Advocating a statistical definition for the BRDF

Pierre Chavel (1) , Yvan R. P. Sortais (2) , Thomas Labardens (1, 3) , Lionel Simonot (4) , M Hébert (1) , Gaël Obein (3)

1 LHC - Laboratoire Hubert Curien
2 Laboratoire Charles Fabry / Photonique Industrielle
3 LCM - Laboratoire commun de métrologie LNE-CNAM
4 PPNa - Physique et Propriétés des Nanostructures [Institut Pprime]

Abstract The definition of BRDF as a ratio of radiance to irradiance assumes that the geometrical optics framework applies, implicitly meaning that spatial coherence and diffraction of light have no significant effect in the reflection process. However, recent applications of BRDF push at increasing the angular resolution and thus at reducing the solid angles for illumination and collection. Therefore speckle, an optical effect inherent to the stochastic nature of scattering objects, becomes apparent. We suggest that BRDF should be redefined as the statistical average over that effect.

Domaines: Optique / photonique

Pierre Chavel, Yvan R. P. Sortais, Thomas Labardens, Lionel Simonot, M Hébert, et al.. Advocating a statistical definition for the BRDF. Journal of Physics: Conference Series, 2022, 2149 (1), pp.012013. ⟨10.1088/1742-6596/2149/1/012013⟩. ⟨hal-03620283v2⟩