An ellipsoidal radiometer, under development by Nils-Erik Gunners in close cooperation with the SP Swedish National Testing and Research Institute, has been characterized using, a 25 mm variable-temperature blackbodv as a radiant source. This radiometer is intended for separating radiation from convection effects in fire test method. The characterization included annular response, responsivity, and purge-gas flow effect studies. The angular response measurements showed that the reflection from the radiometer cavity was higher on one of the cavity halves relative to the other half. Further development work may be necessary to improve the angular response. The responsivity measured with reference to a transfer-standard electrical-substitution radiometer showed dependence on the distance of the radiometer from the blackbody cavity. The purge-gas had the effect of reducing the signal output nearly linearly with flow rate.
, Wetterlund, I.
and DeWitt, D.
Characterization of an Ellipsoidal Radiometer, Journal of Research (NIST JRES), National Institute of Standards and Technology, Gaithersburg, MD
(Accessed December 10, 2023)