Abstract

Following a study by Leger and Perrin in 1975, we have derived a general expression for the correlation of two speckle patterns produced by illuminating a randomly rough surface at two angles and observing at two arbitrary angles. The expression is valid only for single scattering surfaces. Measurements of the angular correlation for particular angles of illumination and viewing broadly confirm the theory. This provides a method of estimating the surface roughness by a non-contact means for singly scattering surfaces. Of more interest to us are surfaces that exhibit multiple scattering: in this case, there is no simple theory and measurements show that the angular correlation is quite different from the single-scattering case.

© 1992 Optical Society of America