Statistical properties of laser speckles produced under illumination from a multimode optical fiber

Abstract

In this paper we study the statistical properties of both speckle patterns incident upon and emerging from a diffuse object under illumination of the laser light generated from a multimode optical fiber. The speckle field resulting from the modal noise at the exit face of the optical fiber is treated as a quasi-homogeneous monochromatic source that describes the quasi-stationary state within a finite region and, simultaneously, has the correlation coefficient that remains to be strictly stationary. The speckle pattern at the object plane in the Fresnel-diffraction field is first investigated by analyzing the propagation of the correlation function of the optical fields emerging from the source and found also to be quasi-homogeneous. Next, the correlation function of the optical field produced at the observation plane by scattering from a moving diffuse object under illumination of the above speckle pattern is analyzed in connection with the source parameters.