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Proceedings Paper

Optical properties of monolithic and granular SiO2-aerogels
Author(s): A. Beck; J. Linsmeier; W. Koerner; H. Scheller; Jochen Fricke
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Paper Abstract

The optical and thermal properties of aerogels play an important role for their application in transparent insulation (TI) or daylighting systems. In this paper the directional-directional transmission tdd as well as the directional-hemispherical transmission tdh are presented for 20 mm thick aerogel specimens. For optimized monolithic aerogels we obtained solar averaged values of -tdh,sol equals (91 +/- 1/4)% and -tdh,vis equals (84 +/- 2)% in the solar and visible spectral region, respectively. The investigated granular aerogels show a visual transmission of -tdh,vis equals (58 +/- 4)% for waterglass as a precursor and of -tdh,vis equals (78 +/- 4)% for tetramethoxysilane. In order to correlate the structural build-up of the SiO2-network of the aerogels with their light scattering properties angular-dependent light and X-ray scattering measurements are performed. To characterize the visual image transmission the modulation transfer function (MTF) was measured for 20 mm thick monolithic layers. In order to explain the measured data a Monte Carlo based simulation model was developed. The analysis yields that the MTF is mainly effected by surface scattering.

Paper Details

Date Published: 9 September 1994
PDF: 12 pages
Proc. SPIE 2255, Optical Materials Technology for Energy Efficiency and Solar Energy Conversion XIII, (9 September 1994); doi: 10.1117/12.185404
Show Author Affiliations
A. Beck, Univ. Wuerzburg (Germany)
J. Linsmeier, Univ. Wuerzburg (Germany)
W. Koerner, Univ. Wuerzburg (Germany)
H. Scheller, Univ. Wuerzburg (Germany)
Jochen Fricke, Univ. Wuerzburg (Germany)

Published in SPIE Proceedings Vol. 2255:
Optical Materials Technology for Energy Efficiency and Solar Energy Conversion XIII
Volker Wittwer; Claes G. Granqvist; Carl M. Lampert, Editor(s)

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