Scattered fields dimensionality analysis
using spatial speckle correlometry
D.A. Zimnyakov
Department of Physics, Saratov State University, Russia,
Blagonravov Mechanical Engineering Institute (Russian Academy of Sciences)
Study of the coherent and incoherent light scattering by fractal structures is now one of the major directions in the field of statistical and correlation optics. Significant interest to this problem was stimulated by classical works of M. Berry, E. Jakeman and others [1,2]. Analysis of the statistical and correlation characteristics of speckle patterns in near and far diffraction zones allows to evaluate the generalized parameters of the fractal-like scatterers illuminated by coherent beams. Method for characterization of two-dimensional fractal structures using the analysis of asymptotic behavior of speckle intensity fluctuations structure function is proposed; two types of 2D-scatterers are taken into consideration: with only amplitude transmittance and with only phase one ("pure amplitude" and "pure phase" objects, respectively). "Fractality" of such objects is manifested in asymptotic behavior of structure functions of the transmittance coefficient and boundary field amplitude distributions (see, e. g. [2]). For the discussed case formation of the scattered field has been described in terms of scalar diffraction theory; relationships between parameters of structure functions of the boundary field amplitude and far-zone intensity fluctuations have been obtained for different observation and illumination conditions. Experimental results obtained for different types of fractal-like scatterers (such as surfaces of specially prepared rough glass plates, random amplitude screens with fractal distributions of local apertures, cellular structures and biotissues) are presented.
Discussed method of the correlation analysis of speckle intensity fluctuations can be proposed as monitoring technique for 2D-scattering structures with fractal properties.