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Proceedings Paper

Spectral and temperature-dependent infrared emissivity measurements of painted metals for improved temperature estimation during laser damage testing
Author(s): Sean M. Baumann; Cameron Keenan; Michael A. Marciniak; Glen P. Perram
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Paper Abstract

A database of spectral and temperature-dependent emissivities was created for painted Al-alloy laser-damage-testing targets for the purpose of improving the uncertainty to which temperature on the front and back target surfaces may be estimated during laser-damage testing. Previous temperature estimates had been made by fitting an assumed gray-body radiance curve to the calibrated spectral radiance data collected from the back surface using a Telops Imaging Fourier Transform Spectrometer (IFTS). In this work, temperature-dependent spectral emissivity measurements of the samples were made from room temperature to 500 °C using a Surface Optics Corp. SOC-100 Hemispherical Directional Reflectometer (HDR) with Nicolet FTS. Of particular interest was a high-temperature matte-black enamel paint used to coat the rear surfaces of the Al-alloy samples. The paint had been assumed to have a spectrally flat and temperatureinvariant emissivity. However, the data collected using the HDR showed both spectral variation and temperature dependence. The uncertainty in back-surface temperature estimation during laser-damage testing made using the measured emissivities was improved from greater than +10 °C to less than +5 °C for IFTS pixels away from the laser burn-through hole, where temperatures never exceeded those used in the SOC-100 HDR measurements. At beam center, where temperatures exceeded those used in the SOC-100 HDR, uncertainty in temperature estimates grew beyond those made assuming gray-body emissivity. Accurate temperature estimations during laser-damage testing are useful in informing a predictive model for future high-energy-laser weapon applications.

Paper Details

Date Published: 31 October 2014
PDF: 12 pages
Proc. SPIE 9237, Laser-Induced Damage in Optical Materials: 2014, 923713 (31 October 2014); doi: 10.1117/12.2068435
Show Author Affiliations
Sean M. Baumann, Air Force Institute of Technology (United States)
National Air and Space Intelligence Ctr. (United States)
Cameron Keenan, Air Force Institute of Technology (United States)
Michael A. Marciniak, Air Force Institute of Technology (United States)
Glen P. Perram, Air Force Institute of Technology (United States)

Published in SPIE Proceedings Vol. 9237:
Laser-Induced Damage in Optical Materials: 2014
Gregory J. Exarhos; Vitaly E. Gruzdev; Joseph A. Menapace; Detlev Ristau; MJ Soileau; Detlev Ristau, Editor(s)

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