Abstract
Measurements of total hemispherical emittance of selected Irtran filters are reported for the temperature range 45°K to 312°K. Values obtained for 1-mm thick specimens are 0.38, 0.23, and 0.15 for Irtran 2, 4, and 6, respectively, at 312°K; 0.49 for Irtran 2 at 75°K and 0.35 and 0.43 for Irtran 4 and 6 at 45°K. All three specimens have emittance maxima of approximately 0.5 at intermediate temperatures. Thicker specimens have somewhat greater values. Total normal emissivity calculated from spectral normal emissivity data for Irtran 2 and 4 agree well with the experimental results. Specific heat measurements of the Irtran specimens for the same temperature range are also reported.
© 1968 Optical Society of America
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