title: Coherence theory of a laser beam passing through a moving diffuser.
abstract: We present the general coherence theory for laser beams passing through a moving diffuser. The temporal coherence of laser beams passing through a moving diffuser depends on two characteristic temporal scales: the laser coherence time and the mean time it takes the diffuser to move past a phase correlation area. In most applications, the former is much shorter than the latter. Our theoretical analysis shows the spatial coherence area of light scattered from a moving diffuser decreases while the coherence time remains unchanged. The conclusion has been confirmed by experiments using a Michelson interferometer and it is not in accordance with the original coherence theory in which both the temporal and spatial coherence of light scattered by a moving diffuser decrease. We also developed a method based on the theory of eigenvalues to calculate the speckle contrast on a screen illuminated by light transmitted through a moving diffuser.
authors.affiliation: Key Laboratory of OptoElectronic Science and Technology for Medicine Ministry of Education, Fujian Normal University, Fuzhou 350007, China.
authors.forename: Gaoming
authors.initials: G
authors.lastname: Li
authors.forename: Yishen
authors.initials: Y
authors.lastname: Qiu
authors.forename: Hui
authors.initials: H
authors.lastname: Li