Open AccessCoherence theory of a laser beam passing through a moving diffuser
Author(s) -
Gaoming Li,
Yishen Qiu,
Hui Li
Publication year - 2013
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.21.013032
Subject(s) - optics , coherence (philosophical gambling strategy) , speckle pattern , physics , coherence time , michelson interferometer , diffuser (optics) , coherence theory , interferometry , laser , degree of coherence , coherence length , light beam , beam (structure) , light source , superconductivity , quantum mechanics
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.