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Proceedings Paper

Evaluation And Control Of The Optical And Thermal Properties Of Low-Emissivity Coatings
Author(s): Joachim Szczyrbowski; Anton Dietrich
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Paper Abstract

The optical and thermal characteristics of silver based interference type low-emissivity coatings for architectural applications are evaluated using basic theoretical thin film relations. It is concluded that in order to characterize the films it is sufficient to measure the sheet resistivity and the light transmission of either the partial layer system glass/oxide/Ag or even the complete layer stack glass/oxide/Ag/oxide in the visible and near infrared region. For our investigation a layer system, consisting of glass/Sn02/Ag/Sn02, was used. The transmission T measured in the visible and near infrared region can be described by the relation 1/T = S/w2 + CT, where the slope S is a known function of the plasma frequency and of the thickness d of the silver layer. The dependence of S on both the optical constants and the thickness of the used oxide films is very weak and may be neglected. Thus, from the measured value of S the thickness of the silver .Layer can be obtained immediately. It is further shown that the so-called normal emissivity en of the considered film is given by en = 4*εo*c*Rm, thus, it is completely given by the measured sheet resistivity. The aesthetic appearance of the coated substrates is defined mainly by the thickness of the oxide films. Finally, it is shown how these investigations can be used in a continuous on-line quality control of the layer properties on large scale production machines.

Paper Details

Date Published: 6 March 1989
PDF: 7 pages
Proc. SPIE 1016, Optical Materials Technology for Energy Efficiency and Solar Energy Conversion VII, (6 March 1989); doi: 10.1117/12.949930
Show Author Affiliations
Joachim Szczyrbowski, Leybold AG (W-Germany)
Anton Dietrich, Leybold AG (W-Germany)

Published in SPIE Proceedings Vol. 1016:
Optical Materials Technology for Energy Efficiency and Solar Energy Conversion VII
Claes-Goeran Granqvist; Carl M. Lampert, Editor(s)

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