Laser speckles produced by a diffuse object under illumination from a multimode optical fiber: an experimental study.

The size and displacement of speckles produced by a diffuse object under illumination from a multimode optical fiber are investigated experimentally to confirm the theory presented in a previous paper [J. Opt. Soc. Am. A 2, 1282 (1985)]. The experimental results show good agreement with the theory. It is verified that the mean size of speckles at the exit face of the fiber can be determined from measurements of the mean size of speckles at the observation plane. Furthermore, it is particularly emphasized that the speckle displacement is given by a relation, which is simpler than the conventional method where a Gaussian laser beam is used for the illumination.