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Proceedings Paper

Evaluation Of Spectral Hemispherical Reflection Measurements In The Infrared And Their Application To Rough Surfaces
Author(s): K Gindele; M Kohl; M Mast
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Paper Abstract

Measurements of the near-normal/hemispherical reflectance in the infrared spectral range can be taken by using integrating spheres as photometric integrators. In the infrared region, where the reflectance of the sphere coating significantly differs from one, the specular component of the reflected flux causes problems due to the different weighting of the specularly and diffusely reflected part by the sphere wall. An evaluation method for circumventing these difficulties is presented. It is shown that the influence of the sample indicatrix can be eliminated with a good accurracy if the specular reflectance factor is known. The considerations are based on investigations in the spectral range from 1 μm to 15 μm performed with a Fourierspectrometer and a gold coated integrating sphere. Examples demonstrate the application of this method for the investigation of samples whose specular reflectance factors change with wavelength. That especially occurs if the selective properties of solar absorber coatings is caused by surface roughness. The described method can be applied to estimate the surface roughness parameters and to characterize the optical properties of selective solar absorber layers.

Paper Details

Date Published: 24 September 1986
PDF: 7 pages
Proc. SPIE 0653, Optical Materials Technology for Energy Efficiency and Solar Energy Conversion V, (24 September 1986); doi: 10.1117/12.938339
Show Author Affiliations
K Gindele, University of Stuttgart (Germany)
M Kohl, University of Stuttgart (Germany)
M Mast, University of Stuttgart (Germany)


Published in SPIE Proceedings Vol. 0653:
Optical Materials Technology for Energy Efficiency and Solar Energy Conversion V
Claes-Goeran Granqvist; Carl M. Lampert; John J. Mason; Volker Wittwer, Editor(s)

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