Hemispherical radiometer for angle resolved measurement of IR scatter and radiation behaviour

Abstract

For certain applications the angular distribution of IR radiation from materials and surfaces could be interesting. Various cases have to be taken into account, such as passive scattering, active radiation from material at a given temperature or the response to a thermal excitation. In further development of a full hemispherical scatterometrical device based on an elliptical mirror, an angular resolved IR radiometer has been developed. In contradiction to traditional goniometer designes the set-up allows to measure a hemispherical radiation distribution without moving parts. One application could be the fast acquisition of large amounts of BRDF data in IR range to be compiled into libraries. The use of imaging sensors reduces the measurement time, therefore even time dependence could be addressed. The paper deals with the instrument design, the calibration, and gives some measurement results.