Investigation of the directional emissivity of materials using infrared thermography coupled with a periodic excitation

International audience; This article concerns the determination of the directional emissivity of materials. Several materials (conducting materials or dielectrics) are investigated and the influence of surface roughness is also considered. The experimental method used for the determination is based on the use of a periodic excitation and the recording of the surface temperature variations of the sample using infrared thermography. Several consecutive measurements are performed for emission angles varying from 0° (for the determinat ion of normal emissivity) to 85°. The experimental device developed (SPIDER instrument) is simple compared to existing devices but the variation of directional emissivity is limited to the spectral bandwith of the camera used.