Laser Speckle from Thin and Cascaded Diffusers
Abstract
The scattering of laser light from a single diffuser and from a cascade of two diffusers is analyzed with particular emphasis on remote sensing. It is shown that diffuser surface properties and the spacing between diffuser planes can be determined remotely by measuring the angular distribution of the radiation pattern or the decorrelation of the far-zone speckle pattern with respect to changes in the wavelength or the angle of incidence of an input plane wave. A general expression is derived for the two-state correlation function of far-zone complex amplitude from a cascade of two diffusers, where the two states are the initial and final values of the wavelength, angle of incidence, angle of observation, and spacing. This function is then related to the two-state correlation function of intensity, which is a measure of the correlation between the initial and final speckle patterns. The two-state correlation function of intensity is evaluated for various double diffuser combinations. The effect of surface height profiles on the radiation pattern is studied. Of particular interest are strong diffusers that have a normally distributed height profile and whose surface height autocorrelation functions are paraboloidal or conical for small spatial offsets. Excellent agreement is obtained between theoretical radiation patterns calculated with conical and paraboloidal autocorrelation functions and experimental radiation patterns measured from ground-glass and acid-etched diffusers, respectively. Keywords: Laser speckle, Double diffusers, Plane-wave probing, Wavelength decorrelation, Remote sensing, Transmission functions, Radiation patterns, Rough surface scattering, and Ground glass.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1988
- Accession Number
- ADA197066
Entities
People
- Lyle G. Shirley
Organizations
- University of Rochester