linearization introduces large errors in the nonlinear parameter estimates. Comparisons of model parameters for the raw emittance data at different temperatures are made.”

Citation
R. J. Pell, J. B. Callis, and B. R. Kowalski, “Noninvasive Polymer Reaction Monitoring by Infrared Emission Spectroscopy with Multivariate Statistical Modeling,” Appl. Spectrosc. 45, 808-818 (1991)

The Raytek North America website includes a table for the emissivity of a large range of non-metallic materials that includes common building materials, ceramics, glasses and natural materials including ice & water in as many as four wavelength regions.

Wavebands covered include 1.0 micrometer (micron), 5.0 microns, 7.9 microns and the 8-14 micron band. No specific data and the limits of the various wavebands and there are many instances where the wavelength region is labelled as “nr” meaning “Not Recommended”.

Infrared Theory Notes-(Last updated 04/11/04, PDF Download of 547kb - 43 pages) contains not only some simple explanations of the key features of Radiation Thermometry, how it works and how IR Thermometers work in various measurement situations, but also provides some unique graphical representations of the transmission of glasses (see pages 30-33).

It also discusses thin plastics. In the latter case, see pages 34-36 for unique emissivity data and curves versus material type and thickness at 3.43 micrometers (microns) and explanations of an alternate choice waveband region at 7.9 microns.