Spatial and Spectral Behavior of Speckle in an Imaging System

Citation

Melville, Richard Devern Samuels (1975) Spatial and Spectral Behavior of Speckle in an Imaging System. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/2KP8-CT79. https://resolver.caltech.edu/CaltechETD:etd-02182005-111421

Abstract

When coherent illumination is reflected from or transmitted through a medium which causes random phase changes in the illumination, a random interference pattern termed speckle results. We have studied speckle in an imaging system and have described and measured the effect of polarization of the illumination, the first order statistics of speckle intensity, and the autocorrelation of speckle intensity as a function of space and wavelength variables. We have measured the relationship between the amount of depolarization of a plane polarized input in transmission through opal glass diffusers of various thicknesses and the effect of this phenomenon on the first and second order statistics of speckle intensity. A relationship between diffuser thickness and the probability density function for speckle intensities has been calculated and measured. The autocorrelation of speckle intensities has been calculated and measured as a function of both the spatial dimension of the speckle pattern and the wavelength of the illumination. We find that the spatial behavior of the autocorrelation depends upon the limiting aperture of the optical system, while the wavelength dependence is a function of the roughness of the diffuser and is only very slightly influenced by the imaging system.

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