Diffuse Reflection from a Plane Surface*

Abstract

The angular dependence of the intensity of radiation scattered from plane diffuse surfaces when these surfaces are illuminated by wideband collimated light has been investigated. The angle between the incident and scattered radiation (scatter angle) was held constant, and the surface was rotated so that the normal to the surface remained in the plane defined by this angle. For constant scatter angle, measured intensities exhibit a systematic variation from those predicted by the use of Lambert’s law of diffuse reflection. Peak deviations of the order of 10% were found in the case of an aluminum oxide pressed powder surface. An empirical expression of diffuse reflection, based on a shape factor proposed by Hill, is introduced and found to agree with the experimental data to within 2%. As the scatter angle is varied, the maximum intensity of scattered radiation observed at the specular angle shows poor agreement with that predicted by the classical Fresnel Law of reflection from a plane surface.