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Proceedings Paper

Measurement Of The Radiometric Properties Of Materials For Building And Aerospace Applications
Author(s): F. J. J. Clarke
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Paper Abstract

Energy gains and losses from the surfaces of buildings, industrial process equipment, radomes and space vehicles, are examples of an area of predictive technology which is becoming increasingly important. Energy gains are predicted using the solar-integrated transmittance and absorptance of the surfaces involved. NPL uses measurements of the spectral hemispherical transmittance and reflectance over the wavelength range 0.3 μm to 2.1 μm to compute the solar transmittance and solar absorptance as part of its existing calibration services. In order to predict energy losses it is necessary to know the spectrally-integrated hemispherical or directional emissivity, and to cope with temperatures from -20°C to + 400°C the wavelength range which needs to be covered is 2.5 to 60 μm. By Kirchhoff's Law, the emissivity under stated conditions is equal to the absorptance calculated from the reflectance and transmittance under corresponding conditions. Because direct measurement of spectral emissivity is impracticable for calibration work at low temperatures, NPL has designed an infrared absolute reflectance/transmittance facility to measure spectral hemispherical/directional radiance factors over an adequate spectral range for a variety of angles of emission. The principles of this design and technique are discussed and illustrated.

Paper Details

Date Published: 18 November 1980
PDF: 8 pages
Proc. SPIE 0234, New Developments and Applications in Optical Radiation Measurement, (18 November 1980); doi: 10.1117/12.958944
Show Author Affiliations
F. J. J. Clarke, National Physical Laboratory (United Kingdom)

Published in SPIE Proceedings Vol. 0234:
New Developments and Applications in Optical Radiation Measurement
A. J. Allnutt, Editor(s)

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